Studies on the Bioactivity and Phycochemistry of Lyngbya Agardh (Cyanophycota)

摘要

The crude methanol extracts of two toxic algae, Lyngbya majuscula (Dillwyn) Harv. and L martensiana Menegh., collected during 1993-1994 from freshwater habitats of Sindh Province of Pakistan, showed a strong antimicrobial activity against 14 bacterial and 20 fungal species, including 7 human- and 5 plant-pathogens and 8 saprophytes, but their cytotoxic activity against brine shrimp larvae was non-significant. From methanol extracts 43 fatty acids were detected by GC-MS, including 15 saturated, 12 mono-, 6 di-, 8 tri- and 2 polyunsaturated acids. In L. majuscula the saturated acids were found in larger amount (54.19%) than unsaturated ones (45.77%), while in L. martensiana the unsaturated acids were present in greater proportion (58%) than saturated acids (41.87%). In the former alga palmitic acid occurred in the highest proportion (22.2%), which in the latter one oleic acid was present in the largest quantity (6.93%). Furthermore, three sterols (beta-sitosterol, 24-isoprophyl-5-cholesten-3-ol and 22-dehydro-24-isopropyl-cholesterol), a triterpene (filican-3-one), an epoxy lipid (nonadeca-9,18-diene-6,7-diol), and two isoprenoid hydrocarbons (woljicene and isowoljicene) were isolated from the extract of L majuscula, and three sterols (stigmasterol, dinosterol and cholesterol), a triterpene (naviotine-A) and a disaccharide (sucrose) were extracted from L martensiana and chemically elucidated by a variety of spectroscopic techniques. Both the species indicated the presence of natural products which are different from one another.