1338 Notes Biol. Pharm. Bull. 24(11) 1338—1341 (2001) Vol. 24, No. 11 Antiproliferative Constituents in the Plants 7. Leaves of Clerodendron bungei and Leaves and Bark of C. trichotomum1) Tsuneatsu NAGAO, Fumiko ABE, and Hikaru OKABE* Faculty of Pharmaceutical Sciences, Fukuoka University, 8–19–1 Nanakuma, Jonan-ku, Fukuoka 814–0180, Japan. Received May 2, 2001; accepted August 3, 2001 The constituents of the leaves of Clerodendron bungei STEUD. (Verbenaceae) and leaves and bark of C. tri- chotomum THUNB. were investigated guided by the antiproliferative activity against three tumor cell lines (MK-1: human gastric adenocarcinoma, HeLa: human uterus carcinoma, and B16F10: murine melanoma). Two phenylethanoid glycoside caffeic acid esters, acteoside and isoacteoside, were isolated as the constituents which selectively inhibit the growth of B16F10 cells. The antiproliferative activities against B16F10 cells of acteoside (GI50: 8 mM), isoacteoside (8 mM) and their methanolysis products, methyl caffeate (26 mM), 3,4-dihydroxyphenethyl alcohol (8 mM), 3,4-dihydroxyphenethyl glucoside (10 mM), desrhamnosyl acteoside (6 mM), and desrhamnosyl isoacteoside (6 mM) suggested that the 3,4- dihydroxyphenethyl alcohol group might be more responsible for the activities of acteoside and isoacteoside than the caffeoyl group. The activities of chlorogenic acid, 3,4-dihydroxyphenylacetic acid, 3-(3,4-dihydroxyphenyl) alanine, 3,4-dihydroxy-phenethylamine hydrochloride, ferulic acid, sinapic acid, and five dihydroxybenzoic acids were also determined and compared with those of the above compounds. Key words Clerodendron; antiproliferative activity; acteoside; isoacteoside; caffeic acid ester; 3,4-dihydroxyphenethyl alcohol Clerodendron bungei STEUD. (Verbenaceae) is a shrub in- benzoic acids and 3,4-dihydroxyphenylacetic acid (Wako digenous to China and it has been cultivated in Japan as a Pure Chemical Industry Ltd., Osaka, Japan), caffeic acid garden plant. The leaves and roots are referred to have been (Sigma Chemical Company, St. Louis, U.S.A.), and chloro- used in prescriptions in Chinese traditional medicine for the genic acid and dopamine hydrochloride (Nacalai Tesque, treatment of malignant lung cancer.2) Inc., Kyoto, Japan). Clerodendron trichotomum THUNB. is a Japanese decidu- Cells MK-1 cells were provided by Prof. M. Katano of ous shrub grown in the mountains and sea-side bushes, and Faculty of Medicine, Kyushu Univerisity, and HeLa and its leaves have an unpleasant smell, which is the source of the B16F10 cells were supplied by Cell Resource Center for Bio- Japanese name of the tree “Kusagi” (ill-smelling tree). The medical Research, Institute of Development, Aging and Can- dried leaves and twigs have been used as the folk remedy for cer, Tohoku University. the treatment of rheumatism and rheumatic articular pain. A Reagents RPMI 1640 medium, fetal bovine serum book on folk remedy comments that the fruits are said to (FBS), and kanamycin sulfate were purchased from Lifetech, have anti-tumor activity. Rockville, MD, U.S.A., and 3-(4,5-dimethylthiazol-2-yl)-2,5- As a part of our work searching for the antiproliferative diphenyltetrazolium bromide (MTT) from Wako Pure Chem- constituents in plants, we examined the activities of the ical Industry Ltd., Osaka, Japan. MeOH extracts of C. bungei and C. trichotomum against Measurement of Antiproliferative Activity against three tumor cell lines, human gastric adenocarcinoma (MK- Tumor Cell Lines Cellular growth was determined using 1), human uterus carcinoma (HeLa) and murine melanoma MTT assay3) on a 96 well microplate as described in the pre- (B16F10) cells. The MeOH extract of the leaves of C. bungei vious paper.4) showed no inhibitory activity against MK-1 and HeLa cell Thus, the tumor cells were maintained in RPMI 1640 growth, but exhibited a weak activity (GI50: 43 mg/ml) medium containing 10% FBS and kanamycin sulfate (100 against B16F10 cell growth. The MeOH extract of the ripe mg/ml). The test samples were dissolved in dimethyl sulfoxide fruits of C. trichotomum showed very low activity (GI50: (DMSO) (20 mg/ml) and diluted with RPMI 1640 medium. 