Anthocidins A⁻D, New 5-Hydroxyanthranilic Acid Related Metabolites from the Sea Urchin-Associated Actinobacterium, Streptomyces sp. HDa1.

Four new 5-hydroxyanthranilic acid related compounds, named anthocidins A⁻D (⁻), two known analogues -lauryl 5-hydroxyanthranilate () and isolauryl 5-hydroxyanthranilate (), together with benzamide (), 3-hydroxy-4-methoxycinnamamide (), and (3-)-hexahydro-3-[(3,4-dihydroxyphenyl)methyl]pyrrolo[1,2-]pyrazine-1,4-dione (), were isolated from the fermentation broth of the marine-derived actinomycete, sp. HDa1, which was isolated from the gut of a sea urchin, , collected from Hainan Island, China. The structures of these secondary metabolites were elucidated on the basis of their 1D and 2D-NMR and mass spectroscopic data, and anthocidin A was confirmed by single-crystal X-ray diffraction with Cu Kα radiation. Anthocidins A⁻D (⁻) feature an acetyl group substitution at the amino group and varying alkyl side chains at the carboxyl group of 5-hydroxyanthranilic acid, and compound was isolated as a natural product for the first time. The cytotoxic and antibacterial activity of compounds ⁻ were evaluated.