The chemistry of the antibiotics chrysomycin A and B. Antitumor activity of chrysomycin A.

The yellow antibiotic chrysomycin, isolated in crystalline form in 1955, is found to consist of two closely related components, a major one, chrysomycin A, and a minor one, chrysomycin B. They differ only through the replacement of a vinyl group of chrysomycin A by methyl in chrysomycin B. The absorption spectrum of chrysomycin A is identical with that of the antitumor antibiotic toromycin (gilvocarcin V, 2064A), while that of chrysomycin B is similarly identical with the one of gilvocarcin M (2064B). The structures of these antibiotics (toromycin, the glivocarcins, and 2064A and B) have been elucidated recently. Chrysomycins A and B thus contain the same chromophores as gilvocarcins V and M, respectively; comparison of 1H and 13C NMR spectra confirms this identity. The chrysomycins differ from these other antibiotics in the C-glycosidic side-chain, which is a methylpentose in the gilvocarcins, a 3,5-dimethylpentose in the chrysomycins. Structure and relative configuration of the latter are given. The biological activity and possible biosynthesis of the chrysomycins are discussed.