Baccharis megapotamica

Allelopathic Agents from Parthenium hysterophorus and Baccharis megapotamica... 

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. 

A moot question at this point concerns peptidyl transferase. How different, or similar are the peptidyl transferases within a given plant species How different are they from species to species, for example Baccharis megapotamica versus B. halimifolia Or are there slight changes in the nature of the 60s ribosomes from species to species ... 

Jarvis BB,Midiwo JO, TuthillD, Bean GA (1981) Interaction Between the Antibiotic Trichothecenes and the Higher Plant Baccharis megapotamica. Science 214 460... 

Jarvis BB, Pena NB, Rao MM, Comezoglu SN, Comezoglu TF, Mandava NB (1985) Allelopathic Agents from Parthenium hysterophorus and Baccharis megapotamica. In Thompson AC (ed.) The Chemistry of Allelopathy. Biochemical Interactions. ACS Symposium Series 268, p. 149... 

Jarvis BB, Comezoglu SN, Rao MM, Pena NB, Boettner FE, Williams TM, Forsyth G, Epling B (1987) Isolation of Macrocyclic Trichothecenes from a Large-Scale Extract of Baccharis megapotamica. J Org Chem 52 45... 

Kupchan SM, Streelman DR, Jarvis BB, Dailey RG, Sneden AT (1977) Isolation of Potent New Antileukemic Trichothecenes from Baccharis megapotamica. J Org Chem 42 4221... 

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... 

Jarvis BB, Comezoglu SN, Ammon HL, Breedlove CK, Miller RW, Woode MK, Streelman DR, Sneden AT, Dailey RG, Kupchan SM (1987) New Macrocyclic Trichothecenes from Baccharis megapotamica. J Nat Prod 50 815... 

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). 

Trichothecenes and related sesquiterpenes have been isolated from the Brazilian plants Baccharis megapotamica and Baccharis cordifolia (Asteraceae) (Fig. 21.12). The compounds are chemically identical to fungal metabolites produced by the soil fungi (Jarvis et al., 1981, 1985, 1988, 1991). Although it had been suggested that these sesquiterpenes are taken up by the plant and chemically modified, more recent evidence indicates that they are synthesized by... 

Jarvis, B. B., J. O. Midiwo, D. Tuthill, and G. A. Bean, Interaction between the antibiotic trichothecenes and the higher plant Baccharis megapotamica. Science, 214, 460-461 (1981). 

Jarvis, B. B., N. B. Pena, M. M. Rao, N. S. Comezoglu, T. CoMEZOGLU, and N. B. Mandava, Allelopathic agents from Parthenium hysteropherus and Baccharis megapotamica, in The Chemistry of Allelopathy (A. C. Tliompson, ed.), ACS Symposium Series, 268,149-159, American Chemical Society, Washington, DC, 1985. 

SPECTRAL data UV, IR, PMR, Mass Spec organism Baccharis megapotamica Spreng (Asteraceae) reference 256... 

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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