New Benzoxazine Secondary Metabolites from an Arctic Actinomycete

Abstract

Two new secondary metabolites, arcticoside (1) and C-1027 chromophore-V (2), were isolated along with C-1027 chromophore-III and fijiolides A and B (3-5) from a culture of an Arctic marine actinomycete <em>Streptomyces</em> strain. The chemical structures of 1-2 were elucidated through NMR, mass, UV, and IR spectroscopy. The hexose moieties in 1 were determined to be D-glucose from a combination of acid hydrolysis, derivatization, and gas chromatographic analyses. Arcticoside (1) and C-1027 chromophore-V (2), which have a benzoxazine ring, inhibited <em>Candida albicans </em>isocitrate lyase. Chromophore-V (2) exhibited significant cytotoxicity against breast carcinoma MDA-MB231 cells and colorectal carcinoma cells (line HCT-116), with IC₅₀ values of 0.9 and 2.7 μM, respectively.