Sonali Ray

Abstract: Black tea is one of the most widely consumed beverages in the world and traditionally known for its antidiabetic and antiobese property. However, the underlying mechanisms of these properties are not studied widely. In this work, we hypothesize that the reason could be because of the inhibition of gut enzymes by the tea derived phytochemicals. Molecular docking was used to explore the efficacy of tea components to inhibit the key enzymes related with Type II diabetes and obesity; α-glucosidase, α-amylase and lipase. Autodock4.2 molecular docking software that applies Lamarckian Genetic Algorithm was used. The ligand structures were retrieved from PubChem and KNApSAcK-3D database. PreADMET web server was used for Toxicity and ADME predictions. Based on this analysis, it has been found that 8-c-ascorbyl-(-)-epigallocatechin, rutin and orientin could be the putative molecules for amelioration of post-prandial hyperglycaemia whereas 8-c-ascorbyl-(-)-epigallocatechin, 8-c-ascorbyl epigallocatechin 3-o-gallate and schaftoside could be used to reduce fat absorption in obese persons. It can be concluded that these phytochemicals or their derivatives can be used for further in-vitro and in-vivo studies to design valuable drugs.

Abstract: The objective of the present study was to determine the inhibitory properties of the infusions and decoctions of four samples of Indian black tea (BT) and some of the tea flavonoids, gallic acid and caffeine, in vitro, against β- glucuronidase, lipase,α-amylase and α-glucosidase. These enzymes are related to liver disorders, obesity and diabetes. The phenolic constituents and caffeine content in the BT extracts were measured quantitatively by HPLC. It was noted that both infusion and decoction of BT had β-glucuronidase inhibitory property close to that of silymarin. Epigallocatechin gallate, epicatechin, and gallocatechin showed higher β-glucuronidase inhibitory activity than that of BT extracts and silymarin. BT extracts also inhibited the enzyme lipase. Thearubigin, theaflavin, epigallocatechin gallate, epicatechin and gallocatechin showed significant lipase inhibitory properties that were superior to the drug orlistat. The tea extracts, flavonoids and gallic acid inhibited the activity of α-amylase and α-glucosidase. Theaflavin and catechin had α-amylase inhibitory activity better than that of acarbose. This in vitro study reveals that BT extract and the phenolic components may have potential benefit for controlling liver disorders, obesity and diabetes.

Abstract: Angiotensin I-converting enzyme inhibitors are used as therapeutic agents for the treatment of hypertension. Regular consumption of black tea (Camellia sinensis (L.) Kuntze, Theaceae) has been reported to lower blood pressure. The aims of the present work were to compare chemical composition and angiotensin I-converting enzyme inhibitory properties of infusion and decoction of four samples of black tea. GC/MS based metabolomics approach helped in identification of fifty-one metabolites including ten organic acids, one inorganic acid, sixteen amino acids, two sugars, five sugar alcohols, fifteen phenols and flavonoids, two fatty acids from infusions and decoctions of four black tea samples. Partial least squares discriminant analysis and orthogonal partial least squares discriminant analysis models showed good classification among the two groups, diffusion and infusion, based on metabolites. Both infusion and decoction inhibited the enzyme. However, the activity differed with samples. Multivariate analysis also segregated extracts on the basis of activity. Thearubigin, theaflavin, catechin inhibited the enzyme. Epicatechin, epigallocatechin gallate, gallic acid, caffeine showed lower activity.

Abstract: Achras sapota L. fruit extracts have previously been reported to have activities against the carbohydrate-digesting enzymes α-amylase and α-glucosidase. The present work was aimed to identify the inhibitors of α-amylase and α-glucosidase using metabolomics and chemometric approaches. Metabolite profile of Achras sapota fruit extracts at different stages of post-harvest ripening was analyzed using GC–MS-based metabolomics approach. The extracts were also assayed for their properties to inhibit the carbohydrate-digesting enzymes α-amylase and α-glucosidase in vitro. The fruit extracts just after harvesting showed maximum activities against the enzymes α-amylase and α-glucosidase. The activities declined with post-harvest ripening. It was observed from the chemometric analysis that gallic acid, chlorogenic acid, benzene-1,2,4-triol, and d-malic acid are responsible for high α-amylase inhibitory activity. Gallic acid and chlorogenic acid are positively correlated with high α-glucosidase inhibitory activity. Inhibition of the two enzymes by gallic acid, benzene-1,2,4-triol, chlorogenic acid, and α-amylase by d-malic acid supported the findings. The present experiment reports the importance of both primary and secondary metabolites for the bioactivity of plant extracts.

