Geographic Differences in DPPH Antioxidant Activity of Curcuma aeruginosa Rhizome Essential Oil from Selected Growing Areas in Java, Indonesia

Abstract

Curcuma aeruginosa (black turmeric), an aromatic medicinal plant used in Indonesian traditional medicine, exhibits chemical composition variations that influence its pharmacological effects depending on the rhizome’s growth location. This study investigated whether the antioxidant activity of Curcuma aeruginosa essential oil varies among rhizomes collected from three growing areas in Java (Batu, Wonogiri, and Majalengka). Essential oils obtained by water–steam distillation were evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. All samples exhibited concentration dependent radical scavenging activity, with strong logarithmic regression models. The Wonogiri oil showed the highest antioxidant activity (IC₅₀ = 3.09 mg/mL), followed by Batu (12.45 mg/mL) and Majalengka (16.78 mg/mL). These results demonstrate geographic differences in the antioxidant potential of Curcuma aeruginosa essential oil. Further GC–MS (Gas Chromatography Mass Spectrometry) analysis is required to identify the volatile compounds responsible for these regional differences.