Bioaccessibility and Absorption Mechanism of Phenylethanoid Glycosides Using Simulated Digestion/Caco-2 Intestinal Cell Models

Noninvasive Detection and Monitoring of the Integrity of the Intestinal Barrier through NIR-II Fluorescence Imaging and Colorimetric Urinalysis

The variation of the integrity of the intestinal barrier is closely related to the occurrence and progression of various diseases, making its accurate detection and monitoring essential to provide reliable information for guiding the refinement of treatment scenarios. Herein, we developed a strategy utilizing glutathione-capped gold clusters (Au-GSH) to achieve simultaneous in vivo second near-infrared (NIR-II) fluorescence imaging and in vitro colorimetric urinalysis for noninvasive detection and monitoring of intestinal barrier integrity. After oral administration, Au-GSH can demonstrate different distribution behaviors in terms of the variation of intestinal barrier integrity. Specifically, Au-GSH could selectively permeate through compromised intestinal barrier to be distributed into the bladder in view of its ultrasmall size below the glomerular filtration cutoff, leading to the rapid excretion through urine. Such process can be visually profiled by collecting NIR-II fluorescence (>1100 nm) emitting from Au-GSH in a noninvasive real-time manner. By virtue of the peroxidase-like activity of Au-GSH, the simple colorimetric urinalysis was further established for evaluating the integrity of the intestinal barrier, advancing the detection and monitoring performance. As a result, our developed strategy successfully detected the damage of intestinal barrier integrity in ulcerative colitis (UC) mice, a common disease characterized by compromised intestinal barrier integrity. Excitingly, the monitoring of restoration of intestinal barrier integrity in both therapeutic and preventative modes for UC mice was also realized by our strategy, making it a promising diagnosis scenario for diseases related to the variation of intestinal barrier integrity.

The intestinal absorption of triptolide for the treatment of rheumatoid arthritis is mediated by transporters

Tripterygium wilfordii Hook. f. is a traditional Chinese herb that is used to treat rheumatoid arthritis (RA). Triptolide (TP), an epoxidized diterpene lactone extracted from this herb, has been suggested to be the primary active and toxic component. In this work, the material basis and molecular mechanism of toxicity induced by T. wilfordii preparations in RA were investigated. Female rats with collagen-induced arthritis were given 500 μg·kg-1 TP intragastrically or intravenously. Compared with that in the control group, the AUClast in the CIA group was 1.7-fold greater after intragastric administration, while this value decreased 22.6 % after intravenous administration, suggesting that the absorption of TP was significantly greater in the CIA group. The results from RT-PCR and probe substrate perfusion indicated that Oatp1a5 expression was upregulated while P-glycoprotein (P-gp) expression was downregulated in the duodenums of CIA rats. Naringin, an inhibitor of Oatp1a5, decreased the Peff of TP in the rat duodenum by 27.9 %, whereas verapamil hydrochloride, an inhibitor of P-gp, increased the Peff by 50.8 %, suggesting that Oatp1a5 and P-gp mediate the uptake and efflux of TP in the rat duodenum, respectively. Furthermore, among the upstream nuclear receptors, the mRNA expression levels and protein expression levels of FXR and VDR were noticeably decreased. In the present study, the absorption of TP in the duodenums of CIA rats significantly increased due to the upregulation of Oatp1a5 expression and the downregulation of P-gp expression, leading to an increase in TP plasma exposure after intragastric administration. The altered expression of Oatp1a5 and P-gp may be related to FXR and VDR.

Verbascoside: comprehensive review of a phenylethanoid macromolecule and its journey from nature to bench

Polyphenolic compounds are among the most widely researched compounds for various therapeutic applications. However, naturally occurring phenylethanoid glycosides are least explored under this class of compounds. One such phenylethanoid glycoside, verbascoside (Vb), abundantly found among 200 species of 23 families, has gained recent attention due to its wide-spectrum therapeutic properties such as antioxidant, antimicrobial, anti-inflammatory, neuroprotective, cardioprotective, skin-protective, and anti-cancer. Despite having multiple therapeutic benefits, due to its large size, the compound has poor bioavailability for oral and topical applications. To meet these limitations, current research on Vb focuses on delivering it through nanoformulations. Presently, most developed formulations are liposome based for various applications, such as corneal epithelial wound healing, anti-neuropathic, anti-wrinkle, anti-hyperalgesia, atopic dermatitis, alopecia, and cutaneous wound healing. Multiple studies have confirmed the least acute and sub-acute toxicity for Vb. Few clinical studies have been performed for the therapeutic application of Vb to manage COVID-19, nephropathy, platelet aggregation, chronic primary glomerulonephritis, and acute hepatitis. Recent studies have shown the immense therapeutic potential of Vb in wound healing, dermatitis, neuroprotection, and anti-cancer activities, which creates a need for developing novel formulations for their respective uses. Long-term toxicity studies and techniques for scaling up Vb production by biotechnological approaches should be emphasized.

Effects of salidroside on atherosclerosis: potential contribution of gut microbiota

Much research describes gut microbiota in atherosclerotic cardiovascular diseases (ASCVD) for that the composition of the intestinal microbiome or its metabolites can directly participate in the development of endothelial dysfunction, atherosclerosis and its adverse complications. Salidroside, a natural phenylpropane glycoside, exhibits promising biological activity against the progression of ASCVD. Recent studies suggested that the gut microbiota played a crucial role in mediating the diverse beneficial effects of salidroside on health. Here, we describe the protective effects of salidroside against the progression of atherosclerosis. Salidroside regulates the abundance of gut microbiotas and gut microbe-dependent metabolites. Moreover, salidroside improves intestinal barrier function and maintains intestinal epithelial barrier function integrity. In addition, salidroside attenuates the inflammatory responses exacerbated by gut microbiota disturbance. This review delves into how salidroside functions to ameliorate atherosclerosis by focusing on its interaction with gut microbiota, uncovering the potential roles of gut microbiota in the diverse biological impacts of salidroside.

