Chemical Study on the Indole Alkaloids from Plant Tissue Cultures

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The joint research among Chiba University (Japan), Chulalongkorn University (Thailand) and Mainz University (Germany) supported by a grant under the Monbusho International Scientific Research brought about many successful results on the subject "The Chemical Study on the Indole Alkaloids from Plant Tissue Cultures".The technology of plant cell suspension cultures was employed for three medicinal plants originally producing the indole alkaloids.I. Biotransformation of Ajmaline in Plant Cell Cultures of Rauwolfia serpentina Benth.From the methanol extracts of the plant cell suspension cultures of R. serpentina, which have been cultivated in the alkaloid-production medium after feeding of ajmaline, four new indole alkaloids, raumacline, N_b-methylraumacline, 19(S)-hydroxy-N_b-methylraumacline, and 6alpha-hydroxyraumacline were isolated. These structures first elucidated by the spectroscopic analysis were unambiguously determined by the biomimetically chemical synthesis from ajmaline. These new compounds are the first examples of the macroline-type indole alkaloids having the trans relationship between the C15 and C16 positions.II. Isolation of Novel Indole Alkaloids from Cell Cultures of Aspidosperma quebracho blanco Schlecht.From the cell suspension cultures of A. quebracho blanco, three novel monoterpenoid indole alkaloids, aspidochibine, 3-oxo-14, 15-dehydrorhazinilam, and 11-hydroxytubotaiwine were isolated, though the production amounts of them were very low at this stage. The structure elucidation and the stereochemical analysis were made by mainly 2D NMR technique. Aspidochibine, bearing a characteristic ten membered lactone, is a completely new structural class of the quebrachamine series.III. Investigation of the Alkaloidal Components in the Cell Culture of Uncaria gambir.No alkaloidal constituent was detected from the cell cultures of Uncaria gambir