A new tyrosine derivative isolated from an actinomycin D producing mangrove rhizosphere soil-derived Streptomyces parvulus A-30.

Chemical investigation of Streptomyces parvulus A-30, isolated from the mangrove plant Rhizophora apiculata rhizosphere soil resulted in the isolation of an optically new metabolite (R)-N-(5-amino-2-hydroxy-1-oxopentyl)-tyrosine (2), and seven known metabolites, including actinomycin D (1), (S)-2-methylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione (3), uracil (4), N-acetyltyramine (5), bis (2-ethylhexyl) phthalate (6), diorcinol (7), and 4-hydroxyphenethyl alcohol (8). Amongst, actinomycin D (1) was found to be a major component (1 g, 5.13%) and compound 3 was isolated as a natural product for the first time. Their structures were unambiguously elucidated on the basis of extensive spectroscopic data and comparison with the data of literature. All compounds isolated were subjected to immunosuppressive and cytotoxic activities evaluation. Compound 1 exhibited significant cytotoxicity against HepG-2 and Hela with IC₅₀ values of 2.62 ± 0.22 and 0.37 ± 0.88 µM, respectively, indicating it is principally responsible for the significant total cytotoxic effect of S. parvulus A-30.