Novel Secondary Metabolites from Marine Sediment-Derived Actinomycetes

Abstract

Marine natural products are emerging source as an attractive drug pipeline based on its enormous biological diversity of origin. Technical advances like scuba diving, manned submarine boosted the interest to the marine natural products three decades ago and there are eight approved marine drugs now. Most of the approved drugs are based on marine natural products isolated from marine invertebrates, but recent study suggest that most of them are produced by microorganisms. In this study, actinomycetes were isolated from marine envirionments and investigated to discover a novel and bioactive marine natural products. A chemical investigation of the actinomycetes, Nocardiopsis sp. CNQ115 isolated from marine sediment collected off the coast of southern California resulted in the isolation of two novel imidazole natural compounds nocarimidazoles A and B. The chemical structures of nocarimidazoles A and B were determined by interpretation of NMR data analyses. No significant antibacterial or cytotoxic activities were observed. Investigation of the chemical components of a Streptomyces sp. 10A085 isolated from mudflat sediments collected on the southern coast of the Korean peninsula led to isolation of four new compounds, anithiactins A ? D. The chemical structures of anithiactins were determined by interpretation of NMR data analyses, while the chemical structure of anithiactin B was established from a combination of NMR spectroscopic and crystallographic data analysis. Anithiactins A ? C displayed moderate acetylcholinesterase inhibitory activity with no significant cytotoxicity.