Antioxidant Activity and Selected Chemical Components of 10 Zingiber spp. in Thailand

Abstract

Zingiber officinale (ginger) is the one of most commonly used spices and is a traditional herbal medicine in Thailand. Thailand is home to various Zingiber wild species. However, the biological activity evidence of these other species is less well studied than that of Z. officinale. In this study, we investigated the rhizomes of 10 Zingiber species to determine the correlations between total phenolic content, total curcuminoid content, and antioxidant activity, as determined by means of DPPH (2,2-Diphenyl-l-picrylhydrazyl) and ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6sulfonic acid) diammonium salt) assays. We also used high-performance liquid chromatography and gas chromatography to determine the quantities of 6-gingerol and terpinen-4-ol, respectively which are the two most important active compounds associated with antioxidant and anti-inflammatory action. Antioxidant activity was highly correlated with total phenolic content. To the best of our knowledge, this is the first report of the antioxidant activities of three of the species (Z. rubens, Z. bisectum, and Z. barbatum). The rhizome extracts of Z. montanum showed the highest total curcuminoid content and yielded the highest amount of essential oil and terpinen-4-ol content. 6-Gingerol was detected in only two species: Z. officinale and Z. cornubracteatum. Our results suggest that Z. montanum may be an excellent natural remedy owing to its considerable antioxidant activity and the large amounts of known bioactive chemical constituents it contains. It may be a source of additional bioactive compounds.