Antibacterial Activity and Phytochemical Analysis of Selected Seaweeds from Mandapam Coast, India

Seaweeds are marine macroscopic algae which form an important component of marine living organisms.The antibacterial activity of three species of seaweeds Codiumadhaerens Anderson (green algae) Sargassum wightii Greville (brown algae), Acanthophora spicifera (Vahl.) Boergs (red algae) from intertidal region of the Mandapam coastal water were analysed against human pathogenic bacteria like Staphylococcus aureus, Vibrio cholerae, Shigelladysentriae, Shigellabodii, Salmonella paratyphi, Pseudomonas aeuroginosa and Klebsiella pneumoniae. The present study was also carried out to investigate the phytochemical constituents like alkaloids, flavanoids, phenols, proteins and free amino acids, saponins, sterols, terpenoids and Sugars in all samples and coumarin and glycosides, quinones and tannin, estimation of biochemical composition (protein, sugar, lipid), photosynthetic pigments like chlorophyll, carotenoid and mineral composition. The results indicated that the maximum protein content (6.396±0.97%) was recorded in the brown alga S. wightii. The maximum carbohydrate content (6.29±0.063%) was recorded in the red alga A. spicifera. The maximum lipid content (1.213±0.02%) was recorded in green alga C. adharens. The highest total phenol (216.65±17.38) and flavanoid (379.99±21.813) was in the brown seaweed S. wightii. The maximum chlorophyll 'a' (0.347±0.051), total chlorophyll (0.438±0.061) and carotenoid (0.670±0.225) were recorded in the brown seaweed S. wightii where as chlorophyll 'b' (0.107±0.016) was highest in C. adharens. Among the 14 minerals analyzed most of them were highest in the red alga A. spicifera. Among the three seaweeds screened for their antibacterial activity the brown alga S. wihgtii is more superior to the red alga A. spicefera and green alga C.adharens in controlling the growth of most of the pathogens tested. The highest zone of inhibition (13mm) was recorded in methanol extract of the red alga against Vibrio cholerae.