Evaluation of biological activity and prebiotic properties of proanthocyanidins with different degrees of polymerization through simulated digestion and in vitro fermentation by human fecal microbiota

The bioactive activity of proanthocyanidins (PAs) is closely associated with their degree of polymerization (DP), however, the effects of PAs with different DP on digestion and gut microbiota have remained unclear. To investigate this, we conducted in vitro simulated digestion and colonic fermentation studies on samples of PAs with different DP. The results showed that PAs was influenced by both protein precipitation and enzymolysis, resulting in a decrease in functional activity. PAs with a high DP were more sensitive to the gastrointestinal environment. The significant clustering trend in colonic fermentation verified the reliability of multivariate statistical techniques for screening samples with distinct functional differences. The gut microbiota analysis showed that oligomeric PAs had a stronger promoting effect on beneficial bacteria, while high polymeric PAs had a greater inhibitory effect on harmful bacteria. This study offers new insights into the biological activity and microbiological mechanisms of PAs with different DP.

Co-assembled whey protein and proanthocyanidins as a promising biocarrier for hydrophobic pterostilbene: Fabrication, characterization, and cellular antioxidant potential

The usage of food-derived polyphenols with different polarities has been limited by their instability and incompatibility. Therefore, a biocarrier was developed by co-assembly of whey protein isolate (WPI) and hydrophilic proanthocyanidin (PC) for loading hydrophobic pterostilbene (PTE). Such biocarrier has superior affinity for PTE than WPI alone, as determined by encapsulation efficiency and loading capacity assay, fluorescence quenching analysis, and molecular docking, whereas the assembly process was characterized by particle size and zeta potential, 3-dimensional fluorescence, and scanning electron microscopy. Circular dichroism and Fourier transform infrared spectroscopy spectra confirmed the α-helix to β-sheet and random coil transition of proteins during the formation of nanocomplexes. Whey protein isolate acted as a mediator through altering the binding mode of PC and PTE, allowing them to perform significant synergistic effects in enhancing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging and reducing H2O2-induced cell damage. This research may serve to develop new protein/polyphenol co-loading systems and offer a reliable nutritional fortification.

Senolytic and senomorphic agent procyanidin C1 alleviates structural and functional decline in the aged retina

Increased cellular senescence burden contributes in part to age-related organ dysfunction and pathologies. In our study, using mouse models of natural aging, we observed structural and functional decline in the aged retina, which was accompanied by the accumulation of senescent cells and senescence-associated secretory phenotype factors. We further validated the senolytic and senomorphic properties of procyanidin C1 (PCC1) both in vitro and in vivo, the long-term treatment of which ameliorated age-related retinal impairment. Through high-throughput single-cell RNA sequencing (scRNA-seq), we comprehensively characterized the retinal landscape after PCC1 administration and deciphered the molecular basis underlying the senescence burden increment and elimination. By exploring the scRNA-seq database of age-related retinal disorders, we revealed the role of cellular senescence and the therapeutic potential of PCC1 in these pathologies. Overall, these results indicate the therapeutic effects of PCC1 on the aged retina and its potential use for treating age-related retinal disorders.

Proanthocyanidins and Phenolic Compounds from the Twigs of Salix chaenomeloides and Their Anti-Lipogenic Effects on 3T3-L1 Preadipocytes

The present study investigated potential bioactive natural products from the EtOH extract of Salix chaenomeloides twigs using column chromatography, leading to the isolation of six compounds (1-6), which were characterized as two proanthocyanidins, procyanidin B2 (1) and procyanidin B1 (2), and four phenolic compounds, 4-hydroxybenzoic acid β-D-glucosyl ester (3), di-O-methylcrenatin (4), p-coumaric acid glucoside (5), and syringin (6) by the comparison of their NMR spectra with the reported data and high-resolution (HR)-electrospray ionization mass spectroscopy (ESI-MS) analysis. We investigated the potential of six compounds (1-6) to inhibit adipogenesis in 3T3-L1 preadipocytes, which showed that the compounds (1-6) significantly reduced lipid accumulation in 3T3-L1 adipocytes without affecting cell proliferation. Notably, compound 1 demonstrated a remarkable 60% and 90% reduction in lipid levels with 50 and 100 µM treatments, respectively. Oil Red O staining results indicated that compound 1 significantly inhibits the formation of lipid droplets, comparable to the effect of T863, an inhibitor of triglyceride used as a positive control, in adipocytes. Compound 1 had no effect on the regulators PPARγ, C/EBPα, and SREBF1 of adipocyte differentiation in 3T3-L1 preadipocytes, but compound 1 activated the fatty acid oxidation regulator, PPARα, compared to the lipogenic-induced control. It also suppressed fatty acid synthesis by downregulating the expression of fatty acid synthase (FAS). Finally, compound 1 induced the mRNA and protein levels of CPT1A, an initial marker of mitochondrial fatty acid oxidation in 3T3-L1. This finding substantiates the anti-lipogenic and lipolytic effects of procyanidin B2 (1) in 3T3-L1 preadipocytes, emphasizing its pivotal role in modulating obesity-related markers.

Visible-light photoactivated proanthocyanidin and kappa-carrageenan coating with anti-adhesive properties against clinically relevant bacteria

The increase of bacterial resistance to antibiotics is a growing concern worldwide and the search for new therapies could cost billions of dollars and countless lives. Inert surfaces are major sources of contamination due to easier adhesion and formation of bacterial biofilms, hindering the disinfection process. Therefore, the objective of this study was to develop a photoactivatable and anti-adhesive kappa-carrageenan coating using proanthocyanidin as a photosensitizer. The complete reduction (>5-log10 CFU/cm3) of culturable cells of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa pathogens was achieved after 30 min of exposure to visible light (420 nm; 30 mW/cm2) with 5 % (w/v) of the photosensitizer. Cell membrane damage was confirmed by measuring potassium leakage, epifluorescence microscopy and bacterial motility analysis. Overall, visible light irradiation on coated solid surfaces mediated by proanthocyanidin showed no cytotoxicity and inactivated clinically important pathogens through the generation of reactive oxygen species, inhibiting bacterial initial adhesion. The developed coating is a promising alternative for a wide range of applications related to surface disinfection and food biopreservation.

Concentration-dependent dual roles of proanthocyanidins on oxidative stress and docosahexaenoic acid production in Schizochytrium sp. ATCC 20888

Antioxidant addition is an effective strategy to achieve docosahexaenoic acid (DHA) overproduction in oleaginous microorganisms. Nevertheless, antioxidants like phenolic compounds sometimes exert pro-oxidant activity. In this work, effects of proanthocyanidins (PAs) on fermentation performance and oxidative stress in Schizochytrium sp. were investigated. Low PAs addition (5 mg/L) reduced reactive oxygen species and enhanced lipogenic enzymes activities and NADPH, resulting in significant increase in lipid (20.3 g/L) by 33.6 % and DHA yield (9.8 g/L) by 53.4 %. In contrast, high PAs addition (500 mg/L) exerted pro-oxidant effects, aggravated oxidative damage and lipid peroxidation, leading to sharp decrease in biomass (21.3 g/L) by 35.1 %, lipid (8.2 g/L) by 46.0 %, and DHA (2.9 g/L) by 54.8 %. Therefore, the antioxidant concentration is especially crucial in DHA production. This study is the first to report concentration-dependant dual roles of PAs in oxidative stress and DHA production in Schizochytrium sp., providing new insights into microbial DHA production.

Cacao Procyanidins-Induced Lifespan Extension in Caenorhabditis elegans in a Nervous System and CaMKII-Dependent Manner

Procyanidins are gaining attention due to their potential health benefits. We found that cacao liquor procyanidin (CLPr) from Theobroma cacao seeds increased the lifespan of Caenorhabditis elegans, a representative model organism for aging studies. The genetic dependence of the lifespan-extending effect of CLPr was consistent with that of blueberry procyanidin, which is dependent on unc-43, osr-1, sek-1, and mev-1, but not on daf-16, sir-2.1, or skn-1. The lifespan-extending effect of CLPr was inhibited by neuron-specific RNA interference (RNAi) targeting unc-43 and pmk-1, and in worms with loss-of-function mutations in the odr-3, odr-1, or tax-4 genes, which are essential in sensory neurons, including AWC neurons. It was also inhibited in worms in which AWC neurons or AIB interneurons had been eliminated, and in worms with loss-of-function mutations in eat-4 or glr-1, which are responsible for glutamatergic synaptic transmission. These results suggest that the lifespan-extending effect of CLPr is dependent on the nervous system. In addition, it also requires unc-43 and pmk-1 expression in nonneuronal cells, as demonstrated by the experiments with RNAi in wild-type worms, the neuronal cells of which are not affected by systemic RNAi. The osr-1 gene is expressed in hypodermal and intestinal cells and regulates the response to osmotic stress along with unc-43/calcium/calmodulin-dependent protein kinase II and the p38 mitogen-activated protein kinase pathway. Consistent with this, CLPr improved osmotic stress tolerance in an unc-43- and pmk-1-dependent manner, and it was also dependent on AWC neurons. The lifespan-extending and osmotic-tolerance-improving activities were attributed to procyanidins with a tetrameric or higher-order oligomeric structure.

