Strychnos 1990 - 2004 - Crops for the Future

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Author Title Year Source title Reference Wright, C. W., D. H. Bray, M. J. Oneill, D. C. Warhurst, J. D. Phillipson, J. Queti Antiamoebic and antiplasmodial activities of alkaloids isolated from Strychnos us 1991 Planta Medica 57(4): 337-340 Abstract Seven alkaloids isolated from Strychnos usambarensis have been assessed for in vitro activities against Entamoeba histolytica and Plasmodium falciparum and for in vivo activity against Plasmodium berghei in mice. Strychnopentamine and 3',4'-dihydrousambarensine were highly active against P. falciparum in vitro, but were inactive and non-toxic against P. berghei in vivo. Usambarensine, usambarine, and 18,19-dihydrousambarine were highly active against E. histolytica in vitro, but were less active against P. falciparum in vitro. N(b)-Methylusambarensine was less active against both protozoa than was usambarensine, and akagerine possessed little antiprotozoal activity. Structure-activity relationships are discussed in the context of the reported cytotoxic and p harmacological properties of these alkaloids. Author Title Year Source title Reference Abstract Alvarez M; Salas M; Deveciana A; Lavilla R; Bosch J Nucleophilic-addition of indole-2-acetic ester enolates to n-alkylpyridinium salts - 1990 Tetrahedron Letters 31(35): 5089-5092 -
Author Title Year Source title Reference Amat, M., A. Linares and J. Bosch A new synthetic entry to pentacyclic Strychnos alkaloids - total synthesis of (+/-)-t 1990 Journal of Organic Chemistry 55(26): 6299-6312 Abstract A new strategy for the synthesis of pentacyclic Strychnos alkaloids has been developed. It consists in the closure of the five-membered E ring by cyclization upon the indole 3-position from a suitably N-substituted tetracyclic system embodying rings ABCD of the alkaloids. Attempts to effect the key cyclization either by Pummerer rearrangement of sulfinylacetamides 4 and 6, from chloroacetamide 12, or from bis(methylthio)acetamide 10b (exocyclic amide carbonyl group) resulted in failure. In the first case dithioacetals 9 and 10, respectively, were formed in good yields. Cyclization from alcohol 13 or from the indole-deactivated acetal 15 and dithiocetal 18 were also unsuccessful: noncyclized products coming from the initially formed oxonium or thionium intermediates 16 were obtained. Cyclization was satisfactorily accomplished in 49% yield by treatment of the N- unsubstituted indole dithioacetal 23 with DMTSF. The resulting pentacycle 25 was converted to 20- deethyltubifolidine (27). A similar treatment from dithioacetal 41a, prepared from the secondary amine 32a, afforded pentacycle 42a, from which the alkaloids tubifoline, tubifolidine, and 19,20- d i h y d r o a k u a m m i c i n e w e r e s y n t h e s i z e d . Author Title Year Source title Reference Abstract Angenot, L., M. L. Belempinheiro, A. F. I. Darocha, P. Poukensrenwart, J. Quetin An indolinic cryptoalkaloid from Strychnos mattogrossensis 1990 Phytochemistry 29(8): 2746-2749 -
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