New butenolides from the photoconductivity screening of Streptomyces antibioticus (Waksman and Woodruff) Waksman and Henrici 1948

Streptomyces antibioticus strain TÜ 99, from which a wide variety of active compounds had been isolated previously, was reinvestigated using an HPLC photoconductivity screening system. Four new compounds were isolated, characterized and their constitutions determined. All four were α,β‐unsaturated γ‐lactones; the most abundant compound 3 (C10H16O4), as well as compound 1 (C9H14O4) had a hydroxy group at C(5) of the lactone ring. The four lactones showed antibiotic activity against Pseudomonas aeruginosa and also a weak inhibition of the chitinase from Serratia marcescens.