The Kavaratamides: Discovery of Linear Lipodepsipeptides from the Marine Cyanobacterium <i>Moorena bouillonii</i> Using a Comparative Chemogeographic Analysis
Byeol Ryu, Evgenia Glukhov, Thaiz R. Teixeira, Conor R. Caffrey, Saranya Madiyan, Valsamma Joseph, Nicole E. Avalon, Christopher A. Leber, C. Benjamin Naman, William H. Gerwick
Abstract
High Resolution Image Download MS PowerPoint Slide Kavaratamide A ( 1 ), a new linear lipodepsipeptide possessing an unusual isopropyl- O -methylpyrrolinone moiety, was discovered from the tropical marine filamentous cyanobacterium Moorena bouillonii collected from Kavaratti, India. A comparative chemogeographic analysis of M . bouillonii collected from six different geographical regions led to the prioritized isolation of this metabolite from India as distinctive among our data sets. AI-based structure annotation tools, including SMART 2.1 and DeepSAT, accelerated the structure elucidation by providing useful structural clues, and the full planar structure was elucidated based on comprehensive HRMS, MS/MS fragmentation, and NMR data interpretation. Subsequently, the absolute configuration of 1 was determined using advanced Marfey’s analysis, modified Mosher’s ester derivatization, and chiral-phase HPLC. The structures of kavaratamides B ( 2 ) and C ( 3 ) are proposed based on a detailed analysis of their MS/MS fragmentations. The biological activity of kavaratamide A was also investigated and found to show moderate cytotoxicity to the D283-medullablastoma cell line.