Assessment of antioxidant activity of citronellal extract and fractions of essential oils of Citrus hystrix DC

Purpose: To evaluate the antioxidant activities and chemical compositions of citronellal extract and fractions of essential oils of Citrus hystrix.Methods: Antioxidant activity was examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Essential oil was produced by steam distillation while isolated citronellal and fractional distillates were obtained on a PiloDist 104-VTU fractional column at 5 mBar pressure and a reflux ratio of 20:10. Gas chromatography-mass spectrometry was used to determine their chemical composition.Results: All the essential oils produced from parts of C. hystrix, i.e., twigs oil (CHT), leaves-twigs oil (CHTL), leaves oil (CHL), and fruit peels oil (CHP), citronellal extract of CHL oil (CHLCE) and the distillation fractions of CHT oil (F1–F9), exhibited antioxidant activity. CHP exhibited the highest antioxidant activity. The chemical composition of CHT, CHTL and CHL was dominated by oxygenated monoterpenes (OMs), whereas that of CHP and F1 comprised mainly of a hydrocarbon monoterpene (HM).Conclusion: The antioxidant activities of essential oils from parts of C. hystrix and the fractions produced by essential oil fractional distillation exhibited a combination of HMs and OMs. Essential oils of CHP and F3 produced from the essential oil fractional distillation of CHT with a nearly equal composition of HM and OM compounds had higher antioxidant activity than the other essential oils and fractions, with IC50 values of 6.43 and 2.40 μL/mL, respectively.Keywords: Citrus hystrix, Essential oil, Hydrocarbon monoterpene, Oxygenated monoterpene, Antioxidant