It is purported that Ginkgo biloba leave extract can improve blood flow by
increasing red blood cell deformability and decreasing red cell aggregation, and
thus, improves red blood cell fluidity and decreases whole blood viscosity (30).
The vascular effects of Ginkgo biloba leave extract may also be mediated via the
endothelium-derived relaxing factor (EDRF), presumed to be nitric oxide (NO),
which relaxes the muscular cells of blood vessels. Nitric oxide has been shown to
inhibit the release of prostacylins from cultured bovine endotheliums cells (30,
31). By scavenging nitric oxide, Ginkgo biloba leave extract could potentiate
the effects of prostacyclins. However, an excess of the free radical nitric oxide
is a deleterious factor and can result in various CNS disorders. Bastianetto
et al. (32, 33) determined that Ginkgo biloba extract (EGb 761) protects and
rescues hippocampal cells against nitric oxide-induced toxicity, and that the
protective and rescuing abilities of EGb 761 are not only attributable to the
antioxidant properties of its flavonoid constituents, but also via their ability to
inhibit NO-stimulated protein kinase C (PKC) activity