Investigation of biological activities of extracts and essential oils obtained from three Thymus L. species

This thesis was desinged to carry out the in vitro antioxidant, antimicrobial and antiviral of hexane, chloroform, water extracts and essential oils of T. pseudopulegioides Klokov&Des-Shost, T. transcaucasicus Ronniger and T. praecox Opiz subsp. grossheimii (Ronniger) Jalas var. grossheimii, all members of genus Thymus L. (Lamiaceae) that is represented by 38 species, in the Turkish flora.The chemical composition of essential oils were determined by employing Gas Chromatography (GC), Gas Chromatography and Mass Spectrometry (GS-MS) analyses. Thymol was found as the main components in the oils of T. pseudopulegioides 58%, T. transcaucasicus 55% ve T. praecox subsp. grossheimii var. grossheimii 29,4%.The oils, hexane and water and chloroform subfractions of methanol extract obtained from each plant sample were screened for their possible antioxidant activities by two complementary test systems, namely 2,2- Diphenylpikrylhydrazyl (DPPH) free radical scavenging and ß-Carotene color bleaching test ? spectrophotometric methods. In 2,2- DPPH, all polar extracts acted as radical scavengers on high proportions. The highest free radical scavenging activity was observed in the essential oil of T. pseudopulegioides (IC50: 2,3 ?g/ml). In ß-Carotene color bleaching test ? spectrophotometric method, hexane and chloroform extracts have high activity. The highest activity was observed in the chloroform extract of T. pseudopulegioides, with 79,95% inhibition rate.Antibacterial, anticandidal, antifungal activities of all extracts and essential oils were determined by using disc diffusion, microwell dilution and MIC agar dilution methods, and employing 9 bacteria, 1 yeast and 3 fungi as test microorganisms. No activity was found in the hexane, chloroform and water extracts. Essential oils of T. pseudopulegioides and T. transcaucasicus showed effective antimicrobial activity against all test microorganisms except for P. aeruginosa. In addition to antibacterial and antifungal activities, these essential oils have very high antifungal activity.All extracts, on the other hand, were found to be ?ineffective? against HSV and Influenza A viruses.