Phenolic compounds from the aerial parts of Rhodiola rosea in Japan, and their antioxidant activity and chemical adaptation to alpine environment

Twelve flavonoids (1-12) including a new flavonol glycoside, hibiscetin 3-O-glucopyranoside-8-O-glucuronopyranoside, ten known galloylglucoses (13-22) and three known phenolic acids (23-25) were isolated from the aerial parts of Rhodiola rosea growing in Japan. Their chemical structures were elucidated by UV-vis spectra, LC-MS, HR-MS, acid hydrolysis, NMR, and/or HPLC, and TLC comparisons with authentic samples. Antioxidant activity of major 14 compounds was measured by H-ORAC method, and two flavonols, herbacetin 3-O-glucoside-8-O-glucuronide, and gossypetin 3-O-glucuronide-8-O-glucoside, showed the strongest activity. Moreover, chemical adaptation to severe alpine environment of R. rosea was discussed.