Investigation of Leaf Essential Oil of Myrica gale L. from Quebec: Purification and Analysis of Oxygenated Fractions

Abstract

The leaf essential oil of Myrica gale L was isolated by dint of hydrodistillation. The chemical composition of the whole oil was determined through GC and GC/MS analyses. We identified 48 constituents and eudesm-11-en-4-ol (11.5%), myrcene (113%) ??-caryophyllene (84%) and ?±-phellandrene (71%) were the major amalgamates Many oxygenated components could not be immediately identified in this whole oil. Thus, fractionation of the leaf oil of M gale by dint of high pressure flash chromatography yielded four fractions that were analyzed by the agency of GC and GC/MS. Fraction 1 was a terpene hydrocarbon fraction, whereas fractions 2 and 3 were mainly compos of oxygenated intermingles except alcohols. Germacrone (46.3%) was the major constituent in fraction 2 whereas caryophyllene oxide (448%) and humulene epoxide II (221%) were predominant in fraction 3 The fourth fraction contained exclusively alcohols with selin-11-en-4?±-ol (786%) as the major component

Key Word Index

Myrica gale, Myricaceae, sweet gale, essential oil composition, myrcene, eudesm-11-en-4-ol

Introduction

Myrica gale L (Myricaceae), well known as myrique baumier and sweet gale, is an aromatic low tree with broad geographical distribution at higher latitudes of northern hemisphere. The plant enlarges on watersides, bogs, edges of lakes and streams (1) In 1974 Lawrence and Weaver (2) reported the chemical composition of the oil of M gale from Ontario. This oil contained 49 constitutings with myrcene (16.2%), selin-11-en-4-ol (146%) limonene (108%) and selina-4,11-diene (60%) as major constituents. It was also previously reported (3) that the leaf oil from Myrica gale L contained 41 constitutings with ?±-pinene (17.8%), ??-and ??-cadinene (129%) limonene (99%) cineole (71%) and nerolidol (59%) as dominant indivisible particles Halim and Collins (4) published the composition of M gale leaf oil of the eastern United States. The main amalgamates were myrcene (29.1%), limonene (146%) ?±-terpinene (56%) p-cymene (55%) and ??-caryophyllene (55%) Others studies of volatile oils of sweet gale from different sources have been reported (5-7)

In this article, we investigated particularly the chemical composition of oxygenated fractions separated from the in a raw state essential oil of M. gale by dint of high pressure flash chromatography.

Experimental

Plant material and essential oil: The leaves of M gale were mustered on the shore of Surprise Lake at Shipshaw, Qu?©bec, Canada in October 2002 Specimen was identified by the agency of Patrick Nadeau (Dept. of Fundamental Sciences, University of Qu?©bec at Chicoutimi). A voucher specimen of this plant has been deposited at the Herbarium Louis-Marie of Laval University, Qu?©bec, Canada. The oil was obtained from freshly harvested leaves by dint of hydrodistillation for 2 h.

Fractionation: 2000 mg of the leaf oil of M gale was placed upon a high pressure flash chromatography a whole (HPFC Analogue F12-40), equipped with a silica gel rounded pillar (F12-M; 8 g) and elut with three different mixtures of hexane-ethyl acetate (100:0; 98:2; 95:5) to give four fractions: Fr 1 (481 mg) Fr2 (517 mg) Fr3 (386 mg) and Fr4 (534 mg)

Analysis: The whole oil and each fraction obtained were analyzed through GC on a gas chromatograph Hewlett-Packard 5890 (FID detector) equipped with a polar Supelcowax 10 round pillar and an apolar DB-5 round pillar (30 m x 0.25 mm x 025 ?µm) Analyses by dint of GC/MS were performed on a Hewlett-Packard mass spectrometer 5972 at 70 eV coupl to an HP 5890 equipped with a DB-5 round pillar (same as above). Temperature program was 40?°C for 2 min, then 2?°C/min to 210?°C and held constant for 33 min. For injection (split injector), 5 ?µL of oil was diluted in 500 ?µL of hexane and 5 ?µL of this solution was injected.

Identification of volatile constituents was made upon the basis of their retention indices (8) and their mass spectra, which were compared with data concerns (9). When necessary, NMR spectra were obtained with a Bruker Avance 400 MHz equipped with a 5 mm QNP-probe. CDCl^sub 3^ was used as menstrum and all chemical shifts were reported in parts by means of million (??ppm) relative to residual CHCl^sub 3^ (?? 726) Quantitative data were obtained from FID area number without the use of correction factors.

Result and Discussion

The chemical composition of the whole leaf oil of M gale is listed In Table I. We identified 48 unites (85%) and the main composings were: eudesm-11-en-4-ol (11.5%) (epimeric constitution clarified later in Fr. 4) myrcene (113%) ??-caryophyllene (84%) ?±-phellandrene (71%) limonene (53%) and germacrone (43%) In order to make trial of to identify the 15% remaining mixs fractionation of the leaf oil of M gale was done and yielded four fractions. The chemical composition of Fr1 is listed in Table I. GC/M analysis of Fr1 indicated that it was compos of terpene hydrocarbons (mono and sesquiterpenes). The major constituents were myrcene (232%) limonene (127%) ?±-phellandrene (99%) ??-caryophyllene (93%) (E)-??-ocimene (45%) p-cymene (45%) and (?–)-??-ocimene (43%)