Study of carotenoids and chlorophylls content in Thymus L. essential oils genus species at the reproductive period

Abstract

The genus Thymus (Thymus L., Lamiaceae L.) is polymorphic, containing various races and forms with minor morphological differences. Up to 200 species have been identified in the world, of which up to 50 are found in Ukraine. Widespread wild essential oil species of the genus Thymus L. in Ukraine are: creeping thyme, Crimean thyme, Dnieper thyme, Marshall's thyme, flea thyme, Pallas's thyme. Successfully cultivated: common thyme, Spanish white thin thyme, Spanish white flowering thyme, creeping thyme, lemon thyme. Thyme is known for its rich chemical composition. Carotenoids and chlorophylls contribute to the accumulation of essential oil, polyphenolic compounds, antioxidant, detoxification and radioprotective effects. For the standardization of raw materials of Thymus L. species, it is advisable to determine the accumulation of carotenoids and chlorophylls during the reproductive period. The purpose of the work is to identify and determine the quantitative content of carotenoids and chlorophylls during the reproductive period in the herb species of the genus Thymus L. of the flora of Ukraine. Raw materials were collected in steppe biocenoses and specialized farms of southeastern Ukraine during the reproductive period (May–September 2018–2023) according to generally accepted methods. They were dried at 35 ºС to a moisture content of no more than 10%. n-Hexane extracts (1:100) were used to identify substances and establish their quantitative content. The determination was made by thin-layer chromatography (TLC) followed by densitometry and spectrophotometry. By the methods of thin-layer chromatography and spectrophotometry in n-hexane extracts from grass species of the genus Thymus L. of flora of Ukraine 4 carotenoids and 2 chlorophylls were identified. Cultivated species had the highest content: Th. vulgaris L. and Th. x citriodorus (Pers.) Schreb. var. «Silver Queen». The accumulation of carotenoids and chlorophylls in the raw materials of the genus Thymus L. during the reproductive period was studied. The results indicate the expediency of standardization of the studied raw materials according to the accumulation of carotenoids and chlorophylls.