Study on the Alkaloid Production of Two Gelsemium Plants by Using their Callus Cultures and Chemical and Pharmacological Investigation of Gelsemium Alkaloids.

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Gelsemium elegant and G.sempervirens belonging to Loganiaceae are known to be toxic and rich sources of indole alkaloids.Callus cultures of Gelsemium plants were successfully obtained from the leaf segments of G.elegans and G.sempervirens, respectively. By the chemical investigation of G.sempervirens callus, it became clear that the callus did not produce alkaloidal constituents.Phylogenetic comparison of DNA among G.elegans, G.sempervirens, Strychnos nux-vomica and Gardneria nutans were investigated. The analysis revealed that the two.Gelsemium plants formed a cluster but they were not closely related.By exhaustive investigation of the, constituents in Gelsemium plants, fourteen alkaloids including four new compounds (14,15-dihydroxygelsenicine, GE-2, GE-3, GE-4) were isolated from the leaves of G.elegans. 14,15-Dihydroxygelsenicine is the first Gelsemium oxindole alkaloid having a vicinal diol. The stricture of the known alkaloid, gelsemoxonine, was revised to be a novel oxindole possessing an azetidine unit. This is the first example of the monoterpenoid indole alkaloid having an azetidine unit in the molecule. From the stems of G.sempervirens, fourteen compounds including three new oxindole alkaloids (GS-1, GS-2, GS-3) and one new iridoid (GSIR-1) were isolated. Among them, six compounds were also isolated from the leaves.Lethal effect of the representative Gelsemium alkaloids on rat hepatocytes (H4-II-E-C3 cell) was evaluated. It was found that koumine and humantenine were quite effective than antitumor reagent, cisplatin.