Antibiotic potentials of red macroalgae Hypnea musciformis (Wulfen) Lamouroux and Hypnea valentiae (Turner) Montagne

Abstract

The methanol extract of Hypnea musciformis inhibited the growth of 66% of the Gram +ve bacteria tested. The crude extracts inhibited the growth of Staphylococcus aureus, Pseudomonas aeruginosa and Vibrio alginolyticus by producing highest inhibitory zone range of 113.04 mm2 . In the aqueous extract, the activity was comparatively less specifically towards Gram -ve bacteria. It was also noted that the Hexane-Benzene (80:20%) fraction (HB5a) of H. musciformis exhibited potent activity not only against Gram -ve bacteria but also against Gram +ve Staphylococcus aureus. The higher bacterial inhibition zones (>78.5 mm2) were recorded in the methanol extracts of macroalgae for Staphylococcus aureus, Vibrio alginolyticus and Pseudomonas aeruginosa and also compared to the commercial antibiotics. The Hypnea valentiae extract at 0.1% was most active against Staphylococcus aureus, Vibrio fischeri, V. alginolyticus, Pseudomonas aeruginosa and Micrococcus luteus at 20oC