Essential Oil Composition of Lavandula stoechas. from Algeria

Abstract

The essential oil of Lavandula stoechas. L. growing spontaneously in Algeria was investigated by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) for the first time. The oil was isolated from the aerial parts of the plant (leaves and flowers) by distillation in a yield of 1.1%. Fifty-four components amounting to ca.. 73% of the oil were identified, the major component being fenchone (31.6%). The other significant constituents were camphor (22.4%), p.-cymene (6.5%), lavandulyl acetate (3.0%), and α-pinene (1.0%). Our results show that the oil consists mainly of oxygenated monoterpenes (62.0%). A comparison with oils from other Lavandula stoechas. from other countries reported in literature shows qualitative and quantitative differences.

Keywords:

• Camphor
• essential oil composition
• fenchone
• Lamiaceae
• Lavandula stoechas. L
• lavandulyl acetate
• p.-cymene

Introduction

The genus Lavandula. belongs to the Lamiaceae family. In Algerian flora, five species are present (Quezel & Santal, 1963). Many species of Lavandula. have been widely used in folk medicine around the world (Schauenberg & Paris, 1977; Mahmoudi, 1982; Baba Aissa, 1991; Ali El-daji, 1996). The oils are traditionally believed to be antibacterial, antifungal, carmitative (smooth muscle relaxing), sedative, antidepressive, and effective for burns and insect bites (Cavangh & Wilkinson, 2002). Today, their essential oils are important for the perfume, cosmetic, flavoring, food manufacturing, and pharmaceutical industries (Boelens, 1995). Various species of the genus Lavandula. are important sources of these essential oils (Gamez et al., 1990; Oszagyan et al., 1996; An et al., 2001; Renaud et al., 2001; Barazandeh, 2002; Nogueira & Romano, 2002). Several plants of this genus have been studied thoroughly from the chemical and pharmacological point of view (Gamez et al., 1988; Guillemain et al., 1989; Jivoretz et al., 1990; Papanov et al., 1992; Maffei & Peracino, 1993; El-Garf et al., 1999; Hohmann et al., 1999; Cavanagh & Wilkinson, 2002).

Lavandula stoechas. L. has been used in Algerian folk medicine as a antiseptic and stimulant agent (Mahmoudi, 1982; Baba Aissa, 1991). Thorough investigation of the biological activities of this species have been reported (Gamez et al., 1987; Gilani et al., 2000). Studies on the chemical constituents of L. stoechas. have been carried out by many investigators and have shown the presence of various compounds including flavonoids (Upson et al., 2000), triterpenes (Topçu et al., 2001), and essential oil (Kokkalou, 1988; Garcia et al., 1989; Valentini et al., 1993; Skoula et al., 1996; Akgün et al., 2001; Kim & Lee, 2002).

As part of our extensive screening program of aromatic and medicinal plants of Algeria, we investigated the chemical composition of essential oil isolated from the aerial parts of L. stoechas. collected from Cherchel (northwest of the Algiers region, Algeria).

Materials and Methods

Plant material

Aerial parts (leaves and flowers) of L. stoechas. were collected from plants growing spontaneously near Cherchel during the flowering period (May–June 2001). The plant was authenticated in the botanical department, National Institute of Agronomic (NIA: Algeria), where a voucher specimen of the plant has been deposited in the herbarium (HNIA/FA/N°: P 69) of this school.

Extraction and isolation

The shade-dried and finely powdered aerial parts (leaves and flowers) of the plant were exhaustively extracted by hydrodistillation for 3 h using a Clevenger-type apparatus with a water-cooled receiver, in order to reduce hydrodistillation overheating artifacts. The oil was extracted from the distillate with diethyl ether and then dried over anhydrous sodium sulfate. After filtration of the sodium sulfate, the solvent was removed by distillation under reduced pressure in a rotary evaporator. Yellow liquid (strong odorous oil) was obtained in a yield of 1.1% based on dried weight of sample. The oil was stored in a sealed glass vial in the dark at 4°C until analysis.

