Bioactive compounds from cyanobacterium Lyngbya majuscula

Abstract

The marine cyanobacterium Lyngbya majuscule has proven to be a rich source of chemically diverse classes of bioactive secondary metabolites. This research describes the chemistry of L. majuscula collected from Ratchamonkol Beach, Trung Province. After using brine shrimp toxicity and ichthyotoxic assays to guide the fractionations, the lipophilic extract of this collection provided three new bioactive depsipeptides, trungapeptins A, B and C. The structures were determined using spectroscopic methods and the absolute configuration of ∝-amino acids were determined using Marfey’s method. Trungapeptins A, B and C contain the unique 3-hydroxy-2-methyl-7-octynoic acid (Hmoya), the 3-hydroxy-2-methyl-7-octenoic acid (Hmoea), and 3-hydroxy-2-methyl-7-octanoic acid (Hmoaa) residues, respectively. Trungapeptin A showed brine shrimp toxicity at 10 ppm and ichthyotoxicity at 6.25 ppm (20 min). However, trungapeptin A exhibited no cytotoxicity against KB and LoVo cells.