Fabrication of 3D engineered intestinal tissue producing abundant mucus by air-liquid interface culture using paper-based dual-layer scaffold

Fabrication of engineered intestinal tissues with the structures and functions as humans is crucial and promising as the tools for developing drugs and functional foods. The aim of this study is to fabricate an engineered intestinal tissue from Caco-2 cells by air-liquid interface culture using a paper-based dual-layer scaffold and analyze its structure and functions. Just by simply placing on a folded paper soaked in the medium, the electrospun gelatin microfiber mesh as the upper cell adhesion layer of the dual-layer scaffold was exposed to the air, while the lower paper layer worked to preserve and supply the cell culture medium to achieve stable culture over several weeks. Unlike the flat tissue produced using the conventional commercial cultureware, Transwell, the engineered intestinal tissue fabricated in this study formed three-dimensional villous architectures. Microvilli and tight junction structures characteristic of epithelial tissue were also formed at the apical side. Furthermore, compared to the tissue prepared by Transwell, mucus production was significantly larger, and the enzymatic activities of drug metabolism and digestion were almost equivalent. In conclusion, the air-liquid interface culture using the paper-based dual-layer scaffold developed in this study was simple but effective in fabricating the engineered intestinal tissue with superior structures and functions.

Analysis of Lemon Verbena Polyphenol Metabolome and Its Correlation with Oxidative Stress under Glucotoxic Conditions in Adipocyte

Lemon verbena has been shown to ameliorate obesity-related oxidative stress, but the intracellular final effectors underlying its antioxidant activity are still unknown. The purpose of this study was to correlate the antioxidant capacity of plasma metabolites of lemon verbena (verbascoside, isoverbascoside, hydroxytyrosol, caffeic acid, ferulic acid, homoprotocatechuic acid, and luteolin-7-diglucuronide) with their uptake and intracellular metabolism in hypertrophic adipocytes under glucotoxic conditions. To this end, intracellular ROS levels were measured, and the intracellular metabolites were identified and quantified by high-performance liquid chromatography with a diode array detector coupled to mass spectrometry (HPLC-DAD-MS). The results showed that the plasma metabolites of lemon verbena are absorbed by adipocytes and metabolized through phase II reactions and that the intracellular appearance of these metabolites correlates with the decrease in the level of glucotoxicity-induced oxidative stress. It is postulated that the biotransformation and accumulation of these metabolites in adipocytes contribute to the long-term antioxidant activity of the extract.

Fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus alleviate the intestinal barrier injury and oxidative stress damage in vitro and in vivo

This study aimed to investigate the alleviative effects of fucosylated chondroitin sulfate from sea cucumber Stichopus chloronotus (fCSSc) on the intestinal barrier injury and oxidative stress damage in vitro and in vivo. The results showed that fCS-Sc protected the intestinal barrier and improved the antioxidant function in H2O2 damaged Caco-2 cells via up-regulating the tight junction proteins and activating Keap1-Nrf2-ARE antioxidant pathway. Furthermore, administration fCS-Sc could ameliorate the weight loss and spleen index decrease in Cyclophosphamide (Cy) treated mice, improve the expressions of ZO-1, Claudin-1, Nrf2, SOD, and NQO-1 in Cy damaged colon tissue, showing significant protective effects against intestinal barrier damage and oxidative stress in vivo. fCS-Sc intervention also alleviated the gut microbiota disorder though increasing the richness and diversity of intestinal bacteria, regulating the structural composition of gut microbiota. fCS-Sc promoted the relative abundance of beneficial microbiota and inhibited the growth of harmful bacteria. This study provided a theoretical basis for the application of fCS-Sc as a prebiotic in chemotherapy.

Transport and interaction mechanism of four pesticide residues from Chaenomeles speciosa across Caco-2 cells

The presence of multiple pesticide residues in agricultural production highlights the need for studying mixture interaction during transepithelial transport. This study applied the Caco-2 cell model to investigate the interaction of four pesticide residues (carbendazim, epoxiconazole, phoxim, and chlorpyrifos) in Chaenomeles speciosa during transepithelial transport. Results demonstrated that co-treatment with pesticide mixtures generally increased the cumulative transport amount of carbendazim and epoxiconazole by 0.32-1.60 times and 0.32-0.98 times, respectively, compared to individual treatments. Notably, the combination of carbendazim and epoxiconazole displayed a significant synergistic effect. The use of transporter inhibitors and molecular docking analysis provided insights into the interaction mechanism, suggesting that the competitive inhibition of MRP2 and/or BCRP binding via π-bonds contributed to the inhibition of BL-to-AP efflux and a significant increase in AP-to-BL influx of carbendazim and epoxiconazole. The results are of great theoretical significance and practical value for risk assessment of multiple pesticide residues in agricultural products.

Necroptosis in Pneumonia: Therapeutic Strategies and Future Perspectives

Pneumonia remains a major global health challenge, necessitating the development of effective therapeutic approaches. Recently, necroptosis, a regulated form of cell death, has garnered attention in the fields of pharmacology and immunology for its role in the pathogenesis of pneumonia. Characterized by cell death and inflammatory responses, necroptosis is a key mechanism contributing to tissue damage and immune dysregulation in various diseases, including pneumonia. This review comprehensively analyzes the role of necroptosis in pneumonia and explores potential pharmacological interventions targeting this cell death pathway. Moreover, we highlight the intricate interplay between necroptosis and immune responses in pneumonia, revealing a bidirectional relationship between necrotic cell death and inflammatory signaling. Importantly, we assess current therapeutic strategies modulating necroptosis, encompassing synthetic inhibitors, natural products, and other drugs targeting key components of the programmed necrosis pathway. The article also discusses challenges and future directions in targeting programmed necrosis for pneumonia treatment, proposing novel therapeutic strategies that combine antibiotics with necroptosis inhibitors. This review underscores the importance of understanding necroptosis in pneumonia and highlights the potential of pharmacological interventions to mitigate tissue damage and restore immune homeostasis in this devastating respiratory infection.

