Baccharis megapotamica baccharin from

The roridin family constitutes another subclass of the trichothecane macrolides. Two examples of this group are roridin E (148) and baccharin Bj (150). The latter is isolated from the plant Baccharis megapotamica and is a potent antileukemic agent. Structurally, this class of compounds is quite similar to the verrucarins discussed above, with the exception of the replacement of the hydroxypentanoic acid-muconic ester linkage by an ether bond and some additional carbon substitution. 

Kupchan SM, Jarvis BB, Dailey RG, Bright W, Bryan RF, Shizuri Y (1976) Baccharin, a Novel Potent Antileukemic Trichothecene Triepoxide from Baccharis megapotamica. J Amer Chem Soc 98 7092... 

In 1983, Still et al. published methods for the total synthesis of roridin E (378) and baccharin B5 (379) (332). Roridin E (378) was isolated for the first time in 1965 from Myrothecium verrucaria and baccharin B5 (379) was obtained in 1976 from the plant Baccharis megapotamica (333,334). 

Kupchan, S. M., B. B. Jarvis, R. G. Dailey, Jr., W. Bright, R. F. Bryan, and Y. Shizuri Baccharin, a novel potent antileukemic trichothecene triepoxide from Baccharis megapotamica. J. Amer. Chem. Soc. 98, 7092 (1976). 

Very recently, the isolation and structure elucidation of baccharin (47), an antileukemic trichothecene triepoxide, from Baccharis megapotamica Spreng (Asteraceae) was reported (Kupchan et al, 1976). This constitutes the first known case of a trichothecene derivative in higher plants. The full structure and stereochemistry of baccharin (47) were established by X-ray analysis. 

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