Gas chromatography

Capillary gas chromatography (GC) was carried out using a Chrompack CP 9002 chromatographic system with a flame ionization detector (FID), equipped with a nonpolar DB-5 capillary column (30 m × 0.25 mm, 0.25-µm film thickness). Oven temperature was programmed from 60°C to 240°C (3 min isothermally) at 3°C/min beginning at 60°C for 3 min. The carrier gas was N₂ with a flow rate of 1 ml/min. The injector and detector were heated to 250°C and 260°C, respectively. The injection volume was 0.2 µl. For poly ethylene glycol (PEG) the parameters were column 30 m × 0.32 mm i.d., 0.25-µm film thickness; oven temperature was programmed from 50°C for 10 min then 2°C/min to 230°C for 15 min. The parameters were the same for the DB-5 column.

Components were quantified as area percentages of total volatiles.

Gas chromatography/mass spectrometry

Gas chromatography/mass spectrometry (GC/MS) analyses were carried out on a trace MS Finnigan capillary gas chromatography quadrupole mass spectrometry system fitted with a DB-5 fused silica capillary column (30 m × 0.25 mm, 0.25-µm film thickness); chromatographic conditions were the same as mentioned above. The carrier gas was He. The mass unit conditions were ion source 250°C, ionization energy 70 eV. The acquisition mass range used was m./z. 40–450.

Identification

In order to determine retention indices (RI), a mixture of n.-alkanes (C₅–C₂₈) was analyzed under the same operative conditions on the DB-5 and PEG columns, and the sample indices were calculated following Van den Dool and Kratz (1963). The identification of the chemical constituents was carried out by comparison of retention indices and mass spectral data with those obtained from the NIST library spectra and the literature (Boelens, 1995; Barazandeh, 2002; Kim & Lee, 2002; Adams, 1995; Davies, 1990).

Results and Discussion

The yield of the essential oil (on a dry-weight basis) was 1.1%. Table 1 lists the constituents in the essential oil, in order of elution from the DB-5 column, the percentage yield, retention indices on both DB-5 and PEG columns, and the techniques used for identification. Fifty-four components amounting to ca.. 73% (by GC peak area) of the total oil were identified. Preliminary GC and GC/MS examinations of the oil indicated that it consists mainly of oxygenated monoterpenes (62.0%). The results in Table 1 show that the oil contained 8.8% monoterpene hydrocarbons, 1.6% oxygenated sesquiterpenes, 0.6% sesquiterpene hydrocarbons, and 0.1% other. The concentrations of sesquiterpene hydrocarbons were relatively low (no compound > 0.2%). The main constituents in the oil were fenchone (31.6%), camphor (22.4%), p.-cymene (6.5%), lavandulyl acetate (3.0%), and α.-pinene (1.0%). However, the oil was characterized by the presence of two dominating constituents (fenchone and camphor with 54.0%) with 33 compounds detected in the range 0.01–0.1%.

Table 1 Chemical composition of essential oil of Lavandula stoechas..

