Phenolic Content and Antioxidant Activity of ethanol extracts of Etlingera pubimarginata (Zingiberaceae), including notes on its Morphology

Abstract

Ethanolic extracts of the dry weight leaves and rhizomes of Etlingera pubimarginata (Elmer) A.D.Poulsen were used in this study to determine its phenolic content and antioxidant activity. Total phenolic content was determined using the Folin-Ciocalteu method, while phosphomolybdenum method was used for the total antioxidant activity. Data revealed that the total phenolic content in E. pubimarginata leaves (27.25 ± 0.72 mg GAE/g dried sample) have greater amount of phenolics than its rhizomes (0.76 ± 0.11 mg GAE/g dried sample). Further, total antioxidant activity of E. pubimarginata was observed higher in leaves (34.83 ± 0.49 mg AAE/g dried sample) than rhizomes (1.82 ± 0.09 mg AAE/g dried sample), as well as the reducing power revealed to have higher amounts in the leaves (24.83 ± 2.99 mg GRPE/g dried sample) than the rhizomes (0.33 ± 0.10 mg GRPE/g dried sample). The high contents of phenolic compounds contribute to the antioxidant activity of extracts of E. pubimarginata. A perfect positive linear relationship was observed among the total phenolic content, total antioxidant activity, and reducing power (r=1, p<0.001) based on the correlation analysis. These imply that E. pubimarginata could be potentially used as a new source of natural antioxidant. Furthermore, a description of the species, including its updated distribution, phenology, and habitat and ecology are provided in this paper.