Chemical composition, antitumor and antimicrobial activity of Thymus vulgaris and T. algeriensis essential oils

Plants from genus Thymus are often used in traditional medicine. Some of these species are important medicinal plants that are used in ethnomedicine. In this work, analysis of phytochemicals and bioactivity evaluation of Thymus vulgaris and T. algericnsis essential oils were done. The chemical composition of oils were evaluated using GC/MS; cytotoxic activity was tested against five human tumor cell lines MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HCT-15 (colon carcinoma), HeLa (cervical carcinoma), HepG2 (hepatocellular carcinoma) and non-tumor cell line PLP2 (porcine liver cell culture); DPPH scavenging activity, reducing power, P-carotene bleaching inhibition and TBARS inhibition were used to assessed the antioxidant potential of oils; antimicrobial activity, minimum inhibitory (MIC) and minimum bactericidal/fungicidal (MBC/MFC) concentrations, were determined using microdilution method. Eight bacterial species isolated from oral cavity were used: S. mutans, S. sanguis, S salivarius, S. pyogenes, S. aureus, P. aeruginosa, L acidophilus and E. feacalis and fifty eight clinical oral Candida spp. along with two reference strains were used. The dominant constituents of T vulgaris oil were: p-cymene ( 18.99%) and thymol (48.92%). The major component of T. algeriensis oil was: thymol (38.50%). Both essential oils inhibited the growth of human tumor cell lines tested. T. algeriensis showed greater potential (GI50 0.062±3.11 - 0.064± 1.51 mg/ml), compared to T. vulgaris (GI50 0.076±5.98 -0.18±2.68 mg/ml). None of the oils showed hepatotoxicity in the porcine liver primary cell culture (GI50 > 0.40 mg/ml). T. algeriensis oil showed stronger antioxidant activity in DPPH scavenging activity and reducing power measurements (EC50 1.64±0.05; 0.68±0.01 mg/ml) versus T. vulgaris (EC50 4.80±0.18; 1.54±0.04 mg/ml). However, T vulgaris oil showed stronger activity in P-carotene bleaching inhibition and TBARS inhibition methods (EC50 0.18±0.04; 0.05±0.00 mg/ml) compared to T algeriensis (EC50 1.56±0.12; 0.31±0.01 mg/ml). T. algeriensis showed higher antimicrobial activity towards the selected bacterial species (MIC 0.02-0.08; MBC 0.04-0.16 mg/ml) compared to T vulgaris (MIC 0.08-0.16; MBC 0.16-0.32 mg/ml). Fungi appeared to be more sensitive and again T. algerienesis oil showed higher activity (MIC 0.005-0.0 I 0; MFC 0 .010-0.020 mg/ml) than T vulgaris oil (MIC 0.04-0.08; MFC 0.08-0.16 mg/ml). The data of this study suggested that the both essential oils, especially T. algeriensis have great potential as natural agents for microbial infections. However, since essential oils are complex mixture of compounds, further study toward single components and their synergism and antagonism is needed. These investigations will be helpful for further utilization of the plant essential oils for their safe use in the pharmaceutical, food and cosmetics industries