New aminophenoxazinones from a marine Halomonas sp.: Fermentation, structure elucidation, and biological activity

The addition of anthranilic acid to the culture medium of the marine derived Halomonas sp. strain GWS-BW-H8hM completely altered the secondary metabolite pattern relative to the standard conditions. The red-orange color of the culture filtrate extract was the result of the production of 2-aminophenoxazin-3-one (1), chandrananimycin C (5) and three new derivatives of 1 with a previously unknown substitution pattern: 2-amino-, 2-amino-S-benzoyl-, and 2-amino-8-(4-hydroxybenzoyl)-6-hydroxyphenoxazin-3 -one (2 similar to 4). The compounds were determined to have antibacterial and cytotoxic activities; a mode of action other than DNA intercalation is discussed.