Antioxidant flavonoids from Alhagi maurorum.

A new flavonoid, isorhamnetin-3-O-[-alpha-l-rhamnopyranosyl-(1 --> 3)]-beta-D-glucopyranoside (1), along with two known flavonoids 3'-O-methylorobol (2) and quercetin 3-O-beta-d-glucopyranoside (3), was isolated from Alhagi maurorum. Their structures were established with the help of mass spectrometry, 1D and 2D NMR spectroscopy, and in comparison with the literature data. Compounds 1 and 2 exhibited moderate antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay.