Procyanidin A2 Research Articles

Brazilian varieties of acerola (Malpighia emarginata DC.) produced under tropical semi-arid conditions: Bioactive phenolic compounds, sugars, organic acids, and antioxidant capacity.

Acerola fruit has gained prominence for its high nutraceutical value, associated with high levels of ascorbic acid and phenolic compounds. The objectives of this study were to analyze the chemistry composition and antioxidant capacity in seven Brazilian varieties of acerola. All acerola genotypes were harvested at the red ripe maturity stage, and the fruit were subjected to metabolite analyses by High-Performance Liquid Chromatography. The varieties presented high levels of ascorbic acid and malic acid. The main sugars observed in acerola were glucose and fructose. Cyanidin-3-rhamnoside was the main phenolic compound in the fruit (149-682mg/kg FW), which had higher concentration in the varieties BRS 235-Apodi, BRS 236-Cereja, and BRS 237-Roxinha. Other phenolic compounds also observed in the fruit were quercetin-3-glucoside, isorhamnetin, catechin, procyanidin A2, naringenin, hesperidin, chlorogenic acid, and trans-resveratrol. In conclusion, the observed wide range of acerola nutraceutical properties was related to the high genetic variability among genotypes. PRACTICAL APPLICATIONS: Brazil is the world's largest producer, consumer and exporter of acerola, with commercial orchards distributed all over the country. According to the Brazilian Ministry of Agriculture, Livestock and Supply, about eighteen registered varieties of acerola have been produced in the country. Among them are the varieties developed by Breeding Programs at the Brazilian Agricultural Research Corporation (Embrapa). Despite the great diversity of studies about acerola composition, only a few studies have focused on analyzing specific varieties. Therefore, limited information is currently available on the profile of metabolites of commercial interest in acerola varieties, such as sugars, organic acids and some phenolics. This study showed that acerola nutraceutical properties was highly dependent on the genotype.

Potential Activity Mechanisms of Aesculus hippocastanum Bark: Antioxidant Effects in Chemical and Biological In Vitro Models

The bark of Aesculus hippocastanum is an herbal remedy used in conditions connected with vascular insufficiency; however, there is a lack of data concerning its mechanisms of action. The present work is a preliminary investigation into some of the potential directions of the bark activity. The phytochemically (qualitative UHPLC-PDA-MS/MS and quantitative UHPLC-PDA assays) characterized extract and its four main constituents (esculin, fraxin, (‒)-epicatechin and procyanidin A2) were first evaluated in terms of their antioxidant capacity. All analytes demonstrated dose-dependent scavenging potential towards the most common in vivo oxidants, with particularly advantageous capacity of the extract and its flavan-3-ol constituents against peroxynitrite (3.37–13.26 mmol AA/g), hydroxyl radical (5.03–8.91 mmol AA/g) and superoxide radical (3.50–5.50 mmol AA/g). Moreover, even at low concentrations (1–5 µg/mL), they protected components of human plasma against oxidative damage inflicted by peroxynitrite, preventing oxidation of plasma protein thiols and diminishing the tyrosine nitration and lipid peroxidation. High efficiency of the analytes was also demonstrated in preventing the peroxynitrite-induced nitrative changes of fibrinogen (up to 80% inhibition for (‒)-epicatechin at 50 µg/mL), an important protein of coagulation cascade. Additionally, the extract and its constituents had, at most, moderate inhibitory activity towards platelet aggregation induced by ADP and only negligible influence on clotting times. The results show that, among the investigated properties, the antioxidant activity might, to the highest extent, be responsible for the bark efficacy in vascular disorders, thus supporting its application in those conditions; they also indicate the directions for future research that would allow for better understanding of the bark activity.

Gut Microbiota Composition Affects Procyanidin A2-Attenuated Atherosclerosis in ApoE-/- Mice by Modulating the Bioavailability of Its Microbial Metabolites.

