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Two new diarylheptanoids from the pericarps of Juglans regia L.
Chinese Chemical Letters 18 (2007) 943–946 www.elsevier.com/locate/cclet
Two new diarylheptanoids from the pericarps of Juglans regia L. Jun Xi Liu, Duo Long Di *, Xin Yi Huang, Chen Li Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China Received 30 December 2006
Abstract Two new cyclic diarylheptanoids juglanin A (1) and juglanin B (2) were isolated from the pericarps of Juglans regia L. Their structures were elucidated by various spectroscopic methods including 2D NMR techniques (COSY, HMQC, HMBC, NOESY) and HR-ESIMS. # 2007 Duo Long Di. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Juglans regia L.; Pericarps; Diarylheptanoids; Juglanin A; Juglanin B
The pericarps of Juglans regia L. (Chinese name: QingLongYi) have been used as a folk medicine for treatment of cancer in Korea, Japan and China. Several naphthoquinones and diarylheptanoids from Juglans species have been reported [1,2]. In a continuation of our investigation to find cytotoxical compounds, we chemically studied the pericarps of J. regia L. collected in Tianshui of Gansu Province and two new cyclic diarylheptanoids were isolated, named as juglanin A (1) and juglanin B (2). In the present paper, the isolation and structural elucidation of 1 and 2 were reported. The dried pericarps of J. regia L. (5 kg) were powdered and extracted at room temperature with 95% ethanol (3 7 days). The solvent was removed under reduced pressure in a rotary evaporator to give a residue (200.0 g), The collected residue was suspended in water (2000 mL) and the suspension was extracted with the same volumes of petroleum ether (60–90 8C), EtOAc and n-BuOH, successively. The EtOAc extract (30 g) was subjected to column chromatography (CC) over silica gel (200–300 mesh, 400 g) eluted with a gradient of petroleum ether (60–90 8C)EtOAc (gradient from10:1–2:1) and accorded to differences in composition indicated by TLC, six crude fractions F1 (3.5 g), F2 (4.0 g), F3 (3.0 g), F4 (4.2 g), F5 (3.4 g) and F6 (5.0 g) were obtained. Compound 1 (15 mg) and compound 2 (16 mg) were isolated from F2 and F5 with petroleum ether (60–90 8C)-EtOAc (6:1 and 4:1) on CC over silica gel (200–300 mesh), respectively. Juglanin A (1) was obtained as colorless needle crystal, mp 148–150 8C, ½a20 D 648(c 0.5, MeOH). Its molecular formula was assigned as C21H24O5 on basis of the HR-ESIMS (m/z = 374.1963 [M + NH4]+, calcd. for C21H28O5N, 374.1962, m/z = 357.1703 [M + H]+, calcd. for C21H25O5, 357.1702) which was confirmed by 1H, 13C NMR (Table 1). The UV spectrum of 1 showed absorption maxima at 280 (log e = 3.66) and the IR spectrum showed strong absorptions at nmax 3440, 2938, 1714, 1611 and 1586 cm1 indicative of a hydroxylated aromatic ring system and a
* Corresponding author. E-mail address: [email protected] (D.L. Di). 1001-8417/$ – see front matter # 2007 Duo Long Di. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.05.028
