title: Determination of free and glucosidically-bound volatiles in plants. Two case studies: L-menthol in peppermint (Mentha x piperita L.) and eugenol in clove (Syzygium aromaticum (L.) Merr. & L.M.Perry).
abstract: This study arises from both the today's trend towards exploiting plant resources exhaustively, and the wide quantitative discrepancy between the amounts of commercially-valuable markers in aromatic plants and those recovered from the related essential oil. The study addresses the determination of both the qualitative composition and the exhaustive distribution of free and glucosidically-bound L-menthol in peppermint aerial parts (Mentha x piperita L., Lamiaceae) and of eugenol in dried cloves (Syzygium aromaticum (L.) Merr. & L.M.Perry, Myrtaceae), two plants known to provide widely ranging essential oil yields. The two markers were investigated in essential oils and residual hydrodistillation waters, before and after enzymatic hydrolysis. Their amounts were related to those in the headspace taken as reference. The results showed that the difference between marker compound in headspace and in essential oil amounted to 22.8% for L-menthol in peppermint, and 16.5% for eugenol in cloves. The aglycones solubilised in the residual hydrodistillation waters were 7.2% of the headspace reference amount for L-menthol, and 13.3% for eugenol, respectively representing 9.3% and 15.9% of their amounts in the essential oil. The amount of L-menthol from its glucoside in residual hydrodistillation waters was 20.6% of that in the related essential oil, while eugenol from its glucoside accounted for 7.7% of the amount in clove essential oil. The yield of L-menthol, after submitting the plant material to enzymatic hydrolysis before hydrodistillation, increased by 23.1%, and for eugenol the increase was 8.1%, compared to the amount in the respective conventional essential oils. This study also aimed to evaluate the reliability of recently-introduced techniques that are little applied, if at all, in this field. The simultaneous use of high-concentration-capacity sample preparation techniques (SBSE, and HS-SPME and in-solution SPME) to run quali-quantitative analysis without sample manipulation, and direct LC-MS glucoside analysis, provided cross-validation of the results.
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy. Electronic address: barbara.sgorbini@unito.it.
authors.forename: Barbara
authors.initials: B
authors.lastname: Sgorbini
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy. Electronic address: cecilia.cagliero@unito.it.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Cagliero
authors.affiliation: Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale "Amedeo Avogadro", Largo Donegani 2/3, I-28100, Novara, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Pagani
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy.
authors.forename: Marla
authors.initials: M
authors.lastname: Sganzerla
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy. Electronic address: lorenzo.boggia@unito.it.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Boggia
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy. Electronic address: carlo.bicchi@unito.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: Bicchi
authors.affiliation: Dipartimento di Scienza e Tecnologia del Farmaco, Università degli Studi di Torino, Via Pietro Giuria 9, I-10125 Torino, Italy. Electronic address: patrizia.rubiolo@unito.it.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Rubiolo
mesh_terms: D005054:Eugenol / Q000032:analysis* / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005960:Glucosides / Q000032:analysis / Q000737:chemistry; D006868:Hydrolysis; D036142:Mentha piperita / Q000737:chemistry*; D008610:Menthol / Q000032:analysis* / Q000737:chemistry; D009822:Oils, Volatile / Q000032:analysis; D035261:Plant Components, Aerial / Q000737:chemistry; D015203:Reproducibility of Results; D027842:Syzygium / Q000737:chemistry*
chemical_list: D005960:Glucosides; D009822:Oils, Volatile; D008610:Menthol; D005054:Eugenol
keywords: Enzymatic hydrolysis; Essential oils; Eugenol; L-menthol; Mentha x piperita L. (Lamiaceae); Monoterpene glucosides; Quantitative determination; Residual distillation waters; Syzygium aromaticum (L.) Merr. & L.M.Perry (Myrtaceae)