Procyanidin A2 (PCA2) has been shown to improve lipid metabolism. However, it remains to know whether it can play a role in preventing atherosclerosis (AS) through gut microbiota. This study examined the effect of PCA2 on high fat diet (HFD)-induced AS in ApoE-/- mice with an intact and antibiotic-depleted microbiota. PCA2 administration for 12 weeks attenuated HFD-induced AS in ApoE-/- mice, evidenced by obviously alleviating the histological abnormalities of the aorta, lipid accumulation, oxidative stress, and inflammation, which were accompanied by downregulating the expression of vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 and upregulating peroxisome proliferator-activated receptor gamma, cholesterol 7 alpha-hydroxylase, and ATP-binding cassette transporter A1. Moreover, PCA2 treatment reshaped the gut microbiota imbalance caused by HFD, especially reducing the ratio of Firmicutes/Bacteroidetes and increasing the abundance of Verrucomicrobia. However, antibiotic intervention almost offset the alleviation of AS by PCA2 and prevented the biotransformation of PCA2 by gut microbiota, thus resulting in a 2327.21-6.27-fold decrease in its microbial metabolites of plasma. There was a marked correlation among the microbiota composition, the bioavailability of PCA2-derived microbial metabolites, and AS indicators. The findings indicate that the gut microbiota robustly influences the bioavailability of microbial metabolites that may partially drive the AS resilience property of PCA2.

Secondary metabolites from Hypericum trichocaulon Boiss. & Heldr., growing wild in the island of crete

Eleven compounds were isolated from the aerial blooming parts of Hypericum trichocaulon Boiss. & Heldr., a narrow endemic plant of the island of Crete (Greece). These compounds comprise one previously undescribed prenylated phloroglycinol derivative (adhyperfoliatin), together with ten known compounds, procyanidin A2, hyperixanthone A, (E)-chlorogenic acid, trans-phytol, five flavonoids, i.e. I3,II8-biapigenin, quercitrin, hyperoside, rutin, myricitrin and one fatty acid. The structures of the isolated compounds were established by means of 1D and 2D NMR, as well as MS spectral analyses. Phloroglucinol derivatives are recognized as chemophenetic markers for the genus Hypericum, and the isolation of adhyperfoliatin contributes to the characterization of the section Drosocarpium Spach, where the under-investigation taxon belongs. Moreover, the investigation of the methanol extract led to the isolation of myricitrin in high amounts, a specialized metabolite which also serves as a marker for this section.

An Optimized Fluorometric Method to Test the Capacities of Cranberry Polyphenols and Metabolites to Inhibit the Adhesion of Type-P and Type-1 Fimbriated Uropathogenic E. coli

Abstract Objectives Adhesion of type-P and type-1 fimbriated uropathogenic E. coli to urinary tract epithelial cells initiates urinary tract infections. This research aimed to optimize and apply a fluorometric method to evaluate the capacities of cranberry polyphenols and metabolites to inhibit such adhesion in vitro. Methods BacLight Green labelled E. coli were incubated with cranberry polyphenols or microbial metabolites of cranberry polyphenols for 30 min at 37°C. Mixture was added to a 96-well microplate containing 1 × 105/well of human uroepithelial T24 cells and incubated for 1 h at 37°C. After incubation, E. coli not adhered were removed by phosphate buffer washing. Fluorescent intensity was measured on a microplate reader at 480 nm excitation and 516 nm emission. Results Stable and strong fluorescent readings were obtained with 800 μmol/L BacLight Green for E. coli labeling and an E. coli to T24 cells ratio of 400:1 for co-incubation. A standard curve was established using 0–63 μM myricetin. The half-maximal inhibitory concentrations (IC50) of myricetin were 13.2 μM against type-P E. coli adhesion and 5.5 μM against type-1 E. coli adhesion. A fraction enriched with procyanidin polymers had IC50 of 57.6 μg/mL against type-P E. coli and 19.3 μg/mL against type-1 E. coli, respectively. Its anti-adhesion activities were more potent than those of cranberry fractions enriched with procyanidin oligomers, flavonols, or anthocyanin. Procyanidin A2 had a maximal inhibition about 35% at 17.3 μM against type-P E. coli, but no anti-adhesion activity was observed against type-1 E. coli. Procyanidin B2 showed a plateaued inhibition about 15% at 173–691 μM against type-P E. coli. Its maximal inhibition against type-1 E. coli was around 25% at 346 μM. Hippuric acid, a major metabolite of cranberry polyphenols, had a maximal inhibition about 20% at 558 μM against type-1 E. coli adhesion, whereas its anti-adhesion activity against type-P E. coli was not detected. Conclusions The optimized fluorometric method showed that both structure and composition of cranberry polyphenols and metabolites affected their abilities to inhibit E. coli adhesion in vitro. Anti-adhesion activities of cranberry polyphenols also depend on type of E. coli fimbriae. Funding Sources University of Florida Research Foundation Seed Fund.

