title: In vitro genotoxicity of Melaleuca alternifolia essential oil in human lymphocytes.
abstract: BACKGROUND
  The volatile essential oil derived from the plant Melaleuca alternifolia, also called tea tree oil (TTO), is largely employed for its antimicrobial properties against several human pathogens. It is used in many topical formulations to treat cutaneous infections.
  
  
  OBJECTIVE
  Since very few studies have been done on the safety and toxicity of the crude Melaleuca alternifolia essential oil, current investigation evaluates the possible genotoxic effects of TTO in human lymphocyte cultures.
  
  
  METHODS
  The composition of current TTO sample was determined by GC/MS and NMR. The level of cytotoxicity in TTO treated cultures was determined by decrease of mitotic index when compared to that in negative control. The genotoxic potential of TTO was assessed by the in vitro mammalian cell micronucleus and the chromosome aberrations (CA) tests.
  
  
  RESULTS
  Twenty-seven compounds were identified, accounting for 98.9% of the constituents. Terpinen-4-ol (42.8%), γ-terpinene (20.4%), p-cymene (9.6%), α-terpinene (7.9%), 1,8-cineole (3%), α-terpineol (2.8%) and α-pinene (2.4%) were the major compounds of the oil sample. None of the tested TTO concentrations (95μg/ml, 182μg/ml and 365μg/ml) caused a significant increase in the observed frequencies of micronuclei when compared to those in the untreated cultures (negative control). Additionally, no significant differences regarding the frequencies of CA were observed among the tested TTO concentrations and the negative control.
  
  
  CONCLUSIONS
  Results demonstrate that TTO, in the tested concentrations, is not genotoxic in in vitro mammalian cells.
authors: Departamento de Biotecnologia, Genética e Biologia Celular, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, Paraná 87020-900, Brazil.
authors: Tais Susane
authors: TS
authors: Pereira
authors: Departamento de Biotecnologia, Genética e Biologia Celular, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, Paraná 87020-900, Brazil. Electronic address: juliane_santanna@hotmail.com.
authors: Juliane Rocha
authors: JR
authors: de Sant'anna
authors: Departamento de Química, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, Paraná 87020-900, Brazil.
authors: Expedito Leite
authors: EL
authors: Silva
authors: Departamento de Engenharia Florestal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 365470-000, Brazil.
authors: Antônio Lelis
authors: AL
authors: Pinheiro
authors: Departamento de Biotecnologia, Genética e Biologia Celular, Universidade Estadual de Maringá, Avenida Colombo 5790, Maringá, Paraná 87020-900, Brazil.
authors: Marialba A Alves
authors: MA
authors: de Castro-Prado
mesh_terms: D000328:Adult; D000890:Anti-Infective Agents / Q000737:chemistry / Q000633:toxicity; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000633:toxicity; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D009152:Mutagenicity Tests; D020947:Tea Tree Oil / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000890:Anti-Infective Agents; D000893:Anti-Inflammatory Agents; D020947:Tea Tree Oil
keywords: Chromosomal aberration test; Genotoxicity; In vitro mammalian cell micronucleus; Melaleuca alternifolia; Mitotic index; Tea tree oil