In vitro antimicrobial activity of solvent extracts of marine brown alga, Hydroclathrus clathratus (C. Agardh) M. Howe from Gulf of Mannar.

Objective: To evaluate the antimicrobial activity of different extracts of Hydroclathrus clathratus (C. Agardh) M. Howe against human bacterial and fungal pathogens.

Methods: The antimicrobial activities of the extracts against various pathogens were tested by using agar well diffusion method.

Results: Maximum activities were recorded by methanolic extract on P. aeruginosa (26.33±1.86mm), S.aureus (21.00±1.78mm), E. coli (19.32±0.89mm), B. subtilis (18.33±1.86mm) and K. Pneumoneae (18.14±1.50 mm). Hexane extract showed maximum antifungal activity against F. oxysporum (18.33±1.86mm) and ethyl acetate showed maximum activity against A. niger (18.33±2.73mm). While, methanolic extract showed more activity against A. flavus (18.00±3.22 mm), C. albicans (18.14±1.50mm) and Penicillium sp. (13.66±1.36mm). However, aqueous extract showed minimum inhibitory effect on the pathogens.

Conclusions: Different solvent extracts of seaweeds used in the present study have shown significant anti-bacterial and anti-fungal action. The study offers opportunities for producing new types of bioactive compounds; however, the mechanism of inhibition and stability of the extracts still are not clear and more studies should be involved.