Phenolic Content and Antioxidant Activity of Leaves and Rhizomes of Etlingera coccinea (Blume) S.Sakai and Nagam. (Zingiberaceae)

Abstract

Most of the Zingiberaceae species in the Philippines have been used as ethnomedicinal plants due to the benefits  they possess. One of these species is Etlingera coccinea (Blume) S.Sakai and Nagam. (Zingiberaceae), a species with a variety of uses in Malaysia, Borneo, and Philippines. In this study, ethanolic extracts of the dry weight leaves and rhizomes of E. coccinea were used to determine its phenolic content and antioxidant activity. The total phenolic content and total antioxidant activity were determined using Folin-Ciocalteu and phosphomolybdenum methods, respectively. Data revealed that the total phenolic content of dry weight, expressed as milligram gallic acid equivalent per gram sample (mg GAE/g sample) recorded that the leaves (11.69 ± 0.47 mg GAE/g sample) have greater amount of phenolics than the rhizomes (0.58 ± 0.06 mg GAE/g sample). The total antioxidant activity (TAA), expressed as milligram ascorbic acid equivalent per gram sample (mg AAE/g sample), obtained  higher activity in the leaves (12.76 ± 0.31 mg AAE/g sample) than the rhizomes (0.85 ± 0.12 mg AAE/g sample), and the reducing power, expressed as milligram gallic acid reducing power equivalent per gram sample (mg GRPE/g sample) also revealed higher activity for the leaves (9.37 ± 1.88 mg GRPE/g sample) compared to rhizomes (0.28 ± 0.07 mg GRPE/g sample). Based on the correlation analysis, a perfect positive linear relationship was observed among the TPC, TAA, and RP (r=1, p<0.001), which means that phenolic compounds significantly contribute to the antioxidant activities of the extracts of E. coccinea. These data imply that E. coccinea could be potentially used as a new source of natural antioxidant. Furthermore, this paper adds information on the habitat and ecology, phenology, and coloured photographs of this species for future related studies and conservation initiatives.