Antimicrobial activity of essential oils isolated from Portuguese endemic species of Thymus.
OBJECTIVE
Thymus species are wild species mostly found in the arid lands of Portugal. Possible antimicrobial properties of Thymus essential oils have been investigated. The chemical composition of the essential oils and the antimicrobial activity of Thymus mastichina (L) L. subsp. mastichina, T. camphoratus and T. lotocephalus from different regions of Portugal were analysed.


RESULTS
Hydrodistillation was used to isolate the essential oils and the chemical analyses were performed by gas chromatography (GC) and GC coupled to mass spectrometry. The antimicrobial activity was tested by the disc agar diffusion technique against Candida albicans, Escherichia coli, Listeria monocytogenes, Proteus mirabilis, Salmonella spp. and Staphylococcus aureus. Pure linalool, 1,8-cineole and a mixture (1 : 1) of these compounds were included. Linalool, 1,8-cineole or linalool/1,8-cineole and linalool/1,8-cineole/linalyl acetate were the major components of the essential oils, depending on the species or sampling place. The essential oils isolated from the Thymus species studied demonstrated antimicrobial activity but the micro-organisms tested had significantly different sensitivities.


CONCLUSIONS
The antimicrobial activity of essential oils may be related to more than one component.


CONCLUSIONS
Portuguese endemic species of Thymus can be used for essential oil production for food spoilage control, cosmetics and pharmaceutical use. Further studies will be required to elucidate the cell targets of the essential oil components.
Faleiro
M L
ML
Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Faro and INETI, IBQTA, Departamento de Tecnologia das Indústrias Químicas, Lisboa and Centro de Biotecnologia Vegetal, FCL, Lisboa, Portugal. mfaleiro@ualg.pt
Miguel
M G
MG
Ladeiro
F
F
Venâncio
F
F
Tavares
R
R
Brito
J C
JC
Figueiredo
A C
AC
Barroso
J G
JG
Pedro
L G
LG
D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D003511:Cyclohexanols / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D000077591:Eucalyptol; D019686:Lamiaceae / Q000737:chemistry*; D039821:Monoterpenes / Q000302:isolation & purification; D009822:Oils, Volatile / Q000494:pharmacology*; D028321:Plant Preparations / Q000494:pharmacology; D018514:Plant Structures / Q000737:chemistry / Q000145:classification; D010946:Plants, Medicinal / Q000737:chemistry / Q000145:classification; D011174:Portugal; D013729:Terpenes / Q000302:isolation & purification
D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents; D003511:Cyclohexanols; D039821:Monoterpenes; D009822:Oils, Volatile; D028321:Plant Preparations; D013729:Terpenes; C074463:linalyl acetate; C018584:linalool; D000077591:Eucalyptol