5. ANTIBIOSIS AND ANTIBIOTICS
307
nemotinic acid (also found as the xyloside, VII), odyssin,
H 3 C—C=C—C=C—CH=C=CH—CH—CH 2 —CH 2 —CO
and odyssic acid,
H 3 C—C=C—C=C—CH=C=CH—CHOH—CH 2 —CH 2 —COOH
all produced by Porta corticola and Poria tenuis, have been shown to be
formed from the head-to-tail linkage of six molecules of an acetate
derivative, the terminal methyl group being eliminated in the former two
compounds, very likely by oxidation and decarboxylation, but retained
in the latter two.
Grifolin, from Grijola confluens, is another example of a similar, yet
more complex, antibiotic produced by a basidiomycete:
(H 3 C) 2 =C=CH—CH 2 —CH 2 —C=CH—CH=CH—CHOH—COH—CH 2 —CH 3
It should be compared with variotin (262b), an antifungal antibiotic
produced by the lower fungus Paecilomyces vanotis var. antibioticus,
in which a tetraene aliphatic acid is combined with the methyl ester of
γ-aminobutyric acid:
H 3 C—CH 2 —CH 2 —CH=COH—CH=C—CH=CH
NH—CH 2 —CH 2 —CH 2 —CO—O—CH 3
Similar polyene moieties are incorporated into other products of lower
fungi such as fumagillin (CIV) (263a), from Aspergillus
fumigatus,
CH ;
CH,
CH
CH
CO
Fumagillin
(CIV)
Palitantin
(CV)
and the two similar compounds (CV) frequentin (Penicillium frequentans, P. cyclopium) and palitantin (the same and P. palitans).