Ansamycins
are a class of macrolactams with diverse bioactivities, characterized
by the unique 3-amino-5-hydroxybenzoic acid moiety. In this study,
the ansamycin gene cluster aas in Streptomyces sp. S35 was activated by the constitutive coexpression of two pathway-specific
regulator genes aas1 and aas10,
and seven novel pentaketide ansamycin aminoansamycins A–G (1–7) were identified. Compound 4 with better antiproliferative activity indicated that the anthranilate
analogues are probably promising building blocks for the production
of unnatural ansamycins with improved activity.
Four new dinorsesterterpenoids, designated as trinulactones A–D (1–4), were isolated from the Streptomyces sp. S006 strain. All the compounds contained a tricyclic skeleton, which was attached to a highly oxygenated unsaturated γ-lactone. Their structures were determined by analysis of their spectroscopic data, mainly 1D, 2D NMR and HR-ESIMS data. In particular, compounds 3a/3b and 4a/4b were identified individually as atropisomers.
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