Pharmaceutical biology of seaweeds from the Karachi coast of Pakistan

A variety of marine benthic algae belonging to the Chlorophyta, Phaeophyta, and Rhodophyta were collected from different coastal areas of Karachi (Pakistan), and several biological tests were conducted on their methanol extracts in order to investigate antibacterial, antifungal, phytotoxic, and insecticidal activities. Brown seaweeds showed greater antibacterial activity than the green and red ones. Botryocladia leptopoda (J.Ag.) Kylin exhibited the greatest antifungal activity and the least was exhibited by Codium shameelii Nizam. The highest phytotoxic activity was displayed by Ulva intestinalis L., and Osmundea pinnatifida (Huds.) Stack. showed the greatest insecticidal activity as compared to the other investigated species. Furthermore, a number of species were analyzed for their elemental composition with the help of a Perkin-Elmer 3100 atomic absorption spectrometer. Elements such as Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Pb, and Zn were determined quantitatively. Among them, Ca, Cr, and Pb were found to occur in the highest proportion in green seaweeds, Co, Cu, Fe, and Zn in highest proportion in brown seaweeds, and Cd, K, Mg, and Na were in highest proportion in the investigated red seaweeds.