Headspace Solid-Phase Microextraction and Ultrasonic Extraction with the Solvent Sequences in Chemical Profiling of Allium ursinum L. Honey

Igor Jerković,Piotr Marek Kuś

doi:10.3390/molecules22111909

Abstract

A volatile profile of ramson (wild garlic, Allium ursinum L.) honey was investigated by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) followed by gas chromatography and mass spectrometry (GC-FID/GC-MS) analyses. The headspace was dominated by linalool derivatives: cis- and trans-linalool oxides (25.3%; 9.2%), hotrienol (12.7%), and linalool (5.8%). Besides direct extraction with dichloromethane and pentane/diethyl ether mixture (1:2, v/v), two solvent sequences (I: pentane → diethyl ether; II: pentane → pentane/diethyl ether (1:2, v/v) → dichloromethane) were applied. Striking differences were noted among the obtained chemical profiles. The extracts with diethyl ether contained hydroquinone (25.8–36.8%) and 4-hydroxybenzoic acid (11.6–16.6%) as the major compounds, while (E)-4-(r-1′,t-2′,c-4′-trihydroxy-2′,6′,6′-trimethylcyclohexyl)but-3-en-2-one predominated in dichloromethane extracts (18.3–49.1%). Therefore, combination of different solvents was crucial for the comprehensive investigation of volatile organic compounds in this honey type. This particular magastigmane was previously reported only in thymus honey and hydroquinone in vipers bugloss honey, while a combination of the mentioned predominant compounds is unique for A. ursinum honey.

Highlights

Ramson is a perennial plant, widely distributed in Europe.Phytochemical investigations of this plant revealed the presence of S-alk(en)yl-L-cysteine-sulfoxides and their degradation products ((poly)sulfides, dithiins, or ajoenes) [1,2]
It contained 58% of Allium ursinum L. pollen grains accompanied by the pollen from Prunus spp. (19%), Acer spp. (14%), and a minor contribution from the grains of Salix spp. (2%), Fraxinus excelsior (1%), Tilia spp. (1%), Asteraceae (1%), Ericaceae (1%), and Brassicaceae (1%)
Significant differences among the chemical profiles obtained from A. ursinum honey volatile organic compounds (VOCs) and the corresponding plant VOCs were expected

Summary

Introduction

Ramson (wild garlic, Allium ursinum L.) is a perennial plant, widely distributed in Europe. Phytochemical investigations of this plant revealed the presence of S-alk(en)yl-L-cysteine-sulfoxides (methiin, alliin, isoalliin, propiin, and ethiin) and their degradation products ((poly)sulfides, dithiins, or ajoenes) [1,2]. Apart from the abovementioned, various sulphur compounds have been detected as constituents of its essential oil, e.g., disulfides, trisulfides, and tetrasulfides [3,4]. A. ursinum has been reported to be a rich source of phenolic compounds (up to 27.9 g GAE (gallic acid equivalent)/. Other identified constituents of interest include lectins, polysaccharides, and fatty acids [1]. A great number of in vitro and in vivo experiments showed that

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Results

Conclusion