Fatty acids and biological activities of crude extracts of freshwater algae from Sindh.

Seven blue-green and 3 green algae were collected from various freshwater habitats of Sindh, (Pakistan), during January 1997-December 1999. Their methanol extracts revealed 17 saturated, 2 monoynoic, 12 monoenoic, 5 diunsaturated, 5 triunsaturated and 6 polyunsaturated fatty acids (FAs), which were identified by GLC and GC-MS. Palmitoleic acid was the most commonly occurring FA, while C15:0, C16:0, C14:1 and C18:1 were the next commonly occurring acids. The unsaturated acids were found in larger proportion (46.50-70.46%) than saturated FAs (16.8239.20%). The blue-green algae did not differ much from green algae of Sindh in their FAcompositions. Their methanol extracts exhibited poor antibacterial but strong antifungal activities. They showed a significant phytotoxic activity but non-significant cytotoxic and insecticidal activities. The extract of Lyngbya hieronymusii enhanced antitumour activity from 20 to 45% with increase in the concentration of extract. Algae belonging to three phyla (Cyanophycota, Chlorophycota and Charophycota) revealed differences in their FA-compositions as well as their bioactivities.