| Ginkgo biloba is a sole representative of the Ginkgoales order, which appeared in the Permian era. Among the constituents extracted from leaves, the flavonoids and the terpene trilactones (ginkgolides and bilobalide) are considered to be responsible for most of the pharmacological activity. Objectives of the study were to: (a) identify a culture medium for optimum Ginkgo callus production and long-term maintenance, (b) optimize medium components for the production of the ginkgolides and bilobalide by callus culturer; and (c) screen for selected biological activities—antitumor and antimicrobial.; Medium components tested on constituent production included different gelling agents and the addition of jasmonic acid and the extract from Pseudomonas species (bacterial elicitor). Tissue grown on phytagar contained more chlorophyll, ginkgolides and bilobalide than tissue grown on media with the other gelling agents. Root-derived callus contained more chlorophyll, ginkgolide and bilobalide than leaf-derived callus when grown on media with 0.8% phytagar. The addition of either synthetic ±(−) jasmonic acid and natural −(−) jasmonic acid induced increased ginkgolide and bilobalide production as compared to production by tissue grown on control medium. Chlorophyll content was less in jasmonic-treated tissue, and the tissue exhibited a slower growth rate. The greatest accumulation of ginkgolides and bilobalide was detected in media amended with 10 mM natural jasmonic acid and 100 mM synthetic jasmonic acid. Root derived callus produced more total ginkgolide than leaf-derived callus when treated with the same level of either form of jasmonic acid, and had a slower growth rate. The polysaccharide elicitor from Pseudomonas sp.. affected growth and chlorophyll content; only trace amounts of ginkgolide and bilobalide were detected.; Biological activity of methanolic extracts of leaves, roots, leaf-derived callus, root-derived callus, ginkgolides A, ginkgolide B and bilobalide, and a commercial Ginkgo product (Tanakan) was assessed using Agrobacterium tumefaciens induced tumor formation on potato discs, and using pure strains of several Gram-negative and Gram-positive bacteria. The Kirby-Bauer technique with saturated filter paper discs placed on inoculated Petri Plates was used to assess antimicrobial activity. The methanolic extracts of leaves, leaf-derived callus, root-derived callus, bilobalide and Tanakan significantly decreased the tumor formation, but less than the positive control, camptothecin. No inhibitory activity was observed with the extracts and the reference standards against Escherichia coli. Extracts from both callus types exhibited a broad range of inhibitory activity against Klebsiella pneumoniae and Pseudomonas aeruginosa, but not E. coli (all Gram-negative), and against all Gram-positive bacterial tested. All extracts and reference compounds exhibited inhibitory activity against Streptococcus pyogenes. (Abstract shortened by UMI.)... |