Quercetin Enhances the Availability of 5-Heptadecylresorcinol by Inhibiting the Expression of P-gp

5-Heptadecylresorcinol (AR-C17), as the most important active monomer, is found in large quantities in wheat and triticale and plays a variety of health benefits, such as antidiabetic, anti-inflammatory, and antitumor. However, the low bioavailability of AR-C17 due to its low water solubility restricts its application. Moreover, the transport mechanism of AR-C17 is not fully understood. Here, we showed that the transport of AR-C17 in vitro was time- and concentration-dependent, and relatively higher temperature and lower pH obviously promoted the transport of AR-C17. Besides, transporters, especially P-glycoprotein (P-gp), markedly affected the transport of AR-C17 as well. Quercetin, a natural synergist in triticale bran (TB), was confirmed as an inhibitor of P-gp to promote the transport of AR-C17 in this study, and the bioavailability of AR-C17 reached the highest when the concentration ratio of quercetin to AR-C17 was 1:1.

Impact of dietary plant flavonoids on 7,8-dihydroxyflavone transepithelial transport in human intestinal Caco-2 cells

7,8-dihydroxyflavone (7,8-DHF) is a biologically active flavone with various physiological activities, including neuroprotection, anti-inflammation, and weight loss. Previous studies have found that the efflux protein P-glycoprotein (P-gp) significantly affects the transepithelial transport of 7,8-DHF in the intestine, resulting in its low oral bioavailability. Based on this, in this study, a Caco-2 monolayer cell model was used to investigate 14 dietary plant flavonoids as potential P-gp inhibitors, and their effects on the transepithelial transport and in vitro digestion of 7,8-DHF were explored. The results showed that among the 14 plant flavonoids, hesperetin, epigallocatechin gallate, fisetin, kaempferol, quercetin, and isoorientin increased and the apparent permeability coefficients (P app) of 7,8-DHF at AP → BL direction and lowered P app value at BL → AP direction to varying degrees, reducing the efflux ratio of 7,8-DHF less than 1.5. In particular, kaempferol and quercetin exhibited the best effect on promoting the transepithelial transport of 7,8-DHF, especially when used at molar concentration ratios of 1:1 and 1:2 with 7,8-DHF. This is beneficial for improving the oral bioavailability of 7,8-DHF. Meanwhile, 7,8-DHF was found to maintain structural stability in simulated saliva, gastric juice, and intestinal juice, and its stability was not affected by the coexistence of quercetin and kaempferol. Overall, this study provided a theoretical basis for seeking natural and safe P-gp inhibitors to improve the oral absorption of natural products.

Synthesis of phenylethanoid glycosides from acrylic esters of glucose and aryldiazonium salts via palladium-catalyzed cross-coupling reactions and evaluation of their anti-Alzheimer activity

Cinnamic acid-containing sugar compounds such as phenylethanoid glycosides are widely present in nature and display various biological activities. In this work, the synthesis of trans-cinnamic acid containing phenylethanoid glycosides was achieved via palladium-catalyzed cross-coupling reactions between glycosyl acrylic esters and aryldiazonium salts. A wide range of functionalized aryldiazonium salts were successfully coupled with 6-O- and 4-O-acrylic esters of glucose under optimized conditions. The reactions proceeded at room temperature in the absence of additives and base. The desired products were obtained in good to excellent yields. Selected compounds from the library were screened for anti-Alzheimer activity, while compound 16 displayed significant inhibitory activities against butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzymes.

Green-Efficient Enzymatic Synthesis and Characterization of Liposoluble 6'/6″-O-Lauryl Phenolic Glycosides with Enhanced Intestinal Permeability

Arbutin, salidroside, polydatin, and phlorizin are typically natural bioactive phenolic glycosides. To improve the liposolubility and bioavailability, highly liposoluble derivatives including 6'-O-lauryl arbutin, 6'-O-lauryl salidroside, 6″-O-lauryl polydatin, and 6″-O-lauryl phlorizin were efficiently synthesized by enzymatic acylation in a green solvent 2-MeTHF. Their reaction conversions reached 84.4, 99.5, 99.8, and 89.1%, respectively, when catalyzed by Lipozyme 435 at 20 mg/mL at 50 °C. As expected, the derivatives had high log P (1.66-2.37) and retained good antioxidant activity, making them potential alternatives to butylated hydroxytoluene (BHT) and tert-butyl-hydroquinone (TBHQ) in lipid systems. Then, the intestinal permeability characteristics and metabolism of phenolic glycosides and their derivatives were investigated based on Caco-2 monolayers. The permeability of polydatin and phlorizin was mainly through active transport, but that of arbutin and salidroside involved both passive diffusion and active uptake. The acylated derivatives suffered from severe CES-mediated hydrolysis but exhibited a larger transported amount than phenolic glycosides.

Acteoside palliates d-galactose induced cognitive impairment by regulating intestinal homeostasis

Acteoside, an important phenylethanol glycoside, is the main active component in Osmanthus fragrans flower. Our previous study found that acteoside showed high antiaging effect but its absorption rate was low. We speculated acteoside palliated aging-related cognitive impairment before being absorbed, that was intestinal homeostasis underlie the antiaging effect of acteoside. In this study, acteoside was confirmed to palliate cognitive impairment in d-galactose induced aging mice. Acteoside treatment dramatically reduced oxidative stress, alleviated intestinal inflammation, restored intestinal mucosal barrier, rebuilt gut microbiome structure and upregulated gut microbiome metabolites short-chain fatty acids (SCFAs) and amino acids (AAs). Furthermore, antibiotic treatment revealed that the antiaging ability of acteoside was abolished in microbiota depleted mice, which offered direct evidence for the essential role of gut microbiota in the attenuation of cognitive impairment of acteoside. Together, our study indicated that acteoside palliated cognitive impairment by regulating intestinal homeostasisand acteoside intake might be a promising nutritional intervention in prevention of neurodegenerative diseases.

A Stability-Indicating Assay for Tetrahydrocurcumin-Diglutaric Acid and Its Applications to Evaluate Bioaccessibility in an In Vitro Digestive Model

A simple and reliable ultra-high-performance liquid chromatographic (UHPLC) method was developed and validated for determination of tetrahydrocurcumin diglutaric acid (TDG) and applied for evaluation of its bioaccessibility. The analytical method was validated to demonstrate as a stability-indicating assay (SIA) according to the ICH Q2(R1) guidelines under various force degradation conditions including thermal degradation, moisture, acid and base hydrolysis, oxidation, and photolysis. The developed chromatographic condition could completely separate all degradants from the analyte of interest. The method linearity was verified in the range of 0.4-12 μg/mL with the coefficient of determination (r²) > 0.995. The accuracy and precision of the method provided %recovery in the range of 98.9-104.2% and %RSD lower than 4.97%, respectively. The limit of detection and quantitation were found to be 0.25 μg/mL and 0.40 μg/mL, respectively. This method has been successfully applied for the bioaccessibility assessment of TDG with the bioaccessibility of TDG approximately four fold greater than THC in simulated gastrointestinal fluid. The validated SIA method can also benefit the quality control of TDG raw materials in pharmaceutical and nutraceutical development.

