Chemical composition of cypress essential oils: Volatile constituents of leaf oils from seven cultivated Cupressus species

Journal of Essential Oil Research: JEOR, Jul/Aug 2003 by Pierre-Leandri, Christelle, Fernandez, Xavier, Lizzani-Cuvelier, Louisette, Loiseau, Andr -Michel, Et al

Received : March 2002

Revised : January 2003

Accepted : February 2003

Abstract

Essential oils from leaves of cypress cultivated in France that originated from various geographic origins were analyzed by GC/MS. In total 120 constituents were characterized, from which 46, 57, 52, 57, 59, 67, and 58 compounds were found in the oils of Cupressus atlantica Gaussen, C. cashmeriana Royle, C. chengiana Hu, C. duclouxiana Hickel, C. funebris Endl., C. guadalupensis S. Wats, and C. macnabiana A. Murr., respectively. The main components of the oils were found to be: [alpha]-pinene and [delta]-3 carene for C. atlantica Gaussen; [alpha]-pinene and sabinene for C. cashmeriana Royle, C. chengiana Hu and C. funebris Endl.; [alpha]-pinene and [alpha]-cadinol for C. macnabiana A. Murr; [alpha]-pinene, terpinen-4-ol and a sesquiterpene for C. guadalupensis S. Wats; limonene and [alpha]-cadinol for C. duclouxiana Hickel.

Key Word Index

Cupressus atlantica, Cupressus cashmeriana, Cupressus chengiana, Cupressus duclouxiana, Cupressus funebris, Cupressus guadalupensis, Cupressus macnabiana, Cupressaceae, essential oil composition, [alpha]-pinene, [delta]-3-carene, sabinene, [alpha]-cadinol, limonene, terpinen-4-ol.

Introduction

The genus Cupressus is thought to be represented by more than 20 species (1) of North Africa, Asia, North America, and Mexico. Its geographic area is limited to the Northern Hemisphere. This number is different to the Farjon's classification, which lists 17 species (2). Cupressus genus classification is not easy; thus, intergenetic and interspecific complexity is important. The problem of classification is observed in natural populations. In our case, hybridation phenomena were strictly controlled and our study was realized with only one cypress per species isolated from its geographic origin. The seven species, Cupressus atlantica Gaussen, C. cashmeriana Royle, C. chengiana Hu, C. duclouxiana Hickel, C. funebris Endl., C. guadalupensis S. Wats., C. macnabiana A. Murr., belonging to Cupressaceae family, are well known by botanists (1,3,4).

Several contributions have been reported on the composition of the leaf oils of cypress from various species and geographic origins (5-10). But, the chemical composition of the leaf oils of seven Cupressus species has, to our knowledge, never been described, excepting C. funebris is reported in previous works (11-13). The aim of this paper is to extend qualitative and quantitative analysis of the oils of these Cupressus species growing in the National Institute of Agronomy Research (INRA) arboretum of Saint Laurent du Var and Frejus in southern France, and to compare their chemical compositions.

Experimental

Source: Terminal branches were collected in June 1997 from cypress of the INRA arboretum (St Laurent du Var and Frejus) in southern France. All the Cupressus species used in this study were 11-13 years old, except C. cashmeriana, which was eight years old. Botanical identification of the plant was conducted by the Claudine Andreoli, INRA, Antibes (France). Voucher specimens of the plants have been deposited in the Herbarium of "Jardin Botanique de la Ville de Nice," Nice, France (B-5156-B-5162).

Plant part: Fresh Cupressus leaves (50 g) cleared of twigs and cones were subjected to hydrodistillation (4 h) using a Clevenger-type apparatus to yield between 0.05-0.2% oil. The oil samples were concentrated (pentane trap removed) with nitrogen and stored at -8[degrees]C until analyzed.

GC/MS: Each oil was analyzed by GC/MS using a Hewlett-Packard 5890/5970A system, with a HP1 column (50 m x 0.20 mm fused silica capillary column, film thickness 0.5 [mu]m). GC oven initial temperature was 60[degrees]C and programmed to 200[degrees]C at a rate of 2[degrees]C/min and 200[degrees]C during 120 min under the following operation conditions: vector gas, helium; injector and detector temperatures, 250 [degrees]C, injected volume, 0.4 [mu]L, splitless 0.83 mn. Retention indices were determined with C^sub 5^ to C^sub 28^ alkane standards as reference. The mass spectra were performed at 70 eV of the mass range of 35-400.

Identification of the constituents was based on comparison of the retention times with those of authentic sample and on computer matching against commercial (Wiley, MassFinder 2.1 Library). In addition, we employed our home made library of mass spectra built up from pure substances and MS literature data (14-16), and confirmed by comparison of retention indices with published index data (17,18). The quantitative data presented in Table I was obtained from electronic integration of TIC data.

Results and Discussion

Table I summarizes the origin of the Cupressus species, plant age (years), number of identified compounds and percentage. Compounds identified by GC/MS, in the present investigation are listed in Table II and Table III. Fifteen compounds were found to be common to all species where we found 11 terpenoids [[alpha]-pinene, sabinene, [beta]-pinene, myrcene, [delta]-3 carene, p-cymene, (E)-[beta]-ocimene, terpinolene, terpinen-4-ol, [alpha]-terpineol, bornyl acetate], one oxygenated sesquiterpene, [alpha]-cadinol, and two diterpenoids, sandaracopimaradiene and manoyl oxide.