α-Glucosidase inhibition and antihyperglycemic activity of prenylated xanthones from Garcinia mangostana

► The potent α-glucosidase inhibitors 1-16 were isolated from Mangosteen. ► An isolated xanthone has a very rare 2-oxoethyl group on C-8. ► The crude extract exhibited a significant glucose reduction in STZ-induced rats.