Phytochemistry and bioactivity of some freshwater green algae from Pakistan

Eleven green algae belonging to the phyla Volvocophyta, Chlorophyta, and Charophyta, were collected from various freshwater habitats of Sindh (Pakistan) during February 1995 and November 1998 and investigated. Their methanol extracts revealed the presence Of D-norandrostane-16-carboxylic acid, P-sitosterol, and trans-phytol. The unsaturated fatty acids were found in larger proportion (54-94%) than the saturated fatty acids (6-40%). The C15:0 and C16:0 were the most commonly occurring fatty acids, followed by C18:1, C19:1, C15:3, and C17:3 acids. These algae resembled green seaweeds of Pakistan to a great extent in their fatty acid composition. Their methanol extract showed poor antibacterial but a strong antifungal activity. They displayed a significant phytotoxic activity but non-significant cytotoxic, insecticidal, and antitumor activities. Algae belonging to the three phyla exhibited differences in their fatty acid, sterol and terpene compositions as well as in their bioactivities. Species belonging to the same genera revealed specific differences among themselves.