Improved uptake and bioavailability of cinnamaldehyde via solid lipid nanoparticles for oral delivery

OBJECTIVE

The purpose of this experiment was to explore the effect of Solid lipid nanoparticles (SLNs) on improving the oral absorption and bioavailability of cinnamaldehyde (CA).

METHODS

CA-SLNs were prepared by high-pressure homogenization and characterized by particle size, entrapment efficiency, and morphology, thermal behavior and attenuated total reflection Fourier transform infrared (ATR-FTIR). In vitro characteristics of release, stability experiments, cytotoxicity, uptake and transport across Caco-2 cell monolayer of CA-SLNs were studied as well. In addition, CA-SLNs underwent pharmacokinetic and gastrointestinal mucosal irritation studies in rats.

RESULTS

CA-SLNs exhibited a spherical shape with a particle size of 44.57 ± 0.27 nm, zeta potential of -27.66 ± 1.9 mV and entrapment efficiency of 83.63% ± 2.16%. Differential scanning calorimetry (DSC) and ATR-FTIR confirmed that CA was well encapsulated. In vitro release of CA-SLNs displayed that most of the drug (90.77% ± 5%) was released in the phosphate buffer, and only a small amount of drug (18.55% ± 5%) was released in the HCl buffer. CA-SLNs were taken up by an energy-dependent, endocytic mechanism mediated by caveolae mediated endocytosis across Caco-2 cells. The CA permeation through Caco-2 cell was facilitated by CA-SLNs. The outcome of the gastrointestinal irritation test demonstrated that CA-SLNs had no irritation to the rats' intestines. Compared with CA dispersions, incorporation of SLNs increased the oral bioavailability of CA more than 1.69-fold.

CONCLUSIONS

It was concluded that CA-SLNs improved the absorption across Caco-2 cell model and improved the oral administration bioavailability of CA in rats.

The pharmacokinetic property and pharmacological activity of acteoside: A review

Acteoside (AC), a phenylpropanoid glycoside isolated from many dicotyledonous plants, has been demonstrated various pharmacological activities, including anti-oxidation, anti-inflammation, anti-cancer, neuroprotection, cardiovascular protection, anti-diabetes, bone and cartilage protection, hepatoprotection, and anti-microorganism. However, AC has a poor bioavailability, which can be potentially improved by different strategies. The health-promoting characteristics of AC can be attributed to its mediation in many signaling pathways, such as MAPK, NF-κB, PI3K/AKT, TGFβ/Smad, and AMPK/mTOR. Interestingly, docking simulation study indicates that AC can be an effective candidate to inhibit the activity of SARS-CoV2 main protease and protect against COVID-19. Many clinical trials for AC have been investigated, and it shows great potentials in drug development.

Profiling of Phenolic Compounds of Fruit Peels of Different Ecotype Bananas Derived from Domestic and Imported Cultivars with Different Maturity

Banana is one of the most produced and consumed fruits in the world and its fruit peel accounts for about 40% of the total fresh quantity of ripe fruit, which is usually regarded as waste and poses serious environmental hazards. However, it is a promising source of natural bioactive compounds including phenolic compounds. Determination of the phenolic compounds in fruit peel from different cultivars and subgroups over a range of maturities provides convincing information for making full use of them. This study developed a sensitive and reliable analytical method—ultra-high performance liquid chromatography—coupled with electrospray ionization tandem mass spectrometry (UPLC-MS/MS) for measuring phenolic compounds in fruit peel from different ecotype cultivars and subgroups with different maturity. The results showed that quinic acid had the highest concentration ratio among the main phenolic compounds in the green/ripe peel of all banana cultivars; among all banana cultivars, the total phenolic compound contents of green banana peel were significantly higher than that of ripe banana peel; the total phenolic compound contents in the green/ripe fruit peel of non-dessert bananas were significantly higher than that of dessert bananas (green: non-dessert banana 1.48 ± 0.44 mg/g vs. dessert banana 0.97 ± 0.12 mg/g; ripe: non-dessert banana 0.26 ± 0.13 mg/g vs. dessert banana 0.19 ± 0.06 mg/g). These data provide a basis for the rational utilization of phenolic compound extractions from banana peel with huge biomass in the next step.

Efficient Enzymatic Synthesis of Lipophilic Phenolic Glycoside Azelaic Acid Esters and Their Depigmenting Activity

In this paper, an enzymatic route for synthesizing phenolic glycoside azelaic acid esters was successfully set up via lipase-catalyzed esterification and transesterification. Among the lipases tested, Candida antarctica lipase B (Novozyme 435) showed the highest activity in catalyzing esterification and Thermomyces lanuginosus (Lipozyme TLIM) gave the highest substrate conversion in catalyzing transesterification for the synthesis of ester. The addition of 4A molecular sieves into the reaction system is found to be an effective method for in situ absorption of the byproduct water and methanol, with which the substrate conversions of the enzymatic esterification and transesterification were 98.7 and 95.1%, respectively. Also, the main product ratios in transesterification were above 99.0% with lipozyme TLIM as a catalyst because the hydrolysis reaction was hindered. The results of the physical and biological properties indicate that all esters had higher Clog p values than their parent compounds. Also, the esters showed higher intracellular tyrosinase inhibitory and depigmentating activities than phenolic glycosides, azelaic acid (AA), and their physical mixtures due to their higher membrane penetration and tyrosinase inhibitory effects. In particular, piceid 6″-O-azelaic acid ester (PIA) showed the strongest inhibitory effect against melanin production. Its inhibitory rate was 77.4% at a concentration of 0.25 mM, about 4.2 times higher than that of arbutin (18.5%).

