Xiu-Qin Li , Zhong-Gui He, Kai-Shun. Bi*, Zong-Hua Song and Liang Xu

Abstract: The volatile composition of the root oils of ten Bupleurum species (B.chinense DC., B.scorzonerifolium Willd., B.microcephalum Diels., B.malconense Shan et Y. Li, B.longicaule Wall. et DC. var. giraldii Wolff, B.marginatum Wall. ex DC, B.bicaule Helm, B.yinchowense Shan et Y. Li, B.wenchuanense Shan et Y. Li, B.smithii Wolff. var. parvifolium Shan et Y. Li) have been studied. The species were collected in their typical habitats of China. The oils were obtained by hydrodistillation and their analyses were performed by GC/FID and GC/MS. Fifty constituents of the oils were identified. The major components of the root oil of B.chinense were hexanal (29.5%), furfural (7.3%), hexanoic acid (7.4%), 2-amylfuran (5.5%) and (E,E)-2,4-decadienal (5.9%). The main components of the root oil of B.scorzonerifolium were hexanal (12.4%), furfural (8.1%), heptanal (9.3%) and dodecanoic acid (5.7%). Sixteen compounds were characterized in the root oil of B.microcephalum, with cyperol (15.6%), heptanal (6.4%) as main constituents. The major components were furfural (13.2%) and p-tolyl-2-propene (7.5%) in the oil of B.malconense. Nineteen compounds were characterized in the root oil of B.longicaule, with hexanal (15.1%), furfural (15.6%) and p-tolyl-2-propene (7.2%) as main constituents. The main constituents were p-tolyl-2-propene (9.2%), p-cymene (8.4%) and cis-linalool oxide (5.4%) in the root oil of B.marginatum. Nineteen compounds were characterized in the root oil of B.bicaule, with 4-tridecen-6-yne (42.6%) as the main constituent. The main compounds were hexanal (30.5%), furfural (11.9%) and hexanoic acid (11.7%) in the root oil of B.yinchowense. The main components were undecane (19.9%), p-tolyl-2-propene (8.5%) and hexanal (6.1%) in the root oil of B.wenchuanense. Twenty-two compounds were characterized in the root oil of B.smithii var. parvifolium, with hexanal (10.8%) and methyl thymol (6.2%). A comparison of the root oil compositions from the ten Bupleurum species showed that the concentration of major compounds was different, but almost all samples were found to contain a series aliphatic derivatives.

Bupleurum species belongs to the plant family Apiaceae, which mainly grow in the northern subtropical area. Bupleurum species are well-known and very important crude drugs in Traditional Chinese Medicine (TCM). Forty species, seventeen varieties and seven forms grow widely across China, and among these Bupleurum species, about seventeen species, six varieties and one form are considered as medicinal herbs (1). In recent years, increasing studies have been carried out on the essential oils from Bupleurum species and the results showed that the root oils possessed significant antifungal (2), anticonvulsive (3) and anti-inflammatory effects (4–6). According to pharmacopoeia of China (7), Radix Bupleuri is derived from the dried root of Bupleurum chinense DC. and Bupleurum scorzonerfolium Willd.. The published results (8,9) revealed that major volatile constituents obtained from B. chinense and B. scorzonerfolium roots were methyl thymol, butylidene phthalide, a-terpineol, terpinen-4-ol, b-pinene, a-pinene, pcymene, (E,E)-2,4-decadienal etc. In a previous investigation on B. falcatum, Zhang. et al. (10) reported that linalool, limonene, b-gurjunene, hexanal, (E)-2-nonenal, heptanal, ar-curcumene and methyl thymol were the main constituents of the oil. Recently, because of the increasing demand for this crude drug, as well as a shortage on the supply of quality goods, oils from different Bupleurum species have been used as medicines at different areas in China. However, to the best of our knowledge, there is no previous report on the composition of the root oils from the other Bupleurum species. Therefore it is important and necessary to investigate further the composition of the root oils from these other Bupleurum species. Due to the species difference and the various growing conditions, the compositions of the root oils from different Bupleurum species ought to have diversity. In the present study, the root oils of ten Bupleurum species including B.chinense DC., B.scorzonerifolium Willd., B.microcephalum Diels., B.malconense Shan et Y. Li, B.longicaule Wall. et DC. var. giraldii Wolff., B.marginatum Wall. ex DC, B.bicaule Helm., B.yinchowense Shan et Y. Li, B.wenchuanense Shan et Y. Li, B.smithii Wolff. var. parvifolium Shan et Y. Li, all collected from their naturalized habitats, were investigated. The aim of the present work is to determine the compositions of the root oils of ten Bupleurum species.