Agric. Chem. Biotechnol. 48(1), 35-37 (2005)
Article
Development of Biologically Active Compounds from Edible Plant Sources XIV.
Cyclohexylethanoids from the Flower of Campsis grandiflora K. Schum.
Dong-Hyun Kim, Young-Jun Oh, Kyung-Min Han, In-Sik Chung, Dae-Keun Kim
1, Sung-Hoon Kim
2, Byoung-Mog Kwon
3, Mi-Hyun Park
4and Nam-In Baek*
Graduate School of Biotechnology & Plant Metabolism Research Center, Kyung Hee University, Suwon 449-701, Korea
1Department of Pharmacy, Woosuk University, Jeonju 565-701, Korea
2Graduate School of East-West Medical Science, Kyung Hee University, Suwon 449-701, Korea
3Korea Research Institute of Bioscience and Biotechnology, KIST, Taejun, 305-333, 4Erom life Co. Ltd., Seoul 135-825, Korea Received December 30, 2004; Accepted March 4, 2005
Campsis grandiflora K. Schum. flower was extracted with 80% aqueous MeOH, and concentrated extract was successively partitioned with EtOAc, n-BuOH, and H2O. From n-BuOH fraction, two cyclohexylethanoids were isolated through repeated silica gel and Sephadex LH-20 column chromatographies. Based on physico-chemical data obtained from NMR, MS, and IR, chemical structures of compounds were determined as 1,4-dihydroxy-3,4-(epoxyethano)-5-cyclohexene (1) and cornoside (2). These compounds were isolated for the first time from C. grandiflora K. Schum flower.
Key words: Campsis grandiflora, cyclohexylethanoid, 1,4-dihydroxy-3,4-(epoxy-ethano)-5-cyclohexene, cornoside.
Campsis grandiflora K. Schum. (Bignoniaceae), known as
‘Neung So Hwa’ in Korea, ‘Ryoshouka’ or ‘Noozenkazura’
in Japan, and ‘Ling Xiao Hua’ in China, is a climbing plant cultivated in the fields of Korea, China, and Japan. The flower of this plant has been used as a traditional medicine in Korea and China, and as an ornamental plant in Japan. The chemical constituents of genus Campsis have been studied by a number of researchers, including iridoid and phenylpropanoid glycosides isolated from Campsis chinensis.1-3) In addition, analyses of the essential oil, phenolics, and boron compounds from C. grandiflora4-5) have been carried out. However, isolation of the chemical component from C. grandiflora has not yet been reported. Isolation of lipids from the flower of C.
grandiflora and their inhibitory effect on FPTase,6) as well as the isolation of six cyclohexylethanoids including three new compounds from the flower of this plant have been reported (kim et al., in submission). Two cyclohexylethanoids were additionally isolated from this plant. This paper reports the isolation and structure determination of these compounds.
Materials and Methods
Instruments. Melting points were determined on an Fisher- John Apparatus and uncorrected. Optical rotations were measured on a JASCO P-1010 digital polarimeter. FAB-MS were recorded on a JEOL JMSAX 505-WA. IR spectra were run on a Perkin Elmer spectrum One FT-IR spectrometer. 1H- NMR (400 MHz) and 13C-NMR (100 MHz) spectra were taken
on a Varian Unity Inova AS 400 FT-NMR spectrometer.
Materials. C. grandiflora K. Schum. was imported from China in March, 2003, and identified by Prof. Dae-Keun Kim, Woosuk University, Jeonju. A voucher specimen (KHU03061) was reserved at the Laboratory of Natural Products Chemistry, KyungHee University, Suwon, Korea.
