Anthocyanins in Rubus fruits and antioxidant and anti-inflammatory activities in RAW 264.7 cells

Rubus Occidentalis and its bioactive compounds against cancer: From molecular mechanisms to translational advances

BACKGROUND

Cancer ranks as the second leading cause of death globally, imposing a significant public health burden. The rise in cancer resistance to current therapeutic agents underscores the potential role of phytotherapy. Black raspberry (BRB, Rubus Occidentalis) is a fruit rich in anthocyanins, ellagic acid, and ellagitannins. Accumulating evidence suggests that BRB exhibits promising anticancer effects, positioning it as a viable candidate for phytotherapy.

PURPOSE

This article aims to review the existing research on BRB regarding its role in cancer prevention and treatment. It further analyzes the effective components of BRB, their metabolic pathways, and the potential mechanisms underlying the fruit's anticancer effects.

METHODS

Ovid MEDLINE, EMBASE, Web of Science, and CENTRAL were searched through the terms of Black Raspberry, Raspberry, and Rubus Occidentali up to January 2023. Two reviewers performed the study selection by screening the title and abstract. Full texts of potentially eligible studies were retrieved to access the details.

RESULTS

Out of the 767 articles assessed, 73 papers met the inclusion criteria. Among them, 63 papers investigated the anticancer mechanisms, while 10 conducted clinical trials focusing on cancer treatment or prevention. BRB was found to influence multiple cancer hallmarks by targeting various pathways. Decomposition of free radicals and regulation of estrogen metabolism, BRB can reduce DNA damage caused by reactive oxygen species. BRB can also enhance the function of nucleotide excision repair to repair DNA lesions. Through regulation of epigenetics, BRB can enhance the expression of tumor suppressor genes, inducing cell cycle arrest, and promoting apoptosis and pyroptosis. BRB can reduce the energy and nutrients supply to the cancer nest by inhibiting glycolysis and reducing angiogenesis. The immune and inflammatory microenvironment surrounding cancer cells can also be ameliorated by BRB, inhibiting cancer initiation and progression. However, the limited bioavailability of BRB diminishes its anticancer efficacy. Notably, topical applications of BRB, such as gels and suppositories, have demonstrated significant clinical benefits.

CONCLUSION

BRB inhibits cancer initiation, progression, and metastasis through diverse anticancer mechanisms while exhibiting minimal side effects. Given its potential, BRB emerges as a promising phototherapeutic agent for cancer treatment.

Small RNA profiling reveals the involvement of microRNA-mediated gene regulation in response to symbiosis in raspberry

Dark septate endophytes (DSEs) can form reciprocal symbioses with most terrestrial plants, providing them with mineral nutrients in exchange for photosynthetic products. Although the mechanism of plant-DSEs is well understood at the transcriptional level, little is known about their post-transcriptional regulation, and microRNAs (miRNAs) for the symbiotic process of DSE infestation of raspberry have not been identified. In this study, we comprehensively identified the miRNAs of DSE-infested raspberry symbiosis using Illumina sequencing. A total of 361 known miRNAs and 95 novel miRNAs were identified in the roots. Similar to other dicotyledons, most of the identified raspberry miRNAs were 21 nt in length. Thirty-seven miRNAs were differentially expressed during colonization after inoculation with Phialocephala fortinii F5, suggesting a possible role for these miRNAs in the symbiotic process. Notably, two miRNAs (miR171h and miR396) previously reported to be responsive to symbiotic processes in alfalfa also had altered expression during raspberry symbiosis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses suggests that miRNAs are mainly involved in regulatory mechanisms, such as biological processes, cellular metabolic processes, biosynthesis of secondary metabolites, plant-pathogen interactions, and phytohormone signaling pathways. This study revealed the potential conservation of miRNA-mediated post-transcriptional regulation in symbiotic processes among plants and provides some novel miRNAs for understanding the regulatory mechanisms of DSE-raspberry symbiosis.

The recovery from agro-industrial wastes provides different profiles of anti-inflammatory polyphenols for tailored applications

Food and agro-industrial processing produce a great amount of side-stream and waste materials that are excellent sources of functional bioactive molecules such as phenolic compounds that recover them can be beneficial not only for food sustainability but also to human for many industrial applications such as flavor compounds and therapeutic applications such as antimicrobial and anti-inflammatory. The treatments and extraction techniques have major effects on the recovery of bioactive compounds. Along with the conventional extraction methods, numerous innovative techniques have been evolved and have been optimized to facilitate bioactive extraction more efficiently and sustainably. In this work, we have summarized the state-of-the-art technological approaches concerning novel extraction methods applied for five most produced crops in Italy; Grape Pomace (GP), Tomato Pomace (TP), Olive Pomace (OP), Citrus Pomace (CP), and Spent Coffee Grounds (SCG), presenting the extraction yield and the main class of phenolic classes, with the focus on their biological activity as an anti-inflammatory in vitro and in vivo studies via describing their molecular mechanism of action.

