Biological activities and chemical composition of solvent extracts of Stoechospermum marginatum (C. Agardh).

The objective of this study was to evaluate the chemical composition CH3OH-CH2Cl2 (1:1) extract and biological activities of various extracts derived from the aerial parts of the brown marine alga Stoechospermum marginatum (C. Agardh). Gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS) were used to analyze the composition of the essential oil. Total phenolics assay demonstrated a high value in hexane extract (HE), with a lower value for chloroform extract (CE), and the lowest value for methanol extract (ME). DPPH (2,2-diphenyl-1-picrylhydrazyl) assay showed that extracts of S. marginatum possess radical scavenging activity (RSA). Tests of the antioxidant property of the extracts revealed both electron and hydrogen transfer mechanisms. The antibacterial activity of the ME, CE, and HE as well as an ethanol extract was estimated against seven Gram-positive and Gram-negative bacteria. The ethanol extract showed the highest antibacterial activity, and the HE showed the lowest.