Biologically active secondary metabolites from Ginkgo biloba.
Three new compounds, (7E)-2beta,3alpha-dihydroxy-megastigm-7-en-9-one (1), 3-[5,7-dihydroxy-2-(4-methoxyphenyl)-4-oxo-4H-chromen-8-yl]-4-methoxybenzoic acid (2), and 4'-O-methyl myricetin 3-O-(6-O-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside (3), were isolated from Ginkgo biloba, together with 27 known compounds. The structures of the new compounds were determined primarily from 1D- and 2D-NMR analysis. The 4-O-methylbenzoic acid structural feature at C-8 in 2 is encountered for the first time. The antioxidant activities of 29 compounds isolated from Ginkgo biloba were evaluated on intracellular reactive oxygen species in HL-60 cells. It was found that quercetin, kampferol, and tamarixetin had antioxidant activity that was approximately 3-fold greater than that of their respective glycosides and also approximately 3-fold greater than that of a standard ascorbic acid with an IC(50) at maximum effectiveness.
Bedir
Erdal
E
National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, and Department of Pharmacology and Pharmacognosy, School of Pharmacy, The University of Mississippi, University, Mississippi 38677, USA.
Tatli
Irem I
II
Khan
Riaz A
RA
Zhao
Jianping
J
Takamatsu
Satoshi
S
Walker
Larry A
LA
Goldman
Peter
P
Khan
Ikhlas A
IA
D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D020441:Ginkgo biloba / Q000737:chemistry*; D006027:Glycosides / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D044949:Kaempferols; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D018515:Plant Leaves / Q000737:chemistry; D011794:Quercetin / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism
D000975:Antioxidants; D005419:Flavonoids; D006027:Glycosides; D044949:Kaempferols; D017382:Reactive Oxygen Species; C006552:kaempferol; D011794:Quercetin