Essential oil of Lippia alba (Mill.) and breast cancer

Neoplastic diseases are the second cause of death worldwide. Although chemotherapy is the most common therapy against cancers, many pharmaceutical companies are focusing their efforts on the production and use of plant-based drugs, basing on their fewer side effects respect to the synthetic drugs currently available. Phytochemicals, commonly synthetized in fruits and vegetables have shown an influence on the development and progression of different tumors by inhibiting cancer cell proliferation and metastatic invasion. Such effects have been linked to their antioxidant and chemopreventive activities, which can be studied for possible future anti-cancer therapies. Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson is an aromatic plant, which essential oil is used in folk medicine of Central and South America for its biological activities: i.e. cytotoxic, antifungal, antibacterial, antiviral and anti-inflammatory, but also antispasmodic, digestive, antiasthmatic, analgesic and sedative. The carvone/limonene chemotype is considered as the most important in South America. In the last years the interest on its antioxidant activity has increased and, nowadays, it is gaining economic importance going beyond the traditional uses in the tea and in the cosmetics industries. So far, few investigations in oncology on the possible use of this essential oil have been performed. The aim of this study was to test the antitumor activity of essential oil of L. alba on breast cancer lines. Triple Negative Breast Cancer (TNBC) cell lines, which lacks the expression of the estrogen, progesterone and human epidermal growth factor receptors (ER- PR- EGFR- ), thus characterized by a great metastatic potential, were selected: SUM149 (a mesenchymal TNBC cells), MDA-MB-231 (a highly aggressive, invasive and poorly differentiated TNBC), MDA MB-468 (a cell line with epithelial morphology that was isolated from a pleural effusion of a 51-year-old Black female patient with metastatic adenocarcinoma of the breast). Preliminary tests were conducted on pure and diluted (1:500 in dimethyl sulfoxide) essential oil to determine the its best concentration, thus the cell lines were treated for 48 hours with plant essential oil. The results showed different responses of the cell lines to the same treatment. In SUM149 and MDA-MB-231 cells the treatment with L. alba oil decreased proliferation, increased antioxidant activity and lipid peroxidation, and showed a high cytotoxic effect associated with the release of lactate dehydrogenase, compared with controls. While, no effect was observed in MDA-MB-468. These results represent an excellent beginning for further studies to understand the beneficial and antineoplastic properties of Lippia alba essential oil and its possible future use in cancer therapy.