Study on the bioaccessibility and bioavailability of Cd in contaminated rice in vitro and in vivo

Cadmium (Cd) is a widespread heavy metal pollutant in the environment that damages human health. In this study, the bioaccessibility and bioavailability of Cd in different Cd-contaminated rice (low pollution level cadmium rice (Rice-L, 0.111 mg/kg), medium pollution level cadmium rice (Rice-M, 0.400 mg/kg), and high pollution level cadmium rice (Rice-H, 0.655 mg/kg)) were estimated and determined by an in vitro digestion model Rijksinstituut voor volksgezondheiden milieu (RIVM), Caco-2 cell model, and mouse model. The results indicated that Cd in the oral cavity (15.65-28.28%) displayed the lowest bioaccessibility comparing with small intestine (90.04-94.73%) and the stomach (99.30-100.70%) in vitro after cooking. In addition, the results showed that the bioaccessibility of Cd in CdCl₂ , CdCl₂ +normal rice (Rice-N), Rice-H, Rice-M, Rice-L group were 99.29%, 92.57%, 90.04%, 94.73%, and 91.11%, respectively; the in vitro bioavailability of Cd in CdCl₂ , CdCl₂ +Rice-N, Rice-H, Rice-M, and Rice-L group were 27.50%, 20.78%, 21.90%, 26.90%, 36.46%, respectively, we found that the group of CdCl₂ is significantly higher than CdCl₂ +Rice-N and Rice-H (p < 0.05), while the targets hazard quotient (THQ) value of rice ingested without considering the in vitro bioavailability is 2.7-4.6 times than the THQ value with considered and the relative bioavailability (RBA) of Cd in Rice-L, Rice-M, Rice-H are 80.25%, 64.32%, and 60.91%, respectively. These results indicate that the rice substrate has impact on the bioaccessibility and bioavailability of Cd, and might overestimate the health risks of Cd if bioavailability was not considered. PRACTICAL APPLICATION: Studying the bioaccessibility and bioavailability of cadmium in rice is a promising strategy to obtain a more accurate human health risk assessment of cadmium exposure in rice, as well as provide a theoretical basis for the formulation of cadmium limit standard in grain, which was also conducive to the rational and full utilization of rice resources in China.

Bioaccessibility and Absorption of Flavonoid C-glycosides from Abrus mollis Using Simulated Digestion, Caco-2 Cell, and In Situ Single-pass Perfusion Models

Abrus mollis is commonly used as a traditional Chinese medicine for the treatment of liver diseases due to its hepatoprotection and anti-inflammation, but the absorption properties of its main bioactive ingredients remain unclear. Our previous studies verified that the flavonoid C-glycosides, including vicenin-2 (1: ), isoschaftoside (2: ), and schaftoside (3: ), were the major active components in A. mollis for hepatic protection against nonalcoholic fatty liver disease, hepatitis, and hepatic fibrosis. This study investigated the bioaccessibility and transport mechanisms of total flavonoid C-glycoside, as well as vicenin-2 (1: ), isoschaftoside (2: ), and schaftoside (3: ), in A. mollis by simulated digestion and use of the Caco-2 cell model. Moreover, this study attempted to verify their absorption properties by in situ gastrointestinal perfusion in rats. Total flavonoid C-glycoside and 1, 2: , and 3: exhibited similar bioaccessibility of 84.58%, 85.13%, 83.05%, and 81.65% respectively after simulated digestion. The transport of total flavonoid C-glycoside in the Caco-2 cell model increased with the concentration, and the transport showed saturation characteristics with the time and concentration of total flavonoid C-glycoside to a certain degree. The Papp values of total flavonoid C-glycoside and the 3 flavonoid C-glycosides were significantly improved by verapamil, probenecid, and EDTA-Na₂. Their absorption properties in the gastrointestinal tract were consistent with that found in Caco-2 cells, and superior absorption rates were observed in the duodenum and jejunum. The absorption pattern of total flavonoid C-glycoside may involve multiple transport pathways, including active transport, passive diffusion, and the paracellular pathway. TFC was actively pumped out by P-glycoprotein and multidrug resistance-associated protein. These results revealed that the bioaccessibility and intestinal absorption characteristic of total flavonoid C-glycoside were consistent with the 3 major flavonoids.

Electrospun Scaffold for Biomimic Culture of Caco-2 Cell Monolayer as an In Vitro Intestinal Model

The Caco-2 cell monolayer has been extensively used for the high-throughput assessing of nutrient absorption, screening of drug permeability, and studying the intestinal physiological process in vitro. The most used Caco-2 cell model is the Transwell model with polycarbonate microporous membranes. However, Caco-2 cells in the classical Transwell model need 21 days to gain an intact and mature monolayer. Electrospun nanofiber scaffolds mimicking the natural extracellular matrix could improve cell adhesion, proliferation, and expression, whereas there are no reports that intestinal cells were cultured on the electrospun nanofiber scaffolds. Here, electrospun polylactic acid (PLA) nanofiber scaffolds were chosen as the ideal scaffolds for Caco-2 cell monolayers to construct a modified Transwell. Cell morphology and polarity were studied. Monolayer barrier properties were assessed by measuring transepithelial electrical resistance (TEER) and the leakage of phenol red. As found, intact Caco-2 cell monolayers were formed on the PLA nanofiber scaffolds after 4 days of culture. After 4 days, the TEER increased to 422 Ω·cm² and the apparent permeability coefficients of phenol red decreased to 1.0 ± 0.1 × 10^-6 cm/s, suggesting that Caco-2 cell monolayers developed a formidable barrier to small molecules on the surface of PLA nanofiber scaffolds. Microvilli and tight junctions were clearly visible after day 3. Besides, Caco-2 cell monolayers on the surface of PLA nanofiber scaffolds presented higher differentiation properties than on the surface of the polycarbonate microporous membrane in traditional Transwell including higher alkaline phosphatase activity and higher P-gp activity. Results of quercetin absorption and probiotics adhesion demonstrated that Caco-2 cell monolayers formed on the surface of PLA nanofiber scaffolds also had better physiological function and prediction function in vitro. Overall, the present study indicated that the Transwell with the structurally and functionally biomimetic electrospun PLA nanofiber scaffold could be potentially developed as a promising in vitro intestinal model.