Injective Programmable Proanthocyanidin-Coordinated Zinc-Based Composite Hydrogel for Infected Bone Repair

Effectively integrating infection control and osteogenesis to promote infected bone repair is challenging. Herein, injective programmable proanthocyanidin (PC)-coordinated zinc-based composite hydrogels (ipPZCHs) are developed by compositing antimicrobial and antioxidant PC-coordinated zinc oxide (ZnO) microspheres with thioether-grafted sodium alginate (TSA), followed by calcium chloride (CaCl2 ) crosslinking. Responsive to the high endogenous reactive oxygen species (ROS) microenvironment in infected bone defects, the hydrophilicity of TSA can be significantly improved, to trigger the disintegration of ipPZCHs and the fast release of PC-coordinated ZnOs. This together with the easily dissociable PC-Zn2+ coordination induced fast release of antimicrobial zinc (Zn2+ ) with/without silver (Ag+ ) ions from PC-coordinated ZnOs (for Zn2+ , > 100 times that of pure ZnO) guarantees the strong antimicrobial activity of ipPZCHs. The exogenous ROS generated by ZnO and silver nanoparticles during the antimicrobial process further speeds up the disintegration of ipPZCHs, augmenting the antimicrobial efficacy. At the same time, ROS-responsive degradation/disintegration of ipPZCHs vacates space for bone ingrowth. The concurrently released strong antioxidant PC scavenges excess ROS thus enhances the immunomodulatory (in promoting the anti-inflammatory phenotype (M2) polarization of macrophages) and osteoinductive properties of Zn2+ , thus the infected bone repair is effectively promoted via the aforementioned programmable and self-adaptive processes.

Experiment and molecular dynamics simulations reveal proanthocyanidin B2 and B3 can inhibit prion aggregation by different mechanisms

Prion diseases are a group of fatal neurodegenerative diseases caused by the misfolding and aggregation of prion protein (PrP), and the inhibition of PrP aggregation is one of the most effective therapeutic strategies. Proanthocyanidin B2 (PB2) and B3 (PB3), the effective natural antioxidants have been evaluated for the inhibition of amyloid-related protein aggregation. Since PrP has similar aggregation mechanism with other amyloid-related proteins, will PB2 and PB3 affect the aggregation of PrP? In this paper, experimental and molecular dynamics (MD) simulation methods were combined to investigate the influence of PB2 and PB3 on PrP aggregation. Thioflavin T assays showed PB2 and PB3 could inhibit PrP aggregation in a concentrate-dependent manner in vitro. To understand the underlying mechanism, we performed 400 ns all-atom MD simulations. The results suggested PB2 could stabilize the α2 C-terminus and the hydrophobic core of protein by stabilizing two important salt bridges R156-E196 and R156-D202, and consequently made global structure of protein more stable. Surprisingly, PB3 could not stabilize PrP, which may inhibit PrP aggregation through a different mechanism. Since dimerization is the first step of aggregation, will PB3 inhibit PrP aggregation by inhibiting the dimerization? To verify our assumption, we then explored the effect of PB3 on protein dimerization by performing 800 ns MD simulations. The results suggested PB3 could reduce the residue contacts and hydrogen bonds between two monomers, preventing dimerization process of PrP. The possible inhibition mechanism of PB2 and PB3 on PrP aggregation could provide useful information for drug development against prion diseases.Communicated by Ramaswamy H. Sarma.

Phytochemical analysis and anthelmintic activity of Combretum mucronatum leaf extract against infective larvae of soil-transmitted helminths including ruminant gastrointestinal nematodes

BACKGROUND

Soil-transmitted helminths (STH) infect more than a quarter of the world's human population. In the absence of vaccines for most animal and human gastrointestinal nematodes (GIN), treatment of infections primarily relies on anthelmintic drugs, while resistance is a growing threat. Therefore, there is a need to find alternatives to current anthelmintic drugs, especially those with novel modes of action. The present work aimed to study the composition and anthelmintic activity of Combretum mucronatum leaf extract (CMLE) by phytochemical analysis and larval migration inhibition assays, respectively.

METHODS

Combretum mucronatum leaves were defatted with petroleum ether and the residue was extracted by ethanol/water (1/1) followed by freeze-drying. The proanthocyanidins and flavonoids were characterized by thin layer chromatography (TLC) and ultra-high performance liquid chromatography (UPLC). To evaluate the inhibitory activity of this extract, larval migration assays with STH and GIN were performed. For this purpose, infective larvae of the helminths were, if necessary, exsheathed (Ancylostoma caninum, GIN) and incubated with different concentrations of CMLE.

RESULTS

CMLE was found to be rich in flavonoids and proanthocyanidins; catechin and epicatechin were therefore quantified for standardization of the extract. Data indicate that CMLE had a significant effect on larval migration. The effect was dose-dependent and higher concentrations (1000 µg/mL) exerted significantly higher larvicidal effect (P < 0.001) compared with the negative control (1% dimethyl sulfoxide, DMSO) and lower concentrations (≤ 100 µg/ml). Infective larvae of Ascaris suum [half-maximal inhibitory concentration (IC50) = 5.5 µg/mL], Trichuris suis (IC50 = 7.4 µg/mL), and A. caninum (IC50 = 18.9 µg/mL) were more sensitive to CMLE than that of Toxocara canis (IC50 = 310.0 µg/mL), while infective larvae of Toxocara cati were largely unaffected (IC50 > 1000 µg/mL). Likewise, CMLE was active against most infective larvae of soil-transmitted ruminant GIN, except for Cooperia punctata. Trichostrongylus colubriformis was most sensitive to CMLE (IC50 = 2.1 µg/mL) followed by Cooperia oncophora (IC50 = 27.6 µg/mL), Ostertagia ostertagi (IC50 = 48.5 µg/mL), Trichostrongylus axei (IC50 = 54.7 µg/mL), Haemonchus contortus (IC50 = 145.6 µg/mL), and Cooperia curticei (IC50 = 156.6 µg/mL).

CONCLUSIONS

These results indicate that CMLE exhibits promising anthelmintic properties against infective larvae of a large variety of soil-transmitted nematodes.

Novel l-Cysteine Incomplete Degradation Method for Preparation of Procyanidin B2-3'-O-Gallate and Exploration of its in Vitro Anti-inflammatory Activity and in Vivo Tissue Distribution

In this study, an effective method for preparation of bioactive galloylated procyanidin B2-3'-O-gallate (B2-3'-G) was first developed by incomplete depolymerization of grape seed polymeric procyanidins (PPCs) using l-cysteine (Cys) in the presence of citric acid. The structure-activity relationship of B2-3'-G was further evaluated in vitro through establishing lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells. The results suggested that the better protective effects of B2-3'-G against inflammation were attributed to its polymerization degree and the introduction of the galloyl group, compared to its four corresponding structural units. In vivo experiments demonstrated that the B2-3'-G prototype was distributed in plasma, small intestine, liver, lung, and brain. Remarkably, B2-3'-G was able to penetrate the blood-brain barrier and appeared to play an important role in improving brain health. Furthermore, a total of 18 metabolites were identified in tissues. Potential metabolic pathways, including reduction, methylation, hydration, desaturation, glucuronide conjugation, and sulfation, were suggested.

Prebiotic proanthocyanidins inhibit bile reflux-induced esophageal adenocarcinoma through reshaping the gut microbiome and esophageal metabolome

The gut and local esophageal microbiome progressively shift from healthy commensal bacteria to inflammation-linked pathogenic bacteria in patients with gastroesophageal reflux disease, Barrett's esophagus, and esophageal adenocarcinoma (EAC). However, mechanisms by which microbial communities and metabolites contribute to reflux-driven EAC remain incompletely understood and challenging to target. Herein, we utilized a rat reflux-induced EAC model to investigate targeting the gut microbiome-esophageal metabolome axis with cranberry proanthocyanidins (C-PAC) to inhibit EAC progression. Sprague-Dawley rats, with or without reflux induction, received water or C-PAC ad libitum (700 μg/rat/day) for 25 or 40 weeks. C-PAC exerted prebiotic activity abrogating reflux-induced dysbiosis and mitigating bile acid metabolism and transport, culminating in significant inhibition of EAC through TLR/NF-κB/TP53 signaling cascades. At the species level, C-PAC mitigated reflux-induced pathogenic bacteria (Streptococcus parasanguinis, Escherichia coli, and Proteus mirabilis). C-PAC specifically reversed reflux-induced bacterial, inflammatory, and immune-implicated proteins and genes, including Ccl4, Cd14, Crp, Cxcl1, Il6, Il1b, Lbp, Lcn2, Myd88, Nfkb1, Tlr2, and Tlr4, aligning with changes in human EAC progression, as confirmed through public databases. C-PAC is a safe, promising dietary constituent that may be utilized alone or potentially as an adjuvant to current therapies to prevent EAC progression through ameliorating reflux-induced dysbiosis, inflammation, and cellular damage.

Proanthocyanidins-Based Synbiotics as a Novel Strategy for Nonalcoholic Fatty Liver Disease (NAFLD) Risk Reduction

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, is a spectrum of liver abnormalities ranging from steatosis to nonalcoholic steatohepatitis (NASH) characterized by excessive lipid accumulation. The prevalence of NAFLD is predicted to increase rapidly, demanding novel approaches to reduce the global NAFLD burden. Flavonoids, the most abundant dietary polyphenols, can reduce the risk of NAFLD. The majority of dietary flavonoids are proanthocyanidins (PACs), which are oligomers and polymers of the flavonoid sub-group flavan-3-ols. The efficacy of PAC in reducing the NAFLD risk can be significantly hindered by low bioavailability. The development of synbiotics by combining PAC with probiotics may increase effectiveness against NAFLD by biotransforming PAC into bioavailable metabolites. PAC and probiotic bacteria are capable of mitigating steatosis primarily through suppressing de novo lipogenesis and promoting fatty acid β-oxidation. PAC and probiotic bacteria can reduce the progression of steatosis to NASH mainly through ameliorating hepatic damage and inflammation induced by hepatic oxidative stress, endoplasmic reticulum stress, and gut microbiota dysbiosis. Synbiotics of PAC are superior in reducing the risk of NAFLD compared to independent administration of PAC and probiotics. The development of PAC-based synbiotics can be a novel strategy to mitigate the increasing incidence of NAFLD.