Antioxidant, Anti-Inflammatory and Cytotoxic Activity of Phenolic Compound Family Extracted from Raspberries (Rubus idaeus): A General Review

Raspberries (Rubus idaeus) possess a wide phenolic family profile; this serves the role of self-protection for the plant. Interest in these compounds have significantly increased, since they have been classified as nutraceuticals due to the positive health effects provided to consumers. Extensive chemical, in vitro and in vivo studies have been performed to prove and validate these benefits and their possible applications as an aid when treating several chronic degenerative diseases, characterized by oxidative stress and an inflammatory response. While many diseases could be co-adjuvanted by the intake of these phenolic compounds, this review will mainly discuss their effects on cancer. Anthocyanins and ellagitannins are known to provide a major antioxidant capacity in raspberries. The aim of this review is to summarize the current knowledge concerning the phenolic compound family of raspberries, and topics discussed include their characterization, biosynthesis, bioavailability, cytotoxicity, antioxidant and anti-inflammatory activities.

Stabilization of Lycium ruthenicum Murr. anthocyanins by natural polyphenol extracts

Anthocyanins are a group of flavonoids widely used as natural pigments and in functional foods. However, the sensitivity of anthocyanins to environment factors limits their utilization. The present study examined the stabilizing effects of polyphenol extracts from raspberry, sea-buckthorn, Lonicera edulis, and blackcurrant on Lycium ruthenicum Murr (LRM)-derived anthocyanins. After light and heat exposure, contents of total anthocyanins and the monomers were detected with the pH differential method and the HPLC. Remarkably, polyphenol extracts from raspberry, Lonicera edulis and blackcurrant extended the half-lives of anthocyanins, while the effect of the sea-buckthorn extracts was negligible. Noticeably, petunidin-3-O-[6-O-(4-O-trans-p-coumaroyl-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside]-5-O-[beta-D-glucopyranoside], the major component of LRM-derived anthocyanins, exhibited a dramatic increase in half-life with the presence of polyphenol extracts from raspberry, Lonicera edulis, and blackcurrant. In summary, our findings suggest the polyphenol extracts could be developed into copigments for stabilization of anthocyanins.

Ultrasound-Assisted Extraction Optimization of Proanthocyanidins from Kiwi (Actinidia chinensis) Leaves and Evaluation of Its Antioxidant Activity

Using ultrasound (US) in proanthocyanidin (PA) extraction has become one of the important emerging technologies. It could be the next generation for studying the US mechnophore impact on the bioactive compound’s functionality. The objective of this study was to demonstrate the potential of US treatment on PAs extracted from kiwifruit (Actinidia chinensis) leaves, and to provide a comprehensive chemical composition and bioactivity relationship of the purified kiwifruit leaves PAs (PKLPs). Several methods like single-factor experiments and response surface methodology (RSM) for the four affected factors on US extraction efficiency were constructed. HPLC-QTOF-MS/MS, cytotoxicity analysis, and antioxidant activity were also demonstrated. In the results, the modeling of PA affected factors showed that 40% US-amplitude, 30 mL/g dry weight (DW) solvent to solid ration (S/S), and 70 °C for 15 min were the optimum conditions for the extraction of PAs. Furthermore, PKLPs exhibited significant radical scavenging and cellular antioxidant activity (p < 0.05). In conclusion, this study’s novelty comes from the broad prospects of using US in PKLP green extraction that could play an important role in maximizing this phytochemical functionality in drug discovery and food science fields.

Antioxidant properties of anthocyanins and their mechanism of action in atherosclerosis

Atherosclerosis develops due to lipid accumulation in the arterial wall and sclerosis as result of increased hyperlipidemia, oxidative stress, lipid oxidation, and protein oxidation. However, improving antioxidant status through diet may prevent the progression of atherosclerotic cardiovascular disease. It is believed that polyphenol-rich plants contribute to the inverse relationship between fruit and vegetable intake and chronic disease. Anthocyanins are flavonoid polyphenols with antioxidant properties that have been associated with reduced risk of cardiovascular disease. The consumption of anthocyanins increases total antioxidant capacity, antioxidant defense enzymes, and HDL antioxidant properties by several measures in preclinical and clinical populations. Anthocyanins appear to impart antioxidant actions via direct antioxidant properties, as well as indirectly via inducing intracellular Nrf2 activation and antioxidant gene expression. These actions counter oxidative stress and inflammatory signaling in cells present in atherosclerotic plaques, including macrophages and endothelial cells. Overall, anthocyanins may protect against atherosclerosis and cardiovascular disease through their effects on cellular antioxidant status, oxidative stress, and inflammation; however, their underlying mechanisms of action appear to be complex and require further elucidation.

