Original Paper Pharmacology	Planta Med 2006; 72: 1296-1299 DOI: 10.1055/s-2006-951688
© Georg Thieme Verlag KG Stuttgart · New York
Ginkgo biloba Leaf Extract Reverses Amyloid β-Peptide-Induced Isoprostane Production in Rat Brain in vitro
Luigi Brunetti1, Giustino Orlando1, Luigi Menghini1, Claudio Ferrante1, Annalisa Chiavaroli1, Michele Vacca1
1 Department of Drug Sciences, G. D'Annunzio University, School of Pharmacy, Chieti, Italy

Abstract

Isoprostanes are prostaglandin (PG) isomers generated from oxygen radical peroxidation of arachidonic acid, which are reliable markers of membrane oxidative damage. Aging is characterized by an imbalance between the generation of reactive oxygen species and antioxidant detoxification pathways. Ginkgo biloba leaf extract is reputed as a neuroprotective antioxidant agent. We have tested the effects of a Ginkgo biloba extract {containing 24.1 % flavonoids and 181 % terpene lactones [bilobalide (0.542 %), ginkgolide A (0.570 %), ginkgolide B (0.293 %), ginkgolide C (0.263 %), and ginkgolide J (0.138 %)]} on the production of 8-iso-PGF_2α from rat brain synaptosomes obtained from young (3 months old) or aged (12 and 24 months old) rats, both in the basal state and after oxidative stress induced by either hydrogen peroxide or amyloid β-peptide. Our findings show that Ginkgo biloba extract pretreatment is able to completely reverse both basal and hydrogen peroxide-stimulated isoprostane production (IC₅₀ of 81.92 μM and 31.89 μM, respectively). Amyloid β-peptide-induced isoprostane production was also inhibited, both in young and aged rats, to a level even lower than that in unstimulated synaptosomes. This suggests that the oxygen radical scavenging properties of the Ginkgo biloba extract are fully effective in young, as well as in old rats, showing a greater inhibition of isoprostane production in the latter.

Key words

Aging - amyloid β-peptide - Ginkgo biloba - ginkgoaceae - hydrogen peroxide - isoprostane - lipid peroxidation - oxidative stress