Effects of Extraction Media on the Chemical and Functional Profiles of Rosemary Extracts for Potential Cosmetic Applications

The increasing use of plant-derived ingredients in cosmetics highlights the need for extraction strategies that preserve bioactive compounds while ensuring extract stability and quality. Rosmarinus officinalis L. is a valuable source of phenolic compounds, terpenoids, and other phytochemicals with antioxidant potential. Since the extraction medium strongly influences extract composition and stability, solvent selection is a key step in developing functional cosmetic ingredients.

This study compares rosemary extracts obtained using media spanning a broad polarity range, from hydrophilic to lipophilic systems. The extracts were characterized by FT-IR, GC-MS, total phenolic content (TPC), DPPH antioxidant activity, colour measurements, UV-Vis monitoring under controlled photoirradiation and varying pH conditions, and peroxide and p-anisidine values. Computational analyses complemented the experimental characterization of the identified phytoconstituents.

TPC analysis showed comparable phenolic extraction for rosemary samples from different geographical sources in hydrophilic media (22.83 and 25.55 mg GAE/g). Combining solvents of different polarities enhanced phenolic extraction by up to 55.2%, reaching 35.43 mg GAE/g. Ethanolic extracts prepared using agricultural- and technical-grade ethanol exhibited DPPH IC₅₀ values of 169.58 and 182.02 µg/mL, respectively. FT-IR analysis highlighted extraction selectivity, with lipophilic media favouring spectral features associated with ester groups and aliphatic chains, while ethanolic extraction enhanced features associated with hydroxyl-containing and phenolic constituents. Photoirradiation of ethanolic extracts at 364 and 546 nm decreased the characteristic UV-Vis bands around 280 and 320-340 nm, indicating degradation of phenolic compounds, while changes around 400 nm suggested the formation of secondary oxidation products.

Overall, the results demonstrate that extraction-medium polarity modulates the chemical profile, antioxidant capacity, and stability of rosemary extracts, supporting an extraction strategy tailored to the desired properties and final cosmetic application.