Unraveling the parahormetic mechanism underlying the health-protecting effects of grapeseed procyanidins

Proanthocyanidins (PACs), the predominant constituents within Grape Seed Extract (GSE), are intricate compounds composed of interconnected flavan-3-ol units. Renowned for their health-affirming properties, PACs offer a shield against a spectrum of inflammation associated diseases, such as diabetes, obesity, degenerations and possibly cancer. While monomeric and dimeric PACs undergo some absorption within the gastrointestinal tract, their larger oligomeric and polymeric counterparts are not bioavailable. However, higher molecular weight PACs engage with the colonic microbiota, fostering the production of bioavailable metabolites that undergo metabolic processes, culminating in the emergence of bioactive agents capable of modulating physiological processes. Within this investigation, a GSE enriched with polymeric PACs was employed to explore in detail their impact. Through comprehensive analysis, the present study unequivocally verified the gastrointestinal-mediated transformation of medium to high molecular weight polymeric PACs, thereby establishing the bioaccessibility of a principal catabolite termed 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (VL). Notably, our findings, encompassing cell biology, chemistry and proteomics, converge to the proposal of the notion of the capacity of VL to activate, upon oxidation to the corresponding quinone, the nuclear factor E2-related factor 2 (Nrf2) pathway-an intricate process that incites cellular defenses and mitigates stress-induced responses, such as a challenge brought by TNFα. This mechanistic paradigm seamlessly aligns with the concept of para-hormesis, ultimately orchestrating the resilience to stress and the preservation of cellular redox equilibrium and homeostasis as benchmarks of health.

Bioguided fractionation of procyanidin B2 as potent anti coxsackie virus B and Herpes simplex from cypress (Cupressus sempervirens L.)

The methanolic extracts of cypress (Cupressus sempervirens L.) collected at three phenological stages were evaluated for their cytotoxicity on Vero cells by MTT test as well as on Herpes simplex (HSV-2) and coxsackie (CVB-3) viruses by plaque reduction assay. The methanolic extract exhibited the highest cytotoxicity against HSV-2 (IC50 = 20.40 µg/mL) and CVB-3 (IC50 = 47.50 µg/mL) at the flowering stage. This extract also exhibited a virucidal action both during the entry of viruses and the release of newly formed virions. The methanolic extract bioguided purification showed that the ethyl-acetate fraction was responsible for virucidal activity. This fraction was endowed with more important selectivity index of 8.15 for HSV-2 and 4.40 for CVB-3. The ethyl acetate fraction was subjected to thin layer chromatography fractionation and identification by HPLC-DAD-ESI-MSn. Results showed that the condensed tannin procyanidin B2 was identified for the first time responsible of the antiviral activity of cypress.

Grape seed-derived procyanidin inhibits glyphosate-induced hepatocyte ferroptosis via enhancing crosstalk between Nrf2 and FGF12

BACKGROUND

Glyphosate (GLY) exposure induces hepatocyte ferroptosis through overproduction of reactive oxygen species, regarded as an important contributor to liver damage. Grape seed-derived procyanidin (GSDP) has been reported to be an effective antioxidant, but whether and, if any, how GSDP can attenuate GLY-induced liver injury via inhibiting ferroptosis is unclear.

PURPOSE

The current study aimed to investigate the hepato-protective effects and possible mechanisms of GSDP.

METHODS

GLY-induced liver damage mice model was established to explore the hepatoprotective roles of GSPE in vivo. Subsequently, bioinformatics methodology was used to predict the key pathways and factors related to the action targets of GSPE against hepatocyte ferroptosis. Finally, we explored the roles of nuclear factor E2 related factor 2 (Nrf2) and fibroblast growth factor 21 (FGF21) in blunting GLY-induced liver damage via suppressing ferroptosis in vitro.

RESULTS

GSDP exerts hepato-protective effects in vivo and in vitro through reduced oxidative stress and inhibited ferroptosis, which was related to the activation of Nrf2. Bioinformatics analysis showed an interaction between Nrf2 and FGF21. Furthermore, Nrf2 inhibition reduced FGF21 expression in the mRNA and protein levels. Fgf21 knockdown suppressed Nrf2 expression level, but recombinant FGF21 protein increased Nrf2 expression and promoted Nrf2 translocation into nucleus, suggesting a crosstalk between Nrf2 and FGF21. Intriguingly, the decreased levels of Nrf2 and FGF21 compromised the protective roles of GSDP against GLY-induced hepatocyte ferroptosis.

CONCLUSION

These findings suggest that GSDP attenuates GLY-caused hepatocyte ferroptosis via enhancing the interplay between Nrf2 and FGF21. Thus, GSDP may be a promising natural compound to antagonize ferroptosis-related damage.

Modulatory role of terminal monomeric flavan-3-ol units in the viscoelasticity of dentin

Flavan-3-ol monomers are the building blocks of proanthocyanidins (PACs), natural compounds from plants shown to mediate specific biologic activities on dentin. While the stereochemistry of the terminal flavan-3-ols, catechin (C) versus epicatechin (EC), impacts the biomechanical properties of the dentin matrix treated with oligomeric PACs, structure-activity relationships driving this bioactivity remain elusive. To gain insights into the modulatory role of the terminal monomers, two highly congruent trimeric PACs from Pinus massoniana only differing in the stereochemistry of the terminal unit (Trimer-C vs. Trimer-EC) were prepared to evaluate their chemical characteristics as well as their effects on the viscoelasticity and biostability of biomodified dentin matrices via infrared spectroscopy and multi-scale dynamic mechanical analyses. The subtle alteration of C versus EC as terminal monomers lead to distinct immediate PAC-trimer biomodulation of the dentin matrix. Nano- and micro-dynamic mechanical analyses revealed that Trimer-EC increased the complex moduli (0.51 GPa) of dentin matrix more strongly than Trimer-C (0.26 GPa) at the nanoscale length (p < 0.001), whereas the reverse was found at the microscale length (p < .001). The damping capacity (tan δ) of dentin matrix decreased by 70% after PAC treatment at the nano-length scale, while increased values were found at the micro-length scale (~0.24) compared to the control (0.18 ; p < .001). An increase in amide band intensities and a decrease of complex moduli was observed after storage in simulated body fluid for both Trimer-C and Trimer-EC modified dentin. The stereochemical configuration of the terminal monomeric units, C and EC, did not impact the chemo-mechanical stability of dentin matrix.

The effects of proanthocyanidin on testicular toxicity in rats exposed to a glyphosate-based herbicide

The purpose of this study is to determine the effects of proanthocyanidin (PA) on spermatological parameters and testicular toxicity in male rats exposed to glyphosate (GLP). In our study, four groups were formed out of 24 male rats, each group would include 6 rats. The rats in the PA group were given a dose of 400 mg/kg/day dissolved in DMSO via gastric gavage. The rats in the GLP+PA groups were first given GLP at the LD50/10 dose of 787.85 mg/kg/day, followed by administering PA at a dose of 400 mg/kg/day dissolved in DMSO via gastric gavage. The rats in the GLP group were given GLP at the LD50/10 dose of 787.85 mg/kg/day dissolved in DMSO via gastric gavage. It was determined that in terms of motility, in comparison to the control group, the decreases in the GLP group and the increases in the PA and GLP+PA groups were statistically significant (p<0.001). The administration of GLP increased DNA damage compared to the control group, but the GLP+PA and PA applications reduced DNA damage (p<0.001). The analysis of testosterone levels indicated a statistically significant reduction in the GLP group compared to the other groups. Consequently, it was determined that PA effectively prevented the decreases in the spermatological parameters lowered as a result of GLP exposure and the oxidative stress and toxicity in testicular tissue.

Proanthocyanidins inhibited colorectal cancer stem cell characteristics through Wnt/β-catenin signaling

BACKGROUND

Cancer stem cells (CSCs) play a key role in tumor cell growth, drug resistance, recurrence, and metastasis. Proanthocyanidins (PC) is widely existed in plants and endowed with powerful antioxidant and anti-aging effects. Interestingly, recent studies have found that PC exhibits the inhibitory effect on tumor growth. However, the role of PC in CSCs of colorectal cancer (CRC) and molecular mechanism remain unclear.

METHODS

CCK-8, colony, and tumorsphere formation assay were used to evaluate cancer cell viability and stemness, respectively. Western blotting was used to detect the protein expression. Tumor xenograft experiments were employed to examine the tumorigenicity of CRC cells in nude mice.

RESULTS

PC decreased the proliferation of CRC cells (HT29 and HCT-116), and improved the sensitivity of CRC cells to oxaliplatin (L-OHP), as well as inhibited tumor growth in nude mice. Further studies showed that PC also down-regulated CSCs surface molecular and stemness transcriptional factors, while suppressed the formations of tumorspheres and cell colony in CRC. In addition, PC-impaired proteins expressions of p-GSK3β, β-catenin and DVL1-3. LiCl, an activator of the Wnt/β-catenin signaling, rescued PC-induced downregulation of CSCs markers, and reduction of tumorspheres and cell colony formation abilities in CRC cells. Furthermore, the effects of PC on inhibiting cell proliferation and enhancing L-OHP sensitivity were impaired by LiCl.

