Effect of biflavones of Ginkgo biloba against UVB-induced cytotoxicity in vitro.
The effect of Ginkgo biloba extract on Ultraviolet B (UVB) irradiated fibroblasts was examined by using a neutral red dye uptake assay and a lactic dehydrogenase (LDH) release assay. Crude extract along with individual components, including flavone-glycosides and biflavones, were applied to cultured normal human skin fibroblasts for 12 hours, and 0, 20, 40 and 80 mJ/cm2 of UVB were irradiated. Two synthetic flavonoids, quercetin and rutin, which have polyphenol structures close to the flavonoids in Ginkgo biloba extract, were used to compare any structure-related activity under the same conditions. At the concentrations (from 0.25 to 2 mg/ml) treated with biflavone components (isoginkgetin/ginkgetin, sciadopitysin) and quercetin, high neutral red dye uptake was detected with gradual increases in UVB irradiation. The time-course release of LDH was determined as the cytotoxicity index (%) during 24 hours following a high dose UVB irradiation (200 mJ/cm2), and the pattern of this cytotoxicity index was similar to that of the neutral red dye uptake results. Sciadopitysin, isoginkgetin/ginkgetin and quercetin treatments lowered cytotoxicity indices to 50.81, 67.81 and 62.19%, respectively, compared to 95.38% for the untreated control. The antioxidant potential of biflavones of Ginkgo biloba could be explained on the basis of structure-related activity; hydroxy- and methyl-substitutions on the basic structure of these flavonoids played a role, as other reports have suggested.
Kim
S J
SJ
Department of Dermatology, Chonnam National University Medical School, Kwangju 501-757, Korea.
D016923:Cell Death / Q000528:radiation effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects* / Q000528:radiation effects*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D020441:Ginkgo biloba / Q000737:chemistry*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009499:Neutral Red; D010946:Plants, Medicinal; D012867:Skin / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects*; D013329:Structure-Activity Relationship; D014466:Ultraviolet Rays / Q000009:adverse effects*
D005419:Flavonoids; D009499:Neutral Red; D007770:L-Lactate Dehydrogenase