944 Table 1 1 H (400 MHz), No.
J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946 13
C NMR (100 MHz) data of 1 in CDCl3 and 2 in CH3COCH3-d6 (TMS, d ppm, J Hz) Juglanin A (1) dC
dH 1 2 3 4 5 6 7 8 9 10 11 12 13a 13b 14 15 16 17 18 19 CH3O-2 CH3O-17 OH-3 CH3O-4 OH-11
6.87 6.55 3.14 1.76 1.53 2.06
(d 8.4) (d, 8.4) (m), 2.38 (m) (m), 1.54 (m) (m) (m)
2.37 (m) 2.72 (dd, 7.2, 16.4) 2.98 (dd, 7.2, 16.4) 5.53(d, 2.0)
6.80 6.66 3.93 3.91 6.01
Juglanin B (2)
(d, 8.4) (dd, 8.4, 2.0) (s) (s) (s)
145.5 139.7 147.9 124.8 126.0 115.8 29.9 24.6 18.9 46.1 210.2 41.1 27.1 134.2 112.9 148.9 146.5 111.8 121.6 61.6 56.1
dH
dC
6.75 (s) 2.88 1.93 1.80 1.77 4.00 2.22 2.91
(m), (m), (m), (m), (m) (m), (m),
2.46 1.65 1.43 1.54
(m) (m) (m) (m)
1.70 (m) 2.80 (m)
7.02 (dd, 7.2, 2.4) 6.82 (d, 7.2) 7.21 (d, 2.4) 6.77 (s)
3.83 (s) 3.24 (s)
125.5 125.6 140.2 148.0 111.2 130.9 30.0 26.4 22.7 39.5 67.3 34.5 26.5 130.8 129.4 116.2 151.4 133.6 125.4
55.6
carbonyl group. In the 13C NMR and DEPT spectrum, the signals due to two aromatic nuclei, a carbonyl group (d 210.2) and six aliphatic carbons along with two methoxyl groups were observed, indicating that 1 is a diarylheptanoid. Analysis of the aromatic signals in the 1H NMR spectra suggested the presence of a 1,2,3,4-tetrasubstituted benzene ring B at d 6.87 (d, 1H, J = 8.4 Hz, H-5), 6.55 (d, 1H, J = 8.4 Hz, H-6) and a ABX system at d 5.53 (d, 1H, J = 2.0 Hz, H-15), 6.66 (dd, 1H, J = 8.4, 2.0 Hz, H-19) and 6.80 (d, 1H, J = 8.4 Hz, H-18) due to 1,3,4-trisubstitutede benzene ring A; the H-15 signal appeared abnormally upfield from other proton signals of the two benzene rings, and this shielding effect is characteristic of diphenylether-type diarylheptanoids that have an ether linkage between C-1 and C-16 [3]; in addition, a phenolic hydroxyl (d 6.01, s, 3-OH) which was exchangeable with D2O and two methoxyl groups at d 3.93 and 3.91 were also confirmed in the 1H NMR spectrum [4]. The correlations in 1H-1H COSY spectrum displayed connectivities between H-12 and H-13, H-7 and H-8-H-9-H-10; the linkages between H-5 and H-6, H-18 and H-19 were been observed, respectively; a weak cross-peak due to the long-range coupling between H-18 and H-15 was also recognized. In the HMBC spectrum (Fig. 1) of 1, the linkage of two benzene rings on the alkyl chain were established by cross peak between H-7 and C-3, 4 and 5, H-13 and C-14, 15 and C-19, respectively; the position of the carbonyl group on the aliphatic chain was established by the HMBC correlation of H-9, 13 with C-11. Two methyoxyl groups
Fig. 1. Key HMBC correlations of 1.
J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946
945
Fig. 2. Structure of juglanin A (1).
were located by the correlations of the methoxy protons at d 61.6 with C-2 (d 139.7), and the protons of C-17-OCH3 (d 56.1) with C-17 (d 146.5). Thus, the structure of juglanin A was proposed as 1 (Fig. 2). Juglanin B (2) was also isolated as colorless needle, mp 181–183 8C, ½a20 D þ 6 (c 0.5, MeOH). Its molecular formula was assigned as C20H22O3 on basis of the HR-ESIMS (m/z = 311.1676 [M + H]+, calcd. for C20H23O3, 311.1647). The UV spectrum of 2 showed absorption maxima at 256 (log e = 3.96), 286 (log e = 3.85) and 298 (log e = 3.81), meanwhile, the IR spectrum showed strong absorptions at nmax 3382, 2931, 1619 and 1595 cm1 indicative of a hydroxyl group and an aromatic ring systems. Analysis of the 1H and 13C NMR spectra (Table 1) of 2 indicated that juglanin B also was a cyclic diarylheptanoid closely related to myricarborin which was isolated from Myrica arborea [5], but differing in the upfield chemical shift at C-11 d 67.3 (d 77.8 in myricarborin). In the 1H NMR spectrum of 2, five aromatic proton signals were observed as two broad singlets at d 6.75 (s, 1H, H-5) and 6.77 (s, 1H, H-19) of benzene ring A, and as an ABX system at d 7.02 (dd, 1H, J = 7.2, 2.4 Hz, H-15), 6.82 (d, 1H, J = 7.2 Hz, H16) and 7.21 (s, 1H, J = 2.4 Hz, H-18) of benzene ring B [6]; additionally, a methoxyl group at d 3.83 (s) were also confirmed in the 1H NMR spectrum. The correlations of the aliphatic protons in the 1H-1H COSY spectrum displayed the connectivities from C-7 to C-13; the correlation of H-13 [d 2.91 (m, 1H), 2.80 (m, 1H)] with H-12 [d 2.22 (m, 1H), 1.70(m, 1H)] in 1H-1H COSY spectrum and the HMBC correlation of H-13 with C-11 (d 67.2) revealed the location of a hydroxyl group at C-11 position. The linkage of two benzene rings on the alkyl chain were established by the HMBC correlations of H-7 with C-5, 6, 19, and H-13 with C-14, 15, C-18, respectively; the biaryl macrocycle skeleton structure of 2 was also confirmed through the HMBC correlations of H-18 with C-2, 14, 17 and H- 19 with C-1, 3, 5; the methyoxyl group was located by the HMBC correlations of the methyoxy protons (d 55.6) with C-4 (d 148.0); the
Fig. 3. Key NOESY correlations of 2.
