Antibacterial activity of starfish Stellaster equestris from Southeast Coast of India

Abstract

Objective: To isolate and characterize the antibacterial compounds from starfish Stellaster equestris (S. equestris). Methods: The starfish S. equestris was collected from Mudasalodai, southeast coast of India. The whole body was extracted with high polar and medium polar solvents such as methanol and ethanol. The antibacterial activity has been tested against human bacterial pathogens using standard disc diffusion method. Results: The present investigation exhibited that the crude methanol extract showed the maximum zone inhibition ((9.7依0.3) mm) against Escherichia coli (E. coli) and Vibrio parahaemolyticus at 100% concentration and minimum was Staphylococcus aureus ((4.0依0.6) mm). The crude ethanol extract showed maximum zone of inhibition in E. coli ((9.70依0.33) mm) and the lowest concentration exhibited the minimum inhibition activity against all bacterial pathogens. The fractions showed the maximum inhibition zone in Klebsiella oxytoca (5.00依0.82 mm), Salmonella typhi (S. typhi) (5.00依0.82) and Staphylococcus aureus ((3.0依2.3) mm). One way ANOVA analysis of antibacterial activity showed no significant difference at 0.05% level (P>0.05). The crude ethanol extract showed the minimum inhibitory concentration against E. coli (100%), Klebsiella pneumoniae (75%), S. typhi (100%) and Vibrio cholerae (100%). The fraction exhibited the minimum inhibitory concentration against Klebsiella pneumonia, Proteus mirabilis, S. typhi, Staphylococcus aureus and Vibrio cholerae at 100% whereas E. coli was at 75% concentration. No bacterial growth was observed against Klebsiella oxytoca at 100% concentration. Conclusions: The result of the present study indicates that the crude and fractions of starfish S. equestris have remarkable antimicrobial activities against human bacterial pathogens. Further fraction has been characterised by using GC-MS and 1