Study on the bioaccessibility and bioavailability of perchlorate in different food matrices in vitro

Perchlorate, a persistent pollutant, interferes with iodine uptake by the thyroid. Perchlorate exposure mainly occurs through ingested food; understanding the bioaccessibility and bioavailability of perchlorate in foods facilitate more accurate human health risk assessments. An in vitro digestion/Caco-2 cell model was used for this research. The bioaccessibility of perchlorate in the control group, lettuce, rice and formula was 93.45%, 70.14%, 70.25%, and 63.68%, respectively. The bioavailability of perchlorate was as follows: control group, 43.45%; rice, 37.17%; lettuce, 35.13%; and formula, 30.72%. The absorptive apparent permeability coefficient (Papp) of the control, lettuce, rice, and formula was 30-101 nm/s, 32-65 nm/s, 54-161 nm/s, and 41-88 nm/s, respectively. The results suggested that the risk from perchlorate was overestimated only when considering the content of perchlorate in foods and that the presence of food matrices reduced perchlorate bioavailability by differing degrees.

Natural P-gp inhibitor EGCG improves the acteoside absorption in Caco-2 cell monolayers and increases the oral bioavailability of acteoside in rats

Acteoside is one of the most widespread phenylethanoid glycosides with pharmacological activities, including antioxidant, neuroprotective property, etc. However, its bioavailability is poor due to the low absorption and P-gp efflux. This study aimed to select food derived P-gp inhibitors for promoting the acteoside absorption and investigate whether the inhibitors could increase the bioavailability and stability of acteoside. Results showed that EGCG and quercetin significantly decreased the BL-to-AP efflux and promoted the AP-to-BL influx of acteoside across Caco-2 monolayers with optimum concentrations of 320 μM EGCG or 240 μM quercetin adding to 320 μM acteoside. EGCG increased the bioavailability of acteoside to 1.43-fold, but quercetin had no such effect. Further study showed that EGCG and quercetin had no effects on the storage and digestion stability of acteoside. This work revealed that EGCG could improve the acteoside absorption across the Caco-2 monolayers and enhance the bioavailability of acteoside in rats.

Therapeutic potential of phenylethanoid glycosides: A systematic review

Phenylethanoid glycosides (PhGs) are generally water-soluble phenolic compounds that occur in many medicinal plants. Until June 2020, more than 572 PhGs have been isolated and identified. PhGs possess antibacterial, anticancer, antidiabetic, anti-inflammatory, antiobesity, antioxidant, antiviral, and neuroprotective properties. Despite these promising benefits, PhGs have failed to fulfill their therapeutic applications due to their poor bioavailability. The attempts to understand their metabolic pathways to improve their bioavailability are investigated. In this review article, we will first summarize the number of PhGs compounds which is not accurate in the literature. The latest information on the biological activities, structure-activity relationships, mechanisms, and especially the clinical applications of PhGs will be reviewed. The bioavailability of PhGs will be summarized and factors leading to the low bioavailability will be analyzed. Recent advances in methods such as bioenhancers and nanotechnology to improve the bioavailability of PhGs are also summarized. The existing scientific gaps of PhGs in knowledge are also discussed, highlighting research directions in the future.

Effects of Different Dietary Flavonoids on Dipeptidyl Peptidase-IV Activity and Expression: Insights into Structure-Activity Relationship

The inhibitory effects of 30 dietary flavonoids on dipeptidyl peptidase-IV (DPP-IV) were investigated to illustrate their quantitative structure-activity relationship (QSAR) and further explore their inhibition at the cellular level. Results of in vitro experiment show that isorhamnetin-3-O-glucoside (IC₅₀, 6.53 ± 0.280 μM) had the strongest inhibition followed by cyanidin-3-O-glucoside (IC₅₀, 8.26 ± 0.143 μM) and isorhamnetin-3-O-rutinoside (IC₅₀, 8.57 ± 0.422 μM). A 3D QSAR model [comparative molecular field analysis, q² = 0.502, optimum number of components (ONC) = 3, R² = 0.983, F = 404.378, standard error of estimation (SEE) = 0.070, and two descriptors; comparative similarity index analysis, q² = 0.580, ONC = 10, R² = 0.999, F = 1617.594, SEE = 0.022, and four descriptors] indicates that the DPP-IV inhibition of flavonoid was facilitated by crucial structural factors. Position 3 of ring C favored bulky, hydrogen bond acceptors and hydrophilic and electron-donating substituents. The presence of minor and electron-withdrawing groups at position 4' of ring B and positions 5 and 7 of ring A could improve DPP-IV inhibition. Moreover, the three flavonoids mentioned above could effectively suppress DPP-IV activity and expression in Caco-2 cells. This work may supply new insights into dietary flavonoids as DPP-IV inhibitors for controlling blood glucose.

Simultaneous Determination of Phenolic Compounds in Plasma by LC-ESI-MS/MS and Their Bioavailability after the Ingestion of Table Olives

The role attributed to polyphenols on human health needs to be correlated with their plasmatic concentrations after food consumption. Then, a method based on liquid-liquid extraction followed by highly sensitive LC-ESI-MS/MS analysis was developed to determinate 16 phenolic compounds in plasma. Validation gave appropriate recovery, matrix effect (80%-120%), linear correlation (R² > 0.995), precision (<15%), LOQ (0.04-2.51 nM), and short chromatographic run. The method was verified after the administration of Arbequina table olives to rats. A single dose of destoned olives was given by gavage, and plasmatic concentrations of polyphenols were analyzed at 30 min. Interestingly, the profile found in plasma greatly differed from that of the olives. Plasmatic concentrations, from highest to lowest, were salidroside, p-coumaric acid, hydroxytyrosol, verbascoside, tyrosol, luteolin, and luteolin-7-O-glucoside. In conclusion, a simple and robust method was developed, enabling the identification and quantification of unaltered polyphenols in plasma after olives consumption, thus demonstrating its suitability for pharmacokinetics studies.