Isolation and Structure Elucidation of Three Dimeric A-type Proanthocyanidins from <i>Empetrum Nigrum</i> L.

Introduction. Urinary tract infections are a common group of diseases worldwide, affecting more than 150 million people every year. In about 30 % of patients with initial infection, UTI becomes chronic. Herbal medicines, along with synthetic diuretics and antibiotics, are widely used for the prevention and treatment of UTIs, which makes the search and isolation of various substances from plant materials an important task. The present study is devoted to the isolation of compounds belonging to the class of proanthocyanidins from the aerial part of the black crowberry (Empetrum nigrum L.).Aim. Method development for the isolation of individual dimeric type A proanthocyanidins from the aerial part of Empetrum nigrum and the elucidation of their chemical structure using modern physicochemical methods of analysis.Materials and methods. Shoots of Empetrum nigrum were collected next to the Saint Petersburg State Chemical-Pharmaceutical University Nursery Garden of Medicinal Plants (Leningrad region, Vsevolozhsky district, Priozerskoe highway, 38 km) in August 2019. Fraction analysis was performed through analytical high-performance liquid chromatography (HPLC) using a Prominence LC-20 (Shimadzu corp., Japan) equipped with a SPD-M20A diode-array detector, as well as by high performance thin layer chromatography (HPTLC) using a CAMAG HPTLC system (Switzerland). The isolation of compounds was carried out by open column chromatography using sorbents with different selectivity, as well as by preparative HPLC using a Smartline system (Knauer, Germany) equipped with a spectrophotometric detector. The structures of the isolated compounds were established by 1D and 2D NMR experiments (Bruker Avance III 400 MHz, Germany), as well as high-resolution mass spectrometry (HR-ESI-MS) (Bruker Micromass Q-TOF, Germany).Results and discussion. Using the developed methods, from the Empetrum nigrum shoots we managed to isolate and characterised three individual compounds belonging to the class of A-type proanthocyanidins. According to NMR and mass spectrometry data, compound 1 is epicatechin-(2β → O → 5, 4β → 6)-epicatechin, with an extremely rare type of intermonomer bond (2β → O → 5, 4β → 6). Compounds 2 and 3 are epicatechin-(2β → O → 7, 4β → 8)-epicatechin (procyanidin A2) and epicatechin-(2β → O → 7, 4β → 8)-catechin (procyanidin A1), respectively. All individual compounds (1-3) were found and isolated from Empetrum nigrum for the first time.Conclusion. As a result of the research, three individual compounds (A-type proanthocyanidins) were isolated from the aerial part of Empetrum nigrum. All individual compounds (1-3) were found and isolated from Empetrum nigrum for the first time. Future assessment of the isolated compounds biological activity is presumed.

Liquid Chromatographic Fingerprints for the Characterization of Flavanol-Rich Nutraceuticals Based on 4-Dimethylaminocinnamaldehyde Precolumn Derivatization

Flavanols consist of a great family of bioactive molecules displaying a wide range of health-promoting attributes for humans, including antioxidant, antimicrobial or anti-inflammatory effects. As a result, botanical species rich in this type of compound are often used to develop nutraceutical products or dietary supplements with recognized healthy attributes. This paper aims at characterizing nutraceutical products using liquid chromatographic fingerprints related to flavanol composition. Catechins and their oligomers were exploited to characterize and authenticate various commercial products prepared with extracts of red berries and medicinal plants. These compounds resulted in interesting descriptors of some fruits and vegetables, thus providing an additional perspective for the study of nutraceuticals. For such a purpose, a new method based on liquid chromatography with UV/Vis detection (HPLC–UV/Vis) with precolumn derivatization with 4-dimethylaminocinnamaldehyde was developed. Results indicated that the separation of flavanols was very complex due to the degradation of procyanidin derivatives. The resulting data sets were analyzed using chemometric methods such as principal component analysis and partial least square–discriminant analysis. Despite the complexity of chromatographic fingerprints, nutraceutical samples could be discriminated according to their main ingredients. In general, catechin and epicatechin were the most abundant compounds in the different samples, and procyanidin A2 was highly specific to cranberry.

