Inula helenium (Compositae) is a widely occurring perennial herb in Europe and East Asia. Its roots have been traditionally used as a diaphoresis and a diuretic expectorant agent in Europe, as a fragrance agent for home medicines in Japan, 1) and as agents of tuberculotic enterorrhea, chronic enterogastritis and bronchitis and a preservative in China.
2)Native Americans used infusion and decoctions of this roots to treat lung disorders and against tuberculosis.3) The investigation of the genus Inula has shown the sesquiterpene lactone and essential oil groups, [4][5][6] and some phenolic acids and flavonoids were evaluated as other constituents of this genus. 7,8) Many sesquiterpenes were isolated from Inula helenium.9-11) The principal ingredient, alantolactone has strong anthelmintic and antibacterial activities.
9)As part of our screening for antiproliferative constituents in natural resources, we examined the roots of I. helenium grown in Tibet. The MeOH extract of the roots of this plant showed antiproliferative activities against three tumor cell lines: human gastric adenocarcinoma cells (MK-1), human uterus carcinoma (HeLa) and mouse melanoma (B16F10) cells.The MeOH extract was partitioned with n-hexane, CHCl 3 , EtOAc, and then n-BuOH. The n-hexane fraction showed strong antiproliferative activity against MK-1, HeLa and B16F10 cells, while the EtOAc and n-BuOH fractions had very low activity as shown in Fig. 1. The n-hexane fraction was fractionated in the manner described in the Materials and Methods section, and seven sesquiterpenes were isolated. The antiproliferative activities of the fractions and seven isolated compounds against MK-1, HeLa, and B16F10 cell lines will be discussed.
MATERIALS AND METHODSMaterial Dried roots were obtained from Mr. Hiroyuki Kaito of Soma Co., 7-9-1 Tanimati, Tyuo-ku, Osaka 542, Japan on December 7, 1999. A voucher specimen (KPU-001952) is deposited in the herbarium of the Department of Pharmaceutical Sciences of Natural Resources, Kyoto Pharmaceutical University, Japan.Cells MK-1 cells were provided by Prof. M. Katano of Faculty of Medicine, Kyushu University, and HeLa and Determination of Antiproliferative Activity Inhibition of the cellular growth was estimated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay described by Mosmann.12) The detailed procedure is shown in the previous paper.
13)Extraction and Isolation The dried roots (1.5 kg) of Inula helenium grown in Tibet were extracted with MeOH at room temperature for 2 weeks. The MeOH extract was then filtered and evaporated under reduced pressure to obtain a viscous mass (555.1 g). This material was suspended with H 2 O and partitioned with n-hexane, CHCl 3 , EtOAc and nBuOH to give each organic fraction, respectively. The antiproliferative activities (GI 50 mg/ml) of these organic fractions are shown in Fig. 1. The H 2 O fraction exhibited no activity.The n-hexane fraction (142 g) was subjected to column chromatography on silica gel (800 g) to give 7 fractions using an increasi...