Abstract: Pancreatic lipase (PL) is a critical enzyme associated with hyperlipidemia and obesity. A previous study of ours suggested that persimmon tannin (PT) was the main component accounting for the antihyperlipidemic effects of persimmon fruits, but the underlying mechanisms were unclear. In this present study, the inhibitory effect of PT on PL was studied and the possible mechanisms were evaluated by fluorescence spectroscopy, circular dichroism (CD) spectra, isothermal titration calorimetry (ITC), and molecular docking. PT had a high affinity to PL and inhibited the activity of PL with the half maximal inhibitory concertation (IC50) value of 0.44 mg/mL in a noncompetitive way. Furthermore, molecular docking revealed that the hydrogen bonding and π–π stacking was mainly responsible for the interaction. The strong inhibition of PT on PL in the gastrointestinal tract might be one mechanism for its lipid-lowering effect.

Abstract: Inhibitory effects of apple polyphenol extract (AP) and procyanidin contained in AP on in vitro pancreatic lipase activity and in vivo triglyceride absorption in mice and humans were examined. AP and procyanidin considerably inhibited in vitro pancreatic lipase activity. However, polyphenols, except for procyanidin, in AP (i.e., catechins, chalcones, and phenol carboxylic acids) showed weak inhibitory activities on pancreatic lipase. Procyanidins separated by normal-phase chromatography according to the degree of polymerization were also examined. Inhibitory effects of procyanidins increased according to the degree of polymerization from dimer to pentamer. On the other hand, pentamer or greater procyanidins showed maximal inhibitory effects on pancreatic lipase. These results suggested that with respect to in vitro pancreatic lipase inhibition, the degree of polymerization was an important factor and oligomeric procyanidin mainly contributed. Next, we performed a triglyceride tolerance test in mice and humans. Simultaneous ingestion of AP and triglyceride significantly inhibited an increase of plasma triglyceride levels in both models. These results suggested that the oligomeric procyanidins contained in AP inhibited triglyceride absorption by inhibiting pancreatic lipase activity in mice and humans.

Abstract: Qingzhuan tea (QZT), a post-fermented tea, has been reported to have anti-obesity and anti-hyperglycemic effects, perhaps due to bioactive compounds that inhibit lipase and α-amylase. It is unknown what chemical constituents' changes and what bioactive compounds occur during the manufacture of QZT. The aim of this study was to determine the secondary metabolites changes that occur during post-fermentation and how these changes affect the ability of QZT to inhibit the activities of lipase and α-amylase. During the processing steps, metabolites levels and their inhibitory effects on lipase and α-amylase were assessed. Changes in content and activities suggested that the first turn over or the second turn over was critical for the formation and conversion of bioactive compounds responsible for the anti-obesity and hypoglycemic effects. The relationship between constituents and activities was further evaluated by correlation analysis, which showed that amino acids and flavonoids might be responsible for the anti-obesity and anti-hyperglycemic effects of QZT. This study clarified that compounds were altered during pile fermentation of QZT and tentatively identified the bioactive compounds formed during QZT manufacture.

Abstract: The flower extracts of two cultivated varieties of Musa X paradisiaca viz. Kanthali and Kancha Kela were assayed against the enzymes α-amylase, α-glucosidase, acetylcholinesterase, β-glucuronidase and Angiotensin I Converting Enzyme, which are related to different diseased states like diabetes, Alzheimer's disease, hepatic disorder and cardiovascular diseases, respectively. The extracts inhibited all the enzymes except α-amylase by Musa X paradisiaca cv. Kanthali. Significantly high activities were observed in both the cultivated varieties for inhibiting the enzymes β-glucuronidase and Angiotensin I Converting Enzyme with respect to the known inhibitors of such enzymes silymarin and Lisinopril, respectively. The chemical constituents present in the methanol extracts were profiled following GC-MS based metabolomics approach. Eleven organic acids, seven sugars and sugar alcohols, six fatty acids, three phenols, two amino acids and a sterol could be identified. Practical Applications The male flowers of Musa X paradisiaca are cooked as vegetable in South-East Asia. The flowers are also useful in diabetes. Enzyme inhibitors have properties to prevent or control different noninfectious diseases. So, the flower extracts of two varieties of the plant were assayed for their activities against the glycosidases, acetylcholinesterase, β-glucuronidase and Angiotensin I Converting Enzyme. The activities of the flower extracts against the enzymes suggest that they may have beneficial effects in controlling diseases.