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.

A Study of Catechin Photostability Using Photolytic Processing

Catechin exhibits numerous physiological characteristics. In this study, we determined the photosensitivity of catechin to various lights under alkaline conditions, and the mechanisms by which catechin generates free radical species and polymerizes via a photoreaction. In addition to this, the application of catechin photolysis was investigated. A solution of catechin is transparent, but turns yellowish under blue light illumination (BLI) in neutral or weak alkaline solutions. When catechin is subjected to BLI, a dimeric catechin (proanthocyanidin) and a superoxide anion radical (O2•−) are generated in a photolytic reaction. When ascorbic acid or gallic acid is added to catechin and the mixture is subjected to BLI at alkaline pH, fewer catechin dimers and less O2•− are produced, because both acids inhibit the photosensitive oxidation of catechin. When AlCl3 is added to catechin and the mixture is subjected to BLI at pH 8, a photolytic reaction is suppressed by AlCl3, and AlCl3 acts as a catalyst for the disconnection of proanthocyanidin during photolysis. Under alkaline conditions, catechin generates O2•− via photosensitive oxidation, which suppresses the growth of Acinetobacter baumannii (A. baumannii) by at least 4 logs, and deactivates its multi-drug-resistant strain. This study shows that catechin photolysis is a process of oxidation, and that it can be safely applied as a tool for environmental applications.

Nonvolatile metabolite alterations during Zijuan black tea processing affect the protective potential on HOECs exposed to nicotine.

Understanding nonvolatile metabolite alterations during processing and their impacts on potential function is crucial for technological innovations in tea manufacturing. In the present work, specific metabolite alterations during Zijuan black tea processing and their potential effects on nicotine-induced human oral epithelial cell (HOEC) injury were investigated. The results showed that leucine, isoleucine, and tyrosine were the main hydrolysis products during withering, and theaflavin-3-gallate (TF-3-G), theaflavin-3'-gallate (TF-3'-G) and theaflavin-3,3'-gallate (TFDG) were mainly formed during rolling. Moreover, oxidation of flavonoid glycosides, catechins and dimeric catechins took place during fermentation. During drying, amino acid conversion became dominant. Meanwhile, processing samples effectively attenuated nicotine-induced oxidative stress and inflammation in HOECs. TF-3'-G, TF-3-G, phenylalanine, and kaempferol-3-coumaroylglucoside exhibited strong associations with protective action, which indicates that modifying the processes in which black tea are produced to be rich in those specific components could be beneficial for the oral health of people who smoke.

Adaptive Chirality of an Achiral Cage: Chirality Transfer, Induction, and Circularly Polarized Luminescence through Aqueous Host–Guest Complexation

Chirality transfer, induction, and circularly polarized luminescence (CPL) using supramolecular hosts, such as macrocycles and cages, have been explored for wide-ranging applications in chiral reco...

Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography–Mass Spectrometry

Tea is rich in catechins and aluminum. In this study, the process of catechin photolysis was applied as a model for examining the effects of aluminum chloride (AlCl3) on the structural changes of catechin and the alteration of aluminum complexes under blue light irradiation (BLI) at pH 8 using liquid chromatography and mass spectrometry techniques. Additionally, the effects of anions on catechin upon the addition of AlCl3 and treatment with BLI were also studied. In this study, when 1 mM catechin was treated with BLI, a superoxide anion radical () was generated in an air-saturated aqueous solution, in addition to forming a dimeric catechin (proanthocyanidin) via a photon-induced redox reaction. The relative percentage of catechin was found to be 59.0 and 95.7 for catechin treated with BLI and catechin upon the addition of 1 mM AlCl3 treated with BLI, respectively. It suggested that catechin treated with BLI could be suppressed by AlCl3, while AlCl3 did not form a complex with catechin in the photolytic system. However, under the same conditions, it was also found that the addition of AlCl3 inhibited the photolytic formation of and reduced the generation of proanthocyanidin, suggesting that the disconnection of proanthocyanidin was achieved by AlCl3 acting as a catalyst under treatment with BLI. The influence of 1 mM fluoride () and 1 mM oxalate () ions on the photolysis of 1 mM catechin upon the addition of 1 mM AlCl3 and treatment with BLI was found to be insignificant, implying that, during the photolysis of catechin, the Al species were either neutral or negatively charged and the aluminum species did not form a complex with anions in the photolytic system. Therefore, aluminum, which is an amphoteric species, has an inherent potential to stabilize the photolysis of catechin in an alkaline conditions, while suppressing the and proanthocyanidin generation via aluminum ion catalysis in the catechin/Al system under treatment with BLI.