Cyanidin-3-O-glucoside attenuates high glucose-induced podocyte dysfunction by inhibiting apoptosis and promoting autophagy via activation of SIRT1/AMPK pathway

Diabetic nephropathy (DN) is a common and complicated chronic kidney disease around the world. To elucidate and find effective therapies of DN is of vital importance. In this paper, we have discovered that cyanidin-3-O-glucoside (C3G), which is one of the anthocyanins, could alleviate high glucose-induced podocyte dysfunction. MTT, flow cytometry assay, and Western blot analysis showed that C3G could reverse the increase of cell apoptosis under high glucose treatment in MPC5 cells by upregulation of Bcl2 and downregulation of Bax and cleaved caspase-3. Moreover, C3G improved the autophagy decrease that was induced by high glucose through regulating the expression level of LC3-II/LC3-I, Beclin1, and p62. In addition, C3G inhibited epithelial-mesenchymal transition (EMT) by increasing E-cadherin and reducing Vimentin. By further study of the mechanisms, we found C3G activated the SIRT1 and AMPK which were inhibited in high glucose condition. Silencing SIRT1 blocked the effect of C3G on regulating cell apoptosis, autophagy, and EMT. In summary, our current findings suggest the protective effect of C3G against high glucose-induced podocyte dysfunction is by improving autophagy and reducing apoptosis and EMT via activating SIRT1/AMPK pathway. It might be a new insight for the treatment of DN.

Bioprospection of Natural Sources of Polyphenols with Therapeutic Potential for Redox-Related Diseases

Plants are a reservoir of high-value molecules with underexplored biomedical applications. With the aim of identifying novel health-promoting attributes in underexplored natural sources, we scrutinized the diversity of (poly)phenols present within the berries of selected germplasm from cultivated, wild, and underutilized Rubus species. Our strategy combined the application of metabolomics, statistical analysis, and evaluation of (poly)phenols' bioactivity using a yeast-based discovery platform. We identified species as sources of (poly)phenols interfering with pathological processes associated with redox-related diseases, particularly, amyotrophic lateral sclerosis, cancer, and inflammation. In silico prediction of putative bioactives suggested cyanidin-hexoside as an anti-inflammatory molecule which was validated in yeast and mammalian cells. Moreover, cellular assays revealed that the cyanidin moiety was responsible for the anti-inflammatory properties of cyanidin-hexoside. Our findings unveiled novel (poly)phenolic bioactivities and illustrated the power of our integrative approach for the identification of dietary (poly)phenols with potential biomedical applications.

Effects of simulated digestion on black chokeberry (Aronia melanocarpa (Michx.) Elliot) anthocyanins and intestinal flora

In this study, the changes of anthocyanin content, total phenols, antioxidant capacity, microbiota composition before and after digestion and intestine fermentation in stomach and intestine were studied. The results indicated that after simulated gastrointestinal digestion, compared with the original sample, the total phenol content and anthocyanin content of intestinal digestion group for 2 h (ID 2 group) decreased by 53.64% and 70.45%, respectively, DPPH inhibition rate was 32.75% and T-AOC values of the extracts decreased to 62.89U/mg. The anthocyanins were identified to be composed of cyanidin-3-arabinoside, cyanidin-3-galactoside, cyanidin-3-xyloside, and cyanidin-3-glucoside. Black Chokeberry (Aronia melanocarpa (Michx.) Elliot) anthocyanins significantly increased the relative richness of Bacteroides, promoted the growth of Bifidobacterium, Blautia, Faecalibacterium, and inhibited the growth of Prevotella, Megamonas, Escherichia/Shigella, etc. Anthocyanins have a positive regulatory effect on intestinal flora. These studies also provide essential information for the development of anthocyanin related health care products and drug products.