CONCLUSIONS

PC exerted an inhibitory effect on CSCs via Wnt/β-catenin in CRC, and may be a potential new class of natural drug for CRC treatment.

Proanthocyanidin enhances the endogenous regeneration of alveolar bone by elevating the autophagy of PDLSCs

OBJECTIVE

This study aimed to investigate the effect of proanthocyanidin (PA) on osteogenesis mediated by periodontal ligament stem cells (PDLSCs) and endogenous alveolar bone regeneration.

BACKGROUND

Leveraging the osteogenic potential of resident stem cells is a promising strategy for alveolar bone regeneration. PA has been reported to be effective in osteogenesis. However, the effect and mechanism of PA on the osteogenic differentiation of PDLSCs remain elusive.

METHODS

Human PDLSCs were treated with various doses of PA to assess the cell proliferation using Cell Counting Kit-8. The osteogenic differentiation ability was detected by qRT-PCR analysis, western blot analysis, Alizarin red S staining, and Alkaline Phosphatase staining. The level of autophagy was evaluated by confocal laser scanning microscopy, transmission electron microscopy, and western blot analysis. RNA sequencing was utilized to screen the potential signaling pathway. The alveolar bone defect model of rats was created to observe endogenous bone regeneration.

RESULTS

PA activated intracellular autophagy in PDLSCs, resulting in enhanced osteogenic differentiation. Moreover, this effect could be abolished by the autophagy inhibitor 3-Methyladenine. Mechanistically, the PI3K/Akt/mTOR pathway was negatively correlated with PA-mediated autophagy activation. Lastly, PA promoted the alveolar bone regeneration in vivo, and this effect was reversed when the autophagy process was blocked.

CONCLUSION

PA may activate autophagy by inhibiting PI3K/Akt/mTOR signaling pathway to promote the osteogenesis of PDLSCs and enhance endogenous alveolar bone regeneration.

Effect of Grape Seed Procyanidins Combined with Allicin on Lipid Levels in Hyperlipidemic Rats

OBJECTIVES

To study the effects of grape seed proanthocyanidins (GSP) combined with allicin on serum lipids level and vascular damage in a rat model of hyperlipidemia.

MATERIALS AND METHODS

SD rats(male, 170-220 gn= 40) were randomized into five groups (n = 8/group): modelhigh fat and cholesterol diet; controlnormal diet; model+low-dose (GSP+allicin )(GSP 45mg/kg, allicin 30mg/kg, orally); model+high-dose (GSP+allicin) (GSP180mg/kg, allicin 90mg/kg, orally) and positive control (model+simvastatin (4 mg/kg)). Normal control group was fed conventionally, and remaining four groups were fed high cholesterol and fat food to replicate the high fat model. After 9 weeks, the normal control group continued to receive regular feeding, while the other groups continued to receive high-fat feeding. At the same time, model and normal control groups were given equal volume of physiological saline by gavage, and the other treatment groups began to receive corresponding drugs by gavage once a day. After 4 weeks, serum levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) as well as high-density lipoprotein cholesterol (HDL-C) in rats were determined. And the body weight of rat, total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and malondialdehyde (MDA)in serum were identified. The level of endothelin-1(ET-1) was quantitative analysis by ELISA assay.

RESULTS

In comparison to normal controls, the model group displayed a marked rise in body weight, an increment in serum concentrations of LDL-C, TG and TC, as well as a decline in HDL (P<0.01), demonstrating successful model replication; All doses of GSP in combination with allicin resulted in a reduction in TG, LDL-C, and TC and an enhancement in HDL-C in contrast to the model control (all P<0.05). High-dose (GSP+allicin ) decreased MDA, and increased T-AOC and SOD activity(all P<0.01). All doses of GSP combined with allicin decreased ET-1 (all P<0.05). In addition, the protective effect of GSP combined with allicin was dose-dependent.

CONCLUSIONS

Studies have shown that GSP combined with allicin can significantly improve blood lipids in hyperlipidemic rats, and this mechanism may be related to antioxidants and reduced endothelial damage.

Peanut skin procyanidins reduce intestinal glucose transport protein expression, regulate serum metabolites and ameliorate hyperglycemia in diabetic mice

One of diabetic characteristics is the postprandial hyperglycemia. Inhibiting glucose uptake may be beneficial for controlling postprandial blood glucose levels and regulating the glucose metabolism Peanut skin procyanidins (PSP) have shown a potential for lowering blood glucose; however, the underlying mechanism through which PSP regulate glucose metabolism remains unknown. In the current study, we investigated the effect of PSP on intestinal glucose transporters and serum metabolites using a mouse model of diabetic mice. Results showed that PSP improved glucose tolerance and systemic insulin sensitivity, which coincided with decreased expression of sodium-glucose cotransporter 1 and glucose transporter 2 in the intestinal epithelium induced by an activation of the phospholipase C β2/protein kinase C signaling pathway. Moreover, untargeted metabolomic analysis of serum samples revealed that PSP altered arachidonic acid, sphingolipid, glycerophospholipid, bile acids, and arginine metabolic pathways. The study provides new insight into the anti-diabetic mechanism of PSP and a basis for further research.

Grape seed proanthocyanidins regulate mitophagy of endothelial cells and promote wound healing in mice through p-JNK/FOXO3a/ROS signal pathway

Skin wound healing is a dynamic and complex process that involves multiple physiological and cellular events. Grape seed proanthocyanidins (GSP) have strong anti-oxidation and elimination of oxygen free radicals, and have been shown to significantly promote wound healing, but the underlying mechanism remains unclear. Studies have indicated that reactive oxygen species (ROS) acts as an upstream signal to induce mitophagy, suggesting that GSP can regulate mitophagy through the signal pathway. This study aimed to investigate whether GSP regulates mitophagy by down-regulating oxidative stress to promote wound healing. In vivo, GSP treatment accelerated wound healing, granulation tissue formation, collagen deposition, and angiogenesis in mice. Moreover, GSP down-regulated ROS levels and promoted the expression of antioxidant proteins by up-regulating the expression of p-JNK/FOXO3a protein, thereby regulating the expression of mitophagy-related proteins. In vitro, 4 μg/mL GSP showed no apparent toxic effects on cells and effectively reduce the oxidative stress damage of cells induced by H2O2. Western blot and superoxide anion fluorescence probe further confirmed that GSP effectively reduced Dihydroethidium content and up-regulated the expression of antioxidant proteins by activation of p-JNK/FOXO3a protein expression, thereby regulating mitophagy. Taken together, the findings from in vitro and in vivo experiments provide new insights into the promotion of wound healing by GSP.

[Research progress on the effects of proanthochanidins in reshaping microbiota and suppressing inflammation]

Proanthocyanidins (PCs) are a class of polyphenols that are composed of flavanate monomers and their polymers, which have antibacterial and anti-inflammatory properties with very few side effects. This article reviews the mechanism by which PCs differentially regulate microbiota, reshape microflora diversity and play a role in suppressing inflammation, providing a reference for the basic research of PCs in improving female vaginal health, and is expected to provide a new idea and breakthrough for the combined use of PCs with other antibacterial drugs in the treatment of vaginitis.

Effects of grape seed-derived proanthocyanidin B2 pretreatment on oxidative stress, endoplasmic reticulum stress and apoptosis of renal tubular epithelial cells in renal ischemia-reperfusion injury model of mice

PURPOSE

To investigate the effect of grape seed-derived proanthocyanidin B2 (GSPB2) pretreatment on acute renal ischemia-reperfusion injury model of mice.

METHODS

50 mice were divided into 5 groups: Sham group: mice were treated with right nephrectomy. GSPB2 group: GSPB2 was injected intraperitoneally 45 min before right nephrectomy. IRI group: right kidney was resected and the left renal arteriovenous vessel was blocked for 45 min. GSPB2 + IRI group: GSPB2 was intraperitoneally injected 45 min before IRI established. GSPB2 + BRU + IRI group: GSPB2 and brusatol (BRU) were injected intraperitoneally 45 min before IRI established. Creatinine and urea nitrogen of mice were detected, and the kidney morphology and pathological changes of each group were detected by HE staining, PAS staining and transmission electron microscopy. Expressions of Nrf2, HO-1, GRP78, CHOP, and cleaved-caspase3 were detected by immunofluorescence staining and western blotting.

RESULTS

Morphology and mitochondrial damages of kidney in GSPB2 + IRI group were significantly alleviated than those in IRI group. Expression levels of Nrf2 and HO-1 were significantly higher in GSPB2 + IRI group than those in IRI group. Expression levels of GRP78, CHOP and cleaved-caspase3 were significantly lower in GSPB2 + IRI group than those in IRI group. However, compared to GSPB2 + IRI group, protective effects of GSPB2 pretreatment were weakened in GSPB2 + BRU + IRI group.

CONCLUSIONS

GSPB2 pretreatment could alleviate oxidative stress damage and reduce apoptosis of renal tubular epithelial cells, which might be related to activating the antioxidant system, up-regulating the expression of Nrf2 and HO-1, inhibiting the expressions of GRP78, CHOP and cleaved-caspase3. However, the protective effect could be reversed by brusatol.