		DB-5
Compound	PEG RI^a.	RI^a.	%
Tricyclene	—	926	0.2
α.-Pinene^b.	1031	941	1.0
α.-Fenchene	1068	952	tr^c.
Benzaldhyde	1504	961	0.1
Sabinene	—	977	tr
β.-Pinene	1120	982	tr
Myrcene	1163	986	tr
α.-Phellandrene	—	1002	0.1
δ.-3-Carene	1140	1012	tr
α.-Terpinene	1194	1015	0.2
ρ-Cymene	1288	1024	6.5
1,8-Cineole	1226	1033	tr
cis.-β.-Ocimene	—	1048	0.1
γ.-Terpinene	1263	1067	0.2
Fenchone	1427	1088	31.6
Terpinolene	1290	1094	0.4
Linalool	1552	1098	0.1
endo.-Fenchol	—	1110	0.4
Camphor	1519	1144	22.4
trans.-Dihydro-α.-terpineol	—	1160	0.9
Borneol	1702	1165	tr
Lavandulol	1682	1171	0.4
Terpinen-4-ol	1625	1176	0.8
p.-Cymene-8-ol	—	1185	0.2
α.-Terpineol	1694	1191	0.5
Myrtenol	1775	1194	tr
Verbenone	1742	1202	0.6
cis.-Ocimenone	—	1235	0.3
Carvone	1715	1243	0.1
Linalyl acetate	1543	1246	0.1
2-Phenyl ethyl acetate	—	1258	0.1
Lavandulyl acetate	1605	1277	3.0
Bornyl acetate	—	1280	tr
Hexyl tiglate	—	1335	tr
α.-Cubebene	1463	1351	0.1
α.-Copaene	1492	1374	tr
Geranyl acetate	1751	1379	tr
α.-trans.-Bergamotene	—	1435	tr
α.-Humulene	—	1450	tr
γ.-Muurolene	—	1478	0.1
Germacrene D	1710	1482	0.1
α.-Muurolene	1729	1499	0.1
γ.-Cadinene	1765	1516	0.1
δ.-Cadinene	1787	1520	tr
Germacrene B	1572	1556	tr
Spathulenol	2138	1576	tr
Caryophyllene oxide	2001	1581	0.9
Globulol	2109	1587	0.1
Longiborneol	—	1593	0.5
Cedrol	2102	1597	tr
1-epi-Cubenol	—	1625	tr
epi-α.-Cadinol	—	1638	tr
Cubenol	2024	1642	tr
α.-Bisabolol	—	1684	tr
Total identified			73.1%

^a.RI, retention index

^b.main compounds in bold font

^c.compositional values less than 0.1% are denoted as traces (tr).

Table 2 Group composition of Lavandula stoechas. essential oil.

Grouped compounds	%
Monoterpene hydrocarbons	8.8
Oxygenated monoterpenes	62.0
Sesquiterpene hydrocarbons	0.6
Oxygenated sesquiterpenes	1.6
Others	0.1

The essential oils of L. stoechas. have been previously analyzed (Kokkalou, 1988; Garcia et al., 1989; Valentini et al., 1993; Skoula et al., 1996; Akgün et al., 2001; Kim & Lee, 2002). In L. stoechas. of Greek origin, it was found that fenchone (30.85%) was the main component (Kokkalou, 1988). In Spanish samples of L. stoechas., fenchone (23.6–68.2%), 1,8-cineole (0.3–52.7%), camphor (1.5–51.6%), and α.-pinene (0.2–8.6%) were present in high amounts (Garcia et al., 1989). Fenchone (28.1–51.8%), camphor (4.1–39.4%), myrtenol (0.9–27.8%), and γ.-gurjumene (0.1–23.6%) were also determined as main components in L. stoechas. oils from Cyprus (Valentini et al., 1993). The major compounds identified in the oil from Turkey were camphor (58.8%), fenchone (33.0%), and α.-pinene (3.5%) (Akgün et al., 2001). In Cretan samples of L. stoechas., it was found that fenchone (44.8%), 1,8-cineole (16.7%), α.-cadinol (7.4%), camphor (6.2%), and α.-pinene (2.2%) were the main components (Skoula et al., 1996).

Examination of our results revealed that limonene, eucalyptol, fenchol, cis.-sabinol, viridiflorol, cis.-pinene-3-ol, and thymol, previously found in L. stoechas. (Kokkalou, 1988; Garcia et al., 1989; Valentini et al., 1993; Skoula et al., 1996; Akgün et al., 2001; Kim & Lee, 2002), could not be identified. The variability in oil composition was present even in several Lavandula. species, and these variations may be sufficient to allow the distinction of different chemotypes, or the result of an adaptative process to particular ecologic conditions.