Chemical composition and In vitro study of antioxidant and antibacterial activities of Sargassum oligocystum Montagne (Sargassaceae, Ochrophyta)

Seaweeds are marine organisms capable of producing diverse biomolecules and other important bioactive compounds with potential pharmacological uses. Proximate composition analysis of S. oligocystum showed high ash, carbohydrate, and protein content with an estimated value of 39.01±0.16%, 21.43±0.37%, and 19.13 ± 0.19% respectively. The macroalga has a phenolic content (TPC) of 30.94 ± 0.06 mg GAE/g. In terms of antioxidant efficiency, high copper reduction capacity (IC50 = 6.97 μg GAE/ml) and potent radical scavenging activity (IC50 = 28.5 μg GAE/ml) were exhibited by S. oligocystum extract, which is more effective than ascorbic acid (control). Also, S. oligocystum extract showed potent antibacterial activities towards Methicillin-Resistant Staphylococcus aureus (MRSA) and Bacillus cereus with minimum inhibitory concentration (MIC) of 125 μg/ml and 250 μg/ml, respectively. This investigation is a pioneering study in the Philippines documenting the use of S. oligocystum as an alternative source of bioactive substances that can be used as novel therapeutic agents in disease treatment.