Effect of Tart Cherry Polyphenols on Osteoclast Differentiation and Activity

Bone is maintained by an intricate balance between bone formation and bone resorption. The presence of inflammation can contribute to an imbalance in bone homeostasis by enhancing differentiation and activity of osteoclasts, the cells that participate in the breakdown of bone. Polyphenols such as flavonoids found in plant-derived foods have been shown to have anti-inflammatory effects in various tissues. Tart cherries are a rich source of such polyphenolic compounds. Using mouse macrophage cells (RAW 264.7), we examined whether tart cherry polyphenols could dose dependently inhibit the proliferation and activity of receptor activator of nuclear factor kappa-B ligand (RANKL) differentiated osteoclasts under inflammatory conditions. Tartrate-resistant acid phosphatase (TRAP) activity and staining of TRAP-positive multinucleated cells, used as indicators of osteoclast differentiation and activity, tended to decrease with tart cherry polyphenols treatment. Osteoprotegerin expression by osteoclasts was decreased in a similar manner. A significant increase in nitrite concentration was observed with the lower doses of tart cherry polyphenols of 50 and 100 μg/mL (P < .05). However, higher doses of tart cherry polyphenols (200 and 300 μg/mL) reduced nitrite concentrations below that of the control that received no tart cherry polyphenols treatment (P < .05). Western blot analyses showed that protein expression of cyclooxygenase-2 (COX-2) followed a similar trend, although results were not statistically significant. On the other hand, tart cherry polyphenols treatments dose dependently increased inducible nitric oxide synthase protein expression, with statistical significance noted at doses of 200 and 300 μg/mL. Overall, our findings suggest that the polyphenols associated with tart cherries potentially inhibit osteoclast differentiation and activity, which may be beneficial to bone health.

Extraction conditions for Rosa gallica petal extracts with anti-skin aging activities

The anti-skin inflammatory activities of rose petal extracts have been described in our previous study. Because skin inflammation is closely linked to skin aging, our study investigated the effects of Rosa gallica petals on skin aging-related activities such as skin whitening and anti-wrinkle properties. Each sample was prepared via extraction using different ethanol ratios with the objective of evaluationg optimal extraction conditions for industrial application. Aqueous 50% (v/v) EtOH extract of R. gallica petal significantly suppressed tyrosinase activity, melanin production, and solar UV-induced matrix metalloproteinase-1, a hall mark of wrinkle formation. In addition, the aqueous 50% (v/v) EtOH extract showed the highest antioxidative effect and had highest flavonoid contents, consistent with the reported anti-aging effects. Overall, our findings suggest that R. gallica petals extracts exhibit anti-aging effects. Furthermore, 50% EtOH extraction, in particular, was optimal for the highest anti-aging, and anti-oxidative effects as well as to obtain the highest flavonoid content.

Anti-inflammatory and wound healing properties of polyphenolic extracts from strawberry and blackberry fruits

The polyphenolic profiles by HPLC-TOF-MS of strawberry 'San Andreas' and blackberry 'Black Satin' crude extracts (CE) were analyzed. Anthocyanin-enriched fractions (AEFs) and proanthocyanidin-enriched fractions (PEFs) were prepared, and all samples were probed for in vitro anti-inflammatory and wound healing effects in a LPS-stimulated RAW 264.7 macrophage model and in a skin fibroblast migration and proliferation assay, respectively. Blackberry samples exhibited higher ROS reduction than strawberry's (up to 50% ROS suppression). Berries CEs exhibited 20% inhibition in Cox-2 gene expression, while AEFs and PEFs were inactive at the same concentration. Strawberry AEF and PEF were more active against IL-1β and IL-6 gene expressions than the similar fractions from blackberry, where PEF was more active than AEF (75% suppression by strawberry PEF). Moreover, berry PEFs were the active polyphenol fraction against iNOS gene expression (50% and 65% gen suppression by strawberry and blackberry PEF, respectively), mirroring results of NO synthesis suppression. The cell migration potential of berry polyphenolics was associated with anthocyanins. AEFs showed fibroblast migration around 50% of that registered for the positive control. Results obtained in this work highlight the anti-inflammatory properties of berry polyphenolics, especially due to proanthocyanidins. Moreover, promising results were obtained about the effects of berry anthocyanins on wound healing.

