STUDIES ON THE BIOACTIVITY AND PHYCOCHEMISTRY OF MICROCYSTIS AERUGINOSA (CYANOPHYCOTA) FROM SINDH

Abstract

A toxic alga, Microcystis aeruginosa (KUtzing) KUtzing was collected from ponds of Mancher Lake, near Thatta, Sindh (Pakistan) during October 1994 and extracted in methanol. The crude extract showed a strong antimicrobial activity against 14 bacterial and 20 fungal species including 7 human-, 5 plant- pathogens and 8 saprophytes, but its cytotoxic activity against brine shrimp larvae was non-significant. A variety of fatty acids (FAs) were detected from the extract by GC-MS, including 7 saturated, 7 mono-, 4 di-, 7 tri- and 2 poly-unsaturated FAs. Oleic acid was present in the higest proportion (30.5 %) followed by hexa- decatetraenoic and pentadecylic acids (9-10 %). Palmitic acid was also present in appreciable quantity (5.9 %). Furthermore cholesterol, stigmasterol, β-sitosterol, phytol and sucrose have also been isolated from this extract and chemically elucidated by a variety of spectroscopic techniques.