Contribution à l’étude phytochimique et activité antibaCtérienne de l’algue verteCaulerpa racemosa de la côte-Mostaganémoise

Abstract

This study aims to valorize the invasive green alga Caulerparacemosa through a phytochemical and antibacterial study of various extracts of this alga. Caulerparacemosa was collected at the Mostagenem coast between April and June. The organic extracts were obtained according to the Soxhlet method, using six solvents (methanol, hexane, ethanol, petroleum ether, chloroform and acetone). A phytochemical screening, evaluation of the antioxidant and antibacterial activity were carried out. The best yield was recorded by acetone (13.02%) and the lowest one (2.22%)by petroleum ether extraction. Qualitative phytochemical tests show the richness of all crude extracts in polyphenol and particularly in flavonoids. The chloroform crude extract was the richestone in several secondary metabolites like tannins, steroids, alkaloids, and coumarins.The antibacterial activity was determined in six bacterial strains (gram positive and gram negative), depending on the disc diffusion method. The chloroformand petroleum ether extracts exhibit the best inhibitory activity against all the tested bacteria and the tested concentrations. However, Klebsiellasp resists to almost all extracts. Staphylococcus aureus ATCC 25923 shows sensitivityto whole extracts.The antioxidant activity was evaluated using the free radical DPPH reduction method. The test CI50was estimated to 1.98 mg / ml and 77.72 mg / ml for the chloroform and the ethanolextract respectively. Finally, the green alga Caulerparacemosa has an interesting antioxidant and antibacterialpotential to be exploited.