| Research Abstract |
1.The leaves of Mitragyna speciosa Korth.have been known as an opium substitute in troditional use by Thai and Malay natives. Reinvestigation of the alkaloidal constituents of the plant in Malaysia resulted in the isolation of four new indole alkaloids, whose unusual structures were elucidated by total synthesis and/or spectroscopic analysis. New synthtic strategy for the chiral total syntheses of minor Mitragyna alkaloids was studied. A potent opioid agonistic property of mitragynine and mitragynine pseudoindoxyl was clarified in vitro experiments. Mitragynine pseudoindoxyl, whose agonistic potency is 20-50 fold greater than that of morphine, acts on mu-and delta-opioid receptors.
2.To establish the synthetic route of new Sarpagine-type Hunteria alkaloids, a model experiment was done, through which a monoterpenoid indole alkaloid, geissoschizine, was synthesized via radical cyclization strategy. Inhibitory effects of corymine, an alkaloidal component from Hunteria zeylanica, on glycine receptors was found.
3.From Nauclea orientalis in Thailand, seven non-alkaloidal and two glycosidic indole compounds were isolated. 10-Hydroxystrictosamide and its pentaacetyl derivative were prepared to examne the C3 stereochemistry.
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