A comparison of the absorption and metabolism of the major quercetin in brassica, quercetin-3-O-sophoroside, to that of quercetin aglycone, in rats

Grain bound polyphenols: Molecular interactions, release characteristics, and regulation mechanisms of postprandial hyperglycemia

Frequent postprandial hyperglycemia causes many chronic diseases. Grain polyphenols are widely recognized as natural active ingredients with high potential to treat chronic diseases due to their excellent postprandial hyperglycemic regulating effects. However, previous studies on polyphenols in grains mainly focused on the functional properties of free polyphenols and the extraction and physicochemical properties of bound polyphenols, ignoring the functional properties of bound polyphenols. Comprehensively understanding the binding properties of grain bound polyphenols (GBPs) and their mechanisms in regulating blood glucose levels is essential for developing and applying grain resources. This review summarizes the molecular interactions between GBPs and grain components and their effects on release characteristics and bioavailability at various stages. Meanwhile, the review focuses on elucidating the regulatory mechanism of post-release GBPs on postprandial hyperglycemia levels, incorporating insights from molecular docking, the gastrointestinal-brain axis, and gut flora. GBPs slow food digestion by occupying the active site of digestive enzymes and altering the secondary structure of enzymes and the hydrophobic environment of amino acid residues to inhibit enzyme activity. They modulate intestinal epithelial transport proteins (SGLT1, GLUT2, and GLUT4) to limit glucose absorption and increase glucose consumption. They also stimulate the release of short-term satiety hormones (CKK, GLP-1, and PYY) through the gastrointestinal-brain axis to decrease post-meal food intake. Furthermore, they optimize gut microbiota composition, promoting short-chain fatty acid production and bile acid metabolism. Therefore, developing functional foods with glucose-modulating properties based on GBPs is crucial for obesity prevention, diabetes management, and low-GI food development.

Advances in flavonoid bioactivity in chronic diseases and bioavailability: transporters and enzymes

Flavonoids, abundant in the human diet, have been extensively studied for their therapeutic bioactivities. Recent research has made significantly advances in our understanding of the biological activities of flavonoids, demonstrating their therapeutic effects for various chronic diseases. However, the generally low bioavailability of flavonoids limits their effectiveness. Therefore, it is essential to explore the pharmacokinetics of flavonoids, paying particular attention to the roles of transporters and metabolizing enzymes. This paper reviews recent studies on the bioactivity of flavonoids, highlighting the importance of transporters and metabolic enzymes in their pharmacokinetics.

Enzymes that catalyze cyclization of β-1,2-glucans

β-1,2-Glucans are physiologically important polymers for interactions such as symbiosis and pathogenesis between organisms and adaptation to environmental changes. However, rarity of β-1,2-glucans in nature limits exploration of related enzymes. Recently, many β-1,2-glucan-degrading enzymes have been found after identification of a novel phosphorylase acting on β-1,2-glucooligosaccharides. The expansion of the repertoire has reached revelation of the cyclization mechanism of cyclic β-1,2-glucan synthase and led to finding of new enzymes catalyzing cyclization of β-1,2-glucans in a manner different from cyclic β-1,2-glucan synthase. In this review, we mainly focus on newly found enzymes that catalyze cyclization of β-1,2-glucans along with existence of β-1,2-glucan-associated carbohydrates in nature and introduction of the repertoire of β-1,2-glucan-degrading enzymes. KEY POINTS: • Newly found domain which cyclizes β-1,2-glucan created a new glycoside hydrolase family. • Cyclization is performed with a unique mechanism. • α-1,6-Cyclized β-1,2-glucan is produced by an enzyme in another newly found family.

