Chemical Composition of the Essential Oil of Microtoena patchoulii [(C.B. Clarke Ex J.D. Hooker) C.Y. Wu et Hsuan]

Journal of Essential Oil Research: JEOR, Jul/Aug 2007 by Senpuku, Manami, Nonaka, Kazuya, Ito, Michiho, Honda, Gisho

Abstract

The chemical components of the essential oil obtained from the steam-distillation of Microtoena patchoulii leaves were investigated by GC and GC/MS, and twenty-one compounds were identified. The major compounds of the oil were patchouli alcohol (54.4%), 1-octen-3-ol (21.4%), and α-guaiene (2.4%). The composition of M. patchoulii oil is similar to that of commercial patchouli oil, and similar pharmacological effects could be expected when it is used as a substitute for Pogostemon cablin.

Key Word Index

Microtoena patchoulii, Lamiaceae, essential oil composition, patchouli alcohol, 1-octen-3-ol

Introduction

Microtoenapatchoulii [(C.B. ClarkeexJ.D. Hooker) C.Y. Wu et Hsuan] is a perennial plant belonging to the family Lamiaceae, growing in the highlands of northeastern India, Myanmar, and southern China (Yunnan) (1). Its fresh leaves have a strong fragrance and are used in folk medicine for coughs, asthma, abdominal pain, and enteritis among people in these areas (2), while Pogostemon cablin, growing in China, India, Indonesia, Malaysia, Philippines, and Sri Lanka (3), has been used for centuries as a fragrance component as well as a herbal drug forthe treatment ofvomiting, dermatitis, headache, fever, and diarrhea, as well as an aphrodisiac, anti-inflammatory, and antiseptic (4). These two herbal drugs are reported to be sometimes mixed together so that M. patchoulii can be found mixed in a bag of P. cablin produced in southeast Asia (1). This happens because both species have thick hairy leaves and a similar smell so they are difficult to distinguish when the leaves are dried and cut; however, from the standpoint of the quality control of patchouli oil, it is necessary to know the chemical composition of the essential oil of M. patchoulii.

While taxonomical studies of M. patchoulii have been previously preformed, no phytochemical analysis of this plant has been reported. In this paper, we report the GC and GC/MS analysis of the essential oil of this plant for the first time.

Experimental

Plant material and essential oil isolation: Microtoena patchoulii were grown in the field of the Experimental Station for Medical Plants, Graduate School of Pharmaceutical Sciences, Kyoto University, and fresh leaves were collected in October.

Fresh leaves (approx. 300 g) were steam-distilled with 1200 mL of distilled water for 2 h using the apparatus designated in the Japanese Pharmacopoeia (5). The isolated oil was collected in hexane and stored in a 0 -20° freezer until used to minimize the loss or degradation of volatile compounds.

Methods of analysis: GC/MS was carried out on a Hewlett Packard 5890 series gas Chromatograph connected to AUTOMASS 50 (JEOL), and operation conditions were as follows: fused silica capillary column, TC-wax (HP), 60 m ? 0.25mm ? 0.25µm; column temperature: 40°0 -130° increasing at 2°/min, holding at 130° for 25 min, 130°0 -140° at 2°/min, holding at 140° for 15 min, 140°0 -200° at 15°/min, ending at 200° for 30 min. Injector: 180°, split; carrier gas: He, 45 cm/sec; column head pressure: 100 IcPa; injection volume: 1.0 pL; ionization energy: 70 eV.

GC analyses were carried out with Hitachi G-5000 GC (FID) under the following operation conditions: fused silica capillary column, TC-wax (HP), 60 m x 0.25 mm x 0.25µm; injector: 180°, split ratio: UlOO; detector: 210°, FID; carrier gas: He, 25 cm/sec; make up gas: N; column head pressure: 200 IcPa; injection volume: 1 µL.

The thermal program was the same as that for the GC/MS analysis.

Identification of components: Chemical components were identified by comparing their retention times and mass spectra with those in the MS data library (NIST 02). The quantitative analysis was achieved with a flame ionization detector (FID).

Results and Discussion

The results of the analysis are shown in Table I, where the chemical components are listed in order of their elution from the GC/MS column.

Twenty-one compounds were identified. The major compounds were patchouli alcohol (54.4%), l-octen-3-ol (21.4%), and α-guaiene (2.4%). l-octen-3-ol was found to comprise more than a fifth of the oil, however, little was found in Et^sub 2^O extraction of M. patchoulii leaves (a few percent or less), which suggests that a reactive sesquiterpene and/or monoterpene compound was degraded during steam-distillation by heat and/or moisture, and turned into 1-octen-3-ol.

α-Guaiene, α-patchoulene, seychellene, δ-guaiene, and patchouli alcohol, which are found in M. patchoulii oil, were also reported as principal constituents of oil from P. cahlin, indicating that the oil compositions of the two species are similar (6,7). Patchouli alcohol, one of the common compounds in these two species, has been reported to have antibacterial and anti-inflammatory activity (8,9). One of the distinctive compounds contained in M. patchoulii was methyl salicylate, which is reported to cure dermatitis and to remove pain by local stimulation and the promotion of blood circulation (10). Two of the monoterpene hydrocarbons found (α- and β-pinene) are also reported to have antifungal activity (11).