Formulation and Stability Testing of a Combination Cream Preparation Containing Centella asiatica (L.) Urb. Extract and Citrus limon (L.) Osbeck Peel Extract with Variations in Tea

Abstract

The combination cream of Centella asiatica (L.) Urb. extract and Citrus limon (L.) Osbeck peel extract has the potential to be developed as a topical formulation due to its antioxidant bioactive compounds. This study aimed to evaluate the effect of triethanolamine (TEA) concentration on the physical stability of the cream, determine the optimum formulation, and assess its antioxidant activity. The cream was formulated with three TEA concentrations: 2.5% (FI), 3% (FII), and 3.5% (FIII). Physical stability was evaluated using a six-cycle cycling test, including organoleptic, homogeneity, pH, adhesiveness, spreadability, and viscosity tests. The results showed that FI and FII met the physical quality requirements based on SNI 16-4399-1996. Repeated Measures ANOVA indicated that FII exhibited the best physical stability, with no significant changes in all evaluated parameters (p > 0.05), whereas FI showed a significant change only in viscosity and FIII showed significant changes in spreadability and viscosity (p < 0.05). The antioxidant activity of FII was determined using the Ferric Reducing Antioxidant Power (FRAP) method, yielding an IC₅₀ value of 10,579.927 ppm, which was classified as weak antioxidant activity. In conclusion, variations in TEA concentration affected the physical stability of the cream, with 3% TEA producing the most physically stable formulation.