Polyphenols and Other Bioactive Compounds of Sideritis Plants and Their Potential Biological Activity

Due to the growing problem of obesity associated with type 2 diabetes and cardiovascular diseases, causes of obesity are extensively investigated. In addition to a high caloric diet and low physical activity, gut microbiota disturbance may have a potential impact on excessive weight gain. Some reports indicate differences in the composition of the intestinal microflora of obese people in comparison to lean. Bioactive compounds of natural origin with beneficial and multifaceted effects on the body are more frequently used in prevention and treatment of many metabolic diseases including obesity. Sideritis scardica is traditionally consumed as mountain tea in the Balkans to strengthen the body and improve mood. Many reports indicate a positive effect on digestive system, weight loss, and prevention of insulin resistance. Additionally, it exhibits antioxidant activity and anti-inflammatory effects. The positive effect of Sideritis scardica extracts on memory and general cognitive abilities is indicated as well. The multilevel positive effect on the body appears to originate from the abundant occurrence of phenolic compounds, especially phenolic acids in Sideritis scardica extracts. However, mechanisms underlying their action require careful discussion and further research. Therefore, the objective of this review is to summarize the available knowledge on the role and mechanism of action of biologically active compounds of Sideritis scardica and other related species from the genus Sideritis.

Salidroside as a potential neuroprotective agent for ischemic stroke: a review of sources, pharmacokinetics, mechanism and safety

Salidroside (Sal) is a bioactive extract principally from traditional herbal medicine such as Rhodiola rosea L., which has been commonly used for hundreds of years in Asia countries. The excellent neuroprotective capacity of Sal has been illuminated in recent studies. This work focused on the source, pharmacokinetics, safety and anti-ischemic stroke (IS) effect of Sal, especially emphasizing its mechanism of action and BBB permeability. Extensive databases, including Pubmed, Web of science (WOS), Google Scholar and China National Knowledge Infrastructure (CNKI), were applied to obtain relevant online literatures. Sal exerts powerful therapeutic effects on IS in experimental models either in vitro or in vivo due to its neuroprotection, with significantly diminishing infarct size, preventing cerebral edema and improving neurological function. Also, the findings suggest the underlying mechanisms involve anti-oxidation, anti-inflammation and anti-apoptosis by regulating multiple signaling pathways and key molecules, such as NF-κB, TNF-α and PI3K/Akt pathway. In pharmacokinetics, although showing a rapid absorption and elimination, bioavailability of Sal is elevated under some non-physiological conditions. The component and its metabolite (tyrosol) are capable of distributing to brain tissue and the later keeps a higher level of concentration. Moreover, Sal scarcely has obvious toxicity or side effects in a variety of animal experiments and clinical trials, but combination of drugs and perinatal use of medicine should be taken more attentions. Finally, as an active ingredient, not only is Sal isolated from diverse plants with limited yield, but also large batches of the products can be harvested by biological and chemical synthesis. With higher efficacy and better safety profiles, Sal could sever as a promising neuroprotectant for preventing and treating IS. Nevertheless, further investigations are still required to explore the pharmacodynamic and pharmacokinetic properties of Sal in the treatment of IS.

Exploring the compatibility mechanism of ShengDiHuang Decoction based on the in situ single-pass intestinal perfusion model

Affecting the absorption of active ingredients in the intestine serves as one of the important compatibility mechanisms of traditional Chinese medicine. The aim of this study was to investigate the compatibility mechanism of ShengDiHuang Decoction (SDHD) by using the single-pass intestinal perfusion in situ model. The major effective ingredients, catalpol, aucubin, acteoside, rehmannioside D, rehmannioside A, rhein, aloe emodin, emodin, chrysophanol, and physcion, were determined by HPLC. By analysing the effects of different concentrations, different pH, intestinal segments, protein inhibitors, and tight junction regulators on SDHD absorption, it was found that catalpol, aucubin, rehmannioside D, rehmannioside A, acteoside, rhein, and chrysophanol may undergo active transport, while aloe-emodin and emodin may undergo passive transport. Catalpol, aucubin, and rehmannioside D may be substrates of BCRP and MRP2, while rehmannioside A and rhein may be substrates of BCRP, and acteoside and chrysophanol may be substrates of P-gp, BCRP and MRP2. By comparing the P_app values of the major effective ingredients between single herb and herb-pairs, the compatibility of rehmannia and rheum could significantly promote the absorption of components in rehmannia. It is verified that rheum has a synergistic effect on the absorption of rehmannia in SDHD.

Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) powdered leaves are effective in treating anxiety symptoms: A phase-2, randomized, placebo-controlled clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) is a plant traditionally used as medicine for anxiety symptoms. This activity was confirmed in preclinical studies. However, its efficacy was never studied in human clinical trials.

AIM OF THE STUDY

We aimed to test the hypothesis that the herbal medicine of A. polystachya is superior to placebo for the treatment of anxiety-related symptoms in adults after 8 weeks.

PATIENTS AND METHODS

This was a randomized, double-blind, placebo-controlled, phase-2 clinical trial. Fifty-four adults with self-reported anxiety symptoms were randomly allocated to receive either capsules containing A. polystachya powdered leaves (300 mg, twice a day) or placebo (maltodextrin), for 8 weeks. The intensity of anxiety symptoms was assessed by the Hamilton Anxiety Ranking Scale (HAM-A) at baseline and after 2, 4 and 8 weeks. All analyses were adjusted for physical activity (assessed by the International Physical Activity Questionnaire [IPAQ], short version) and gender.

RESULTS

We confirmed the presence of acteoside (chromatographic analysis) and carvone and limonene (gas chromatography) as major constituents in our plant material. Only patients that received A. polystachya experienced a significant decrease in their HAM-A scores, with none or mild side-effects.

CONCLUSION

Administration of powdered leaves of A. polystachya, rich in acteoside, carvone and limonene, to adults with anxiety symptoms was significantly superior to placebo in decreasing HAM-A scores after 8 weeks. This finding confirms the ethnopharmacological use of this plant for anxiety symptoms.

