STATISTICAL OPTIMIZATION OF MEDIUM COMPONENTS BY PLACKETT BURMAN DESIGN AND RESPONSE SURFACE METHODOLOGY FOR ENHANCED ANTIOXIDANT ACTIVITY BY XYLARIA FEEJEENSIS HMJAU22039

STATISTICAL OPTIMIZATION OF MEDIUM COMPONENTS BY PLACKETT BURMAN DESIGN AND RESPONSE SURFACE METHODOLOGY FOR ENHANCED ANTIOXIDANT ACTIVITY BY XYLARIA FEEJEENSIS HMJAU22039 Durga Rebbapragada Rajagopal Kalyanaraman

Objective: To enhance the antioxidant potential of Xylaria feejeensis by statistical optimization. The components of potato dextrose yeast extract (PDYEB) medium: potato infusion, dextrose and yeast extract were investigated to optimize antioxidant activity by Plackett-Burman design (P-B design). The interaction between the critical components of the medium and incubation time was further investigated by Response Surface Method (RSM) and the culture conditions were optimized for enhancing antioxidant activity. Central composite design (CCD) was employed and quadratic response surface model was used to analyze the data using analysis of variance (ANOVA).Methods: The antioxidant potential was measured by 1-1diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, nitric oxide (NO) scavenging assay. The antioxidant activity was compared with total phenolic content measured by Folin-Ciocalteau (FC) reagent based assay. Results: Plackett-Burman design revealed dextrose and yeast extract to be the most significant components of PDYEB medium (p<.0001). ANOVA analysis showed that the model was highly significant (p<0.0001) for antioxidant activity measured by DPPH, NO scavenging and TPC (total phenolic content). The model was justified by applying the optimized conditions and values of 87.38%, 56.43%, 27.28 mg/g for DPPH, NO scavenging and TPC respectively were obtained. The estimated optimum conditions of the variables for the antioxidant activity and phenolic content are 12.72g of dextrose, 1.67g yeast extract, and incubation period of 23.43 d. Conclusion: The study highlights the importance of various components of the medium and the physiochemical limitations in antioxidant potential and phenol production of the fungal strain.