Phytochemical and genetical variability of species from section Serpyllum (Mill.) Benth. genus Thymus L. (Lamiaceae) in Serbia

Abstract

In terms of the number of species, the genus Thymus is one of the most important genera within the Lamiaceae family. The number of species may vary depending on the approach of the author, but if the concept of minimal variability is chosen 215 species have been described. This genus is divided into 8 sections. In Flora of Serbia, 31 species and more than 100 ifraspecific taxa have been described, all of which belong to section Serpyllum, except Thymus comptus and Th. striatus (Sect. Hyphodromi) and Th. vulgaris (Sect. Thymus). Reproductive isolation between species seems to be weak, which makes taxonomical studies in this genus even more difficult. Species of genus Thymus are used as aromatic and medicinal plants in both traditional and modern medicine in all regions where they grow. The aim of this work was to describe different chemotypes within species and population of this genus and, by analysis of surface flavonoids and AFLP markers, provide better insight into genetic and evolutional relationships among the populations and species of the genus Thymus from Serbia. This work included populations of Th. pulegioides (Subsect. Alternantes), Th. glabrescens, Th. maschallianus and Th. pannonicus (Subsect. Isolepides), Th. balcanus and Th. praecox (Subsect. Peudomarginati). Analysis of essential oils was done by TD-GC-MS system, and compounds were identified by comparing RI and/or mass spectra with published data. 103 compounds were identified. Three major group of essential oil compounds were identified: monoterpene hydrocarbons, oxygenated monoterpene hydrocarbons and sesquiterpene hydrocarbons. Based on relative abundance of compounds, Corelation, PCA and Cluster analysis were performed, and it revealed the existence of several chemotypes, such as geraniol, phenol, germacrene-D, citral, linalool, (E)-caryophyllene, α-terpinyl acetate and linalyl acetate chemotype.

Rod Thymus je po broju vrsta jedan od najznaĉajnijih u okviru familije Lamiaceae. U zavisnosti od pristupa autora broj vrsta unutar roda varira, meĊutim ukoliko se izabere pristup minimalne varijabilnosti, prema raspoloţivim podacima opisano je 215 vrsta ovog roda. Vrste ovog roda podeljene su u osam sekcija. U flori Srbije opisana je, do sada, 31 vrsta i preko 100 infraspecijskih taksona, koje sve pripadaju podsekciji Serpyllum, sa izuzetkom vrsta Thymus comptus i Th. striatus (Sect. Hyphodromi) i Th. vulgaris (Sect. Thymus). Reproduktivna izolacija izmeĊu vrsta ovog roda je izuzetno slaba što ĉini taksonomska istraţivanja još teţim. Vrste roda Thymus koriste se kao lekovite i aromatiĉne biljke u tradicionalnoj i zvaniĉnoj medicini u svim krajevima u kojima se javljaju. Cilj ovog rada je bio da se opišu razliĉiti hemotipovi unutar vrsta i populaciju ovog roda kao i da se analizom površinskih flavonoida i AFLP markera poboljša uvid u genetiĉke i evolutivne odnose izmeĊu populacija vrsta ovog roda sa podruĉja Srbije. U ovo istrţivajne ukljuĉene su populacije vrsta Th. pulegioides (Subsect. Alternantes), Th. glabrescens, Th. maschallianus i Th. pannonicus (Subsect. Isolepides), Th. balcanus i Th. praecox (Subsect. Peudomarginati) Analiza sastava etarskih ulja vršena je pomoću TD-GC-MS sistema, a jedinjenja su odreĊen uporeĊivanjem RI i/ili masenog spektra sa literaturnim podacima. Identifikovana su ukupno 103 jedinjenja. Identifikovane su, po brojnosti, tri glavne grupe jedinjenja: seskviterpenski ugljovodonici, oksigenovani monoterpenski ugljovodonici i monoterpenski ugljovodonici. Statistiĉka obrada sastava etarskih ulja ukljuĉila je korelacije, analizu glavnih komponenti i klaster analizu. Statistiĉka obrada je pokazala da se, po relativnoj zastupljenosti jedinjenja, mogu razlikovati geraniolni, fenolni, germakren-D, citralni, linaloolni, (E)-kariofilen, α-terpinil acetat i linalil acetatni hemotip.