Comparison of Antioxidant effects of Polysaccharides of Mixed Microalgae Isolates Glagah Beach Yogyakarta and East Java, Indonesia

Indonesia is a country with a large marine and has a very high biodiversity of microalgae. Previous research has identified mixed microalgae from Glagah Beach, Yogyakarta, and several beaches in East Java. This study aims to extract polysaccharides and assessed the antioxidant activity of polysaccharides from those microalgae. Polysaccharides of Spirulina platensis, a mixed microalgae Glagah, and a mixed microalgae East Java were extracted by the alkaline method. The extraction rate and protein and carbohydrate content of polysaccharides of each of microalgae were calculated. The antioxidant activity of polysaccharides was observed in vitro using the DPPH assay method. The highest extraction rate was obtained from Glagah microalgae followed by S. platensis and East Java microalgae with values of 13.575%, 9.75%, and 2.375%, respectively. On the other hand, the carbohydrate content of the polysaccharides from Glagah microalgae was the lowest, followed by S. platensis and East Java microalgae, 1.2 mg/mL, 13.33 mg/mL, and 21.925 mg/mL, respectively. The protein content in polysaccharides from Glagah microalgae was the highest, followed by East Java microalgae and S. platensis the lowest, 2.23 mg/mL, 1.01 mg/mL, and 0.67 mg/mL, respectively. Based on the results of IC50 values, the antioxidant activity of mixed microalgae polysaccharides from Glagah and East Java was included in the active/moderate category, 125.21 µg/mL and 127.11 µg/mL, respectively, while the antioxidant activity of polysaccharide S. platensis was low, 171.82 µg/mL. In conclusion, Glagah and East Java Microalgae Polysaccharides have the opportunity to be promoted as health ingredients to overcome free radicals.