Structure elucidation and synthesis of hydroxylated isatins from Streptomycetes

Abstract

Abstract Chemical investigation of terrestrial and marine streptomycete isolates led to the identification of two new natural pigments, namely, 6-hydroxyisatin (3) and 6-hydroxy-5-methoxyisatin (4). Additionally, the strains delivered numerous known compounds, among them N β -acetyltryptamine, N-acetyltyramine, phenylacetamide, N-(2-phenethyl)acetamide, 1-acetyl-β-carboline, tyrosol, 2′-deoxyadenosine, 2′-deoxythymidine, anthranilic acid, 2′-deoxyuridine, indolyl-3-acetic acid, indolyl-3-carboxylic acid, and p-hydroxybenzoic acid. The isatin structures were deduced by NMR and mass studies and further confirmed by synthesis and by X-ray diffraction of the isomeric 5-hydroxy-6-methoxyisatin (5).