antimicrobial, nitric oxide radical scavenging and cytotoxic properties of thymus daenensis essential oil

objective: despite toxic effects of some essential oils, their use is not under control. with a view to increasing trend of utilisation of herbal products, some biological aspects of thymus daenensis are repoted here for the first time. materials and methods: antimicrobial properties using disk diffusion and dilution tests, nitric oxide radical scavenging by marcocci et al method and cytotoxic properties employing dimethylthiazolyl diphenyltetrazolium bromide reduction test were carried out with thymus daenensis and commercial thyme essential oils and their main chemical compound, thymol. results: the microbial sensitivity to the oils were in candida albicans> e.coli> s.aureus> p. aeruginosa order. the minimum inhibitory and microbicidal concentrations were in the range of 0.04-10mg/ml. nitric oxide radical scavenging was dose dependent with an ic50 of 5, 75, 863 µg, and total phenolics of 644.07±6.79, 16.94±2.55, 10.33±2.31µg gallic acid equivalent per mg sample and total flavonoid content of 73.51±1.34, 0.56±0.02, 0.21±0.09 mg catechin equivalent per gram t.daenensis oil, commercial thyme oil and thymol respectively. the concentrations from t.daenensis oil, commercial thyme oil and thymol required to exert 50% fatal effect (ic50) on healthy human normal lymphocytes and hela cells were 1455, 12.10, 2867 and 4.95, 3.61, 1730 µg respectively. conclusion: t. daenensis with its good antimicrobial property can prevent formation of toxic reactive oxygen species and as a good antioxidant, it can directly scavenge no and o2−. with a view to cancerous cells killing properties of the oils at their lowest concentrations without fatal effect on normal healthy cells, feasibility of their application in combating cancerous cells may be promising.