Transepithelial transport mechanisms of 7,8-dihydroxyflavone, a small molecular TrkB receptor agonist, in human intestinal Caco-2 cells

7,8-Dihydroxyflavone (7,8-DHF), as a high-affinity TrkB receptor agonist, has been extensively explored in many human disorders involving brain-derived neurotrophic factor (BDNF) such as Alzheimer's disease, Parkinson's disease, depression, and obesity. However, to date, the transepithelial transport mechanisms of 7,8-DHF in the intestines remain unclear. The aim of our work was to quantify and to characterize in vitro transport of naturally occurring 7,8-DHF distinguished by its physicochemical and pharmacological properties. We discussed the transport mechanisms of 7,8-DHF using the Caco-2 cell model to determine the bi-directional permeability with different environmental factors (time, concentration, pH, metabolic inhibitors etc.). The influx and efflux characteristics of 7,8-DHF were also clarified. 7,8-DHF was poorly transported across Caco-2 cell monolayers by mainly passive diffusion via a transcellular pathway and not a paracellular pathway. The transport of 7,8-DHF was time and concentration-dependent in both the apical (AP) to basolateral (BL) side and the reverse direction. Interestingly, decreasing the pH from 7.4 to 6.0 markedly enhanced 7,8-DHF transport. It is noteworthy that 7,8-DHF transport was strongly inhibited by metabolic inhibitors and was highly dependent on temperature. The efflux ratio (ER) values at different concentrations were all above 1.5, indicating the existence of the efflux transporter. We found that breast cancer resistance protein (BCRP) was not involved in 7,8-DHF secretion and that the transport mechanism of 7,8-DHF was passive transport with an active efflux mediated by P-glycoprotein (P-gp) and multidrug resistance associated proteins (MRPs), particularly MRP 2. Moreover, the use of various influx transporter inhibitors in Caco-2 cells showed that organic cation transporters (OCTs) and organic anion-transporting polypeptides (OATPs) participated in 7,8-DHF transport. Taken together, the elucidated transport characteristics of 7,8-DHF provide useful information for designing novel and efficient delivery systems and avoiding food-food or food-drug interactions.

An Integrated Approach to Characterize Intestinal Metabolites of Four Phenylethanoid Glycosides and Intestinal Microbe-Mediated Antioxidant Activity Evaluation In Vitro Using UHPLC-Q-Exactive High-Resolution Mass Spectrometry and a 1,1-Diphenyl-2-picrylhydrazyl-Based Assay

Intestinal bacteria have a significant role in metabolism and the pharmacologic actions of traditional Chinese medicine active ingredients. Phenylethanoid glycosides (PhGs), as typical phenolic natural products, possess wide bioactivities, but low oral bioavailability. The aim of this work was to elucidate the metabolic mechanism underlying PhGs in the intestinal tract and screen for more active metabolites. In this study, a rapid and reliable method using an effective post-acquisition approach based on advanced ultra-high-performance liquid chromatography (UHPLC) coupled with hybrid Quadrupole-Orbitrap high resolution mass spectrometry (Q-Exactive-HRMS) provided full MS and HCD MS² data. Thermo Scientific™ Compound Discoverer™ software with a Fragment Ion Search (FISh) function in one single workflow was developed to investigate the intestinal microbial metabolism of four typical PhGs. Furthermore, antioxidant activity evaluation of PhGs and their related metabolites was simultaneously carried out in combination with a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to understand how intestinal microbiota transformations modulate biological activity and explore structure–activity relationships (SARs). As a result, 26 metabolites of poliumoside, 42 metabolites of echinacoside, 42 metabolites of tubuloside, and 46 metabolites of 2′-acetylacteoside were identified. Degradation, reduction, hydroxylation, acetylation, hydration, methylation, and sulfate conjugation were the major metabolic pathways of PhGs. Furthermore, the degraded metabolites with better bioavailability had potent antioxidant activity that could be attributed to the phenolic hydroxyl groups. These findings may enhance our understanding of the metabolism, pharmacologic actions, and real active forms of PhGs.

Salidroside ameliorates Adriamycin nephropathy in mice by inhibiting β-catenin activity

Salidroside is a major phenylethanoid glycoside in Rhodiola rosea L., a traditional Chinese medicine, with multiple biological activities. It has been shown that salidroside possesses protective effects for alleviating diabetic renal dysfunction, contrast‐induced‐nephropathy and other kidney diseases. However, the involved molecular mechanism was still not understood well. Herein, we examined the protective effects of salidroside in mice with Adriamycin (ADR)‐induced nephropathy and the underlying molecular mechanism. The results showed that salidroside treatment ameliorates proteinuria; improves expressions of nephrin and podocin; and reduces kidney fibrosis and glomerulosclerosis induced by ADR. Mechanistically, ADR induces a robust accumulation of β‐catenin in the nucleus and stimulates its downstream target gene expression. The application of salidroside largely abolishes the nuclear translocation of β‐catenin and thus inhibits its activity. Furthermore, the activation of β‐catenin almost completely counteracts the protective roles of salidroside in ADR‐injured podocytes. Taken together, our data indicate that salidroside ameliorates proteinuria, renal fibrosis and podocyte injury in ADR nephropathy, which may rely on inhibition of β‐catenin signalling pathway.

Elucidation of the Intestinal Absorption Mechanism of Loganin in the Human Intestinal Caco-2 Cell Model

Loganin, iridoid glycosides, is the main bioactive ingredients in the plant Strychnos nux-vomica L. and demonstrates various pharmacological effects, though poor oral bioavailability in rats. In this study, the intestinal absorption mechanism of loganin was investigated using the human intestinal Caco-2 cell monolayer model in both the apical-to-basolateral (A-B) and the basolateral-to-apical (B-A) direction; additionally, transport characteristics were systematically investigated at different concentrations, pHs, temperatures, and potential transporters. The absorption permeability (PappAB) of loganin, which ranged from 12.17 to 14.78 × 10-6cm/s, was high at four tested concentrations (5, 20, 40, and 80μM), while the major permeation mechanism of loganin was found to be passive diffusion with active efflux mediated by multidrug resistance-associated protein (MRP) and breast cancer resistance protein (BCRP). In addition, it was found that loganin was not the substrate of efflux transporter P-glycoprotein (P-gp) since the selective inhibitor (verapamil) of the efflux transporter exhibited little effects on the transport of loganin in the human intestinal Caco-2 cells. Meanwhile, transport from the apical to the basolateral side increased 2.09-fold after addition of a MRP inhibitor and 2.32-fold after addition of a BCRP inhibitor. In summary, our results clearly demonstrate, for the first time, a good permeability of loganin in the human intestinal Caco-2 cell model and elucidate, in detail, the intestinal absorption mechanism and the effects of transporters on iridoid glycosides compounds.