Procyanidin B2 alleviates uterine toxicity induced by cadmium exposure in rats: The effect of oxidative stress, inflammation, and gut microbiota

Environmental exposure to hazardous materials causes enormous socioeconomic problems due to its deleterious impacts on human beings, agriculture and animal husbandry. As an important hazardous material, cadmium can promote uterine oxidative stress and inflammation, leading to reproductive toxicity. Antioxidants have been reported to attenuate the reproductive toxicity associated with cadmium exposure. In this study, we investigated the potential protective effect of procyanidin oligosaccharide B2 (PC-B2) and gut microbiota on uterine toxicity induced by cadmium exposure in rats. The results showed that the expression levels of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were reduced in utero. Proinflammatory cytokines (including tumor necrosis factor-α, interleukin-1β and interleukin-6), the NLRP3 inflammasome, Caspase-1 and pro-IL-1β were all involved in inflammatory-mediated uterine injury. PC-B2 prevented CdCl2-induced oxidative stress and inflammation in uterine tissue by increasing antioxidant enzymes and reducing proinflammatory cytokines. Additionally, PC-B2 significantly reduced cadmium deposition in the uterus, possibly through its significant increase in MT1, MT2, and MT3 mRNA expression. Interestingly, PC-B2 protected the uterus from CdCl2 damage by increasing the abundance of intestinal microbiota, promoting beneficial microbiota, and inhibiting harmful microbiota. This study provides novel mechanistic insights into the toxicity of environmental cadmium exposure and indicates that PC-B2 could be used in the prevention of cadmium exposure-induced uterine toxicity.

Procyanidins: A promising anti-diabetic agent with potential benefits on glucose metabolism and diabetes complications

Diabetes mellitus (DM) is a complex disease with alarming worldwide health implications and high mortality rates, largely due to its complications such as cardiovascular disease, nephropathy, neuropathy, and retinopathy. Recent research has shown that procyanidins (PC), a type of flavonoid, have strong antioxidant and free radical elimination effects, and may be useful in improving glucose metabolism, enhancing pancreatic islet cell activity, and decreasing the prevalence of DM complications. This review article presents a systematic search for peer-reviewed articles on the use of PC in the treatment of DM, without any language restrictions. The article also discusses the potential for PC to sensitise DM medications and improve their efficacy. Recent in vivo and in vitro studies have demonstrated promising results in improving the biological activity and bioavailability of PC for the treatment of DM. The article concludes by highlighting the potential for novel materials and targeted drug delivery methods to enhance the pharmacokinetics and bioactivity of PC, leading to the creation of safer and more effective anti-DM medications in the future.

Effects of grape seed procyanidins on antioxidant function, barrier function, microbial community, and metabolites of cecum in geese

The gut is the first line of defense for body health and is essential to the overall health of geese. Grape seed procyanidins (GSPs) are proverbial for their antioxidant, anti-inflammatory, and microflora-regulating capabilities. This study aimed to inquire into the influences of dietary GSPs on the intestinal antioxidant function, barrier function, microflora, and metabolites of geese based on 16S rRNA sequencing and metabolomics. In total, 240 twenty-one-day-old Sichuan white geese were randomly divided into 4 groups, each of which was supplied with 1 of 4 diets: basal diet or a basal diet supplemented with 50, 100, or 150 mg/kg GSPs. Diets supplemented with GSPs at different concentrations significantly increased the total antioxidant capacity and superoxide dismutase activity in cecal mucosa (P < 0.001). Dietary supplementation with 50 or 100 mg/kg GSPs significantly increased catalase activity (P < 0.001). The serum diamine oxidase, D-lactic acid, and endotoxin concentrations were decreased by GSP supplementation in the goose diet. Dietary GSP supplementation increased microbial richness and diversity, enhanced the relative abundance of Firmicutes, and decreased that of Bacteroidetes in the cecum. Diets supplemented with 50 or 100 mg/kg GSPs enriched Eubacterium coprostanoligenes and Faecalibacterium. Dietary GSPs substantially raised the acetic and propionic acid concentrations in the cecum. The butyric acid concentration increased when the GSP dosage was 50 or 100 mg/kg. Additionally, dietary GSPs increased the levels of metabolites that belong to lipids and lipid-like molecules or organic acids and derivatives. Dietary GSP supplementation at 100 or 150 mg/kg reduced the levels of spermine (a source of cytotoxic metabolites) and N-acetylputrescine, which promotes in-vivo inflammation. In conclusion, dietary supplementation with GSPs was beneficial to gut health in geese. Dietary GSPs improved antioxidant activity; protected intestinal barrier integrity; increased the abundance and diversity of cecal microflora; promoted the proliferation of some beneficial bacteria; increased the production of acetic, propionic, and butyric acids in the cecum; and downregulated metabolites associated with cytotoxicity and inflammation. These results offer a strategy for promoting intestinal health in farmed geese.

Microbiological and Clinical Effects of a Proanthocyanidin-enriched Extract from Rumex acetosa in Periodontally Healthy Carriers of Porphyromonas gingivalis: a Randomized Controlled Pilot Study

Rumex acetosa significantly inhibits the adhesion of Porphyromonas gingivalis (P. g.) to eukaryotic host cells in vitro. The objective of this randomized placebo-controlled pilot-trial was to analyze effects of a mouth rinse containing 0.8% (w/w) of a quantified proanthocyanidin-enriched extract from Rumex acetosa (RA1) on microbiological, clinical, and cytological parameters in systemically healthy individuals without history of periodontitis, harboring P. g. intraorally. 35 subjects received a supragingival debridement (SD) followed by mouth rinsing (3 times daily) with either RA1 mouth rinse solution (test) or placebo (control) for 7 days as adjunct to routine oral hygiene. Supragingival biofilm samples were taken at screening visit, baseline (BL), 2, 4, 7 and 14 days after SD. P. g. and 11 other oral microorganisms were detected and quantified by rtPCR. Changes in the oral microbiota composition of one test and one control subject were assessed via high throughput 16S rRNS gene amplicon sequencing. Approximal Plaque Index (API) and the modified Sulcular Bleeding Index (SBI) were assessed at BL, 7- and 14-days following SD. Brush biopsies were taken at BL and 14 d following SD. Intergroup comparisons revealed no significant microbiological, cytological, and clinical differences at any timepoint. However, a significant reduction in SBI at day 14 (p = 0.003) and API at day 7 (p = 0.02) and day 14 (p = 0.009) was found in the test group by intragroup comparison. No severe adverse events were observed. The results indicate that RA1 mouth rinse is safe but does not seem to inhibit colonization of P. g. or improve periodontal health following SD.

Photoperiod-Dependent Effects of Grape-Seed Proanthocyanidins on Adipose Tissue Metabolic Markers in Healthy Rats

SCOPE

Variations in photoperiod patterns drive metabolic adaptations in mammals, involving important changes in body weight and adiposity. Moreover, (poly)phenols can help heterotrophs adopt metabolic adaptations to face the upcoming environmental conditions. Particularly, proanthocyanidins from grape-seeds show photoperiod-dependent effects on different metabolic parameters. The present study aims to explore whether grape-seed proanthocyanidin extract (GSPE) consumption differently affects the expression of metabolic markers in WAT (subcutaneous and visceral depots) and BAT in a photoperiod-dependent manner.

METHODS AND RESULTS

GSPE (25 mg kg-1  day-1 ) is orally administrated for 4 weeks to healthy rats exposed to three photoperiods (L6, L12, and L18). In WAT, GSPE consumption significantly upregulates the expression of lipolytic genes in all photoperiods, being accompanied by increased serum concentrations of glycerol and corticosterone only under the L6 photoperiod. Moreover, adiponectin mRNA levels are significantly upregulated in response to GSPE regardless of the photoperiod, whereas Tnfα and Il6 expression are only downregulated in L6 and L18 photoperiods but not in L12. In BAT, GSPE upregulates Pgc1α expression in all groups, whereas the expression of Pparα is only increased in L18.

CONCLUSIONS

The results indicate that GSPE modulates the expression of important metabolic markers of WAT and BAT in a photoperiod-dependent manner.

Procyanidin improves experimental colitis by regulating macrophage polarization

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic disease with an unclear pathogenesis for which successful treatments are still lacking. It has been reported that procyanidin, a natural antioxidant, relieves colitis, but the specific mechanism is elusive.

PURPOSE

Our present study was designed to investigate the effects of procyanidin on colitis and the regulation of the M1 macrophage phenotype and related signaling pathways.

METHODS

In vivo, we used two classic colitis models to observe the effect of procyanidin on macrophage polarization. In vitro, we further validated the therapeutic effect of procyanidin in the RAW264.7 cell line and peritoneal macrophages.

RESULTS

The current findings provide new evidence that procyanidin ameliorated dextran sulfate sodium (DSS)-induced colitis by preventing the polarization of macrophages to the M1 type and downregulating the levels of proinflammatory factors in cells. We also showed that procyanidin prevented lipopolysaccharide (LPS)-induced elevation of inflammatory cytokines and the activation of proinflammatory macrophages, which was achieved by activating the STAT3 and NF-κB pathways.

CONCLUSIONS

This is the first study to demonstrate that procyanidin alleviates experimental colitis by inhibiting the polarization of proinflammatory macrophages. These data reveal new ideas for the pathogenesis and treatment of inflammatory diseases.

