The seasonal variation of the inhibitory effect of bioactive extracts of a marine algae (Corallina officinalis) collected from the Algerian west coast

Algae are increasingly becoming the center for interest due to researchers for their composition of various important bioactive molecules. The objective of this study is to investigate the seasonal variations in the concentrations of flavonoids, polyphenols, chlorophyll a, chlorophyll b, and carotenoids, as well as the antimicrobial activity of methanolic extracts from the red alga Corallina officinalis collected from western Algeria. The results of the biochemical assays show that the best polyphenol contents are recorded by the summer extract with a concentration of 33.29 μgEqAG/mg. The recorded flavonoid contents are 967.33; 869; 239.66 and 156 µgEQ/mg for summer, autumn, spring and winter respectively. For chlorophyll a and b the winter extract recorded the highest values. The best results of antibacterial tests were noted for the summer season with diameters of 14.33 mm against the two-bacteria E. coli and Staphylococcus aureus resistant to methicillin (SARM). The autumn extract gave low activity against E. coli, Pseudomonas, SARM and Klebsiella. For the winter extract we noted resistance against B. cereus, Pseudomonas and B. subtilis while E. coli, SARM, Klebsiella and the yeast Candida albicans recorded low activity. For the spring extract, resistance was observed against all the bacteria tested except for the E. coli and Klebsiella strains. The extracts obtained can be used as an antibacterial due to their rich content of bioactive molecules. The best results of antibacterial tests are noted for the summer season.