Structural Diversity and Anti-Diabetic Potential of Flavonoids and Phenolic Compounds in Eriobotrya japonica Leaves

Eriobotrya japonica (Thunb.) Lindl., commonly known as loquat, is a plant belonging to the Rosaceae family. While its fruit is widely consumed as food and used in traditional medicine, research on other parts of the plant remains insufficient. Therefore, the chemical constituents and biological activities of its leaves were investigated. Phytochemical analysis of E. japonica leaves identified 30 compounds, including flavonoids, phenolics, and megastigmanes. The flavonoids isolated from the leaves include flavones, flavans, flavolignans, flavonoid glycosides, and coumaroyl flavonoid glycosides. Coumaroyl flavonoid rhamnosides were characteristically present in E. japonica leaves, and the configurations of coumaric acids, as well as the binding position to the rhamnose in each compound, were identified through detailed NMR analysis. Notably, three of them were isolated from this plant for the first time. Phenolic compounds were found to be present as conjugates with organic acids, such as quinic acid, shikimic acid, and glucose. Flavonoid and phenolic compounds demonstrated significant antioxidant and α-glucosidase inhibitory effects, whereas megastigmanes showed little activity. Notably, coumaroyl flavonoid rhamnosides, which consist of flavonoids combined with the phenolic acid, coumaric acid, exhibited excellent anti-diabetic effects. Further molecular docking analysis confirmed that these compounds effectively bind to the α-glucosidase enzyme. In conclusion, the present study identified flavonoid and phenolic components with various structures in E. japonica leaves and clarified their anti-diabetic and antioxidant effects. These findings support the beneficial potential of E. japonica leaves for the treatment and/or prevention of metabolic diseases.

The bioavailability, absorption, metabolism, and regulation of glucolipid metabolism disorders by quercetin and its important glycosides: A review

Quercetin and its glycosides (QG), vitally natural flavonoid, have been popular for health benefits. However, the absorption and metabolism affect their bioavailability, and the metabolic transformation alters their biological activities. This review systematically summarizes the bioavailability and pathways for the absorption and metabolism of quercetin/QG in vivo and in vitro, the biological activities and mechanism of quercetin/QG and their metabolites in treating glucolipid metabolism are discussed. After oral administration, quercetin/QG are mainly absorbed by the intestine, undergo phase II metabolism in the small intestine and liver to form conjugates and are metabolized into small phenolic acids by intestinal microbiota. Quercetin/QG and their metabolites exert beneficial effects on regulating glucolipid metabolism disorders, including improving insulin resistance, inhibiting lipogenesis, enhancing thermogenesis, modulating intestinal microbiota, relieving oxidative stress, and attenuating inflammation. This review enhances understanding of the mechanism of quercetin/QG regulate glucolipid metabolism and provides scientific support for the development of functional foods.

Metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion/Caco-2 cell transport, and their prebiotic effects during colonic fermentation

The health-promoting activities of polyphenols and their metabolites originating from germinated quinoa (GQ) are closely related to their digestive behavior, absorption, and colonic fermentation; however, limited knowledge regarding these properties hinder further development. The aim of this study was to provide metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion and Caco-2 cell transport, whilst also investigating the changes in the major polyphenol metabolites and the effects of prebiotics during colonic fermentation. It was found that germination treatment increased the polyphenol content of quinoa by 21.91%. Compared with RQ group, 23 phenolic differential metabolites were upregulated and 47 phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after simulated digestion, 7 kinds of phenolic differential metabolites were upregulated and 17 kinds of phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after cell transport, 7 kinds of phenolic differential metabolites were upregulated and 9 kinds of phenolic differential metabolites were downregulated in GQ group. In addition, GQ improved the bioaccessibilities and transport rates of various polyphenol metabolites. During colonic fermentation, GQ group can also increase the content of SCFAs, reduce pH value, and adjust gut microbial populations by increasing the abundance of Actinobacteria, Bacteroidetes, Verrucomicrobiota, and Spirochaeota at the phylum level, as well as Bifidobacterium, Megamonas, Bifidobacterium, Brevundimonas, and Bacteroides at the genus level. Furthermore, the GQ have significantly inhibited the activity of α-amylase and α-glucosidase. Based on these results, it was possible to elucidate the underlying mechanisms of polyphenol metabolism in GQ and highlight its beneficial effects on the gut microbiota.

