Bioactive Potential of Rosmarinus officinalis Essential Oil: Phytochemical Profiling and In Vitro Antioxidant and Anti-Inflammatory Activities

Abstract

Abstract: Rosmarinus officinalis L. (syn. Salvia rosmarinus), commonly known as rosemary, is a medicinally important aromatic plant rich in bioactive volatile constituents with potential antioxidant and anti-inflammatory properties. The present study evaluated the phytochemical composition, antioxidant activity, cytotoxicity, and in vitro anti-inflammatory potential of R. officinalis essential oil. Fresh leaves were collected, authenticated, shade-dried, and subjected to hydrodistillation using a Clevenger-type apparatus. The obtained essential oil was characterized by GC–MS, while antioxidant activity was evaluated using the DPPH radical-scavenging assay. Cytotoxicity was assessed in RAW 264.7 macrophage cells using the MTT assay, and anti-inflammatory activity was evaluated through inhibition of protein denaturation. GC–MS analysis identified several volatile constituents, including α-pinene, limonene, 1,8-cineole, linalool, camphor, borneol, α-terpineol, eugenol, β-caryophyllene, α-humulene, germacrene D, and caryophyllene oxide. Eugenol (43.52%) and β-caryophyllene (19.51%) were the predominant constituents, suggesting their possible contribution to the biological activity of the essential oil. In the DPPH assay, the essential oil exhibited moderate antioxidant activity with an IC₅₀ of 136.5 ± 0.05 µg/mL compared with 2.502 ± 0.02 µg/mL for ascorbic acid. The MTT assay indicated moderate cytotoxicity toward RAW 264.7 cells, with an IC₅₀ of 101.5 ± 0.11 µg/mL. In the protein denaturation assay, the essential oil demonstrated moderate inhibitory activity with an IC₅₀ of 195.3 ± 0.07 µg/mL compared with 97.26 ± 0.01 µg/mL for diclofenac.