Fig. 4. Structure of juglanin B (2).
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J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946
ether function between C-3 and C-17 was located by the downfield chemical shift at d 151.4 (d 150.3 in myricarborin). This proposed structure was further supported by NOESY spectrum (Fig. 3) in which the key correlation were observed between H-11 and H-18, H-12 and H-18, H-13 and H-15; meanwhile, the correlation from the proton of hydroxyl group at C-11 to H-11 was also supported the location of the ether function between C-3 and C-17. The absolute configuration (R) of the hydroxyl group at C-11 was determined through comparison the optical rotations data with those literatures [3,5,7] and the negative Cotton effects at 252(43.4), 297 nm(38.0) and the positive one at 206(+32.9), 225 nm(+15.9) in the CD spectrum (c = 0.0005, MeOH) [6,7]. In conclusion the structure of juglanin B was determined as 2 (Fig. 4). Acknowledgments This work was supported by the Great Research Project of CAS (KGCX2-SW-213-08) and the ‘‘Hundreds of Talents Program’’ of CAS. References [1] [2] [3] [4] [5] [6] [7]
K.S. Lee, G. Li, S.H. Kim, J. Nat. Prod. 65 (2002) 1707. M. Morihara, N. Sakurai, T. Inoue, Chem. Pharm. Bull. 45 (1997) 820. G. Li, M.L. Xu, H.G. Choi, Chem. Pharm. Bull. 51 (2003) 262. Z.H. Jiang, T. Tanaka, C. Inutsuka, Chem. Pharm. Bull. 49 (2001) 737. M. Tene, H.K. Wabo, P. Kamnaing, Phytochemistry 54 (2000) 975. Y. Takeda, T. Fujita, T. Shingu, Chem. Pharm. Bull. 35 (1987) 2569. B.S. Joshi, W. Pelletier, J. Nat. Prod. 59 (1996) 759.
Two new diarylheptanoids from the pericarps of Juglans regia L. Jun Xi Liu, Duo Long Di *, Xin Yi Huang, Chen Li Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China Received 30 December 2006
Abstract Two new cyclic diarylheptanoids juglanin A (1) and juglanin B (2) were isolated from the pericarps of Juglans regia L. Their structures were elucidated by various spectroscopic methods including 2D NMR techniques (COSY, HMQC, HMBC, NOESY) and HR-ESIMS. # 2007 Duo Long Di. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Juglans regia L.; Pericarps; Diarylheptanoids; Juglanin A; Juglanin B
The pericarps of Juglans regia L. (Chinese name: QingLongYi) have been used as a folk medicine for treatment of cancer in Korea, Japan and China. Several naphthoquinones and diarylheptanoids from Juglans species have been reported [1,2]. In a continuation of our investigation to find cytotoxical compounds, we chemically studied the pericarps of J. regia L. collected in Tianshui of Gansu Province and two new cyclic diarylheptanoids were isolated, named as juglanin A (1) and juglanin B (2). In the present paper, the isolation and structural elucidation of 1 and 2 were reported. The dried pericarps of J. regia L. (5 kg) were powdered and extracted at room temperature with 95% ethanol (3 7 days). The solvent was removed under reduced pressure in a rotary evaporator to give a residue (200.0 g), The collected residue was suspended in water (2000 mL) and the suspension was extracted with the same volumes of petroleum ether (60–90 8C), EtOAc and n-BuOH, successively. The EtOAc extract (30 g) was subjected to column chromatography (CC) over silica gel (200–300 mesh, 400 g) eluted with a gradient of petroleum ether (60–90 8C)EtOAc (gradient from10:1–2:1) and accorded to differences in composition indicated by TLC, six crude fractions F1 (3.5 g), F2 (4.0 g), F3 (3.0 g), F4 (4.2 g), F5 (3.4 g) and F6 (5.0 g) were obtained. Compound 1 (15 mg) and compound 2 (16 mg) were isolated from F2 and F5 with petroleum ether (60–90 8C)-EtOAc (6:1 and 4:1) on CC over silica gel (200–300 mesh), respectively. Juglanin A (1) was obtained as colorless needle crystal, mp 148–150 8C, ½a20 D 648(c 0.5, MeOH). Its molecular formula was assigned as C21H24O5 on basis of the HR-ESIMS (m/z = 374.1963 [M + NH4]+, calcd. for C21H28O5N, 374.1962, m/z = 357.1703 [M + H]+, calcd. for C21H25O5, 357.1702) which was confirmed by 1H, 13C NMR (Table 1). The UV spectrum of 1 showed absorption maxima at 280 (log e = 3.66) and the IR spectrum showed strong absorptions at nmax 3440, 2938, 1714, 1611 and 1586 cm1 indicative of a hydroxylated aromatic ring system and a
* Corresponding author. E-mail address: [email protected] (D.L. Di). 1001-8417/$ – see front matter # 2007 Duo Long Di. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.05.028
