Effect of Ginkgo biloba extract on the rat heart mitochondrial function

Ginkgo biloba L. (Ginkgoaceae) originated from China, first introduced to Europe in the 18th century, it is now distributed all over the world. The leaves of Ginkgo biloba include a rich complex of active compounds responsible for various pharmacological properties. Ginkgo biloba extract improves blood circulation, protects against oxidative cell damage, blocks platelet aggregation that could be important for prevention of cardiovascular diseases. Therefore the fluid extract from Ginkgo biloba leaves was prepared and tested for it is effect on rat mitochondrial function. Our data showed that 0.5 microl/ml of GE (containing 0.57 ng/ml of rutin, 0.23 ng/ml of quercitrin, 0.105 ng/ml of hyperosid and 0.02 ng/ml of quercetin) had no effect on the State 2 respiration rate of mitochondria with all used substrates: pyruvate+malate, succinate and palmitoyl-L-carnitine. Further increase in GE concentration (2 and 4 microl/ml), increased the State 2 respiration rate with all respiratory substrates in a dose-dependent manner (by 35-116%). The State 3 respiration rate was not affected by GE. In order to identify which compounds of GE could be responsible for the observed effects, we measured the effect of pure flavonoids: rutin, quercetin, hyperosid and quercitrin on mitochondrial respiration. All flavonoids (except of hyperosid) at maximal used concentration, comparable/identical to that in GE, stimulated the State 2 respiration rate only by 8-20%, i.e. less effectively as compared to GE. Therefore, for the explanation of the GE-induced uncoupling of oxidative phosphorylation, other biologically active compounds of GE have to be taken into account in future studies.