Effect and mechanism of total flavonoids of Lichi Semen on CCl_4-induced liver fibrosis in rats, and prediction of Q-marker

This paper was to investigate the effect of total flavonoids of Lichi Semen(TFL) on carbon tetrachloride(CCl_4)-induced liver fibrosis in rats, analyze and predict its mechanism of action and potential quality markers(Q-marker). Firstly, male SD rats were taken and injected subcutaneously with a 40% CCl_4-vegetable oil solution twice a week for 8 consecutive weeks to establish a rat model of liver fibrosis. The rats with liver fibrosis were randomly divided into model group, silybin group(43.19 mg·kg~(-1)), Fuzheng Huayu Capsules group(462.75 mg·kg~(-1)), and TFL groups(100 mg·kg~(-1) and 25 mg·kg~(-1)), with normal rats as a blank group, 10 rats in each group. Except for the blank group, the rats in the other groups were subcutaneously injected with 40% CCl_4-vegetable oil solution of a maintenance dose, once a week. The rats in various treatment groups received corresponding doses of drugs, while the rats in the blank group and model group received the same volume of normal saline once a day for 4 weeks. At the end of the experiment, blood was collected from the abdominal aorta and the liver tissues were collected. The levels of total bilirubin(TBiL), direct bilirubin(DBiL), indirect bilirubin(IBiL), alanine aminotransferase(ALT), and aspartate aminotransferase(AST) in serum were detected by using an automatic biochemical detector. Masson staining was used to observe the histopathological changes of rat liver. Then, the chemical compositions of TFL were collected, and the action targets of these chemical compositions were predicted through SWISS database and reverse molecular docking server(DRAR-CPI). After screening of disease targets of liver fibrosis by Gene Cards database, the protein-protein interaction was analyzed with use of STRING database, and GO(gene ontology) analysis and KEGG(Kyoto encyclopedia of genes and genomes) enrich analysis were also carried out. Moreover, an iTRAQ proteomics technology was used to determine protein expression in liver tissues of rats in TFL, model and blank groups to verify the targets. Furthermore, Cytoscape software was used to establish and visualize the network of chemical components, targets and pathways, and predict the potential Q-marker of TFL. The results showed that the levels of TBiL, DBiL, IBiL, ALT, and AST in the model group were significantly higher than those in the blank normal group(P<0.05), and the above levels in the treatment groups were lower than those in the model group, but with no significant differences. Masson staining showed that the liver damage and the degree of fibrosis were severe in the model group, and were relieved to different degrees in the treatment groups. Then, 74 chemical components were screened, which could act on 865 targets such as EGFR and SRC, participating in the regulation of cancer pathways, PI3 K-Akt signaling pathway, HIF-1 signaling pathway and other signaling pathways closely related to liver fibrosis. Pinocembrin, quercetin, epicatechin, procyanidin A2, naringenin, nobiletin, phlorizin and rutin showed the highest correlation with liver fibrosis-related targets and pathways. Proteomics results showed that a total of 18 proteins among the 45 proteins predicted by internet pharmacology were identified, among which 6 proteins were significantly expressed, including 5 up-regulated proteins and 1 down-regulated protein. The protein expression of ALB, PLG, HSP90 AA1, EGFR and MAP2 K1 was significantly returned to a normal state in the TFL treatment groups. In conclusion, TFL may demonstrate the anti-hepatic fibrosis and potential hepatoprotective effects by regulating the expression of ALB, PLG, HSP90 AA1, EGFR and MAP2 K1, which may be associated with the regulation of multiple signaling pathways related to liver fibrosis such as PI3 K-Akt pathway. Pinocembrin, quercetin, epicatechin, procyanidin A2, naringenin, nobiletin, phlorizin and rutin could be regarded as potential Q-markers of TFL for quality control.

