New flavonoid glycosides from Xanthium strumarium with their protein tyrosine phosphatase 1B inhibitory activity.

Two new flavonoid glycosides named 6-hydroxy-3-methoxy-apigenin 7-O-α-ʟ-rhamnopyranoside (1) and 3-hydroxyl-apigenin 8-C-ß-ᴅ-xylopyranoside (2), along with five known compounds (3-7), were isolated from Xanthium strumarium. Their structures were elucidated on the basis of spectroscopic and physicochemical analyses. All compounds were evaluated for in vitro inhibitory activity against PTP1B. Among them, compounds 1 and 5 showed significant inhibitory activity on PTP1B with IC50 values of 11.3 ± 1.7 and 8.9 ± 0.7 µM, respectively.