New natural products from Clinopodium thymifolium (Scop.) Kuntze (Lamiaceae)

Abstract

Clinopodium thymifolium (Scop.) Kuntze (syn. Micromeria thymifolia (Scop.) Fritsch) is an aromatic plant species widespread in the Mediterranean region, from north-eastern Italy across the Western Balkans to Hungary and Albania [1,2]. C. thymifolium has been used in folk medicine of the Mediterranean area for a long time [3]. Also, due to a high content of the essential oil in its leaves, it is used as a condiment and sometimes used in cooking [4,5]. For this reason, and the marked tendency to broaden the use of condiments and spices, some efforts are being made to introduce this plant as a new crop species (currently successfully cultivated in northern Italy) [4]. The beneficial effects of Lamiaceae species on human health have been frequently ascribed to essential-oil ingredients. Volatiles of C. thymifolium have been well studied – previous studies showed that the qualitative compositions of the investigated C. thymifolium oils were very mutually similar and dominated by oxygenated p-menthane monoterpenoids [6,7]. However, in this work, a comprehensive chemical analysis, in combination with detailed spectral analyses and chemical synthesis of selected compounds, has led to the identification of a series of esters of menthol stereoisomers in C. thymifolium essential oil, including some new natural products.