LC–MS/MS analysis, antioxidant and anticholinergic properties of galanga (Alpinia officinarum Hance) rhizomes

Abstract

Galanga (Alpinia officinarum Hance) is a pungent and aromatic rhizome, which is a member of the ginger family (Zingiberaceae). The rhizomes of this plant have been used as a traditional medicine in far east countries for relieving stomach ache, invigorating the circulatory system, treating colds, and reducing swelling. The aim of this study was to investigate antioxidant and anticholinergic properties of galanga. For this purpose, we elucidated the antioxidant activity of water (WEG), ethanol (EEG) and water/ethanol (50:50 v/v WEEG) extracts of galanga by different in vitro antioxidant assays. Radical scavenging activities of galanga extracts were performed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) radical scavenging assays. Also, reducing power galanga extracts were evaluated by Cu2+–Cu+ reducing (CUPRAC) and Fe3+–Fe2+ reducing and [Fe3+−(TPTZ)2]3+–[Fe2+–(TPTZ)2]2+ (FRAP) abilities. Finally, Fe2+ chelating activity by pipyrdyl reagent and anticholinergic activities of galanga extracts were realised. All galanga extracts demonstrated antioxidant activity. α-Tocopherol ((2R)-2,5,7,8-tetramethyl-2-[(4R,8R)-(4,8,12-trimethyltridecyl)]-6-chromanol), trolox (3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl- 2H-1-benzopyran-2-carboxylic acid), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were used as positive controls. On the other hand, IC50 values were calculated for DPPH, ABTS+ scavenging Fe2+ chelating, and anticholinergic effects of galanga extracts. This study clearly showed that galanga had marked antioxidant, anticholinergic effect, reducing ability, radical scavenging and metal binding activities.