Antibacterial activity of Seaweed extracts against human pathogenic bacteria

Abstract

Seaweeds are screened extensively for their activity against human bacterial pathogens. In the present study, the petroleum ether, butanol, chloroform, acetone and methanol extracts of seaweed species, viz., Caulerpa racemosa, Padina gymnospora, Sargassum wightii and Ulva fasciata were investigated for their antibacterial properties by well diffusion method against human pathogenic bacteria (Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus and Streptococcus mutans). Preliminary qualitative analysis on the chemical constituents of the twenty seaweed crude extracts revealed the predominant presence of phenols and tannins. Antibacterial activity of the seaweed extracts were represented by zone of inhibition. The order of maximum antibacterial activity (represented by very strong zone of inhibition) was exhibited by Padina gymnospora petroleum ether extract against Staphylococcus aureus (23.6mm) and Pseudomonas aeruginosa (21.6mm), and its butanol extract against Pseudomonas aeruginosa (20.5mm). From the overall results of the present study, it was observed that Padina gymnospora extracts exhibited maximum antibacterial activity, attributed to the presence of the active chemical constituents, especially phenols and tannins. Further in depth studies are recommended, as Padina gymnospora extracts could serve as an additional implement to natural antibacterial agents.