84 mg/ml), however, those from the leaves and the bark ex- Fifty microliters of the tumor cell suspension (23105 hibited much stronger activity (GI50: 20 mg/ml and 16 mg/ml, cells/ml) and 50 ml of the test sample solution were plated in respectively) against B16F10 cell growth than that of the the wells and incubated at 37 °C for 48 h under 5% CO2. leaves of C. bungei. These results prompted us to investigate After cultivation, 10 ml of MTT solution (5 mg/ml) was added the active constituents. to the wells. After incubation for 2 h under the above-men- tioned conditions, the medium was removed, and then, 100 ml MATERIALS AND METHODS DMSO was added to solubilize the MTT-formazan product. The absorbance at 570 nm was measured on the Bio-Rad Materials The leaves of C. bungei were collected in model 550 microplate reader (Hercules, CA, U.S.A.). The Fukuoka City in June, 2000 and air-dried. The leaves and percent cell growth inhibition was calculated as GI5(12 3 bark of C. trichotomum were collected at Munakata City in A/B) 100 (A: OD570 of the tumor cells with the test sample, October, 2000, and air-dried. The phenolic compounds are B: OD570 of the tumor cells without the test sample). commercial ones: cinnamic acid and DL-3-(3,4-dihydrox- Extraction and Fractionation. From C. bungei Leaves: yphenyl) alanine (Tokyo Chemical Industry Co., Ltd., Tokyo, The dried leaves (270 g) were powdered and extracted with Japan), p-coumaric acid, ferulic acid, sinapic acid, dihydroxy- MeOH (1.5 l) under reflux for 1 h. After decantation, the ∗ To whom correspondence should be addressed. e-mail: [email protected] © 2001 Pharmaceutical Society of Japan November 2001 1339 residue was again extracted in the same way. The MeOH ex- ml) the reaction mixture was neutralized with NaHCO3, acid- tract (45 g) was suspended in water (2 l) and extracted with ified with acetic acid, and MeOH was evaporated. The aque- CHCl3. The aqueous solution was passed through a column ous solution was passed through a column of MCI gel CHP of polystylene resin, Diaion HP 20 (500 ml) and the column 20P (30 ml) and then washed with MeOH. The MeOH eluate was successively washed with water, 70% MeOH, MeOH, (3.49 g) was repeatedly chromatographed on YMC Gel and AcOEt. The CHCl3 extract (2 g), water eluate (30 g), (ODS-AQ) (100 ml) using 40% MeOH as an eluant to give MeOH eluate (2.3 g), and the AcOEt eluate (6 g) showed no three fractions (Fr. 1: 224 mg, Fr. 2: 1.84 g, Fr. 3: 779 mg). activity. The 70% MeOH eluate (6 g) was further fractionated The column was then washed with MeOH to give Fr. 4 by Sephadex LH 20 column chromatography (50% MeOH) (437 mg). Fraction 2 was subjected to silica gel column chro- and preparative HPLC (Shiseido Capcell PAK C18, 40% matography (CHCl3–MeOH–H2O, 8:2:0.1) to give Fr. 2-1 MeOH) to give compounds 1 (464 mg, 0.17%) and 2 (85 mg, (789 mg) and Fr. 2-2 (525 mg). Fraction 2-1 was purified by 0.03%). preprative HPLC (Capcell PAK C18, 40% MeOH) to give From C. trichotomum Leaves: The dried leaves (250 g) compound 3 (659 mg), and from Fr. 2-2, 1 (420 mg) was re- were extracted and fractionated monitoring the activity in the covered. same way as for the MeOH extract from the leaves of C. Fraction 3 was fractionated in the same manner as for Fr. 2 bungei to give 1 (1.06 g, 0.42%) and 2 (376 mg, 0.15%). to give compound 4 (392 mg) and 2 (49 mg). Fraction 4 was From C. trichotomum Bark: The dried bark (50 g) was chromatographed on silica gel (2% MeOH in CHCl3) to give powdered and extracted with MeOH in the same way as de- compound 5 (116 mg). scribed above. The MeOH extract (9 g) was suspended in Another 5.1 g of the 60% MeOH eluate was dissolved in 60% MeOH and passed through the column of Diaion HP 20 0.5 N methanolic HCl (40 ml) and refluxed for 6 h. The reac- and the column was washed with 60% MeOH, MeOH, and tion mixture was diluted with water, neutralized with AcOEt. The 60% MeOH eluate was concentrated to remove NaHCO3, acidified with acetic acid, and concentrated to re- MeOH, and the aqueous solution was passed through a col- move MeOH. The resulting aqueous solution was passed umn of Diaion HP 20, washed with water, 60% MeOH and through a column of Diaion HP 20 (50 ml) and washed with MeOH. The H2O eluate (4.6 g), MeOH eluate (0.85 g), and water, 20% MeOH, and 60% MeOH. The water eluate and AcOEt eluate (0.65 g) showed no or weak activity, and the the 20% MeOH eluate were combined and chromatographed activity was localized in the second 60% MeOH eluate on LH-20 (120 ml), and then purified by silica gel chro- (3.1 g). The 60% MeOH eluate (1 g) was subjected to the matography (10% MeOH–CHCl3) to give compounds 6 preparative HPLC (Shiseido Capcell PAK C18, 40% MeOH) (467 mg) and 7 (368 mg). The 60% MeOH eluate was chro- to give 1 (630 mg, 3.68%) and 2 (155 mg, 0.9%). matographed on silica gel (5% MeOH in CHCl3) to give 5 Methanolysis of the Acteoside-Rich Fraction, Prepara- (672 mg). tion of Methyl Caffeate, Desrhamnosyl Derivatives of Identification of the Compounds The structures of the Acteoside and Isoacteoside, 3,4-Dihydroxyphenethyl Al- compounds were identified by NMR and MS spectral analy- cohol and its Monoglucoside The above-mentioned 60% ses as shown in the Chart.