GC-MS analysis and antimicrobial properties of methanolic extracts of the Marine Algae <i>Skeletonema costatum</i> and <i>Chaetoceros</i> spp.

Abstract

In this report, we describe the antimicrobial potential and phytochemical constituents of two Nigerian marine algae; Skeletonema costatum and Chaetoceros spp. The minimum inhibitory concentration (MIC) of the methanolic extract of the algae spp. was determined against 7 clinical isolates (Enterococcus faecalis, Staphylococcus aureus ATCC 25923, Bacillus species, Klebsiella pneumonia, Salmonella typhi, Escherichia coli ATCC 25922 and Candida albicans) using broth dilution method. The volatile constituents of the extracts were analyzed using the Gas Chromatography- Mass Spectrometry technique. The results showed that S. costatum inhibited all isolates except Salmonella typhi and ATCC E.coli while Chaetoceros spp. had no inhibitory effect on Candida albicans. The MIC values of the two algae extract was least; < 2.0 mg/ml and highest; 10 mg/ml for the test isolates. A total of 42 and 25 volatile compounds which includes 9- Octadecenamide, (Z) - as the major constituent were obtained in S. costatum and Chaetoceros spp. respectively. Other compounds identified were known antimicrobial compounds; 1-Hexacosanol, Eugenol, Benzenesulfonamide, 4-methyl-N-phenyl- and Thiazole, 4-(4-aminophenyl)-2-methylamino- as well as some phytochemicals such as flavonoids, tannins, terpenoids, steroids and phenols. These may account for the antibiotic property of the algae extracts. This study showed that S. costatum and Chaetoceros spp. possess antimicrobial compounds which may be explored for therapeutic purposes.

Keywords: Antimicrobial, Marine algae, Clinical isolates, GC-MS, Phytochemicals.

Biokemistri 28(1): 24–33