Microstructured Polymer System Containing Proanthocyanidin-Enriched Extract from Limonium brasiliense as a Prophylaxis Strategy to Prevent Recurrence of Porphyromonas gingivalis

Periodontal diseases are a global oral health problem affecting almost 10% of the global population. Porphyromonas gingivalis is one of the main bacteria involved in the initiation and progression of inflammatory processes as a result of the action of the cysteine proteases lysin- and arginine-gingipain. Surelease/polycarbophil microparticles containing a lyophilized proanthocyanidin-enriched fraction from the rhizomes of Limonium brasiliense, traditionally named "baicuru" (ethyl acetate fraction), were manufactured. The ethyl acetate fraction was characterized by UHPLC by the presence of samarangenins A and B (12.10 ± 0.07 and 21.05 ± 0.44%, respectively) and epigallocatechin-3-O-gallate (13.44 ± 0.27%). Physiochemical aspects of Surelease/polycarbophil microparticles were characterized concerning particle size, zeta potential, entrapment efficiency, ethyl acetate fraction release, and mucoadhesion. Additionally, the presence of the ethyl acetate fraction-loaded microparticles was performed concerning potential influence on viability of human buccal KB cells, P. gingivalis adhesion to KB cells, gingipain activity, and P. gingivalis biofilm formation. In general, all Surelease/polycarbophil microparticles tested showed strong adhesion to porcine cheek mucosa (93.1 ± 4.2% in a 30-min test), associated with a prolonged release of the ethyl acetate fraction (up to 16.5 ± 0.8% in 24 h). Preincubation of KB cells with Surelease/polycarbophil microparticles (25 µg/mL) resulted in an up to 93 ± 2% reduced infection rate by P. gingivalis. Decreased activity of the P. gingivalis-specific virulence factors lysin- and arginine-gingipain proteases by Surelease/polycarbophil microparticles was confirmed. Surelease/polycarbophil microparticles decreased biofilm formation of P. gingivalis (97 ± 2% at 60 µg/mL). Results from this study prove the promising activity of Surelease/polycarbophil microparticles containing ethyl acetate fraction microparticles as a prophylaxis strategy to prevent the recurrence of P. gingivalis.

Protective Effects of Proanthocyanidin-Rich Fraction from Red Rice Germ and Bran on Lung Cell Inflammation via Inhibition of NF-κB/NLRP3 Inflammasome Pathway

The activation of the NLRP3 inflammasome pathway during infectious pathogen-induced immunopathology can lead to chronic inflammation and various adverse health outcomes. Identification of functional foods with anti-inflammatory properties is crucial for preventing inflammation triggered by NLRP3 inflammasome activation. This study aimed to investigate the anti-inflammatory properties of a proanthocyanidin-rich fraction obtained from red rice germ and bran against lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced condition in A549 lung cells. The proanthocyanidin-rich fraction from Yamuechaebia 3 red rice extract (YM3-PRF) was obtained using column chromatography with Sephadex LH20, and its total proanthocyanidin content was determined to be 351.43 ± 1.18 mg/g extract using the vanillin assay. A549 lung cells were pretreated with YM3-PRF at concentrations of 5-20 μg/mL prior to exposure to LPS (1 μg/mL) and ATP (5 nM). The results showed that YM3-PRF significantly inhibited the expression of inflammatory mRNAs (NLRP3, IL-6, IL-1β, and IL-18) and the secretion of cytokines (IL-6, IL-1β, and IL-18) in a dose-dependent manner (p < 0.05). Mechanistically, YM3-PRF exerted its anti-inflammatory effects by inhibiting NF-κB translocation and downregulating proteins associated with the NLRP3 inflammasome pathway (NLRP3, ASC, pro-caspase-1, and cleaved-caspase-1). These findings suggest that the proanthocyanidin-rich fraction from red rice germ and bran has protective effects and may serve as a potential therapeutic option for chronic inflammatory diseases associated with NLRP3 inflammasome activation.

The natural tannins oligomeric proanthocyanidins and punicalagin are potent inhibitors of infection by SARS-CoV-2

The Coronavirus Disease 2019 (COVID-19) pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 Vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention.

Condensed tannins, novel compounds and sources of variation determine the antiparasitic activity of Nordic conifer bark against gastrointestinal nematodes

The antiparasitic potential of plants could offer a vital solution to alleviating the costs of gastrointestinal nematode (GIN) infections in ruminant production globally. Leveraging known bioactive molecules, however, is complex, where plant species, extraction processes and seasonality impact bioavailability and efficacy. This study assessed the impact of a comprehensive set of factors on the antiparasitic activity of Norwegian conifers to identify bark compounds specific against GIN. Antiparasitic activity was determined using in vitro assays targeting morphologically distinct life stages of ovine GIN: the egg hatch assay and larval motility assay. In depth characterisation of the chemical composition of the bark extracts was carried out using chromatographic separation, UV-absorbance, and molecular mass profiles to identify compounds implicated in the activity. Three key findings emerged: (1) the activity of bark extracts varied markedly from 0 to 100% antiparasitic efficacy, owing to tree species, extraction solvent and seasonality; (2) the GIN exhibited species-and stage-specific susceptibility to the bark extracts; (3) the presence of condensed tannins, amongst other compounds, was associated with anthelmintic activity. These findings add new insights into urgently needed alternative parasite control strategies in livestock.

Effects of proanthocyanidins and dialdehyde chitosan on the proliferation and differentiation of bovine myoblast for cultured meat production

Cultured meat technology intends to manufacture meat by cultivating muscle stem cells in vitro, which is an emerging methodology in meat production. However, the insufficient stemness of bovine myoblasts cultivated in vitro declined the ability of cell expansion and myogenic differentiation, which limited the production of cultured meat. Therefore, in this study, we introduced proanthocyanidins (PC, natural polyphenolic compounds) and dialdehyde chitosan (DAC, natural polysaccharides) to explore the effects of proliferation and differentiation of bovine myoblasts in vitro. The experiment results revealed that PC and DAC promoted cell proliferation by improving the transition from G1 to the S phase as well as cell division in G2. Meanwhile, the myogenic differentiation of cells was further boosted by the combined PC and DAC up-regulation of MYH3 expression. Moreover, the study revealed the synergistic effect of PC and DAC on enhancing the structural stability of collagen, and bovine myoblasts demonstrated excellent growth and dispersion ability on collagen scaffolds. It is concluded that both PC and DAC promote the proliferation and differentiation of bovine myoblasts, contributing to the development of cultured meat production systems.

Ultra-stretchable, tissue-adhesive, shape-adaptive, self-healing, on-demand removable hydrogel dressings with multiple functions for infected wound healing in regions of high mobility

Bacterial infection in the most mobile area usually leads to delayed healing and functional restriction, which has been a long-term challenge in clinic. Developing hydrogel-based dressings with mechanical flexibly, high adhesive and anti-bacterial properties, will contribute to the healing and therapeutic effects especially for this typical skin wound. In this work, composite hydrogel named PBOF through multi-reversible bonds between polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion demonstrated a 100 times ultra-stretch ability, 24 kPa of highly tissue-adhesive, rapid shape-adaptability within 2 min and self-healing feature within 40 s, was designed as the multifunctional wound dressing for the Staphylococcus aureus-infected skin wound in the mice nape model. Besides, this hydrogel dressing could be easily removed on-demand within 10 min by water. The rapid disassembly of this hydrogel is related to the formation of hydrogen bonds between polyvinyl alcohol and water. Moreover, the multifunctional properties of this hydrogel include strong anti-oxidative, anti-bacteria and hemostasis derived from oligomeric procyanidin and photothermal effect of ferric ion/polyphenol chelate. The killing ratio of the hydrogel on Staphylococcus aureus in infected skin wound reached 90.6% when exposed to 808 nm irradiation for 10 min. Simultaneously, reduced oxidative stress, suppressed inflammation, and promoted angiogenesis all together accelerated wound healing. Therefore, this well-designed multifunctional PBOF hydrogel holds great promise as skin wound dressing especially in the high mobile regions of the body. STATEMENT OF SIGNIFICANCE: An ultra-stretchable, highly tissue-adhesive, and rapidly shape-adaptive, self-healing and on-demand removable hydrogel based on multi-reversible bonds among polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion is designed as dressing material for infected wound healing in the movable nape. The rapid on-demand removal of the hydrogel relates to the formation of hydrogen bonds between polyvinyl alcohol and water. This hydrogel dressing shows strong antioxidant capacity, rapid hemostasis and photothermal antibacterial ability. This is derived from oligomeric procyanidin and thephotothermal effect of ferric ion/polyphenol chelate, which eliminates bacterial infection, reduces oxidative stress, regulates inflammation, promotes angiogenesis, and finally accelerates the infected wound healing in movable part.

Metabolism disturbance by light/dark cycle switching depends on the rat health status: the role of grape seed flavanols

Changes in light/dark cycles and obesogenic diets are related to the disruption of circadian rhythms and metabolic disorders. Grape seed flavanols have shown beneficial effects on metabolic diseases and, recently, a circadian system modulation has been suggested to mediate their health-enhancing properties. Therefore, the aim of this study was to evaluate the grape seed (poly)phenol extract (GSPE) effects in healthy and obese rats after a light/dark cycle disruption. Forty-eight rats were fed a standard (STD) or cafeteria (CAF) diet for 6 weeks under STD conditions of a light/dark cycle (12 h light per day, L12). Then, animals were switched to a long (18 h light per day, L18) or short (6 h light per day, L6) photoperiod and administered a vehicle (VH) or GSPE (25 mg kg-1) for 1 week. The results showed changes in serum lipids and insulin and metabolomic profiles dependent on the photoperiod and animal health status. GSPE administration improved serum parameters and increased the Nampt gene expression in CAF rats and modified the metabolomic profile in a photoperiod-dependent manner. Metabolic effects of light/dark disturbance depend on the health status of the rats, with diet-induced CAF-induced obese rats being more affected. Grape seed flavanols improve the metabolic status in a photoperiod-dependent manner and their effects on the circadian system suggest that part of their metabolic effects could be mediated by their action on biological rhythms.

