Isolation of Homodolastatin 16, a New Cyclic Depsipeptide from a Kenyan Collection of Lyngbya majuscula

Abstract

An examination of an organic extract of the cyanobacterium Lyngbya majuscula, collected from Wasini Island off the southern Kenyan coast, led to the isolation of the known cyclic depsipeptide antanapeptin A (1), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclic depsipeptide, homodolastatin 16 (2). The structures of these two compounds were determined from NMR and mass spectrometry data. Homodolastatin 16, a higher homologue of the potential anticancer agent dolastatin 16, exhibited moderate activity against oesophageal and cervical cancer cell lines.

Chirality determination of unusual amino acids using precolumn derivatization and liquid chromatography–electrospray ionization mass spectrometry

“…In fact, it already has been successfully applied to naturally occurring marine peptides [41]. Separations were done in acetic acid-acetonitrile/methanol phases.…”

Natural Proline-Rich Cyclopolypeptides from Marine Organisms: Chemistry, Synthetic Methodologies and Biological Status

“…Moreover, nostophycin bears a novel β-amino acid moiety “Ahoa” in its structure [50]. Macrocyclic depsipeptides, homodolastatin 16 and dolastatin 16 contain the new and unusual amino acid units “Pval” and “Admpa” [51,52]. Besides this, structural features for pahayokolides A and B include a pendant N -acetyl- N -methylleucine, both E - and Z -dehydrobutyrines, a homophenylalanine and an unusual polyhydroxy amino acid [48].…”

“…UIC 10339 [49], toxic cyanobacterium Nostoc sp. 152 [50], Kenyan cyanobacterium Lyngbya majuscule [51], mollusks like Papua New Guinea mollusk (sea hare) Dolabella auricularia [52] and alga like Indonesian red alga (Rhodophyta) Ceratodictyon spongiosum containing the symbiotic sponge Sigmadocia symbiotica [10]. Structures of diverse proline-rich cyclopeptides from marine tunicates and cyanobacteria are tabulated in Figure 2.…”

Use of Marfey's reagent and analogs for chiral amino acid analysis: Assessment and applications to natural products and biological systems

“…The methods confirmed the presence of l-Pro and N-Me-d-Ile in the depsipeptide. In addition, small amounts of d-Pro were detected as side-product [61].…”

“…Rogers et al [66] determined the absolute configurations of fistularin-3, 11-epi-fistularin-3, and a related bis-oxazolidinone, obtained from Verongid marine sponges, by microscale hydrolysis followed by derivatization with MR. The method(s) were also applied to the characterization of marine peptides [61].…”