Indole alkaloids from a traditional medicinal plant: Tabernaemontana elegans Staph

Traditionally used medicinal plants have played an important role in the discovery of antitumor compounds and most of the drugs obtained from natural sources to treat cancer have plant origin [1]. Currently, we are studying Tabernaemontana elegans Staph. (leaves), which was collected in Mozambique. Tabernaemontana (Apocynaceae) not only is a large genus that is both chemically complex and interesting but also is a very rich source of indole alkaloids with intriguing carbon skeletons and novel biological activities like cytotoxicity and acetylcholinesterase inhibitory activity [2–4]. Extensive column chromatography, preparative TLC, and HPLC of the basic fraction of the crude methanolic extract yielded seven indole alkaloids, three of which contained β-carboline skeleton and four were heterocyclic monoindole alkaloids with different saturation and substitution patterns. The fractionation was guided by the brine shrimp lethality assay. The structure assignments of these isolated compounds were based on IR, low resolution ESIMS, high resolution EIMS, 1D NMR (¹H, ¹³C, DEPT) and 2D NMR (COSY, HMBC, HMQC) spectroscopic data.

Acknowledgements: The authors wish to thank Fundação para a Ciência (FCT), Portugal (grant-SFRH/BPD/30492/2006).

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