Phospholipid breakdown and choline release under hypoxic conditions: inhibition by bilobalide, a constituent of Ginkgo biloba.
A marked increase of choline release from rat hippocampal slices was observed when the slices were superfused with oxygen-free buffer, indicating hypoxia-induced hydrolysis of choline-containing phospholipids. This increase of choline release was suppressed by bilobalide, an ingredient of Ginkgo biloba, but not by a mixture of ginkgolides. The EC50 value for bilobalide was 0.38 microM. In ex vivo experiments, bilobalide also inhibited hypoxia-induced choline release when given p.o. in doses of 2-20 mg/kg 1 h prior to slice preparation. The half-maximum effect was observed with 6 mg/kg bilobalide. A similar effect was noted after p.o. administration of 200 mg/kg EGb 761, a ginkgo extract containing approximately 3% of bilobalide. We conclude that ginkgo extracts can suppress hypoxia-induced membrane breakdown in the brain, and that bilobalide is the active constituent for this effect.
Klein
J
J
Department of Pharmacology, University of Mainz, Germany.
Chatterjee
S S
SS
Löffelholz
K
K
D000818:Animals; D002794:Choline / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology*; D004224:Diterpenes; D004353:Drug Evaluation, Preclinical; D005663:Furans / Q000494:pharmacology*; D046934:Ginkgolides; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D002534:Hypoxia, Brain / Q000188:drug therapy* / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D010743:Phospholipids / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
D003517:Cyclopentanes; D004224:Diterpenes; D005663:Furans; D046934:Ginkgolides; D010743:Phospholipids; D010936:Plant Extracts; C073710:bilobalide; D002794:Choline