• Bulletin of the Korean Chemical Society
• /
• v.30 no.7
• /
• pp.1459-1462
• /
• 2009

Two new flavone glycosides, giraldiin A and B, together with three known compounds, annulatin, myricetin 3-O-$\alpha$- L-rhamnopyranoside and gallic acid, were isolated from the ethanol extract of the root of Pteroxygonum giraldii Damm. et Diels. The structures of giraldiin A and B are designated as 3'-($\alpha$-L-arabinopyranosyloxy)-4',5,5',7- tetrahydroxy-3-methoxyflavone and 4'-($\beta$-D-glucopyranosyloxy)-5,5',7-trihydroxy-2',3-dimethoxyflavone, respectively, on the basis of detailed spectroscopic analyses. The free radical scavenging activity of giraldiin A was evaluated by decolouring spectrophotometry of pentamethine cyanine dye (Cy5) with $Fe^{2+}-H_2O_2$ Fenton radical generating system. The results indicated the hydroxyl free radical scavenging activity of giraldiin A (E$D_{50}$ = 23.7 nmol/mL) is higher than that of some known antioxidants such as rutin, puerarin, daidzein and 2,6-di-tertbutyl-4-methylphenol.

• Journal of Nutrition and Health
• /
• v.42 no.3
• /
• pp.278-290
• /
• 2009

This study aims to evaluate the changes of flavonoid contents and antioxidants activity of Jeju native citrus fruits juice according to the harvest date. Flavonoids such as quercatagetin, narirutin, hesperidin and neohesperidin were contained most plentifully in the juice of Jigak (Citrus aur-antium) by 573.73 mg/100 mL, Sadoogam (C. pseudogulgul) by 393.99 mg /100 mL, Soyooja by 29.63 mg/100 mL and Jigak (C. aurantium) by 201.23 mg/100 mL in the late August, respectively. The highest contents of nob-iletin, sinensetin and tangeretin among polymethoxyflavones were found in the juice of Hongkyool (C. tachibana) by 7.39 mg/100 mL, 2.24 mg/100 mL, 0.63 mg/100 mL in the late August, respectively. 3,5,6,7,8,3',4'- Heptamet- hoxyflavone recorded the highest amount in Punkyool (C. tangerina) by 0.27 mg/100 mL in the late August, but the other polymethoxyflavones including 3',4',7,8-tetramethoxyflavone, 3',4'-dimethoxyflavone, 4'-methoxyflavone, 5,6,7,3',4',5'-hexamethoxyflavone, scutellarein tetramethylether were observed only trace amount in all the citrus fruits. Flavonoid contents in the citrus fruit juices were the highest during early maturation and decreased rapidly while ripening. Total polyphenol contents were the highest in the late August and decreased with ripening. However from the late December, the contents were increased again. Antioxidant activities of the fruits were evaluated as electron donating ability and were the lowest in the late September and increased with the fruit ripening. These results suggest that quercetagetin among all the flavonoids was most plentiful in Jigak and Dangyooja (C. grandis), so that the fruits could be used for industrial material of flavonoids and antioxidant agents.