Anti-proliferative effects of Rosmarinus officinalis L. (Rosemary) against human breast and liver carcinoma cells

Plant-derived products have been proven as beneficial medicinal treatments for various cancers. Rosmarinus officinalis L. (Rosemary - RM) is gaining increasing attention as an agent in cancer chemoprevention and therapy, due to its antioxidant, immunomodulatory, and anti-inflammatory properties. Herein, the anti-proliferative effects of RM leaves methanolic extract on human breast (triple-negative MDA-MB-231 and estrogen receptor-positive MCF-7), and liver cancer cells (HepG2 and HUH-7) relative to non-cancerous human cartilage chondrocytes (C20A4) are evaluated. Methyl thiazolyl tetrazolium (MTT) cell viability assay is used to determine drug effectiveness after 24- and 48-h incubation periods. The residual extract from RM leaves is prepared and directly used in a fine powder after all solvents are evaporated. Five dosages of RM extract (0.05, 0.0625, 0.1, 0.125, and 0.25 mg/mL), identified by trial and error, and a negative control group are investigated. The RM extract is characterized by GC-MS and consists of three main compounds: eucalyptol (1,8-cineole), camphor (2-bornanone), and borneol ((2S)-1,7,7-trimethylbicyclo[2,2,1]heptan-2-ol). Our study demonstrates that dose-dependent treatment of RM extract leads to selective antioxidant, anti-proliferative and cytotoxic effects on breast carcinoma cell lines MDA-MB-231 and MCF-7, in comparison to C20A4 cells. The effect of RM extract on both liver carcinoma cell lines HepG2 and HUH-7 is insignificant compared to C20A4 cells. The optimum dosage of RM extract identified to counteract cancer cells is 0.25 mg/mL. However, further research is needed to determine mechanistic data. Overall, RM extract may have potential therapeutic value in the prevention and/or treatment of various types of cancer.