Analytical Methods for the Determination of Quercetin and Quercetin Glycosides in Pharmaceuticals and Biological Samples

Flavonoids are plant-derived compounds that have several health benefits, including antioxidative, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects. Quercetin is a flavonoid that is widely present in various fruits, vegetables, and drinks. Accurate determination of quercetin in different samples is of great importance for its potential health benefits. This review, is an overview of sample preparation and determination methods for quercetin in diverse matrices. Previous research on sample preparation and determination methods for quercetin are summarized, highlighting the advantages and disadvantages of each method and providing insights into recent developments in quercetin sample treatment. Various analytical techniques are discussed including spectroscopic, chromatographic, electrophoretic, and electrochemical methods for the determination of quercetin and its derivatives in different samples. UV-Vis (Ultraviolet-visible) spectrophotometry is simple and inexpensive but lacks selectivity. Chromatographic techniques (HPLC, GC) offer selectivity and sensitivity, while electrophoretic and electrochemical methods provide high resolution and low detection limits, respectively. The aim of this review is to comprehensively explore the determination methods for quercetin and quercetin glycosides in diverse matrices, with emphasis on pharmaceutical and biological samples. The review also provides a theoretical basis for method development and application for the analysis of quercetin and quercetin glycosides in real samples.

A comprehensive view on the quercetin impact on bladder cancer: Focusing on oxidative stress, cellular, and molecular mechanisms

Bladder cancer (BC) is known as a prevalent genitourinary malignancy and has a significant mortality rate worldwide. Despite recent therapeutic approaches, the recurrence rate is high, highlighting the need for a new strategy to reduce the BC cell progression. Quercetin, a flavonoid compound, demonstrated promising anticancer properties and could be used in the management of various malignancies such as BC. This comprehensive review summarized quercetin's cellular and molecular mechanisms underlying anticancer activities. The study's findings indicated that quercetin prevents the proliferation of the human BC cell line, promotes apoptosis of BIU-87 cells, reduces the expression of p-P70S6K, and induces apoptosis by p-AMPK. Moreover, quercetin restricts tumor growth through the AMPK/mTOR cascade and prevents colony formation of human BC cells by triggering DNA damage. Studying this review article will help researchers better understand quercetin's functional role in the prevention and treatment of BC.

Quality Marker Discovery and Quality Evaluation of Eucommia ulmoides Pollen Using UPLC-QTOF-MS Combined with a DPPH-HPLC Antioxidant Activity Screening Method

Pollen, as an important component of Eucommia ulmoides (EUP), is rich in nutrients and is receiving increasing attention. At present, there are no reports on research related to the chemical composition and quality standards of EUP, and there are significant quality differences and counterfeit phenomena in the market. This study used a UPLC-QTOF-MS system to identify 49 chemical components in EUP for the first time. In the second step, 2,2-diphenyl-1-picrylhydrazyl (DPPH)-HPLC antioxidant activity screening technology was used to identify the main active components of EUP, quercetin-3-O-sophoroside (QSH), quercetin-3-O-sambubioside (QSB), and quercetin 3-O-neohesperidoside (QNH), and their purification, preparation, and structure identification were carried out. Third, molecular docking was used to predict the activity of these components. Fourth, the intracellular ROS generation model of RAW264.7 induced by H2O2 was used to verify and evaluate the activity of candidate active ingredients to determine their feasibility as Q-markers. Finally, a quality control method for EUP was constructed using the three selected components as Q-markers. The identification of chemical components and the discovery, prediction, and confirmation of characteristic Q-markers in EUP provide important references for better research on EUP and the effective evaluation and control of its quality. This approach provides a new model for the quality control of novel foods or dietary supplements.

Structural, in vitro digestion, and fermentation characteristics of lotus leaf flavonoids

Bioaccessibility and bioactivity of flavonoids in lotus leaves are related to their characteristics in gastrointestinal digestion and colonic fermentation. The aim of this study is to investigate the stability of lotus leaf flavonoids (LLF) in simulated gastrointestinal digestion, and its modulation on gut microbiota in vitro fermentation. Results showed that LLF mainly consisted of quercetin-3-O-galactoside, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, and kaempferol-3-O-glucoside. These flavonoids kept stability with only a small fraction degraded in simulated gastric and intestinal fluids. In vitro fermentation, LLF stimulated the growth of Actinobacteria and Firmicutes, inhibited the growth of Proteobacteria, and induced the production of fermentation gases and short-chain fatty acids. Interestingly, supplementation of soluble starch significantly improved the utilization of LLF by the intestinal flora. These results revealed that LLF shaped a unique biological web with Lactobacillus and Bifidobacterium spp. as the core of the biological network, which would be more beneficial to gut health.

