The Optimization of Sodium Alginate and Propylene Glycol in Antioxidant Gel Formulation Containing White Turmeric Extract (Curcuma zedoaria)

Abstract

Temu putih rhizome (Curcuma zedoaria) has an antioxidant activity. This study aimed to optimize the combination of sodium alginate and propylene glycol in gel formulations and compare the antioxidant activity of the ethanol extract and gel form. Gel formulations were developed using a Simplex Lattice Design, with varying ratios of sodium alginate (A) and propylene glycol (B): F1 (3% A:8% B), F2 (2% A:9% B), F3 (2.5% A:8.5% B), F4 (1% A:10% B), and F5 (1.5% A:9.5% B). Physical properties were evaluated to determine the optimal formula using Design Expert version 13 and one-sample t-test. Antioxidant activity was assessed via the DPPH method. Results showed that sodium alginate increased viscosity and adhesiveness, while propylene glycol improved spreadability and pH. The optimal formulation contained 2.98% sodium alginate and 8% propylene glycol. The ethanol extract and gel showed IC₅₀ values of 50.169 ppm and 67.675 ppm, respectively.