Author/Authors :
SERASPE, EBONIA B. University of the Philippines Visayas - College of Arts and Sciences - Division of Biological Sciences, Philippines , TICAR, BERNADETH F. Gyeongsang National University, Korea , TICAR, BERNADETH F. University of the Philippines Visayas - College of Arts and Sciences - Department of Chemistry, Philippines , FORMACION, MINDA J. University of the Philippines Visayas - College of Arts and Sciences - Division of Biological Sciences, Philippines , PAHILA, IDA G. University of the Philippines Visayas - College of Arts and Sciences - Department of Chemistry, Philippines , de la PENA, MILAGROS R. Southeast Asian Fisheries Development Center (SEAFDEC) - Aquaculture Department (AQD), Philippines , AMAR, EDGAR C. Gyeongsang National University, Korea
Abstract :
The antibacterial properties of the microalgae Chaetoceros calcitrans were assessed. Samples of C. calcitrans were first extracted in methanol, and then in different organic solvents of increasing polarity, n-hexane (n-Hex), dichloromethane (DCM) and ethyl acetate (EA) by liquid-liquid extraction. Solvent extracts were screened for antibacterial activity against four species of bacteria: Gram positive, Staphylococcus aureus and Bacillus subtilis; and Gram negative, Escherichia coli and Vibrio harveyi, with Amoxicillin as positive control, N-Hex extract, with significantly lower antibacterial activity than Amoxicillin, showed significantly higher activity than DCM and EA extracts, and least in methanolic extract. High antibacterial activity of n-Hex extract against all the microorganisms indicates that the bioactive components could be non-polar since the activity decreased as the solvent became more polar like methanol, and finally lost in aqueous extract. Results also showed that the extracts have a broad spectrum activity. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all solvent extracts on all microorganisms tested ranged from 125 to 500 μg.mL^-1. Partial purification and characterisation of the extracts confirmed the antibacterial activity in the non-polar fraction, which could be terpenes. The results suggest a good prospect in using C. calcitrans against Vibrio and other bacterial species.
