Plant alkaloids immunosuppressive activity

Lai JH, Ho LJ, Kwan CY, Chang DM, Lee TC. Plant alkaloid tetrandrine and its analog block CD28-costimulated activities of human peripheral blood T cells—Potential immunosuppressant in transplantation immunology. Transplantation 1999 68(9) ... 

In 2005, Honda et al. pubhshed a first total synthesis of a quinohzidine alkaloid using RCM as one of the key steps, namely, (—)-deoxynupharidine (246) [80]. The alkaloid was isolated from plants of the genus Nuphar and exhibited amongst others immunosuppressive activity. Its synthesis commenced with a stereoselective construction of the enantiopure 5,6-disubstituted piperidinone building block 244 by modification and ring expansion of the protected D-pyroglutamic acid derivative 243 (Scheme 2.53). Subsequent RCM of 244 (catalyst [Ru]-II, benzene, 60°C) afforded quinolizidinone 245 in 96% yield, whereafter three consecutive steps led to the natural product itself... 

The list of commercial products from natural sources could fill volumes. It must be emphasized that their discoveries range from systematic searches, to tradition to chance favors the prepared mind. The latter is reemphasized in the discovery of the alkaloids from the periwinkle plant (vincristine and vinblastine) which were first screened for their hypoglycemic activity based on reports of their use by local groups in Madagascar. While the hypoglycemic response could not be confirmed under controlled laboratory conditions, an immunosuppressive effect due to... 

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