A GC-MS Study of the Subcritical Water and Ethanolic Extracts of Rosemary (Rosmarinus officinalis L.) Leaves

Objective: To compare the efficiency of subcritical water vs. ethanol-water solutions for extracting components from rosemary leaves. Methods: Rosemary leaves were extracted using ethanol-water solutions (10–95%) via maceration/reflux and with subcritical water (130–150°C). Extracts were analyzed by GC-MS, both directly and after derivatization. Results and Discussion: About 100 components were identified. Ethanolic solutions were superior for extracting volatile terpenoids (e.g., camphor, borneol). Subcritical water at 150°C was most effective for non-volatile compounds, yielding the highest content of rosmarinic acid and other phenolic/carboxylic acids. Extraction efficiency for non-volatiles increased with temperature. Conclusions: 95% ethanol is optimal for volatile compound extraction, while subcritical water at 150°C is best for non-volatiles like rosmarinic acid. Subcritical water is a viable green method for obtaining bioactive compounds from rosemary.