Volatile Components of Cirsium japonicum DC.

Abstract

The chemical composition of the essential oil from the fresh flower, root part and dried rootstock (crude drug) of Cirsium japonicum DC. was determined by GC and GC/MS. As a result, 29 components, which amounted to 94.5% and 97.3% of the total components detected, were identified in the fresh flower and root oils, respectively. The major component of the fresh root oil was aplotaxene (78.8%), and the main component of the fresh flower oil was hexadecanoic acid (28.1%). The root oil was rich in aplotaxenes, while the flower oil was rich in aliphatic acids and hydrocarbons. On the other hand, 67 components, which amounted to 92.6% of the total components detected, were identified in the oils of dried rootstock, with hexadecanoic acid (14.4%), caryophyllene oxide (12.6%), khusinol (6.3%), pentadecanoic acid (6.3%) and myristic acid (4.7%) as the major components. The dried root oil was rich in sesquiterpenoids.

Key Word Index

Cirsium japonicum, Compositae, essential oil composition, aplotaxene, caryophyllene oxide, heptacosane, pentadecanoic acid, hexadecanoic acid, oleoamide.

Introduction

Cirskimjaponicum DC. (Japanese name: Noazami) is a perennial herb of the Compositae growing from the subfrigid zone to the subtropical zone. Cirsiumjaponicum is the only species which appears in the spring. The boiled fresh root ofC.japonicum is used for Japanese food and the dried root is used for folklore medicine. Several polyolefines (aplotaxenes and 1-pentadecene) and polyacetylene alcohols (ciryneol A-E) have beenisolated from the root of C. japonicum (1-4). Several sesquiterpene hydrocarbons, cyperene, β-caryophyllene, thujopsene and a-himachalene have been isolated as well. Aplotaxene, dihydro-, tetrahydro-, and hexahydroaplotaxene are especially renowned as ether extract C17-components from the fresh root of C. japonicum (1). Tetrahydroaplotaxene is also famous for a biogenetically important intermediate from oleic acid to C17-acetylene compounds. A flavonoid, hispidulin 7-neohesperidoside, has been isolated together with cirsimaritin 4'-glucoside and acacetin 7-rutinoside from the butanol soluble part of the methanol extract of the whole plants (5). The traditional Chinese medicine Cirsi rhizonm et radix (Japanese name: Taikei) originating from the root of C. japonicum is listed in Japanese and Chinese Pharmacopoeia and has been used to treat rheumatoid arthritis, hemateinesis and hematuria for its antihemorrhagic and antifiammatoryproperties in Japan and China. Pectolinarin, which is the antihemorrhagic andhemostatic substance, has been isolated from C.japonicum. In pharmalogical study, pectolinarin has been identified as hemostatically active principle in vivo (6). The oil components from plants used for drugs have been investigated in our research on the flavor ingredients (7-11). There is no study of the components of the oil ofC.japmicum. The flavor ingredients of C. japonicum are of great interest because of the very useful herb that is used as crude drug. In this study, the composition of the oils from the fresh flowers, roots and dried rootstock (crude drug) of C. japonicum were investigated in detail.

Experimental

Plant material: Plants were collected in Hashimoto, Wakayama, Japan in May 2001. A voucher specimen is kept at the medicinal herb garden of Kinki University in Higashiosaka, Osaka, Japan. Commercially available air-dried rootstock (C. rhizoma et radix) ofC.japonicumwas purchased from Takasago Yakugyo Co. (Osaka, Japan). Samples could be classified into three samples: 1) fresh flower part, 2) fresh root part and 3) dried rootstock (C. rhizoma et radix).

oilpreparationandanalysis: Fresh flowers (65.0 g), roots (225 g) and rootstock (1 kg) of C. japonicum were hydrodistilled with a Likens-Nickerson-type apparatus, using diethyl ether as solvent. GC was carried out using a Hewlett-Packard 5890 equipped with a flame ionization detector on a capillary column (TC-WAX FFS Fused Silica 60 m × 0.25 mm, 0.25 µm film thickness). The column temperature was programmed from 80°-240°C at a rate of 3°C/min and held at 240°C. The injector and detector temperatures were 250°C and 280°C. The flow rate of carrier gas (He) was 1.0 mL/min. Quantitative data were obtained from FID peak areas without the use of correction factors.

GC/MS was carried out with an HP 5972. GC columns and conditions were the same as described above. The rate of the canier gas (He) was 0.6 mL/min. The detector interface temperature was set at 280°C with the actual temperature in the MS source reaching approximately 180°C and the ionization voltage 70 eV.

The components of these oils were identified by comparison of their mass spectra with those of a computer library or with authentic samples on the basis of retention indices and confirmed by analyses of authentic samples from our previous work.

Results and Discussion

The yield of oils obtained by steam distillation from the fresh flowers, roots and dried rootstock of C. japomcum was 0.13%, 0.15% and 0.013% (w/w), respectively (Table I). Distinct qualitative and quantitative differences were observed in the three oils studied. A gas chromatogram of the fresh flower part and root part (Figures 1-2) showed the presence of 29 components, which amounted to 94.5% and 97.3% of the total components detected (Table II). The major components of the fresh flower oil were hexadecanoic acid (28.1%), oleoamid (11.3%), heptacosane (10.9%), pentadecanoic acid (10.8%) and heptadecanoic acid (9.1%). The main component of the fresh root oil was aplotaxene (78.8%). α-Bisabolene (0.2%), dihydrocarveol (0.6%), β-bisbolen-12-ol (0.4%), caryophyllene oxide (0.7%), germacrene D 4-ol (0.5%) and spathulenol (0.5%) were newly identified as fresh root oil components. A gas chromatogram of the dried rootstock is presented in Figure 3, in which 78 components of the oil were separated. Sixty-seven components, which amounted to 92.6% of the total components detected, were identified (Table II). The main components of this oil were hexadecanoic acid (14.4%), caryophyllene oxide (12.6%), khusinol (6.3%), pentadecanoic acid (6.3%) and tetradecanoic acid (4.7%).