Metabolites from marine invertebrates and their symbiotic microorganisms: molecular diversity discovery, mining, and application

Metabolites from marine organisms have proven to be a rich source for the discovery of multiple potent bioactive moleculeswith diverse structures. In recent years, we initiated a program to investigate the diversity of the secondary metabolites frommarine invertebrates and their symbiotic microorganisms collected from the South China Sea. In this review, representativecases are summarized focusing on molecular diversity, mining, and application of natural products from these marineorganisms. To provide a comprehensive introduction to the field of marine natural products, we highlight typical moleculesincluding their structures, chemical synthesis, bioactivities and mechanisms, structure-activity relationships as well as biogenesis. The mining of marine-derived microorganisms to produce novel secondary metabolites is also discussed through theOSMAC strategy and via partial chemical epigenetic modification. A broad prospectus has revealed a plethora of bioactivenatural products with novel structures from marine organisms, especially from soft corals, gorgonians, sponges, and theirsymbiotic fungi and bacteria.

Antimicrobial Chlorinated Carbazole Alkaloids from the Sponge-Associated Actinomycete Streptomyces diacarni LHW51701

Four new chlorinated carbazole alkaloids,chlocarbazomycins(CCBs)A-D,were isolated from sponge associated bacterium Streptomyces diacarni LHW51701.Their structures were elucidated via spectroscopic techniques(including HRESIMS,ID&2D NMR),and X-ray crystallographic analysis.Structurally,the 4-chloro coupled with 3-methoxyl substituents in the tricycle nucleus of CCBs A-D and the A/-methoxyl group of CCB-D are rare in naturally occurred tricyclic carbazole alkaloids.Moreover,CCBs A-D do not bear the typical Cl poro-alkyl and C2 meto-methyl side chains of bacterial tricycle carbazoles,suggesting a novel mechanism of aromatic ring formation in biosynthesis.The biological evaluation showed that CCB-C possessed inhibitory activities against pathogenic microorganisms including methicillin-resistant Staphylococcus aureus(MRSA),Mycobacterium smegmatis,Bacillus mycoides,and Candida albicans.