Bioactive compounds and antifungal activity of three different seaweed species Ulva lactuca, Sargassum tenerrimum and Laurencia obtusa collected from Okha coast, Western India

Objective: To evaluate bioactive compounds responsible for antifungal activity from seaweeds of Okha coast, Western India. Methods: Each species were extracted with different solvents with increasing polarity: hexane, ethyl acetate, chloroform and methanol using Soxhlet apparatus. The antifungal activity was determined by agar diffusion plate method by using fluconazole, ketoconazole and amphotericin B as standards. Gas chromatography-mass spectrometer analysis was done for identification of bioactive compounds present in crude extract. Results: The gas chromatography-mass spectrometer analysis of all the extracts revealed the presence of steroids, fatty acids and esters compounds. Among the three species, the maximum crude extract yield (53.46%) and the largest inhibition zone (36 mm) were recorded in methanol extract of Ulva lactuca, whereas the minimum crude extract yield and inhibition zone were recorded in chloroform extract of the same species as 0.5% and 10 mm, respectively. Methanol and ethyl acetate extract showed the maximum antifungal activity and the major important compounds like steroids, fatty acids and esters were detected with higher amount in all the extracts. Conclusions: The present study revealed that the different seaweed extracts showed moderate to significant antifungal activity against the strains tested as compared with the standard fungicides, and polar solvents methanol and ethyl acetate were comparatively efficient for extraction of different metabolites that are responsible for antifungal activity