Quantitative determination of essential oils obtained at different collection times of some natural thyme species in the region of Diyarbakır

In this thesis study, Thymbra spicata L. var. spicata L., Thymbra sintenisii Bornm. et Aznav. subsp. sintenisii Bornm. et Aznav., Origanum vulgare L. subsp. gracile (C. KOCH) Ietswaart, Satureja hortensis L. and Satureja macrantha C. A. Meyer species were collected at different collection times (beginning of flowering, full bloom and end of flowering phases) and it was aimed to examine these species in detail in terms of the ratio of essential oils, components and biological activity. In the study, both 5 species were compared with each other and the flowering period of each species (flowering beginning, full blooming period and flowering period) was divided into three and the essential oil ratios, components and biological activities were examined in detail. Essential oils were obtained by hydrodistillation method from collected plant drugs and the composition of essential oils was determined by GC-MS. Antimicrobial, antioxidant (total phenolic, DPPH, CUPRAC and ABTS), anticholinesterase (AChE and BChE inhibitors), tyrosinase and urease activities of essential oils obtained from three different periods of 5 different thyme species were determined. In addition, the toxic effects of essential oils on healthy cell line (PDF) and cytotoxic effects on colon cancer (HT-29) and breast cancer (MCF-7) were determined by MTT method. In general, while the oil ratios during the flowering period of the 5 species belonging to the genus Thymbra, Origanum and Satureja are the highest, it is the full flowering period for the 4 species (Thymbra spicata, O. vulgare subsp. gracile, Satureja hortensis, Satureja macrantha), but only in the Thymbra syntenisii species. The highest oil rate was obtained at the end of flowering period. In general, the samples collected at the end of flowering period of the species we examined have higher component richness, while the samples collected during the full flowering period are seen to be richer in terms of component ratios. It can be said that the phenolic contents of the 15 samples examined do not differ according to their periods. When the antioxidant activities of all studied thyme species were examined, it was determined that the essential oil samples in different periods generally showed low activity in the DPPH method, but were very active in the ABTS method. In general, it was determined that all thyme samples studied showed high acetylcholinesterase and butyrylcholinesterase enzyme inhibition activities. When looking at their antimicrobial effects, most of the essential oils showed strong antimicrobial activity with higher activity than the positive control. It is seen that its antimicrobial effect varies according to the period and the microorganism it affects. Finally, it was determined that all the samples studied were highly active against the colon cancer cell line (HT-29), but all the samples studied on the healthy human cell line (PDF) showed a certain level of toxic effect.