Extraction Method and Solvent Effect on Antioxidant and Anti-lipase Activities of Nostoc sp. MRB-1 from the Peatlands in Oxbow Hanjalutung Lake, Indonesia

The increasing utilization of microalgae as a natural resource of bioactive compounds encourages finding efficient and cost-effective ways to extract those compounds. Therefore, the present study aimed to evaluate two solvents and two extraction methods to obtain extracts of microalgae Nostos sp. MRB-1. The extracts were evaluated regarding phenolic content, antioxidant, and anti-lipase activities. The results showed that maceration using ethanol obtained the highest phenolic content (11.77±1.47 GAE mg/g dry extract) and anti-lipase activity with the value of 23.01±1.66% at 0.38 mg/mL. While the extract obtained from the ultrasound using hexane exhibited the highest antioxidant activity with a value of 39.68±0.07% at 0.8 mg/mL. These results demonstrate that maceration using ethanol is more effective for phenolic extraction from microalgae. In microalgae, phenolic content positively correlates with anti-lipase activity, but the opposite was verified, phenolic compounds are not contributors to the antioxidant activity of Nostoc sp. MR-1 extract