Antimicrobial properties and metabolite profiling of the ethyl acetate fractions of Sinularia polydactyla and Cespitularia simplex surrounding Mauritius Island

Abstract

Abstract. Jahajeeah D, Bhoyroo V, Ranghoo-Sanmukhiya M. 2023. Antimicrobial properties and metabolite profiling of the ethyl acetate fractions of Sinularia polydactyla and Cespitularia simplex surrounding Mauritius Island. Indo Pac J Ocean Life 7: 133-142. Soft corals form an integral part of the reef ecosystem. This study assessed the antibacterial activities of Mauritius Island's soft corals and their different natural compounds having important biological properties. Antimicrobial assays and GCMS-MS analysis were performed using ethyl acetate extracts of Sinularia polydactyla and Cespitularia simplex. The results for both species indicated significant activity against most clinically pathogenic bacterial strains tested. In addition, S. polydactyla and C. simplex extracts gave the most potent action spectra yielding the largest inhibition zone diameter, especially against the Gram-positive Staphylococcus aureus (8.73 ± 2.87 and 6.00 ± 1.20 mm), respectively. The MIC also confirmed that the Gram-positive Bacillus subtilis and S. aureus strains were the most susceptible bacteria when exposed to the soft coral extracts, while Pseudomonas aeruginosa and Escherichia coli were the most resistant Gram-negative strains. The biochemical profile of the extracts showed the presence of terpenoids, steroids, flavonoids, coumarins, and quinones. GCMS-MS analysis also identified 151 compounds in S. polydactyla and 91 compounds in C. simplex. Several previously published studies have shown the biological activities of different species of Cespitularia; however, this is the first study to demonstrate the antibacterial activity and compound profiling of C. simplex. Although studies have been carried out on S. polydactyla extracts, compounds such as 25-Hydroxycholesterol and spathulenol have not yet been reported. The results from the study suggest that both S. polydactyla and C. simplex are potential sources of novel antibiotics and possess a myriad of chemical compounds which may lend themselves to bioprospecting.