In Vitro Antioxidant and Antiglycation Activity of Zingiber zerumbet (Wild Zinger) Rhizome Extract

Abstract

Rhizomes of Zingiber zerumbet (Family: Zingiberaceae) is also known as wild zinger or shampoo zinger. Most of the biological activities reported for this plant are attributed to phenolic contents and volatile principles. Hence, a detailed investigation of antioxidant and antiglycation activities of Zingiber zerumbet rhizome was carried out. The ethyl acetate extract of Zingiber zerumbet rhizome (ZZE) was prepared and tested for phytoconstituents. Antioxidant and antiglycation activity of ZZE was determined by standard methods. Upon phytochemical investigations of ZZE showed the presence of phenols, flavonoids and terpenoids. ZZE had a total phenolic content of 331.93±1.23 mg/ml gallic acid equivalent and total flavonoid content of 198±2.65 mg/ml of quercetin equivalent. ZZE also showed a significant total antioxidant activity (86.04±0.98 mg/ml ascorbic acid equivalent). Further, ZZE scavenged DPPH and ABTS radical with an IC₅₀ of 117.65±1.45 and 78.72±1.12 µg/ml respectively. Similarly, hydroxyl, superoxide, hydrogen peroxide and nitric oxide radicals were scavenged with an IC₅₀ of 39.90±0.77, 185.49±0.97, 144.71±3.75 and 89.87±1.02 µg/ml respectively. The IC₅₀ values in O-phenanthroline (iron-chelating capacity), β- carotene bleaching and lipid peroxidation assays were 189.63±2.21, 317.24±0.34 and 94.45±2.76 µg/ml respectively. The observed antioxidant activity can be attributed mainly to the total phenolics and flavonoids present in ZZE. Furthermore, ZZE also demonstrated antiglycation activity in hemoglobin-glucose and BSA-glucose assays, but the activity was not significant when compared to the standards quercetin and aminoguanidine. Results of this study confirm the antioxidant and antiglycation potentials of Zingiber zerumbet rhizomes.