Bioactivity and Phycochemistry of Two Species of Spirogyra Link (Zygnemophyceae) from Pakistan

The filaments of two grass green algae, Spirogyra hyaline Cleve and S. rhizoides Randhawa were collected from freshwater habitats in Sindh province of Pakistan and extracted in methanol. Their crude extracts showed strong antimicrobial activity against 14 bacterial and 20 fungal species, including 7 human- & 5 plant-pathogens and 8 saprophytes, but their cytotoxic activity against brine shrimp larvae was non-significant. Methanol extracts of the two species revealed the presence of 34 different fatty acids including 15 saturated, 19 unsaturated acids. In the former species saturated acids were much lesser in proportion (28.6%) than unsaturated ones (71.4%), while in the latter species saturated acids were slightly larger in proportion (52.5%) than unsaturated ones (47.5%). Furthermore, four sterols, one diterpene, two triterpenes, and two carbohydrates were also obtained from these extracts. Both the species differed in the composition of their natural products.