Objective: To search for structurally novel and biologically active compounds from the secondary metabolites of gorgonian-derived actinomyces.
Methods: Strains of actinomyces with antimicrobial activities were screened by biological methods. Then, those active strains were cultured under different conditions to obtain crude extracts. Subsequently, the chemical diversities of the extracts were investigated by reverse phase high-performance liquid chromatography (RP-HPLC) and thin layer chromatography (TLC), while the bioactivities of the extracts were evaluated by antifouling and antibacterial assays. A target strain Streptomyces sp. SCSGAA0009 was selected to further study by large-scale fermentation on modified ISP2 medium. The compounds were isolated by column chromatography over silica gel, Sephadex LH-20, and semipreparative HPLC, and their structures were determinated by spectroscopic analysis.
Results: The target strain was identified as actinomyces, Streptomyces sp. SCSGAA0009. A new alkaloid N-(2-(1H-indol-3-yl)ethyl) propionamide (1) and a known compound phenazine-1-carboxylic acid (2) were purified from the culture broth. Compound 2 showed moderate antibacterial activity against Escherichia coli and Pseudoaltermonas piscida, and exhibited strong antilarval settlement activity towards Bugula neritina larva.
Conclusion: Bioactive and new compounds can be achieved from the secondary metabolites of gorgonian-derived microorganisms from South China Sea.