Oyster shell-derived nano-hydroxyapatite and proanthocyanidin pretreatment on dentinal tubule occlusion and permeability before and after acid challenge-an in vitro study

This in vitro study evaluated the dentinal tubule occlusion (TO), depth of penetration (DoP), and dentin permeability (DP) of oyster shell-derived nanohydroxyapatite (os-nHAp) with and without 15% proanthocyanidin (PA) pretreatment. os-nHAp was synthesized via the precipitation method and it was characterized. The morphology and particle size of os-nHAp were analyzed using a high-resolution transmission electron microscope (HRTEM). Cytotoxicity of os-nHAp, PA/os-nHAp, and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) was assessed by (3-(4,5-dimethythiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) assay using human osteosarcoma (MG-63) cell line. One hundred and ninety-seven dentin discs of 3 mm thickness were prepared from the crown portion of extracted human teeth. The dentinal surfaces of the discs were etched for 2 min with 6% citric acid to simulate dentin hypersensitivity. Five discs were randomly selected and the patency of dentinal tubules was confirmed using a scanning electron microscope (SEM). The remaining 192 discs were divided into four groups (n = 48) depending on the type of remineralization as follows: group 1: os-nHAp, group 2: PA/os-nHAp, group 3: CPP-ACP, and group 4: no treatment. The remineralization protocol was followed for 21 days. Out of the 48 dentin discs in each group, 32 discs were used to evaluate dentinal tubule occlusion (TO) and depth of penetration (DoP) using SEM. The remaining 16 discs were subjected to an assessment of dentin permeability (DP) using a hydraulic conductance model. TO, DoP and DP were evaluated after remineralization and acid challenge. Characterization studies confirmed the presence of pure phase apatite. HRTEM confirmed the nanometric particle size of os-nHAp. MTT assay results showed that all the tested materials exhibited >80% cell viability when tested up to a concentration of 100 µg/mL. The results demonstrated a significantly higher mean percentage of TO, DoP, and lesser mean DP after remineralization in groups 1, 2, and 3 (p < 0.05). After the acid challenge, group 3 showed a significant reduction in TO and DoP, and increased DP (p < 0.05). However, no such changes were observed in groups 1 and 2. Within the limitations of this study, it can be concluded that os-nHAp and PA/os-nHAp could serve as potential and durable therapeutic agents in the treatment of dentin hypersensitivity.

Combinations of grape seed procyanidin extract and milk thistle silymarin extract against lung cancer - The role of MiR-663a and FHIT

AIMS

Grape seed procyanidin extract (GSE), and milk thistle silymarin extract (MTE) contain structurally distinct polyphenols, and each agent has been shown to exert antineoplastic effects against lung cancer. We hypothesize that combinations of GSE and MTE will additively enhance their anticancer effects against lung cancer.

MATERIALS AND METHODS

The anti-proliferative effects of GSE, MTE and combinations were evaluated in lung neoplastic cell lines. A dose range finding (DRF) study to determine safety, bioavailability and bioactivity, followed by human lung cancer xenograft efficacy studies were conducted in female nude mice with once daily gavage of leucoselect phytosome (LP), a standardized GSE, and/or siliphos, a standardized MTE. The roles of tumor suppressors miR-663a and its predicted target FHIT in mediating the additive, anti-proliferative effecs of GSE/MTE were also assessed.

KEY FINDINGS

GSE with MTE additively inhibited lung preneoplastic and cancer cell proliferations. Mice tolerated all dosing regimens in the DRF study without signs of clinical toxicity nor histologic abnormalities in the lungs, livers and kidneys. Eight weeks of LP and siliphos additively inhibited lung tumor xenograft growth. Plasma GSE/metabolites and MTE/metabolites showed that the combinations did not decrease systemic bioavailabilities of each agent. GSE and MTE additively upregulated miR-663a and FHIT in lung cancer cell lines; transfection of antisense-miR-663a significantly abrogated the anti-proliferative effects of GSE/MTE, upregulation of FHIT mRNA and protein. LP and siliphos also additively increased miR-663a and FHIT protein in lung tumor xenografts.

SIGNIFICANCE

Our findings support clinical translations of combinations of GSE and MTE against lung cancer.

Proanthocyanidins: Impact on Gut Microbiota and Intestinal Action Mechanisms in the Prevention and Treatment of Metabolic Syndrome

The metabolic syndrome (MS) is a cluster of risk factors, such as central obesity, hyperglycemia, dyslipidemia, and arterial hypertension, which increase the probability of causing premature mortality. The consumption of high-fat diets (HFD) is a major driver of the rising incidence of MS. In fact, the altered interplay between HFD, microbiome, and the intestinal barrier is being considered as a possible origin of MS. Consumption of proanthocyanidins (PAs) has a beneficial effect against the metabolic disturbances in MS. However, there are no conclusive results in the literature about the efficacy of PAs in improving MS. This review allows a comprehensive validation of the diverse effects of the PAs on the intestinal dysfunction in HFD-induced MS, differentiating between preventive and therapeutic actions. Special emphasis is placed on the impact of PAs on the gut microbiota, providing a system to facilitate comparison between the studies. PAs can modulate the microbiome toward a healthy profile and strength barrier integrity. Nevertheless, to date, published clinical trials to verify preclinical findings are scarce. Finally, the preventive consumption of PAs in MS-associated dysbiosis and intestinal dysfunction induced by HFD seems more successful than the treatment strategy.

Alkaline oxidization can increase the in vitro antiparasitic activity of proanthocyanidin-rich plant extracts against Ascarissuum

Proanthocyanidins (PAs) are a class of plant specialized metabolites with well-documented bioactivities such as antiparasitic effects. However, little is known about how the modification of PAs influences their bioactivity. The objective of this study was to investigate a wide range of PA-containing plant samples to determine if extracts containing PAs modified by oxidation had altered antiparasitic activities, compared to the original extracts that had not been modified in alkaline conditions. We extracted and analyzed samples from 61 proanthocyanidin-rich plants. The extracts were then oxidized under alkaline conditions. We used these non-oxidized and oxidized proanthocyanidin-rich extracts to conduct a detailed analysis of direct antiparasitic effects against the intestinal parasite Ascaris suum in vitro. These tests showed that the proanthocyanidin-rich extracts had antiparasitic activity. Modification of these extracts significantly increased the antiparasitic activity for the majority the extracts, suggesting that the oxidation procedure enhanced the bioactivity of the samples. Some samples that showed no antiparasitic activity before oxidation showed very high activity after the oxidation. High levels of other polyphenols in the extracts, such as flavonoids, was found to be associated with increased antiparasitic activity following oxidation. Thus, our in vitro screening opens up the opportunity for future research to better understand the mechanism of action how alkaline treatment of PA-rich plant extracts increases their biological activity and potential as novel anthelmintics.

Oligomeric Proanthocyanidin Complex from Avocado Seed as A Promising α-glucosidase Inhibitor: Characteristics and Mechanisms

Although considered an abundant source of agricultural by-products, avocado (Persea americana Mill.) seed, with several biological activities and bioactive components, might become a promising resource for phytopharmaceutical development. In this study, through bioassay-guided isolation of the main α-glucosidase inhibitors in avocado seed, we discovered the major α-glucosidase inhibitor to be avocado seed oligomeric proanthocyanidin complex (ASOPC). Thiolysis and UPLC-DAD-HRESIMS showed the presence of A- and B-type procyanidins, and B-type propelargonidin with (epi)afzelechin as extension unit. Mean degree of polymerization (mDP) of ASOPC was calculated as 7.3 ± 1. Furthermore, ASOPC appeared to be a strong, reversible, competitive inhibitor of α-glucosidase, with IC₅₀ value of 0.1 µg/mL, which was significantly lower than Acarbose (IC₅₀ = 75.6 µg/mL), indicated that ASOPC is a potential natural α-glucosidase inhibitor. These findings would contribute to the direction of utilizing avocado seed bioactive components with the possibility to be used as natural anti-diabetic agents.

Grape-Seed Proanthocyanidins Modulate Adipose Tissue Adaptations to Obesity in a Photoperiod-Dependent Manner in Fischer 344 Rats

Seasonal rhythms drive metabolic adaptations that influence body weight and adiposity. Adipose tissue is a key regulator of energy homeostasis in the organism, and its healthiness is needed to prevent the major consequences of overweight and obesity. In this context, supplementation with proanthocyanidins has been postulated as a potential strategy to prevent the alterations caused by obesity. Moreover, the effects of these (poly)phenols on metabolism are photoperiod dependent. In order to describe the impact of grape-seed proanthocyanidins extract (GSPE) on important markers of adipose tissue functionality under an obesogenic environment, we exposed Fischer 344 rats to three different photoperiods and fed them a cafeteria diet for five weeks. Afterwards, we supplemented them with 25 mg GSPE/kg/day for four weeks. Our results revealed that GSPE supplementation prevented excessive body weight gain under a long photoperiod, which could be explained by increased lipolysis in the adipose tissue. Moreover, cholesterol and non-esterified fatty acids (NEFAs) serum concentrations were restored by GSPE under standard photoperiod. GSPE consumption slightly helped combat the obesity-induced hypertrophy in adipocytes, and adiponectin mRNA levels were upregulated under all photoperiods. Overall, the administration of GSPE helped reduce the impact of obesity in the adipose tissue, depending on the photoperiod at which GSPE was consumed and on the type of adipose depots.

