Antioxidative Flavonol Glucuronides and Anti-HBsAg Flavonol from Rotala rotundifolia

Abstract Two new flavonol glucuronides, quercetin 3-O- β - d -2″-acetylglucuronide ( 1 ) and quercetin 3-O- β - d -2″-acetylglucuronide methyl ester ( 2 ), along with four known flavonoids ( 3 - 6 ) were isolated from the whole parts of Rotala rotundifolia . The structures of 1 and 2 were elucidated by application of various spectroscopic methods, including 1D and 2D NMR techniques. Biological evaluation showed that all of isolated flavonoid compounds have potent anti-oxidative activities by DPPH and superoxide anion methods, and kaempferol ( 3 ) and quercetin ( 4 ) exhibited significant anti-HBV activity assayed by anti-HBsAg production. The HPLC fingerprint with photodiode array detection (HPLC-DAD) for quality control of R. rotundifolia partitioned EtOAc layer was also established.