Effect of HPMC Concentration on the Characteristics of a Peel-Off Gel Mask Containing Lemon (Citrus limon L.) Peel Extract and DPPH Antioxidant Activity of the Extract

Abstract

Free radicals can induce oxidative stress, leading to cellular damage and contributing to accelerated skin ageing. Lemon peel (Citrus limon L.) contains various secondary metabolites, including flavonoids, tannins, alkaloids, and saponins, which have potential antioxidant activity. Lemon peel extract can be formulated into a peel-off gel mask, whose physical characteristics may be influenced by the type and concentration of the gelling agent, including hydroxypropyl methylcellulose (HPMC). This study aimed to evaluate the effect of different HPMC concentrations on the physical characteristics of a peel-off gel mask containing lemon peel extract and to determine the antioxidant activity of the extract using the DPPH method. This experimental study employed maceration extraction using 96% ethanol. The obtained extract was subjected to qualitative phytochemical screening and antioxidant activity testing using the DPPH method. The extract was subsequently formulated into peel-off gel masks containing HPMC at concentrations of 3%, 4%, and 5%. Physical evaluations included organoleptic properties, homogeneity, pH, viscosity, drying time, spreadability, and adhesion. The extraction yield was 12.12%. Phytochemical screening confirmed the presence of flavonoids, tannins, alkaloids, and saponins. The IC₅₀ values of vitamin C and lemon peel extract were 7.18 ± 0.30 ppm and 69.64 ± 7.24 ppm, respectively. Variations in HPMC concentration had a significant effect on spreadability (p = 0.049), but did not significantly affect pH, viscosity, drying time, or adhesion. In conclusion, lemon peel extract exhibited strong antioxidant activity and has potential as an active ingredient in peel-off gel mask formulations, while variations in HPMC concentration primarily affected the spreadability of the preparation