Comparative Study of Extraction Methods on the Antioxidant Activity of Curcuma caesia Roxb. Leaf Extract Using the DPPH Assay

Abstract

Antioxidants are compounds capable of inhibiting or delaying the oxidation of other molecules, thereby protecting biological systems from oxidative damage caused by free radicals. Natural antioxidants derived from plants have gained increasing attention due to their safety and potential health benefits. One such plant is black turmeric (Curcuma caesia Roxb.), which is widely recognized for its medicinal properties and rich content of bioactive secondary metabolites. The leaves of C. caesia contain various phytochemical constituents, including flavonoids, alkaloids, and phenolic compounds, which are known to exhibit significant antioxidant activity. This study aimed to evaluate the antioxidant activity of ethanol extract of C. caesia leaves using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and to compare the effectiveness of two extraction techniques, namely maceration and water bath-assisted maceration, using 96% ethanol as the solvent. The extracts obtained from both methods were analyzed for their ability to scavenge DPPH radicals, and the antioxidant activity was expressed in terms of IC₅₀ values. The results showed that the ethanol extract obtained through the maceration method exhibited an IC₅₀ value of 19.7921 µg/mL, while the water bath-assisted maceration method yielded a slightly lower IC₅₀ value of 19.5868 µg/mL. Both values fall within the range of 10–50 μg/mL, indicating strong antioxidant activity. The slight difference in IC₅₀ values suggests that the water bath-assisted maceration method may enhance extraction efficiency, although both methods are effective in obtaining bioactive compounds with high antioxidant potential. In conclusion, C. caesia leaf ethanol extract demonstrates strong antioxidant activity, and both extraction methods are suitable for isolating antioxidant compounds, with water bath-assisted maceration showing marginally better performance. These findings support the potential use of black turmeric leaves as a natural source of antioxidants for pharmaceutical and nutraceutical applications.

KEYWORDS: Extraction; phytochemical; radical; oxidation; spectrophotometry.