Cyclic Voltammetry and Spectrophotometric Determination of Antioxidant Activities of Selected Ginger Species

Abstract

Introduction: Zingiberaceae rhizomes are commonly investigated due to their applications in food and traditional medicine use. However, less scientific attention was given to their leaves.Aim: This study primarily aimed to compare the antioxidant activity of the leaves and rhizomes of common Zingiberaceae plants, namely: Zingiber officinale, Curcuma longa, and Etlingera elatior.Methods: Antioxidant activity of the water and ethanol extracts of the leaves and rhizomes of the studied plants was determined using cyclic voltammetry (CV) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays.Results: Very low positive correlation (r = 0.22) of antioxidant activities was observed between DPPH and CV methods. In both DPPH and CV methods, E. elatior has generally higher antioxidant activity in leaves than in rhizomes and water extracts than ethanol extracts. Higher antioxidant activity was observed in leaves than in rhizomes for Z. officinale and C. longa for both water and ethanol extracts. In general, water extracts of the three ginger plants have higher antioxidant activity than their ethanol extracts.Conclusion: Both CV and DPPH assays revealed that leaves of common gingers studied are potential sources of antioxidants.

Keywords: Cyclic voltammetry; DPPH radical scavenging activity; Gingers