Isolation of cyclohexylethanoids. The dried and powdered flower of C. grandiflora (6 kg) was extracted at r.t. with 80%
aqueous MeOH (45 l × 3). The extracts were partitioned with water (4 l), EtOAc (4 l × 3), and n-BuOH (4 l × 3). The n- BuOH extract (CGB, 85 g) was applied to the silica gel column (Φ9 × 18 cm) chromatography (c.c.) eluted with CHCl3: MeOH : H2O (12 : 3 : 1 9 : 3 : 1 7 : 3 : 1, lower layer) and monitored by thin layer chromatography (TLC) to produce 18 fractions (CGB1 to CGB18). CGB3 (5 g) was subjected to the silica gel c.c. (Φ4.8 × 17 cm) eluted with CHCl3: MeOH (50 : 1) to afford 18 fractions (CGB3-1 to CGB3-18), and the obtained fraction CGB3-11 (505 mg) was applied to the silica gel c.c. (Φ4 × 10 cm) eluted with n-hexane : EtOAc (1 : 5) to give 10 fractions (CGB3-11-1 to CGB3-11-10). CGB3-11-6 (179 mg) fraction was subjected to the silica gel c.c. (Φ3.5 × 10 cm) eluted with CHCl3: MeOH (10 : 1), sprayed with H2SO4, and heated on the TLC to ultimately produce purified compound 1 (20 mg) showing the unique yellow color of a cyclohexylethanoid.
Compound 1 {1,4-dihydroxy-3,4-(epoxyethano)-5-cyclohexenol}:
Colorless crystals (CHCl3-benzene), m.p. 97-98oC; [α]D+ 102.0o (c = 1.2, MeOH); positive FAB/MS m/z: 157(M+H)+; IRν(Films, cm−1) 3400, 1675; 1H-NMR(400 MHz, pyridine-d5, δ) 6.15(1H, ddd, J = 9.8, 1.8, 1.0 Hz, H-6), 6.10(1H, dd, J = 9.8, 2.0 Hz, H-5), 4.58(1H, m, H-1), 4.49(1H, dd, J = 11.0, 4.8 Hz, H-3), 4.32(1H, ddd, J = 9.6, 8.0, 6.8 Hz, H-2'a),
*Corresponding author
Phone: +82-31-201-2661; Fax: +82-31-201-2157 E-mail: [email protected]
36 Dong-Hyun Kim et al.
4.11(1H, ddd, J = 8.3, 8.0, 3.2 Hz, H-2'b), 2.55(1H, dddd, J = 12.5, 4.8, 4.8, 1.0 Hz, H-2a), 2.25(1H, ddd, J = 12.4, 6.8, 3.2 Hz, H-1'a), 2.15(1H, ddd, J = 12.4, 9.6, 8.3 Hz, H-1'b), 2.03(1H, ddd, J = 12.5, 11.0, 9.6 Hz, H-2b); 13C-NMR(100 MHz, pyridine-d5, δ) 133.2(C-6), 130.6(C-5), 83.4(C-3), 76.9 (C-4), 67.2(C-2'), 65.3(C-1), 39.8(C-1'), 39.7(C-2).
CGB16 (17 g) containing remarkable cyclohexylethanoid was applied to the silica gel c.c. (Φ6 × 15 cm) eluted with CHCl3 : MeOH : H2O (9 : 3 : 1, lower layer) to give 14 fractions (CGB16-1 to CGB16-14), and CGB16-8 (61 mg) was subjected to the silica gel c.c. (Φ3.8 × 9 cm) eluted with CHCl3 : MeOH : H2O (9 : 3 : 1, lower layer) to afford 5 fractions (CGB16-8-1 to CGB16-8-5). CGB16-8-2 (20 mg) was purified by Sephadex LH-20 c.c. (2 × 40 cm) using CHCl3 : MeOH : H2O (9 : 3 : 1, lower layer) as the eluting solution to ultimately produce compound 2 (10 mg).
Compound 2 (cornoside): Oils (CHCl3-MeOH), [α]D -19.5o (c = 1.5, MeOH); positive FAB/MS m/z: 317(M+H)+; IRν (Films, cm−1) 3410, 1710, 1690; 1H-NMR(400 MHz, CD3OD, δ) 7.01(each 1H, d, J = 9.6 Hz, H-3, 5), 6.11(each 1H, d, J = 9.6 Hz, H-2, 6), 4.21(1H, d, J = 7.6 Hz, H-1'), 3.99(1H, dt, J = 10.0, 6.4 Hz, H-2'a), 3.63(1H, dt, J = 10.0, 6.4 Hz, H-2'b), 2.04(2H, t, J=6.4 Hz, H-1''); 13C-NMR(100 MHz, CD3OD, δ) 187.8(C-1), 154.3(C-3, 5), 127.8(C-2, 6), 104.2(C-1''), 78.0 (C-5''), 77.9(C-3''), 75.0(C-2''), 71.6(C-4''), 69.2(C-4), 65.7(C- 2'), 62.7(C-6''), 41.0(C-1').