Rice Bran Lipidome Identifies Novel Phospholipids, Glycolipids, and Oxylipins with Roles in Lipid Metabolism of Hypercholesterolemic Children

SCOPE

The purpose of the study is to characterize the chemical diversity in rice bran (RB) lipidome and determines whether daily RB consumption for 4 weeks may modulate plasma lipid profiles in children.

METHODS AND RESULTS

Untargeted and targeted lipidomics via ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-MS/MS) are applied to identify bioactive RB lipids from a collection of 17 rice varieties. To determine the impact of RB (Calrose-USA variety) supplementation on plasma lipid profile, a secondary analysis of plasma lipidome is conducted on data recorded in a clinical study (NCT01911390, n = 18 moderately hypercholesterolemic children) before and after 4 weeks of dietary intervention with a control or RB supplemented (15 g day^-1 ) snack. Untargeted lipidomic reveals 118 lipids as the core of lipidome across all varieties among which phospholipids are abundant and oxylipins present. Phytoprostanes and phytofurans are quantified and characterized. Lipidome analysis of the children plasma following RB consumption reveals the presence of polar lipids and oxylipins alongside putative modulations in endocannabinoids associated with RB consumption.

CONCLUSION

The investigation of novel polar lipids, oxylipins, phytoprostanes, and phytofurans in RB extracts provides support for new health-promoting properties interesting for people at risk for cardiometabolic disease.

Quercetin-3-O-α-L-arabinopyranosyl-(1→2)-β-D-glucopyranoside Isolated from Eucommia ulmoides Leaf Relieves Insulin Resistance in HepG2 Cells via the IRS-1/PI3K/Akt/GSK-3β Pathway

For nearly 2000 years, Eucommia ulmoides Oliver (EUO) has been utilized in traditional Chinese medicine (TCM) throughout China. Flavonoids present in bark and leaves of EUO are responsible for their antioxidant, anti-inflammatory, antitumor, anti-osteoporosis, hypoglycemic, hypolipidemic, antibacterial, and antiviral properties, but the main bioactive compound has not been established yet. In this study, we isolated and identified quercetin glycoside (QAG) from EUO leaves (EUOL) and preliminarily explored its molecular mechanism in improving insulin resistance (IR). The results showed that QAG increased uptake of glucose as well as glycogen production in the palmitic acid (PA)-induced HepG2 cells in a dose-dependent way. Further, we observed that QAG increases glucose transporters 2 and 4 (GLUT2 and GLUT4) expression and suppresses the phosphorylation of insulin receptor substrate (IRS)-1 at serine⁶¹², thus promoting the expression of phosphatidylinositol-3-kinase (PI3K) at tyrosine⁴⁵⁸ and tyrosine¹⁹⁹, as well as protein kinase B (Akt) and glycogen synthase kinase (GSK)-3β at serine⁴⁷³ and serine⁹, respectively. The influence posed by QAG on the improvement of uptake of glucose was significantly inhibited by LY294002, a PI3K inhibitor. In addition, the molecular docking result showed that QAG could bind to insulin receptors. In summary, our data established that QAG improved IR as demonstrated by the increased uptake of glucose and glycogen production through a signaling pathway called IRS-1/PI3K/Akt/GSK-3β.

Apocynum venetum, a medicinal, economical and ecological plant: a review update

Apocynum venetum L. is an important medicinal perennial rhizome plant with good ecological and economic value. Its leaves have many pharmacological effects such as anti-inflammatory, anti-depression, anti-anxiolytic, etc., while its fibers have the title of "king of wild fibers". Furthermore, it was suitable for the restoration of degraded saline soil in arid areas. An increasing studies have been published in the past years. A scientometric analysis was used to analyze the publications of Apocynum venetum L. to clearly review the pharmacology, fiber application of Apocynum venetum L. and the potential value with its similar species (Apocynum pictum Schrenk) to the environment.

