The first biosynthetic studies of the azinomycins: acetate incorporation into azinomycin B

13 C-Labelled acetate efficiently labels the antitumour natural product azinomycin B, revealing a polyketide origin for the naphthoate fragment, that threonine is the probable precursor of the enol fragment, and that α-ketoglutarate is a probable precursor of the aziridine fragment