Physical Stability of Gel of Read Algae (Eucheuma spinosum) Extract and Evaluation of its Antioxidant effect

Red algae (Eucheuma spinosum) was reported has excellent antioxidant activity. It was collected from Gili Tangkong, Sekotong District, West Lombok, West Nusa Tenggara. The research aims to determine antioxidant activity of the gel form of red algae ethanol extract by DPPH (1,1-diphenyl-2-picrylhydrazil) method. The extract was prepared into gel formulate in various concentrations: F1(10%); F2(20%) and F3(30%) (w/w) by using combination carbopol 940 and HPMC as polymer bases. The physicochemical parameters of gel formulation (organoleptic, pH, spreadability, adhesion) were determined. Stability studies of gel have carried out for 21 days at viscosity and an antioxidant activity using the DPPH method. The results showed that all formulations complied with the required characteristics, which stability analysis did not change significantly in pH, organoleptic, consistency, adhesivity and spreadability during storage. Antioxidant activity of all formulas showed that the value of IC50 on F1 198.88 ppm (weak intensity: 151<IC₅₀<200 ppm); F2 153.85ppm and F3 101.18ppm (medium intensity: 101ppm<IC₅₀<150ppm). The result of this value showed the the gel extract which was made was have antioxidant activity and the most effective one was on the FIII.