Optimization of The Lip Balm Formulation Containing Sappan (Caesalpinia sappan L.) Wood Extract and the In Vitro Evaluation of its Sun Protection Factor

Lip balm is essential for maintaining lip hydration and safeguarding against sun exposure. Sappan wood possesses the ability to function as a sunscreen due to its content of chemicals like flavonoids, phenolics, and alkaloids. This study aimed to ascertain the ideal concentrations of carnauba wax and olive oil in lip balm formulations, including Sappan wood extract, as well as to evaluate the in vitro Sun Protection Factor (SPF) value. The extraction was conducted via the maceration technique. The optimization of lip balm formulations was conducted by varying the concentrations of carnauba wax and olive oil across eight successive trials. The characteristics assessed for the lip balm formulation were organoleptic properties, pH, melting point, hardness, moisture retention, hedonic evaluation, and skin irritation potential. The ideal formulation, comprising 3% carnauba wax and 16.5% olive oil, was achieved by the Simplex Lattice Design approach using Design Expert software v.13, yielding a desirability value of 0.881. The panelists preferred the optimal formula based on the findings of the hedonic test conducted via a questionnaire. The validation of the optimal formula indicated no substantial discrepancy between the projected response and the experimental outcomes. An in vitro SPF test was conducted on the optimal formulation, yielding an SPF value of 22.49, which is categorized as medium-protection.