Chemical composition, antimicrobial, antioxidant and antitumor activity of Thymus serpyllum L., Thymus algeriensis Boiss. & Reut and Thymus vulgaris L. essential oils

Aromatic plant species of genus Thymus are important medicinal plants, highly recommended due to a range of therapeutic properties of their essential oils, commonly known as thyme oil: antirheumatic, antiseptic, antispasmodic, antimicrobial, cardiac, carminative, diuretic and expectorant. The oil is also beneficial in boosting the immune system and helps to fight colds, flu, infectious diseases and chills. It is proved to be a urinary antiseptic, being very helpful for cystitis and urethritis. Scientific validation of traditional uses, and phytochemical and bioactivity evaluation of essential oils from Thymus serpyllum, Thymus algeriensis and Thymus vulgaris were performed. GC/MS analysis revealed thymol as a major component of T. algeriensis, T. vulgaris and T. serpyllum, with its contribution to the oil 56.0%, 48.9% and 38.5%, respectively. All three essential oils (EOs) exhibited a significant antimicrobial activity against all tested strains, the T. serpyllum oil being the most potent one (MIC 2.5–5 μg/mL, MBC 5–10 μg/mL; MIC 1–2 μg/mL, MFC 2–4 μg/mL). In addition, the T. serpyllum oil revealed the highest antioxidant activity in all conducted assays and it was the most effective one against all tested cell lines, presenting GI50 values of 7.02–52.69 μg/mL. Moreover, none of the EOs showed toxicity at tested concentrations (>400 μg/mL) for porcine liver primary cell culture. In addition to their well-known traditional use in food and cosmetics, the great potential of tested Thymus essential oils for application in oral diseases and anticancer treatments, encourage further investigation.Ministry of Education, Science and Technological Development of Serbia for financial support (Grant № 173032). The authors are also grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support of research centre CIMO (PEst-OE/AGR/UI0690/2011). Â. Fernandes and R.C. Calhelha thank FCT, POPH-QREN and FSE for their grants (SFRH/BD/76019/2011 and SFRH/BPD/BPD/68344/2010, respectively)