ABSTRACT
Two new cyclic depsipeptides, companeramides A (1) and B (2), have been isolated from the phylogenetically characterized cyanobacterial collection that yielded the previously reported cancer cell toxin coibamide A (collected from Coiba Island, Panama). The planar structures of the companeramides, which contain 3-amino-2-methyl-7-octynoic acid (Amoya), hydroxy isovaleric acid (Hiva), and eight α-amino acid units, were established by NMR spectroscopy and mass spectrometry. The absolute configuration of each companeramide was assigned using a combination of Marfey's methodology and chiral-phase HPLC analysis of complete and partial hydrolysis products compared to commercial and synthesized standards. Companeramides A (1) and B (2) showed high nanomolar in vitro antiplasmodial activity but were not overtly cytotoxic to four human cancer cell lines at the doses tested.
Subject(s)
Antineoplastic Agents/isolation & purification , Cyanobacteria/chemistry , Depsipeptides/isolation & purification , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Chromatography, High Pressure Liquid , Depsipeptides/chemistry , Depsipeptides/pharmacology , Drug Screening Assays, Antitumor , Humans , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , PanamaABSTRACT
Coibamide A (1) is a new, potent antiproliferative depsipeptide which was isolated from a marine Leptolyngbya cyanobacterium collected from the Coiba National Park, Panama. The planar structure of 1 was elucidated by a combination of NMR spectroscopy and mass spectrometry. Exhaustive 1D and 2D NMR spectroscopy included natural abundance 15N and variable temperature experiments; mass spectrometry included TOF-ESI-MSn and FT-MSn experiments. Chemical degradation followed by chiral HPLC- and GC-MS analyses was used to assign the absolute configuration of 1. This highly methylated cyclized depsipeptide exhibited an unprecedented selectivity profile in the NCI 60 cancer cell line panel and appears to act via a novel mechanism.