Mediterranean Food Industry By-Products as a Novel Source of Phytochemicals with a Promising Role in Cancer Prevention

The Mediterranean diet is recognized as a sustainable dietary approach with beneficial health effects. This is highly relevant, although the production of typical Mediterranean food, i.e., olive oil or wine, processed tomatoes and pomegranate products, generates significant amounts of waste. Ideally, this waste should be disposed in an appropriate, eco-friendly way. A number of scientific papers were published recently showing that these by-products can be exploited as a valuable source of biologically active components with health benefits, including anticancer effects. In this review, accordingly, we elaborate on such phytochemicals recovered from the food waste generated during the processing of vegetables and fruits, typical of the Mediterranean diet, with a focus on substances with anticancer activity. The molecular mechanisms of these phytochemicals, which might be included in supporting treatment and prevention of various types of cancer, are presented. The use of bioactive components from food waste may improve the economic feasibility and sustainability of the food processing industry in the Mediterranean region and can provide a new strategy to approach prevention of cancer.

Time-Series-Dependent Global Data Filtering Strategy for Mining and Profiling of Xenobiotic Metabolites in a Dynamic Complex Matrix: Application to Biotransformation of Flavonoids in the Extract of Ginkgo biloba by Gut Microbiota

Efficient characterization of xenobiotic metabolites and their dynamics in a changing complex matrix remains difficult. Herein, we proposed a time-series-dependent global data filtering strategy for the rapid and comprehensive characterization of xenobiotic metabolites and their dynamic variation based on metabolome data. A set of data preprocessing methods was used to screen potential xenobiotic metabolites, considering the differences between the treated and control groups and the fluctuations over time. To further identify metabolites of the target, an in-house accurate mass database was constructed by potential metabolic pathways and applied. Taking the extract of Ginkgo biloba (EGB) co-incubated with gut microbiota as an example, 107 compounds were identified as flavonoid-derived metabolites (including 67 original from EGB and 40 new) from 7468 ions. Their temporal metabolic profiles and regularities were also investigated. This study provided a systematic and feasible method to elucidate and profile xenobiotic metabolism.

Characterization of Extracts of Coffee Leaves (Coffea arabica L.) by Spectroscopic and Chromatographic/Spectrometric Techniques

Coffea arabica L. leaves represent a viable alternative to the canonical matrices used for preparation of beverages, such as tea leaves and grounded coffee beans. Coffee leaves infusions are rich in antioxidant phenolic compounds and have a lower concentration of caffeine. Due to increasing interest in this field, a complete study of the bioactive compounds as chlorogenic acids, xanthones and alkaloids is noteworthy. C. arabica leaves were subjected to ultrasound-assisted extraction, and the extracts were studied via nuclear magnetic resonance spectroscopy (NMR) and chromatographic techniques coupled with mass spectrometry (HPLC-MSn) to identify and quantify the secondary metabolites profile through an untargeted data dependent approach. A quantitative analysis was performed for the major components—chlorogenic acids, mangiferin, caffeine and trigonelline—via HPLC-MS in Single Ion Monitoring (SIM) mode. In total, 39 compounds were identified. The presence of these bioactive compounds proved the strong potential of C. arabica leaves as functional food and as an alternative to classic infused beverages.

Pharmacological action of quercetin against testicular dysfunction: A mini review

The testis is an immune-privileged organ susceptible to oxidative stress and inflammation, two major factors implicated in male infertility. A reduction in the concentration and activities of testicular function biomarkers has been shown to correlate with impaired hypothalamic-pituitary-testicular axis and oxidative stress. However, the use of natural products to ameliorate these oxidative stress-induced changes may be essential to improving male reproductive function. Quercetin possesses several pharmacological activities that may help to combat cellular reproduction-related assaults, such as altered sperm function and reproductive hormone dysfunction, and dysregulated testicular apoptosis, oxidative stress, and inflammation. Studies have shown that quercetin ameliorates testicular toxicity, largely by inhibiting the generation of reactive oxygen species, with the aid of the two antioxidant pharmacophores present in its ring structure. The radical-scavenging property of quercetin may alter signal transduction of oxidative stress-induced apoptosis, prevent inflammation, and increase sperm quality in relation to the hormonal concentration. In this review, the therapeutic potential of quercetin in mediating male reproductive health is discussed.

