In vitro antioxidant and antiglycation activity of zingiber zerumbet (wild zin-ger) rhizome extract

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. Antioxi-dant 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 scav-enged 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 respec-tively. 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.