Optimisation of a Red Shoot Leaves Extract Emulgel Using Simplex Lattice Design

Red Shoot Leaves (RSL) contain various secondary metabolites, including alkaloids, triterpenoids, phenolic compounds, flavonoids, saponins, tannins, and anthocyanins. The total flavonoid content of RSL was 14.46 mg QE/g extract, while the total phenolic content of the 70% ethanolic extract was 858.9±0.0076 mg GAE/g extract. This study aimed to determine the optimal emulgel formulation by optimising the combination of two gelling agents, Hydroxypropyl Methylcellulose (HPMC; X1) and Carbopol 940 (X2). The optimisation was performed to obtain an emulgel with desirable physical characteristics. A Simplex Lattice Design was implemented using Design-Expert software, with three response variables: pH (Y1), spreadability (Y2), and adhesiveness (Y3). Seven experimental runs were conducted, resulting in pH values ranging from 5.87 to 6.18, spreadability values from 4.0 to 5.5 cm, and adhesiveness values from 3.99 to 6.94 s. The optimal formulation consisted of 4.28% HPMC and 0.71% Carbopol 940. The resulting emulgel exhibited a white, homogeneous, odourless, semisolid appearance with a smooth texture. The optimised RSL emulgel met the required physical quality parameters, with a pH of 6.2±0.02, spreadability of 5.6±0.20 cm, adhesiveness of 4.7±0.13 s, viscosity of 196.7±5.77 dPa·s, and an Oil-in-Water (O/W) emulsion type.