The Targeting of Noncoding RNAs by Quercetin in Cancer Prevention and Therapy

The dietary flavonoid quercetin is ubiquitously distributed in fruits, vegetables, and medicinal herbs. Quercetin has been a focal point in recent years due to its versatile health-promoting benefits and high pharmacological values. It has well documented that quercetin exerts anticancer actions by inhibiting cell proliferation, inducing apoptosis, and retarding the invasion and metastasis of cancer cells. However, the exact mechanism of quercetin-mediated cancer chemoprevention is still not fully understood. With the advances in high-throughput sequencing technologies, the intricate oncogenic signaling networks have been gradually characterized. Increasing evidence on the close association between noncoding RNA (ncRNAs) and cancer etiopathogenesis emphasizes the potential of ncRNAs as promising molecular targets for cancer treatment. Available experimental studies indicate that quercetin can dominate multiple cancer-associated ncRNAs, hence repressing carcinogenesis and cancer development. Thus, modulation of ncRNAs serves as a key mechanism responsible for the anticancer effects of quercetin. In this review, we focus on the chemopreventive effects of quercetin on cancer pathogenesis by targeting cancer-relevant ncRNAs, supporting the viewpoint that quercetin holds promise as a drug candidate for cancer chemoprevention and chemotherapy. An in-depth comprehension of the interplay between quercetin and ncRNAs in the inhibition of cancer development and progression will raise the possibility of developing this bioactive compound as an anticancer agent that could be highly efficacious and safe in clinical practice.

Comparison of Flavonoid O-Glycoside, C-Glycosideand Their Aglycones on Antioxidant Capacity and Metabolism during In Vitro Digestion and In Vivo

Flavonoids are well known for their extensive health benefits. However, few studies compared the differences between flavonoid O-glycoside and C-glycoside. In this work, flavonoid O-glycoside (isoquercitrin), C-glycoside (orientin), and their aglycones (quercetin and luteolin) were chosen to compare their differences on antioxidant activities and metabolism during in vitro digestion and in vivo. In vitro digestion, the initial antioxidant activity of the two aglycones was very high; however, they both decreased more sharply than their glycosides in the intestinal phase. The glycosidic bond of flavonoid O-glycoside was broken in the gastric and intestinal stage, while the C-glycoside remained unchanged. In vivo, flavonoid O-glycoside in plasma was more elevated than C-glycoside on the antioxidant activity; however, flavonoid C-glycoside in urine was higher than O-glycoside. These results indicate that differences of flavonoid glycosides and their aglycones on antioxidant activity are closely related to their structural characteristics and metabolism in different samples. Aglycones possessed higher activity but unstable structures. On the contrary, the sugar substituents reduced the activity of flavonoids while improving their stability and helping to maintain antioxidant activities after digestion. Especially the C-glycoside was more stable because the stability of the C–C bond is higher than that of the C–O bond, which contributes to the difference between flavonoid O-glycoside and C-glycoside on the absorption and metabolism in vivo. This study provided a new perspective for comparing flavonoid O-glycoside, flavonoid C-glycoside, and their aglycones on their structure–activity relationship and metabolism.

