THE CHEMISTRY OF THE ANTIBIOTICS CHRYSOMYCIN A AND B ANTITUMOR ACTIVITY OF CHRYSOMYCIN A

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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 gilvocarcins, 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.