Screening and evaluation of active compounds in polyphenol mixtures by HPLC coupled with chemical methodology and its application

An off-line high performance liquid chromatography (HPLC) coupled with chemical methods has been developed to evaluate antioxidant activity of 11 standard polyphenol compounds (SPCs) and vitamin C (Vc) in terms of radical scavenging abilities. The structure-activity relationships of each SPC were also discussed. SPCs showed different abilities in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis-3-ethyl-benzthiazoline-6-sulphonate (ABTS+) and hydroxyl (OH) free radicals. Among SPCs, quercetin and kaempferol, as typical flavonoids, displayed the greatest radical-scavenging activities and even exhibited higher activity in OH radical removal ability than that of Vc. Furthermore, the proposed method was also applied to screening polyphenolic antioxidant components from Cichorium endivia L. (C. endivia) seed extract. The results indicated that cynarin in the extract was a more active compound to scavenge DPPH and ABTS+ radicals than chlorogenic acid, while chlorogenic acid had stronger capacity in scavenging OH free radicals.

Anti-inflammatory effects of Dioscorea alata L. anthocyanins in a TNBS-induced colitis model

The purple yam, Dioscorea alata L., is an important source of starch, vitamins and polyphenols. Five different pigments from the purple tubers of this plant were separated by high-performance liquid chromatography-mass spectrometry, and the anthocyanin fraction (DACN) was collected. The anti-inflammatory effects of DACNs were investigated at different concentrations and compared with the standard colitis treatment, 5-aminosalicylic acid, in a trinitrobenzenesulfonic acid (TNBS)-induced colitis mouse model. Macro- and microscopic parameters including body weight change, disease activity index (DAI) and intestinal histology were used for the determination of the anti-inflammatory effects of DACNs. The gene expression levels of tight junction-related proteins in the intestine, myeloperoxidase activity, inducible nitric oxide synthase activity in colonic tissues and pro-inflammatory cytokine production in serum were also measured to elucidate the mechanism of DACN action. Eighty micrograms of DACNs per kilogram of body weight produced potent anti-inflammatory effects in the mouse model of inflammatory bowel disease (IBD), as shown by the DAI (2.78 ± 0.38 vs. 0.44 ± 0.51). Therefore, DACNs may be applied as a potential food supplement in IBD therapy.

Stability improvement of natural food colors: Impact of amino acid and peptide addition on anthocyanin stability in model beverages

Anthocyanins are prone to chemical degradation and color fading in the presence of vitamin C. The potential of three amino acids (l-phenylalanine, l-tyrosine, l-tryptophan) and a polypeptide (ε-poly-l-lysine) in prolonging the color stability of purple carrot anthocyanins (0.025%) in model beverages (0.05% l-ascorbic acid, citric acid, pH 3.0) stored at elevated temperature (40°C/7 days) was examined. In the absence of amino acids or peptides, anthocyanin degraded at first-order reaction rate. Addition of amino acids or peptide (0.1%) increased the color stability of anthocyanins, with the most significant improvement observed for l-tryptophan. The average half-life of anthocyanin color increased from 2 days to 6 days with l-tryptophan addition. Fluorescence quenching measurements revealed that the l-tryptophan interacted with anthocyanins mainly through hydrogen bonding, although some hydrophobic interaction may also have been involved. Overall, this study suggests that amino acid or peptide addition may prolong the color stability of anthocyanin in beverage products.

Phytochemical Composition and Biological Activities of Selected Wild Berries (Rubus moluccanus L., R. fraxinifolius Poir., and R. alpestris Blume)

Berries, from the genus Rubus, are among the vital components in a healthy diet. In this study, 80% methanol extracts from the three wild Rubus species (Rubus moluccanus L., Rubus fraxinifolius Poir., and Rubus alpestris Blume) were evaluated for their phytochemical contents (total phenolics, flavonoid, anthocyanin, and carotenoid content), antioxidant (DPPH, FRAP, and ABTS assays), antiacetylcholinesterase, and antibacterial activities. GC-MS was used for quantification of naturally occurring phytochemicals. The results showed that R. alpestris contained the highest total phenolic [24.25 ± 0.1 mg gallic acid equivalent (GAE)/g] and carotenoid content [21.86 ± 0.63 mg β-carotene equivalents (BC)/g], as well as the highest DPPH scavenging and FRAP activities. The highest total flavonoid [18.17 ± 0.20 mg catechin equivalents (CE)/g] and anthocyanin content [36.96 ± 0.39 mg cyanidin-3-glucoside equivalents (c-3-gE)/g] have been shown by R. moluccanus. For antibacterial assays, R. moluccanus and R. alpestris extracts showed mild inhibition towards Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Salmonella enteritidis. Anticholinesterase activity for all extracts was in the range of 23-26%. The GC-MS analysis revealed the presence of at least 12, 21, and 7 different organic compounds in 80% methanol extracts of R. alpestris, R. moluccanus, and R. fraxinifolius, respectively, which might contribute to the bioactivity.