Docking Characterization and in vitro Inhibitory Activity of Flavan-3-ols and Dimeric Proanthocyanidins Against the Main Protease Activity of SARS-Cov-2.

We report to use the main protease (Mpro) of SARS-Cov-2 to screen plant flavan-3-ols and proanthocyanidins. Twelve compounds, (–)-afzelechin (AF), (–)-epiafzelechin (EAF), (+)-catechin (CA), (–)-epicatechin (EC), (+)-gallocatechin (GC), (–)-epigallocatechin (EGC), (+)-catechin-3-O-gallate (CAG), (–)-epicatechin-3-O-gallate (ECG), (–)-gallocatechin-3-O-gallate (GCG), (–)-epigallocatechin-3-O-gallate (EGCG), procyanidin A2 (PA2), and procyanidin B2 (PB2), were selected for docking simulation. The resulting data predicted that all 12 metabolites could bind to Mpro. The affinity scores of PA2 and PB2 were predicted to be −9.2, followed by ECG, GCG, EGCG, and CAG, −8.3 to −8.7, and then six flavan-3-ol aglycones, −7.0 to −7.7. Docking characterization predicted that these compounds bound to three or four subsites (S1, S1′, S2, and S4) in the binding pocket of Mpro via different spatial ways and various formation of one to four hydrogen bonds. In vitro analysis with 10 available compounds showed that CAG, ECG, GCG, EGCG, and PB2 inhibited the Mpro activity with an IC50 value, 2.98 ± 0.21, 5.21 ± 0.5, 6.38 ± 0.5, 7.51 ± 0.21, and 75.3 ± 1.29 μM, respectively, while CA, EC, EGC, GC, and PA2 did not have inhibitory activities. To further substantiate the inhibitory activities, extracts prepared from green tea (GT), two muscadine grapes (MG), cacao, and dark chocolate (DC), which are rich in CAG, ECG, GAG, EGCG, or/and PB2, were used for inhibitory assay. The resulting data showed that GT, two MG, cacao, and DC extracts inhibited the Mpro activity with an IC50 value, 2.84 ± 0.25, 29.54 ± 0.41, 29.93 ± 0.83, 153.3 ± 47.3, and 256.39 ± 66.3 μg/ml, respectively. These findings indicate that on the one hand, the structural features of flavan-3-ols are closely associated with the affinity scores; on the other hand, the galloylation and oligomeric types of flavan-3-ols are critical in creating the inhibitory activity against the Mpro activity.

The interaction mechanism of β-casein with oligomeric proanthocyanidins and its effect on proanthocyanidin bioaccessibility

The interaction mechanism between β-casein and five types of oligomeric proanthocyanidins, including procyanidins B1, B2, B3, A2, and C1 was investigated using spectroscopy and molecular docking. The fluorescence spectroscopy results showed that B1, B2, B3, and A2 can quench the intrinsic fluorescence of β-casein by static quenching and C1 by both dynamic and static quenching. All five proanthocyanidins can form a binding site with β-casein, and the corresponding binding ability was as follows: procyanidins B1 (KA= 1317 ± 159 L⋅mol−1) > B2 (KA= 759 ± 179 L⋅mol−1) > B3 (KA= 761 ± 72 L⋅mol−1) > C1 (KA=138 ± 48 L⋅mol−1) > A2 (KA=99 ± 6.1 L⋅mol−1). According to thermodynamic analysis and molecular docking, the binding forces of proanthocyanidins with β-casein were mainly induced by hydrophobic interactions, van der Waals forces, and hydrogen bindings. Circular dichroism and Fourier-transform infrared spectroscopy supported the changes in the secondary structure of β-casein induced by proanthocyanidins. The interaction between β-casein and proanthocyanidins did not significantly reduce the digestion of β-casein but increased the recovery rate of procyanidin B1 by 8.9% during in vitro gastrointestinal digestion. This study laid the foundation for the application of β-casein-proanthocyanidins complex in the food industry.

