Inhibition of alpha-glucosidase and pancreatic lipase by a flavonoid-rich aqueous extract of Drymis andina: in vitro and in vivo studies

J. I. MOSSE; D. RETTA; B. GASTALDI; F.M. SOFRAS; M. GALLEANO; S.B. GONZALEZ; C. G. FRAGA

Kobe

Congreso; 9th International Conference on Polyphenols and Health (ICPH); 2019

ICPH

Background: There is a great body of evidence regarded the positive effects of polyphenols in the treatment of obesity. The interest in local plants have increased considerably in the last years as potential sources of natural antiobesity compounds. In this work we studied an extract of Drymis Andina, a native plant from Patagonian Argentine region, as inhibitor of digestive enzymes.Materials and methods: A lyophilized extract was prepared from a 5% aqueous extracts (5 g of plant material as dry powder/100 mL of boiling water). Phenolics and total flavonoid content were measured by Folin?Ciocalteu and aluminium trichloride methods, respectively. In vitro lipase inhibition was measured by using porcine pancreatic lipase monitoring the cleavage of 1,2-Odilauryl-rac-glycerol-3-glutaric acid. In vitro alpha-glucosidase inhibition was measured by using the enzyme from S. cerevisiae with p-nitrophenyl-alpha-D-glucoside as substrate. In vivo studies were carried out in C57BL6 male mice. Acarbose and orlistat were used as positive controls in in vitro and in vivo studies.Results: The lyophilized extract, reconstituted with water to 18 mg/ml, has a total phenol content of 0.70±0.02 mg (gallic acid equivalents) and a total flavonoid content of 0.35 ± 0.01 mg (quercetin equivalents). The calculated IC50 for the in vitro inhibition of alpha-glucosidase and lipase were 0.10±0.03 mg/ml and 2.04±0.08 mg/ml, respectively. For oral maltose tolerance test, maltose (400 mg/kg bw.) was administered 5 min later than water/extract/inhibitor, and glycemia was measured at 0, 30, 60, and 120 min. Doses of 45, 90, and 180 mg/kg decreased significantly the AUC for the postprandial glycemia in 34%, 38% and 68%, respectively. For oral lipid tolerance test, olive oil (5 mL/kg b.w.) was administered 15 min later than water/extract/inhibitor and triglyceridemia was measured at 0, 1, 2, 3, and 4 h. Dose of 180 mg/kg decreased significantly the postprandial triglyceridemia (AUC) in 78%.Conclusion: The aqueous extract of D. andina showed inhibitory actions on alpha-glucosidase and lipase activities, both in vitro and in vivo. Further experiments will be carried out to identify the compounds responsible for these effects and the mechanisms involved. D. andina could be beneficial to ameliorate fat deposition associated to the high consumption of lipids and/or carbohydrates.Support: UBACyT 20020170100586BA (MG), 20020160100132BA (CGF), and PIP-CONICET 11220170100585CO (MG).Keywords: Patagonia Argentina native plant-obesity-diabetes-digestive enzymes.