Composition and antibacterial, anti-inflammatory, antioxidant, and anticancer activities of Rosmarinus officinalis L. essential oil

Rosemary is a culinary herb that is widely used in traditional medicine for its nutritional value and pharmacological properties. The aim of this study was to investigate the composition, in vitro anticancer, antioxidant, and antibacterial activities of rosemary essential oil. Rosemary essential oil components were simultaneously analysed by GC/MS and GC/FID techniques. Different concentrations of rosemary essential oil were incubated for 24 and 48 h with HepG2 and EV304 cells. Cell viability was measured by MTT assay. Anticancer activities of rosemary essential oil were investigated by immunocytochemistry using antibodies directed against Ki-67, β-catenin, c-myc, Oct-3/4, and IL-8. Anti-inflammatory and antioxidant activity were evaluated with protein denaturation and DPPH assays, respectively. The anti-bacterial effect of rosemary essential oil was analysed by Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae with the broth microdilution and agar zone diffusion methods. Camphor (15.1%), verbenone (14.3%), α-pinene (13.6%), 1,8-cineole (11.8%), and borneol (7.9%) were determined as the major compounds of rosemary essential oil. The activities of the oil were found to be 508.7 µg/ml and 525.7 µg/ml against HepG2 and ECV304 cells, respectively. Ki-67, β-catenin, c-myc, Oct-3/4, and IL-8 immunoreactivities were significantly reduced in rosemary essential oil-treated HepG2 cells. Ki-67 and β-catenin immunoreactivities were significantly decreased only in rosemary essential oil-treated ECV304 cells. Also, the essential oil showed antioxidant and free radical scavenging activities. Rosemary essential oil showed effective antibacterial activity on E. coli and K. pneumoniae. Thus, rosemary essential oil could be a potential candidate as a therapeutic agent in cancer treatment.