Passiflora ligularis leaf ultrasound-assisted extraction in the optimization of flavonoid content and enhancement of hypoglycemic activity

ABSTRACT

Among the different metabolites found in the Passiflora species, flavonoids have been related to some of thetherapeutic effects of these plants. In the case of Passiflora ligularis, the presence of these metabolites has beenrelated to a promising hypoglycemic effect. This study aimed to optimize the total flavonoid content of P. ligularisleaf extract to improve its therapeutic activity. The effect of three variables (ethanol percentage, temperature, andtime) on the ultrasound-assisted flavonoid extraction was evaluated by means of response surface methodology. Theeffect of increasing the flavonoid content on the extract activity was evaluated with an in vitro antiglycation assayand an in vivo glucose tolerance test in mice. The optimal extraction conditions were 63% ethanol, 70ºC, and 33minutes. The predicted maximum flavonoid yield (57.77 mg-equivalent isoquercetin/g dry extract) correlated with theexperimental value (59.76 ± 1.90 mg-equivalent isoquercetin/g dry extract) and the extraction process proved to behighly reproducible, suggesting that ultrasound-assisted extraction is a simple, inexpensive, and effective alternativetechnique for the extraction of flavonoids in Passiflora species. Moreover, the optimized extract exhibited the highestantiglycation activity against all the experimental design treatments and showed an enhanced hypoglycemic effect inmice compared to a traditionally extracted beverage.