ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF Caulerpa racemosa EXTRACT WITH A COMBINATION OF SOLVENTS AND VARIATION OF MACERATION TIME

Abstract

Seaweed from the Chlorophyta and Rhodophyta groups is widely used as food in Indonesia. Caulerpa racemosa, a type of Chlorophyta, contains bioactive antioxidant and antibacterial compounds, including terpenoids, polyphenols, alkaloids, and flavonoids. This study aimed to determine the optimal extraction conditions (concentration, solid:solvent ratio, and duration) of C. racemosa using Deep Eutectic Solvents (DES) based on antioxidant and antibacterial activity. This study used independent variables (5%, 10%, and 15%), solid:solvent ratio (1:10, 1:15, and 1:20); and maceration time (24, 48, and 72 h maceration times). The optimization process was carried out using the response surface methodology (RSM) with a Box–Behnken design using Design Expert software v13. The antioxidant activity of C. racemosa extract ranged from 28.46±0.067 to 50.50±0.067 mg TE/g dry weight (DW). The concentration of the DES solvent and maceration time had a significant effect (p<0.05), whereas the solid-to-solvent ratio did not show a significant effect (p>0.05). Antioxidant activity decreased at 15% DES owing to differences in solvent polarity and viscosity, whereas lower viscosity increased the extraction efficiency. Optimal conditions were obtained at 10% DES, a ratio of 1:20, and a maceration time of 72 h. Antibacterial activity against Vibrio harveyi (13 mm) and Vibrio parahaemolyticus (14.8 mm) was also highest under these conditions, possibly due to an increase in the bioactive compound extracts. These results indicate that the optimized extraction method is suitable for developing aquaculture and functional food products.