Variability in the Content of Phenolic Compounds in Plum Fruit.

The aim of this study was to determine the composition and content of phenolic compounds in extracts of plum fruit. Fruit of 17 plum cultivars were analyzed. Fruit samples were collected in 2019 from fruit trees with “Myrobalan” (P. cerasifera Ehrh.) and “Wangenheim Prune” (P. domestica L.) rootstocks. The following glycosides of the flavonol group were identified: avicularin, isorhamnetin-3-O-rutinoside, isoquercitrin, hyperoside, rutin, and an aglycone quercetin. Compounds of the flavan-3-ol group were identified, such as (+)-catechin, procyanidin C1, and procyanidin A2, along with chlorogenic acid attributed to phenolic acids and a non-phenolic cyclitol–quinic acid. Of all the analytes identified in plum fruit samples, quinic acid predominated, while chlorogenic acid predominated among all the identified phenolic compounds, and rutin predominated in the flavonol group. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) revealed that fruit samples of “Kubanskaya Kometa”, “Zarechnaya Raniaya”, “Duke of Edinburgh”, “Jubileum”, and “Favorita del Sultano” cultivars had different quantitative content of phenolic compounds from that observed in other samples. The highest total amount of phenolic compounds was found in the European plum samples of the “Zarechnaya Rannyaya” cultivar, while the amount of quinic acid was the highest in plum fruit samples of the “Jubileum” cultivar.

Unravelling high-affinity binding compounds towards transmembrane protease serine 2 enzyme in treating SARS-CoV-2 infection using molecular modelling and docking studies

The coronavirus disease-19 (COVID-19) outbreak that is caused by a highly contagious severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a zoonotic pandemic, with approximately 24.5 million positive cases and 8.3 lakhs deaths globally. The lack of effective drugs or vaccine provoked the research for drug candidates that can disrupt the spread and progression of the virus. The identification of drug molecules through experimental studies is time-consuming and expensive, so there is a need for developing alternative strategies like in silico approaches which can yield better outcomes in less time. Herein, we selected transmembrane protease serine 2 (TMPRSS2) enzyme, a potential pharmacological target against SARS-CoV-2, involved in the spread and pathogenesis of the virus. Since 3D structure is not available for this protein, the present study aims at homology modelling and validation of TMPRSS2 using Swiss-model server. Validation of the modelled TMPRSS2 using various online tools confirmed model accuracy, topology and stereochemical plausibility. The catalytic triad consisting of Serine-441, Histidine-296 and Aspartic acid-345 was identified as active binding site of TMPRSS2 using existing ligands. Molecular docking studies of various drugs and phytochemicals against the modelled TMPRSS2 were performed using camostat as a standard drug. The results revealed eight potential drug candidates, namely nafamostat, meloxicam, ganodermanontriol, columbin, myricetin, proanthocyanidin A2, jatrorrhizine and baicalein, which were further studied for ADME/T properties. In conclusion, the study unravelled eight high affinity binding compounds, which may serve as potent antagonists against TMPRSS2 to impact COVID-19 drug therapy.

Variability in the Qualitative and Quantitative Composition and Content of Phenolic Compounds in the Fruit of Introduced American Cranberry (Vaccinium macrocarpon Aiton).

The aim of this study was to determine the composition and content of phenolic compounds in ethanol extracts of eight different cultivars of American cranberry (Vaccinium macrocarpon Aiton) fruit using spectrophotometric and UPLC-ESI-MS/MS analysis and to evaluate the antioxidant activity in vitro of these extracts. The highest total amount of phenolic compounds evaluated via Folin–Ciocalteu spectrophotometry was detected in American cranberry fruit samples of the ‘Bain’ clone, and the highest total amount of flavonoids was found in samples of the ‘Drever’ and ‘Baiwfay’ cultivars. The highest total amount of the individual phenolic compounds (519.53 ± 25.12 mg/g DW) identified and quantitatively evaluated via chromatography was detected in samples of the ‘Searles’ cranberry cultivar. In the studied cranberry samples, the predominant phenolic compounds were hyperoside, quercetin, and procyanidin A2, while the amounts of other compounds were significantly lower. HCA and PCA revealed that ‘Woolman’, ‘Holliston’, ‘Pilgrim, and ‘Searles’ fruit samples had different quantitative content of phenolic compounds from other cranberry cultivars. Meanwhile, fruit of ‘Baiwfay’, ‘Drever’, ‘Bain’, and ‘Bergman’ were similar in their phytochemical profile.