Results and Discussion
The flower of C. grandiflora was extracted with 80%
aqueous MeOH, and the concentrated extract was successively partitioned with EtOAc, n-BuOH, and H2O. From the n-BuOH fraction, two cyclohexylethanoids were isolated through repeated silica gel and Sephadex LH-20 column chromatographies.
Compound 1, colorless crystals, showed absorbance bands at 3400 and 1675cm−1 in the IR spectrum (MeOH) due to hydroxyl and double bond, respectively, and a molecular ion peak (M+H)+ at m/z 157 in the positive FAB/MS. In the 1H- NMR spectrum of 1, two olefinic methine signals at δ6.15(1H, ddd) and δ6.10(1H, dd), which indicate the presence of a pyran ring by the coupling constant, two oxygenated methine signals at δ4.58(1H, m) and δ4.49(1H, dd), an oxygenated methylene signal at δ4.32 (1H, ddd) and δ4.11(1H, ddd), and two
methylene signals at δ2.55 (1H, dddd), δ2.25 (1H, ddd), δ2.15 (1H, ddd), and 2.03 (1H, ddd) were observed. The 13C-NMR spectrum of 1 exhibited eight carbons consisting of two olefinic methine signals at δ133.2 and δ130.6, an oxygenated quaternary signal at δ76.9, two oxygenated methine signals at δ83.4 and δ65.3, one oxygenated methylene signal at δ67.2, and two methylene signals at δ39.8 and δ39.7. To confirm the position of each carbon, 2D-NMRs including gCOSY, gHSQC, and gHMBC were performed. A series of the partial structure was inferred by gCOSY, and the carbon and proton signals were exactly assigned by gHSQC. In addition, based on the spectrum of gHMBC, sites of the functional groups were verified. Through comparison of these NMR data with those in the literature,7) compound 1 was identified as 1,4-dihydroxy- 3,4-(epoxyethano)-5-cyclohexene, previously isolated from Millingtonia hortensis.
Compound 2, oils, showed absorbance bands due to the hydroxyl (3410 cm−1), carbonyl (1710 cm−1), and olefine (1690 cm-1) in the IR spectrum (MeOH), and molecular ion peak (M+H)+ at m/z 317 in the positive FAB/MS. In the 1H-NMR spectrum, the partial structure of a para disubstituted bezene was confirmed from the olefine signals at δ7.01(2H, d), δ6.11(2H, d), one hexose was confirmed by an anomeric signal at δ4.21 (1H, d), and several oxygenated methine and methylene signals at δ3.92 - δ3.53. In addition, an oxygenated methylene signal at δ3.99 (1H, dt) and δ3.63 (1H, dt) and a methylene signal at δ2.04 (2H, t), which showed the mutual coupling, were observed, thus confirming the existence of an oxygenated ethyl group. In the 13C-NMR spectrum, 14 signals consisting of a ketone signal at δ187.8 and four olefinic methine signals overlapped two by two at δ154.3 and δ127.8 were observed. In addition, one each oxygenated quaternary, oxygenated methylene, and methylene at δ69.2, 65.7, and 41.0, respectively, were observed. By comparing the chemical shifts of the sugar with those in the literature,8) hexose was determined to be a glucopyranose. Compound 2 was finally identified as a cornoside by comparing the physical and spectral data with those of compounds isolated from M.
hortensis.7) Compounds 1 and 2 were isolated for the first time from this plant.
Because the flower of C. grandiflora has been used traditionallyin Korea for the treatment of diseases related to hematemesis, menopause, and menstrual irregularity,9) studies on the biological activities related to arteriosclerosis and hyperpiesia, among others, of compounds 1 and 2 should be performed.
Acknowledgments. This study was supported by the BioGreen 21 Program of the Rural Development Administration, Republic of Korea, and by a grant from the Korea Science &
Technology Foundation through the Plant Metabolism Research Center, KyungHee University.
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Cyclohexylethnoids of Campsis grandiflora 37
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