RESEARCH JOURNAL OF PHARMACY AND TECHNOLOGY

Dunaliella tertiolecta is a marine microalgae rich in pharmacologically important xanthophyll carotenoid, zeaxanthin. This study demonstrated ultrasound assisted extraction (UAE) of zeaxanthin from D. tertiolecta (NIOT 141). Initially, the solvent type and antioxidant concentration for zeaxanthin extraction were optimized using one-variable-at-a-time (OVAT) experiments. Subsequently, three factors influencing the UAE yield of zeaxanthin like sonication time, sonication temperature and solid (algal biomass): liquid (solvent) ratio were investigated using response surface methodology (RSM). Both identification and quantification of zeaxanthin was done with aid of RP-HPLC (Reverse phase high pressure liquid chromatography). The data obtained from the experimental runs were fitted into a quadratic model. The model for maximizing the zeaxanthin extraction yield from D. tertiolecta had a high coefficient of determination of 0.9801. The optimized parameters for UAE of zeaxanthin from D. tertiolecta were sonication time of 33.6 min, sonication temperature of 59.2oC with a solid-liquid ratio 1: 62 (g ml⁻¹) and a predicted zeaxanthin content of 13.42 mg g⁻¹. The optimized UAE process parameters were verified by triplicate validation experiments and a zeaxanthin content of 13.85 ± 0.15 mg g⁻¹ was obtained. This further confirmed the reliability and precision of the RSM design. The zeaxanthin yield obtained in the optimized UAE of zeaxanthin content was 2.2 fold higher than the zeaxanthin content obtained by conventional solvent extraction process (6.24 ± 0.05 mg g⁻¹). Zeaxanthin from D. tertiolecta was purified and characterized using UHPLC-MS. The results indicated that D. tertiolecta can be used as a potential source of zeaxanthin.