Biological activities of Ginkgo extracts.

The biological activity of methanolic the extracts of leaves, roots, leaf-derived callus, root-derived callus, ginkolide A, ginkgolide B, bilobalide and a commercial Ginkgo product (Tanakan) was assessed. Bioassays consisted of the Agrobacterium tumefaciens-induced potato tumor assay and a Kirby-Bauer microbial sensitivity assay with pure strains of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus pyogenes. Methanolic extracts of leaves, leaf-derived callus, root-derived callus, bilobalide and Tanakan inhibited tumor formation significantly, but more weakly than the positive control, camptothecin. No activity against E. coli was detected, but extracts from both callus types inhibited the growth of K. pneumonia, P. aeruginosa, S. aureus, S. epidermidis and S. pyogenes. All extracts and reference compounds inhibited the growth of S. pyogenes. Leaf and root tissues contained the highest levels of ginkgolide A, as compared to the callus tissues; leaf tissue contained more of all three marker compounds than the callus tissues.