Phytochemical screening and evaluation of the antioxidant and antibacterial potential of Zingiber officinale extracts

Abstract

Zingiber officinale roscoe rhizome has been very popular worldwide as a spice, but an auxiliary medicine in treatment of various disorders. In this study, we controlled the effect of the heating extraction in the case of ethyl acetate, ethanol and aqueous extracts on the antioxidant and antibacterial properties. Compounds of ethyl acetate extract were identified by gas chromatography-mass spectrometry (GC-MS). Results showed that zingiberene was present as the major compound (23.71%; 31.70%) followed by β-sesquiphellandrene (15.08%; 16.64%) and curcumene (16.47%; 14.42%) in the ethyl acetate extracts at 20°C and 40°C, respectively. The mineral composition of ginger rhizomes was carried out by the inductively coupled plasma–atomic emission spectroscopy (ICP–AES) analysis. Moreover, ethanol extracts presented the highest polyphenol content (297.63 and 322.11 µg EAG/mg Ex) at 20°C (EET1) and 40°C (EET2), respectively. The two ethanolic extracts were the most active against the DPPH free radicals with IC50 of 98.62 and 77.23 µg/mL, respectively. The two ethyl acetate extracts EAC1 and EAC2 revealed the best antibacterial efficiency compared to the other extracts against all bacterial strains with MIC values ranging from 0.03 to 0.12 mg/mL and MBC values ranging from 0.06 to 0.24 mg/mL. Results showed a good agreement between the antioxidant power of extracts and their content of phenolic compounds.