Determination of Total Flavonoid And Antioxidant Activity of The Lempuyang Gajah (Zingiber zerumbet Sm.) Rhizome Fraction Using Spectrophotometry Method

Abstract

Oxidative stress induced  by free  radicals contributes to cellular damage and various degenerative diseases. Zingiber zerumbet (lempuyang gajah) rhizomes are rich in flavonoids, which exhibit potential antioxidant and anti-inflammatory properties. This study investigated the total flavonoid content and antioxidant activity of rhizome fractions to identify natural antioxidant sources. Rhizomes were subjected to liquid-liquid extraction, yielding water, ethyl acetate, methanol, and n-hexane fractions. Total flavonoids were quantified via colorimetric assay, and antioxidant activity was assessed using the DPPH method with UV-Vis spectrophotometry. The water fraction provided the highest extract yield (76.00%), followed by ethyl acetate (20.33%), methanol (2.67%), and n-hexane (1.00%). Flavonoid content was highest in the ethyl acetate fraction (29.25 mg QE/g), while methanol, water, and n-hexane fractions contained 5.64, 5.55, and 5.55 mg QE/g, respectively. Antioxidant assays revealed that the ethyl acetate fraction exhibited very strong activity with an IC₅₀ of 17.11 μg/mL, whereas methanol and water fractions showed strong activity with IC₅₀ values of 53.55 μg/mL and 64.44 μg/mL, respectively. The n-hexane fraction demonstrated negligible activity (IC₅₀ = 905.55 μg/mL). In conclusion, the water fraction offers the highest extraction yield, whereas the ethyl acetate fraction possesses the greatest flavonoid content and strongest antioxidant potential, highlighting its promise as a natural antioxidant source.