The anti-hyperuricemic effect of flavonoid extract of saffron by-product and its pharmacokinetics in rats after oral administration

Only the dried stigma of the saffron, a flower deemed as the most valuable spice globally, is utilized for industrial production. Hence, there exists a growing interest in utilizing saffron floral bio-residues. The anti-hyperuricemic activity of a flavonoid extract from saffron floral bio-residues was assessed in potassium oxonate-induced hyperuricemia mice. In addition, an ultra-high performance liquid chromatography-triple quadrupole mass spectrometry method was established and validated to determine the pharmacokinetics of five main flavonoids and three phase-II metabolites in rat plasma after oral administration of the flavonoid extract for the first time. Compared with pharmacokinetic parameters of kaempferol-3-O-sophoroside, the most abundant flavonoid in the extract, and its aglycone kaempferol, we observed that coexisting compounds significantly reduced the absorption, accelerated the excretion of kaempferol-3-O-sophoroside, while significantly increasing the absorption and prolonging the residence time of kaempferol in the flavonoid extract. These results suggest the promising potential of the flavonoid extract from saffron floral bio-residues as an anti-hyperuricemic agent. Kaempferol was absorbed in plasma at high concentrations owing to the biotransformation of kaempferol glycosides in vivo.

Dereplication of phenolic derivatives of three Erythroxylum species using liquid chromatography coupled with ESI-MSn and HRESIMS

INTRODUCTION

Given the diversity of secondary metabolites produced by species of the genus Erythroxylum, in addition to the many methods that have already been described in the literature, modern screening and identification methodologies, such as dereplication, represent an efficient and quick strategy compared to the classic techniques linked to natural product research.

OBJECTIVE

The objective of the present study was to determine the phenolic profiles obtained from three species of Erythroxylum (Erythroxylum pauferrense Plowman, Erythroxylum pulchrum A.St.-Hil. and Erythroxylum simonis Plowman) by dereplication using liquid chromatography coupled with ESI-MSⁿ and HRESIMS.

MATERIAL AND METHODS

Ethyl acetate and n-butanolic fractions from crude ethanolic extract of Erythroxylum species were analyzed by HPLC-ESI-MSⁿ and HPLC-HRESIMS, in order to identify its corresponding compounds. Experiments were performed in negative ionization mode, and the metabolites were provisionally identified based on deprotonated molecules, molecular formulas, fragmentation patterns and literature data. The corresponding isolated compounds were characterized by ¹ H and ¹³ C NMR spectroscopy.

RESULTS

According to the dereplication method, it was possible to establish and compare the phenolic profile of the corresponding species by the assignment of 55 compounds, most of which were first described in these species and among which some were also new to the Erytroxylum genus. Additionally, nine compounds were isolated, including biphenyl-3,3',4,4'-tetraol, where the mass spectral data were not sufficient for their identification, and reported for the first time in the Erythroxylaceae family.

CONCLUSION

This research contributes to the phytochemical knowledge of the Erythroxylum genus and demonstrates the importance of the dereplication method regarding the investigation of natural products, enabling accurate identification of the metabolites while avoiding the efforts and material expenses involved in the isolation of known compounds.

Exploring the interaction of quercetin-3-O-sophoroside with SARS-CoV-2 main proteins by theoretical studies: A probable prelude to control some variants of coronavirus including Delta

The aim of this study was to investigate the mechanism of interaction between quercetin-3-O-sophoroside and different SARS-CoV-2's proteins which can bring some useful details about the control of different variants of coronavirus including the recent case, Delta. The chemical structure of the quercetin-3-O-sophoroside was first optimized. Docking studies were performed by CoV disease-2019 (COVID-19) Docking Server. Afterwards, the molecular dynamic study was done using High Throughput Molecular Dynamics (HTMD) tool. The results showed a remarkable stability of the quercetin-3-O-sophoroside based on the calculated parameters. Docking outcomes revealed that the highest affinity of quercetin-3-O-sophoroside was related to the RdRp with RNA. Molecular dynamic studies showed that the target E protein tends to be destabilized in the presence of quercetin-3-O-sophoroside. Based on these results, quercetin-3-O-sophoroside can show promising inhibitory effects on the binding site of the different receptors and may be considered as effective inhibitor of the entry and proliferation of the SARS-CoV-2 and its different variants. Finally, it should be noted, although this paper does not directly deal with the exploring the interaction of main proteins of SARS-CoV-2 Delta variant with quercetin-3-O-sophoroside, at the time of writing, no direct theoretical investigation was reported on the interaction of ligands with the main proteins of Delta variant. Therefore, the present data may provide useful information for designing some theoretical studies in the future for studying the control of SARS-CoV-2 variants due to possible structural similarity between proteins of different variants.

