Analysis of exudate compounds of Thymus species

Acetone exudates of 13 Thymus species were analyzed for their composition by gas chromatography/mass spectrometry (GC/MS) and thin-layer chromatography (TLC). The studied species are members of the section Hyphodromi (Thymus atticus, T. perinicus, T. striatus, T. zygioides and T. comptus) and section Serpyllum (T. longedentatus, T. longicaulis, T. pulegioides, T. moesiacus, T. albanus, T. jankae, T. stojanovii and T. sibthorpii). Some of the studied species are endemic. Triterpene acids (oleanolic and ursolic) were found as dominant compounds in the exudates. Isomers thymol and carvacrol were determined as the most common monoterpenes. All exudates were established to be rich in straight-chain alkane (hexacosane). TLC analysis was performed for the identification of flavonoid aglycones. Apigenin, luteolin, naringenin, taxifolin and eriodictyol were identified as the most common flavonoids in the profiles of the studied species. Methyl derivatives of apigenin were determined only in the exudates of the separate species. Exudate compounds of Bulgarian Thymus species are reported for the first time in the present study. Moreover, some endemic thyme species’ phytochemical compositions are presented here for the first time. This is the first time that micromeric acid is reported in the Thymus genus.