Quorum Sensing Related Cyclic Dipeptides from Marine Actinomycetes

Abstract

As marine environmental conditions are extremely different from terrestrial ones, it is surmised that marine actinomycetes have different characteristics from those of terrestrial counterparts and, therefore, might produce different types of bioactive compounds. In our ongoing research to develop the biomedical potential from marine actinomycetes, we isolated six cyclic-dipeptides (diketopiperazines, DKPs) from marine actinomycetes and identified as proline-based DKPs. DKPs are connected with two amino acids, formed lactam structure, and discovered as metabolites of various bacteria and fungi. Also, DKPs possess powerful and useful biological activities including anticancer and antimicrobial activities. Recently, it was reported that one of DKPs is related with quorum sensing. Bacterial cells can communicate with each other via small diffusible signal molecules, a process commonly termed quorum sensing. One out of six DKPs was isolated as a quorum sensing signal molecule, and two of DKPs were connected by two D-amino acids, which is rare in nature. The structural characterization of the DKPs and their biological activities will be discussed in this presentation.