Tomato (Solanum lycopersicum L.) seed: A review on bioactives and biomedical activities

The processing of tomato fruit into puree, juices, ketchup, sauces, and dried powders generates a significant amount of waste in the form of tomato pomace, which includes seeds and skin. Tomato processing by-products, particularly seeds, are reservoirs of health-promoting macromolecules, such as proteins (bioactive peptides), carotenoids (lycopene), polysaccharides (pectin), phytochemicals (flavonoids), and vitamins (α-tocopherol). Health-promoting properties make these bioactive components suitable candidates for the development of novel food and nutraceutical products. This review comprehensively demonstrates the bioactive compounds of tomato seeds along with diverse biomedical activities of tomato seed extract (TSE) for treating cardiovascular ailments, neurological disorders, and act as antioxidant, anticancer, and antimicrobial agent. Utilization of bioactive components can improve the economic feasibility of the tomato processing industry and may help to reduce the environmental pollution generated by tomato by-products.

Role of Polyphenols on Gut Microbiota and the Ubiquitin-Proteasome System in Neurodegenerative Diseases

Today, neurodegenerative diseases have become a remarkable public health challenge due to their direct relation with aging. Accordingly, understanding the molecular and cellular mechanisms occurring in the pathogenesis of them is essential. Both protein aggregations as a result of the ubiquitin-proteasome system (UPS) inefficiency and gut microbiota alternation are the main pathogenic hallmarks. Polyphenols upregulating this system may decrease the developing rate of neurodegenerative diseases. Most of the dietary intake of polyphenols is converted into other microbial metabolites, which have completely different biological properties from the original polyphenols and should be thoroughly investigated. Herein, several prevalent neurodegenerative diseases are pinpointed to explain the role of gut microbiota alternations and the role of molecular changes, especially UPS down-regulation in their pathogenesis. Some of the most important polyphenols found in our diet are explained along with their microbial metabolites in the body.

Triterpene glycosides and phenylpropane derivatives from Staurogyne concinnula possessing anti-angiogenic activity

After anti-angiogenic activity screening, the potential n-butanol layer partitioned from the ethanol extract of Staurogyne concinnula was conducted. Further purification by Diaion HP20 column and preparative HPLC chromatography, four undescribed triterpenoid saponin derivatives, along with the known baptisiasaponin I, and four known phenylpropanoid glycosides were isolated and characterized from n-butanol layer. The structures of isolated compounds were elucidated by ESI-MS, 1D, and 2D MNR data. Biological evaluation revealed that baptisiasaponin I possessed significant anti-angiogenic effects (IC₅₀ 4.0 ± 0.2 μM). Further mechanism of action of baptisiasaponin I by inhibition of integrin/FAK/paxillin signaling pathway and its downstream effectors as MMP2 and MMP9 are also presented.

Insights in the Recalcitrance of Theasinensin A to Human Gut Microbial Degradation

Due to low bioavailability of dietary phenolic compounds in small intestine, their metabolism by gut microbiota is gaining increasing attention. The microbial metabolism of theasinensin A (TSA), a bioactive catechin dimer found in black tea, has not been studied yet. Here, TSA was extracted and purified for in vitro fermentation by human fecal microbiota, and epigallocatechin gallate (EGCG) and procyanidin B2 (PCB2) were used for comparison. Despite the similarity in their flavan-3-ol skeletons, metabolic fate of TSA was distinctively different. After degalloylation, its core biphenyl-2,2',3,3',4,4'-hexaol structure remained intact during fermentation. Conversely, EGCG and PCB2 were promptly degraded into a series of hydroxylated phenylcarboxylic acids. Computational analyses comparing TSA and PCB2 revealed that TSA's stronger interflavanic bond and more compact stereo-configuration might underlie its lower fermentability. These insights in the recalcitrance of theasinensins to degradation by human gut microbiota are of key importance for a comprehensive understanding of its health benefits.