In vitro Cytotoxicity of Australian Tea Tree Oil using Human Cell Lines

Abstract

Abstract Cytotoxicity of Australian tea tree oil (oil of Melaleuca alternifolia) and its major oxygenated monoterpenes: terpinen-4-ol, 1,8-cineole and α-terpineol were investigated using the MTS [(3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium)] assay at two exposure times: 4 and 24 h on five different human cell lines. These cell lines included: Hep G2, a heptaocellular carcinomic human cell line; HeLa, an epithelioid carcinomic cell line; MOLT-4, a human lymphoblastic leukaemic T-cell line; K-562, a human chronic myelogenous leukaemia cell line; and CTVR-1, an early B-cell line from the bone marrow cells of a patient with acute myeloid leukaemia. The overall rating for cytotoxicity of tea tree oil and its components was α-terpineol>tea tree oil>terpinen-4-ol> 1,8-cineole and with comparison with the controls used mercuric chloride>tea tree oil>aspirin. Antimicrobial activity (MICs) displayed a similar pattern where α-terpineol>terpinen-4-ol>tea tree oil> 1,8-cineole. The IC50 (a concentration that causes a reduction by half of the activity of mitochondrial dehydrogenase) value of tea tree oil ranged from 0.02 g/L for the Hep G2 cell line to 2.8 g/L for the HeLa cell line.