Anti-oxidant activity of polysaccharides extracted from Isocrysis galbana using RSM optimized conditions.

In this present study, Box-Behnken design was used to optimize the polysaccharide extraction conditions from marine microalgae Isocrysis galbana. The independent factors include extraction time (A), extraction temperature (B) and water to raw material ratio (C). The experimental values were fitted to a second order polynomial equation using multiple regression analysis and statistical method (ANOVA). ANOVA results indicated that all factors including A-C had significant impact on I. galbana polysaccharides extraction. Our p (p<0.001) value demonstrated high significance for the regression model with the adjusted coefficient (R(adj)(2)) value of 0.9822. The optimal conditions for efficient yield of polysaccharide were A - 3.60 h, B - 67.02 °C and C - 10.43 giving maximum polysaccharide yield of 10.0345%. Model was verified by modifying the optimal conditions (A - 3.5 h, B - 65 °C, C - 10% and A - 3.6 h, B - 67 °C, C - 10%) toward practical application. The obtained yields 9.98±0.19% and 9.16±0.45 were comparable with the optimized condition which was indicated that our model is accurate. FTIR characterization study revealed that the extracted polysaccharide might be belongs to the family of lambda-carrageenan. Scavenging activity of hydrogen peroxide, DPPH and superoxide anion in vitro results showed that polysaccharides had a good potential as an antioxidant.