Marine actinobacteria: a source for discovering of new drugs

Marine actinobacteria are virtually unlimited sources of novel secondary metabolites and are very important from therapeutic and industrial points of view. There are more than 22,000 known microbial secondary metabolites, 70% of which are produced by actinobacteria. Actinobacteria from terrestrial sources have been examined and identified since the 1950s, for many significant antibiotics, anticancer, anti-tumor and immunosuppressive activities. However, obtaining the previously discovered metabolites from terrestrial actinobacteria habitats attracted studies to different ecological habitats. The ecological role of actinobacteria in the marine environment is greatly neglected.  Currently, the existence of marine actinobacteria have received considerable attention due to the structural diversity, unique biological activities of their secondary metabolites and a growing need for the development of new and potent therapeutic agents. In recent years, newly discovered secondary metabolites have shown a range of biological activities such as antibacterial, antifungal, anticancer, antitumor, cytotoxic, anti-inflammatory, anti-parasitic, anti malaria, antiviral, antioxidant, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.