New onoceranoid xyloside from Lansium parasiticum.

A novel onoceranoid triterpene xyloside named methyl lansioside C (1) together with two known glycosides (2 and 3) were isolated from polar fraction of the fruit peels of Lansium parasiticum. The structure and absolute configuration of the new compound were established using extensive spectroscopic techniques as well as Mosher's method. The antioxidant activity and α-glucosidase inhibitory effect of the isolated compounds were evaluated. Compounds 1 and 3 displayed moderate radical scavenging activity with SC50 values of 14.5 and 13.7 mM, respectively. However, all isolated compounds exhibited no inhibition against α-glucosidase.