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

MOSSE, JUANA I.; GASTALDI, BRUNO; GALLEANO, M; GONZÁLES, SILVIA B.

Congreso; IX International Conference of Polyphenols and Health; 2019

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 analysed an extract of Drymis Andina, a native plant from Patagonian Argentine region, as inhibitors of digestive enzymes.Materials and methods: Lyophilized was prepared from a 5% aqueous extracts (100 mL of boiling water was added to 5 g of plant material (dry powder). Phenol content and total flavonoid content were measured by Folin?Ciocalteu and aluminum trichloride methods, respectively. In vitro lipase inhibition was measured by using porcine pancreatic lipase monitoring the cleavage of 1,2-O-dilauryl-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 on C57BL6 male mice. Acarbose and orlistat were used as positive controls in in vitro and in vivo studies.Results: The reconstituted aqueous extract of D. andina (18 mg/ml) showed a total phenol content of 0.70±0.02 mg (gallic acid equiv.) and a total flavonoid content of 0.35 ± 0.01 mg (quercetin equiv.). In the in vitro assays, the IC50 were 0.10±0.03 mg/mL and 2.04±0.08 mg/mL for alpha-glucosidase and lipase, respectively. For oral maltose tolerance test, maltose (400 mg/kg b.w.) was administered 5 min later than water/extract/inhibitor, and glucemia was measured at 0, 30, 60, and 120 min. Doses of 45, 90, and 180 mg/kg decreased significantly the postprandial glucemia 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 in 78%.Conclusion: The aqueous extract of D. andina showed both inhibitory activities, with higher efficiency as alpha-glucosidase inhibitor than lipase inhibitor. Further experiments will be carried out to identify the compounds responsible for these effects. The introduction of D. andina as infusion before the consumption of refined carbohydrates and/or fat rich food could be beneficial not only to prevent fat deposition but also to reduce the negative impact on metabolism promoted by high levels of postprandial glucose and TG.