Abstract
Oxidative stress, caused by an imbalance between free radical production and the body's antioxidant defense system, contributes to various degenerative diseases. Natural antioxidants from plants, such as temulawak (Curcuma xanthorrhiza* Roxb.), offer a safer alternative. This study aimed to determine the effect of ethanol concentration (50%, 70%, and 96%) on the antioxidant activity of temulawak leaf extract. Extraction was performed using the maceration method, and antioxidant activity was measured using the ABTS (2,2′-azinobis (3 ethylbenzothiazoline-6-sulfonic acid)) assay, expressed as IC₅₀ values. The results showed a trend of decreasing IC₅₀ values with increasing ethanol concentration. The lowest IC₅₀ value was obtained at 96% ethanol (39.21 ± 22.43 ppm), followed by 70% (54.01 ± 12.31 ppm) and 50% (80.37 ± 18.24 ppm), indicating the highest antioxidant activity at 96% ethanol. These findings suggest that 96% ethanol is the most effective solvent for extracting antioxidant compounds from temulawak leaves, likely due to its better polarity suitability for extracting semipolar bioactive compounds such as flavonoids and phenolics. This study provides scientific information on optimal extraction conditions and supports the potential use of temulawak leaves as a natural antioxidant source.