Exposure to ultraviolet (UV) radiation induces the formation of free radicals that damage
skin cells, leading to premature aging and an increased risk of chronic skin disorders. Although
chemical and physical sunscreens are widely used, they still have limitations, including the
potential for skin irritation, systemic absorption, environmental impact, and aesthetic drawbacks
such as a white cast. Therefore, the development of safer and more environmentally friendly
natural sunscreen products is needed. Lime peel (Citrus aurantiifolia) contains flavonoids,
alkaloids, tannins, and saponins with antioxidant activity, indicating its potential as a natural
sunscreen agent.
This study aimed to formulate a spray gel sunscreen containing ethanol extract of lime peel
and to determine its in vitro Sun Protection Factor (SPF) using a UV–Vis spectrophotometer.
Three formulations were prepared with different extract concentrations: 5% (F1), 10% (F2), and
15% (F3), along with a control without extract (F0). The formulations were evaluated for
organoleptic properties, homogeneity, pH, viscosity, spreadability, and SPF values at wavelengths
of 290–320 nm.
The results showed that all formulations were thick, homogeneous, and had a neutral pH
of 6, meeting SNI requirements. Viscosity decreased with increasing extract concentration, from
132 ± 8.00 mPa·s (F0) to 72 ± 4.00 mPa·s (F3), but all values remained within the acceptable
range for spray gels. All formulations produced a uniform and smooth spray pattern. SPF values
increased with extract concentration, with F1 at 10, F2 at 13, and F3 at 15. F1 and F2 were
classified as low protection, while F3 showed medium protection. These findings indicate that lime
peel ethanol extract has potential as a natural sunscreen active, although further formulation
optimization is required to improve its UV protective effectiveness