Genistein and Procyanidin B2 Reduce Carcinogen-Induced Reactive Oxygen Species and DNA Damage through the Activation of Nrf2/ARE Cell Signaling in Bronchial Epithelial Cells In Vitro

Cancer is one of the leading causes of death worldwide. Chemotherapy and radiation therapy are currently providing the basis for cancer therapies, although both are associated with significant side effects. Thus, cancer prevention through dietary modifications has been receiving growing interest. The potential of selected flavonoids in reducing carcinogen-induced reactive oxygen species (ROS) and DNA damage through the activation of nuclear factor erythroid 2 p45 (NF-E2)-related factor (Nrf2)/antioxidant response element (ARE) pathway was studied in vitro. Dose-dependent effects of pre-incubated flavonoids on pro-carcinogen 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKAc)-induced ROS and DNA damage in human bronchial epithelial cells were studied in comparison to non-flavonoids. The most effective flavonoids were assessed for the activation of Nrf2/ARE pathway. Genistein, procyanidin B2 (PCB2), and quercetin significantly suppressed the NNKAc-induced ROS and DNA damage. Quercetin significantly upregulated the phosphorylated protein kinase B/Akt. PCB2 significantly upregulated the activation of Nrf2 and Akt through phosphorylation. Genistein and PCB2 significantly upregulated the phospho-Nrf2 nuclear translocation and catalase activity. In summary, genistein and PCB2 reduced the NNKAc-induced ROS and DNA damage through the activation of Nrf2. Further studies are required to understand the role of dietary flavonoids on the regulation of the Nrf2/ARE pathway in relation to carcinogenesis.

Litchi procyanidins inhibit colon cancer proliferation and metastasis by triggering gut-lung axis immunotherapy

Litchi chinensis seed, as a valuable by-product of the subtropical fruit litchi (Litchi chinensis Sonn.), has been confirmed to be rich in procyanidins (LPC). The anticarcinogenic properties of procyanidins has been primarily attributed to their antioxidant and anti-inflammatory activities. However, there is a comparative paucity of information on if and how LPC inhibits colon cancer. Here, LPC significantly inhibited CT26 colon cancer cells proliferation and metastasis in vivo and in vitro. In CT26 lung metastatic mice, the anti-metastatic effect of LPC relied on its regulation of gut microbiota such as increase of Lachnospiraceae UCG-006, Ruminococcus, and their metabolites such as acetic acid, propionic acid and butyric acid. In addition, LPC significantly inhibited CT26 colon cancer cells metastasis through increasing CD8⁺ cytotoxic T lymphocytes infiltration and decreasing the number of macrophages. Antibiotics treatment demonstrated that the therapeutic effect of LPC depended on the gut microbiota, which regulated T cells immune response. Taken together, LPC had strong inhibitory effects on colon cancer pulmonary metastasis by triggering gut-lung axis to influence the T cells immune response. Our research provides a novel finding for the utilization of procyanidins in the future, that is, supplementing more fruits and vegetables rich in procyanidins is beneficial to the treatment of colon cancer, or it can be used as an adjuvant drug in clinical anti-tumor immunotherapy.

Proanthocyanidins Delay Fruit Coloring and Softening by Repressing Related Gene Expression during Strawberry (Fragaria × ananassa Duch.) Ripening

Proanthocyanidins (PAs), also known as condensed tannins, are widespread throughout the plant kingdom, presenting diverse biological and biochemical activities. Being one of the most abundant groups of natural polyphenolic antioxidant, PAs are applied to improve plant tolerance to (a)biotic stresses and delay the senescence of fruit by scavenging the reactive oxygen species (ROS) and enhancing antioxidant responses. The effects of PAs on coloring and softening of strawberries (Fragaria × ananassa Duch.), a worldwide demanded edible fruit and typical material for studying non-climacteric fruit ripening, were firstly assessed in this work. The results showed that exogenous PAs delayed the decrease in fruit firmness and anthocyanins accumulation but improved the fruit skin brightness. Strawberries treated with PAs had similar total soluble solids, total phenolics, and total flavonoids, but lower titratable acidity content. Moreover, the contents of endogenous PAs, abscisic acid and sucrose, were somehow increased by PA treatment, while no obvious change was found in fructose and glucose content. In addition, the anthocyanin- and firmness-related genes were significantly repressed, while the PA biosynthetic gene (anthocyanin reductase, ANR) was highly up-regulated by PA treatment at the key point for fruit softening and coloring. In summary, the results presented in this study suggest that PAs slow down strawberry coloration and softening by inhibiting the expression of related genes, which could be helpful for a better understanding of the biological role of PAs and provide a new strategy to regulate strawberry ripening.

Proanthocyanidins attenuates ferroptosis against influenza-induced acute lung injury in mice by reducing IFN-γ

BACKGROUND

Acute lung injury (ALI) is associated with high morbidity and mortality and is partly driven promoted by ferroptosis. Proanthocyanidins (PAs) is a natural bioactive flavonoid with anti-inflammatory and antioxidant activities. PAs can also significantly protect against acute lung inflammation and ferroptosis in alveolar epithelial cells. However, it is unclear whether PAs can alleviate ALI by reducing ferroptosis. This study aimed to evaluate the protective effects of PAs and the potential mechanisms against Influenza A virus (IAV)-induced ALI.

METHODS

Mice were inoculated nasally with IAV to induce ALI. IAV-induced pulmonary inflammation and ferroptosis was tested by measuring the levels of malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11) and acyl-CoA synthetase long-chain family member (ACSL4) in lung tissue. The potential targets that PAs protect against IAV-induced ALI were determined via a systemic pharmacological analysis. The molecular mechanism of PAs in ALI treatment was investigated by assessing the level of inflammation and ferroptosis markers using Western Blot and quantitative real-time PCR.

RESULTS

Systemic pharmacological analysis suggested that PAs protect against IAV-induced pneumonia thorough TGF-β1 and its relative signaling pathway. PAs effectively alleviated histopathological lung injury, reduced inflammatory cytokines and chemokines secretion, which were increased in IAV-infected mice. Meanwhile, PAs further prevented mouse airway inflammation in ALI, concomitant with the decreased expression TGF-β1, smad2/3, p-Smad2, p-Smad3 and ferroptosis mediator IFN-γ. Furthermore，IFN-γ promotes cell lipid peroxidation and ferroptosis，PAs significantly reduced MDA and ACSL4 levels and upregulated GSH, GPX4, and SLC7A11.

CONCLUSION

Overall, PAs can attenuate ferroptosis against IAV-induced ALI via the TGF-β1/Smad2/3 pathway and is a promising novel therapeutic candidate for ALI.

Anti-Inflammatory, Anti-Bacterial, and Anti-Fungal Activity of Oligomeric Proanthocyanidins and Extracts Obtained from Lignocellulosic Agricultural Waste

It has now been proven that many pathogens that cause infections and inflammation gradually mutate and become resistant to antibiotics. Chemically synthesized drugs treating inflammation most often only affect symptoms, but side effects could lead to the failure of human organs' functionality. On the other hand, plant-derived natural compounds have a long-term healing effect. It was shown that sea buckthorn (SBT) twigs are a rich source of biologically active compounds, including oligomeric proanthocyanidins (PACs). This study aimed to assess the anti-pathogenic and anti-inflammatory activity of water/ethanol extracts and PACs obtained from the lignocellulosic biomass of eight SBT cultivars. The anti-pathogenic activity of extracts and PACs was studied against pathogenic bacteria Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Bacillus cereus and fungus Candida albicans in 96-well plates by the two-fold serial broth microdilution method. The anti-bacterial activity of purified PACs was 4 and 10 times higher than for water and water/ethanol extracts, respectively, but the extracts had higher anti-fungal activity. Purified PACs showed the ability to reduce IL-8 and IL-6 secretion from poly-I:C-stimulated peripheral blood mononuclear cells. For the extracts and PACs of SBT cultivar 'Maria Bruvele' in the concentration range 0.0313-4.0 mg/mL, no toxic effect was observed.

Anti-Streptococcus mutans, anti-adherence and anti-acidogenic activity of Uvaria chamae P. Beauv

ETHNOPHARMACOLOGICAL RELEVANCE

Streptococcus mutans a key pathogen, produces biofilm, acids and extracellular polysaccharides in the oral cavity; which leads to the development of dental caries. Control of these pathogenic markers can prevent dental caries. Uvaria chamae P. Beauv. is a medicinal plant traditionally used for many ailments including oral infections. Root, leaves and bark extracts has proven antibacterial activity including activity against caries causing S. mutans. However, its effect on the virulence properties of S. mutans, responsible for the development of dental caries, has not been studied.

AIM OF THE STUDY

This study investigated the phytochemical constituents, anti-S. mutans, anti-adherence and anti-acidogenic activity of U. chamae root extract.

MATERIALS AND METHODS

Extracts were prepared and phytochemical analysis was performed. Minimum inhibitory concentrations (MIC) were determined, and MIC and sub-MIC concentrations of the best solvent were selected for their effect on the virulence factors of S. mutans. The results were analysed using one-way ANOVA and Wilcoxon Rank Sum Tests.

RESULTS

The dichloromethane extract, with proanthocyanidin as a major chemical constituent, produced an MIC of 0.02 mg/ml. At 6 h, exposure to 0.005, 0.01, and 0.02 mg/ml extract significantly reduced S. mutans adherence by 39, 59, and 77% respectively (p < 0.05). Uvaria chamae also significantly inhibited acid production in S. mutans at 10, 12, 14 and 16 h (p < 0.05). At ½ MIC, the plant extract caused remarkable downregulation of the virulence genes responsible for the adherence, biofilm formation, extracellular polysaccharide synthesis and acid production.

CONCLUSIONS

This suggests that U. chamae extract may potentially be used to inhibit the proliferation of S. mutans and silencing the expression of pathology-related genes, which will prevent the development of dental caries.