Isolation and characterization of secondary metabolites from Gaultheria tenuifolia berries.

Gaultheria berries (Ericaceae) are consumed as food or used in folk medicine throughout the world. In the present study, Gaultheria tenuifolia berries were studied to describe their polyphenol and iridoid composition, aroma volatiles, and cytoprotective effects. In total, 14 metabolites were isolated using a combination of countercurrent chromatography and Sephadex LH-20, namely, cyanidin-3-O-β-galactoside, cyanidin-3-O-β-arabinoside, 3-O-caffeoylquinic acid, 5-O-caffeoylshikimic acid, quercetin, quercetin-3-O-β-glucuronide, quercetin-3-O-β-rutinoside, quercetin-3-O-β-glucoside, quercetin-3-O-β-arabinoside, quercetin-3-O-β-rhamnoside, 6α-hydroxydihydromonotropein-10-trans-cinnamate, monotropein-10-trans-cinnamate, and an (epi)-catechin dimer and trimer. Other flavan-3-ols, proanthocyanidins, and iridoids were tentatively identified by spectroscopic and spectrometric means in the fruit extracts. The tentative volatile organic compound characterization pointed to methyl salicylate as responsible for the aroma of this species. The extracts showed significant cytoprotective effects in an oxidative stress model in human gastric epithelial cells. This is the first report on the isolation, characterization, and potential biological activity of secondary metabolites from G. tenuifolia berries and insights on its possible application as a functional food. PRACTICAL APPLICATION: Berries are desirable fruit species because of their phytochemical composition and pleasant taste. Gaultheria berries are special due to their high content of iridoids and the presence of salicylic acid derivatives. Aroma of native berries is relevant for the development of new products reflecting the local identity and use of fruits. The present work involves cooperation of academia and industry on the constituents of the native products. The results provided in this article could be useful for the introduction of this species in the food and nutraceutical industries.

Procyanidin A2, a polyphenolic compound, exerts anti-inflammatory and anti-oxidative activity in lipopolysaccharide-stimulated RAW264.7 cells.

Procyandin A2 (PCA2) is a polyphenolic compound which is isolated from grape seeds. It has been reported that PCA2 exhibits antioxidative and anti-inflammatory effects, but its molecular mechanism is still poorly understood. This study tests the hypothesis that PCA2 suppresses lipopolysaccharide (LPS)-induced inflammation and oxidative stress through targeting the nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and NF-E2-related factor 2 (Nrf2) pathways in RAW264.7 cells. PCA2 (20, 40, 80 μM) exhibited no significant cytotoxicity in RAW264.7 cells and showed an inhibitory effect on an LPS-induced nitrite level. Pro-inflammatory cytokines like tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), prostaglandin E2 (PGE2), nitric oxide (NO), and reactive oxygen species (ROS) were suppressed by PCA2 with a concentration range of 0–80 μM. The mRNA levels of TNF-α and IL-6 were inhibited by PCA2 (80 μM). The hallmark-protein expression of the NF-κB (p-IKKα/β, p-IκBα, and p-p65) and MAPK (p-p38, p-JNK, and p-ERK) pathways were decreased by PCA2 in LPS-stimulated RAW264.7 cells. In addition, immunofluorescence results indicated that PCA2 (80 μM) promoted the translocation of NF-κB/p65 from the cytoplasm into the nucleus. PCA2 upregulated the expressions of Nrf2 and HO-1 and downregulated the expression of Keap-1. Simultaneously, PCA2 (80 μM) reversed LPS-induced Nrf2 translocation from the nucleus into the cytoplasm. Collectively, PCA2 protect cells against the damage from inflammation and oxidative injury, which suggest a potential therapeutic strategy for inflammatory and oxidative stress through targeting NF-κB, MAPK, and Nrf2 pathways in RAW264.7 cells.