CHEMICAL COMPOSITION OF THE ESSENTIAL OILS OF SOME TAXA OF THE GENUS CLINOPODIUM (LAMIACEAE) FROM SICILY

Abstract

The genus Clinopodium L. (Lamiaceae) is known for its medical uses in folk medicine and as a spice in Italian food. Recently, several taxa previously assigned to Satureja L. and Calamintha Mill. have been transferred to this genus (1). Pharmacological studies reveal, for instance, that Calamintha nepeta (L.) Savi [Clinopodium nepeta Kuntze subsp. nepeta], commonly known as “nepetella”, exhibits cholagogue, expectorant, sedative and antibiotic properties (2); furthermore, the essential oil of its aerial parts showed an antifungal activity (3). The apical flowering parts and leaves of Clinopodium vulgare L. are used in popular medicine for their carminative and emmenagogue properties (1); recently, the essential oil of its aerial parts was found to possess remarkable radical-scavenging and antioxidant activities (4). In Madeira Island, the local population uses the leaves of Clinopodium ascendens Samp. as a mouth freshener and to alleviate headache and toothache; furthermore, the essential oil of its aerial parts exhibited remarkable antibacterial and antifungal activities (5). Here, the chemical composition of the essential oils of four taxa of Clinopodium growing wild in Sicily is reported. In particular, were investigated Clinopodium nepeta Kuntze subsp glandulosum (Req.) Govaerts from Cava Grande (Avola, Siracusa), Clinopodium nepeta Kuntze subsp. nepeta from Cave di Cusa (Campobello di Mazzara, Trapani), Clinopodium raimondoi Spadaro, Faqi & Mazzola from Palermo (Fondo Patti, San Gabriele) and Clinopodium nepeta Kuntze subsp. ascendens B. Bock. from Castelbuono (Madonie, Palermo). The essential oils, extracted by hydrodistillation according to the European Pharmacopoeia, were analysed by GC and CG/MS. In the four oils, 48 compounds in all were identified: 27 for Clinopodium nepeta subsp. glandulosum (98,4% of the total oil), 19 for Clinopodium nepeta subsp. nepeta (98,6% of the oil), 26 for Clinopodium raimondoi (96,5% of the oil) and 38 for Clinopodium nepeta subsp. ascendens (93,5% of the oil). In C. nepeta subsp. glandulosum, the most abundant compounds were trans-dihydrocarvone (36.5%), carvone (19.2%) and cis-dihydrocarvone (13.0%). On the whole, the oil was constituted mainly of monoterpenes (81.5%) and sesquiterpenes (13.4%). In the first fraction, oxygen-containing monoterpenes (73.4%) prevailed over monoterpene hydrocarbons (8.16%). In C. nepeta subsp. nepeta, the main components were cis-piperitone oxide (39.0%), piperitenone (36.0%) and limonene (7.7%). Monoterpenes constituted the most abundant fraction of the oil (91.0%), with a prevalence of oxygen-containing monoterpenes (81.5%). Piperitenone oxide (59%) cis-piperitone oxide (22.2%) and limonene (6.0%) were the main compounds of C. raimondoi. As in the other oils studied, monoterpenes constituted the main fraction and accounted for 90.2% of the total oil with a prevalence of oxygen-containing monoterpenes (82.4%) over monoterpene hydrocarbons (7.8%). In C. nepeta subsp. ascendens, the main compounds were carvone (14.4%), trans-isopulegone (11.5%) and mint furanone (8.9%). On the whole, the main fraction was constituted of monoterpenes (81.1%). Among these, monoterpene hydrocarbons (73.4%) were the most abundant components of the oil. In conclusion, all four oils share a high percentage of monoterpenes and a scarce amount of sesquiterpenes. Previous papers on the analysis of the essential oils of Clinopodium sp.pl. showed that the monoterpenes group is usually dominant, although the main component may vary. The results of the present study concur with these findings.