α-Glucosidase inhibitory activities of constituents from Psidium guajava leaves.

Psidium guajava is a plant of the Myrtaceae with various pharmacological activity. In this study, the water extract and the isolated compounds from guava leaves were evaluated for in vitro α-glucosidase inhibition using spectrophotometric method. Ellagic acid, quercetin, quercetin-3-O-glucuronide, avicularin, isoquercitrin, and quercetin-3-galactoside showed α-glucosidase inhibitory activity, and their IC ₅₀ value were 25.0, 41.0, 53.5, 46.9, 60.0 and 72.1 μg/mL, respectively compared with the positive control acarbose (IC ₅₀ 49.2 μg/mL). This study could provide a theoretical basis for the application of Psidium guajava in the treatment of hyperglycemia.