Optimization of sustainable processes for the development of semi-solid microemulsions containing plant active...

This study presents a sustainable extraction process for obtaining plant active substances (PAS) from the leaves of Salvia rosmarinus Spenn. (rosemary) and semi-solid microemulsions (SSME) at the same time. The extraction method uses a sustainable solvent system of surfactants, co-surfactants, and water, yielding high PAS miscibility.

The method was developed using pseudo-ternary phase diagrams, particle size determination and ultrasound-assisted extraction. Optimization was performed via response surface methodology, assessing antioxidant capacity, total phenols, terpenoids, and flavonoids for efficiency evaluation.

Optimal extraction conditions, identified using response surface methodology, which produced SSME with high antioxidant capacity (0.04 to 0.150 mmol/ml) and significant polyphenolic content (0.055 to 0.219 mg of gallic acid/ml). Additionally, the resulting formulations showed a total terpenoid content of 0.04 to 0.150 mmol/ml and a total flavonoid content of 5.4 to 10.5 mg/ml mg quercetin equivalent/ml. The droplet size and polydispersity index values of the optimized extracts were evaluated, yielding mean droplet sizes below 250 nm, indicating the presence of microemulsions. By means of UPLC-ESI-MS/MS the primary PAS were identified, validating the effectiveness of the extraction process in isolating of bioactive compounds with therapeutic potential.

This eco-friendly method not only aligns with green chemistry principles but also supports the development of PAS-rich SSME as candidates for dermal therapies.