In vitro peroxynitrite scavenging activity of 6-hydroxykynurenic acid and other flavonoids from Gingko biloba yellow leaves.
As part of our research on phytochemicals that exert protective effects against diseases related to reactive nitrogen species, we have evaluated the scavenging activity of the yellow leaves of Ginkgo biloba on ONOO-. The methanol extract and ethyl acetate fraction obtained from yellow leaves of G. biloba evidenced a marked scavenging activity on authentic ONOO-. Repeated column chromatography of the active ethyl acetate soluble fraction on silica gel, Sephadex LH-20, and RP-18, resulted in the purification of 15 known compounds, including sciadopitysin (1), ginkgolide B (2), bilobalide (3), isoginkgetin (4), kaempferol (5), luteolin (6), protocatechuic acid (7), bilobetin (8), amentoflavone (9), beta-sitosterol glucopyranoside (10), kaempferol 3-O-rhamnopyranoside (11), kaempferol 3-O-glucopyranoside (12), kaempferol 3-O-[6"'-O-p-coumaroyl-beta-D-glucopyranosyl(1 --> 2)-alpha-L-rhamnopyranoside] (13), kaempferol 3-O-rutinoside (14), and 6-hydroxykynurenic acid (15). Among the compounds isolated, flavonoids (5, 6 and 11-14), protocatechuic acid (7), and 6-hydroxykynurenic acid (15) all exhibited marked scavenging activities on authentic ONOO-. The IC50 values of 5-7, 11-14 and 15 were as follows: 2.86 +/- 0.70, 2.30 +/- 0.04, 2.85 +/- 0.10, 5.60 +/- 0.47, 4.16 +/- 1.65, 2.47 +/- 0.15, 3.02 +/- 0.48, and 6.24 +/- 0.27 microM, respectively. DL-Penicillamine (IC50 = 4.98 +/- 0.27 microM) was utilized as a positive control. However, the other compounds (1-4, 8-10) exerted no effects against ONOO-.
Hyun
Sook Kyung
SK
Faculty of Food Science and Biotechnology, Pukyong National University, Busan 608-737, Korea.
Jung
Hyun Ah
HA
Chung
Hae Young
HY
Choi
Jae Sue
JS
D000431:Ethanol; D005419:Flavonoids / Q000737:chemistry*; D016166:Free Radical Scavengers; D020441:Ginkgo biloba / Q000737:chemistry*; D007736:Kynurenic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol; D009569:Nitric Oxide / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry; D030421:Peroxynitrous Acid / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D012997:Solvents; D013481:Superoxides / Q000737:chemistry
C428563:6-hydroxykynurenic acid; D005419:Flavonoids; D016166:Free Radical Scavengers; D016877:Oxidants; D012997:Solvents; D013481:Superoxides; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D000431:Ethanol; D007736:Kynurenic Acid; D000432:Methanol