Evaluation of radical scavenging activity of rhizome extracts of Alpinia galanga and Zingiber officinale

Abstract

2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of ethanolic and water extracts of rhizomes of Alpinia galanga (Lengkuas) and two varieties of Zingiber officinale (Ginger) was evaluated. Butylhydroxytoluene (BHT), a known radical scavenger, was used to serve as positive control. Malaysian ginger ethanloic and water extracts from dried ginger (MGEE and MGWED) showed a good to excellent activity. Thailand ginger water extracts from fresh and dried ginger (TGWEF and TGWED) and ethanolic extract from dried ginger (TGEE) exhibited an average to excellent radical scavenging activity. Malaysian lengkuas water extracts from fresh and dried lengkuas (MLWEF and MLWED) and ethanolic extract from dried lengkuas (MLEE) exhibited a good to excellent activity. In addition, the IC50 values were calculated for all the extracts and are listed separately. MGWED, MGEE and MLEE showed IC50 values (< 0.03 mg/mL) less than BHT (~0.12 mg/mL), indicated that these extracts are having better scavenging activity than BHT. TGWEF showed an IC50 value (~0.13 mg/mL) close to BHT. For all other extracts, the IC50 values are slightly higher than BHT.