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

GASTALDI, B; FRESIA SILVA SOFRÁS; GALLEANO, M.; JUANA I. MOSELE; RETTA D.; GONZALEZ, S.; FRAGA, C.

Kobe

Conferencia; 9 th International Conference on Polyphenols and Health; 2019

Background: There is a great body of evidence regarded the positive effects of polyphenols in thetreatment of obesity. The interest in local plants have increased considerably in the last years aspotential sources of natural antiobesity compounds. In this work we studied an extract of DrymisAndina, 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 ofplant material as dry powder/100 mL of boiling water). Phenolics and total flavonoid content weremeasured by Folin?Ciocalteu and aluminium trichloride methods, respectively. In vitro lipaseinhibition 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 usingthe enzyme from S. cerevisiae with p-nitrophenyl-alpha-D-glucoside as substrate. In vivo studieswere carried out in C57BL6 male mice. Acarbose and orlistat were used as positive controls in invitro and in vivo studies.Results: The lyophilized extract, reconstituted with water to 18 mg/ml, has a total phenol contentof 0.70±0.02 mg (gallic acid equivalents) and a total flavonoid content of 0.35 ± 0.01 mg (quercetinequivalents). The calculated IC50 for the in vitro inhibition of alpha-glucosidase and lipase were0.10±0.03 mg/ml and 2.04±0.08 mg/ml, respectively. For oral maltose tolerance test, maltose (400mg/kg bw.) was administered 5 min later than water/extract/inhibitor, and glycemia was measuredat 0, 30, 60, and 120 min. Doses of 45, 90, and 180 mg/kg decreased significantly the AUC for thepostprandial glycemia in 34%, 38% and 68%, respectively. For oral lipid tolerance test, olive oil (5mL/kg b.w.) was administered 15 min later than water/extract/inhibitor and triglyceridemia wasmeasured at 0, 1, 2, 3, and 4 h. Dose of 180 mg/kg decreased significantly the postprandialtriglyceridemia (AUC) in 78%.Conclusion: The aqueous extract of D. andina showed inhibitory actions on alpha-glucosidase andlipase activities, both in vitro and in vivo. Further experiments will be carried out to identify thecompounds responsible for these effects and the mechanisms involved. D. andina could bebeneficial to ameliorate fat deposition associated to the high consumption of lipids and/orcarbohydrates.Support: UBACyT 20020170100586BA (MG), 20020160100132BA (CGF), and PIP-CONICET11220170100585CO (MG).