944 Table 1 1 H (400 MHz), No.
J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946 13
C NMR (100 MHz) data of 1 in CDCl3 and 2 in CH3COCH3-d6 (TMS, d ppm, J Hz) Juglanin A (1) dC
dH 1 2 3 4 5 6 7 8 9 10 11 12 13a 13b 14 15 16 17 18 19 CH3O-2 CH3O-17 OH-3 CH3O-4 OH-11
6.87 6.55 3.14 1.76 1.53 2.06
(d 8.4) (d, 8.4) (m), 2.38 (m) (m), 1.54 (m) (m) (m)
2.37 (m) 2.72 (dd, 7.2, 16.4) 2.98 (dd, 7.2, 16.4) 5.53(d, 2.0)
6.80 6.66 3.93 3.91 6.01
Juglanin B (2)
(d, 8.4) (dd, 8.4, 2.0) (s) (s) (s)
145.5 139.7 147.9 124.8 126.0 115.8 29.9 24.6 18.9 46.1 210.2 41.1 27.1 134.2 112.9 148.9 146.5 111.8 121.6 61.6 56.1
dH
dC
6.75 (s) 2.88 1.93 1.80 1.77 4.00 2.22 2.91
(m), (m), (m), (m), (m) (m), (m),
2.46 1.65 1.43 1.54
(m) (m) (m) (m)
1.70 (m) 2.80 (m)
7.02 (dd, 7.2, 2.4) 6.82 (d, 7.2) 7.21 (d, 2.4) 6.77 (s)
3.83 (s) 3.24 (s)
125.5 125.6 140.2 148.0 111.2 130.9 30.0 26.4 22.7 39.5 67.3 34.5 26.5 130.8 129.4 116.2 151.4 133.6 125.4
55.6
carbonyl group. In the 13C NMR and DEPT spectrum, the signals due to two aromatic nuclei, a carbonyl group (d 210.2) and six aliphatic carbons along with two methoxyl groups were observed, indicating that 1 is a diarylheptanoid. Analysis of the aromatic signals in the 1H NMR spectra suggested the presence of a 1,2,3,4-tetrasubstituted benzene ring B at d 6.87 (d, 1H, J = 8.4 Hz, H-5), 6.55 (d, 1H, J = 8.4 Hz, H-6) and a ABX system at d 5.53 (d, 1H, J = 2.0 Hz, H-15), 6.66 (dd, 1H, J = 8.4, 2.0 Hz, H-19) and 6.80 (d, 1H, J = 8.4 Hz, H-18) due to 1,3,4-trisubstitutede benzene ring A; the H-15 signal appeared abnormally upfield from other proton signals of the two benzene rings, and this shielding effect is characteristic of diphenylether-type diarylheptanoids that have an ether linkage between C-1 and C-16 [3]; in addition, a phenolic hydroxyl (d 6.01, s, 3-OH) which was exchangeable with D2O and two methoxyl groups at d 3.93 and 3.91 were also confirmed in the 1H NMR spectrum [4]. The correlations in 1H-1H COSY spectrum displayed connectivities between H-12 and H-13, H-7 and H-8-H-9-H-10; the linkages between H-5 and H-6, H-18 and H-19 were been observed, respectively; a weak cross-peak due to the long-range coupling between H-18 and H-15 was also recognized. In the HMBC spectrum (Fig. 1) of 1, the linkage of two benzene rings on the alkyl chain were established by cross peak between H-7 and C-3, 4 and 5, H-13 and C-14, 15 and C-19, respectively; the position of the carbonyl group on the aliphatic chain was established by the HMBC correlation of H-9, 13 with C-11. Two methyoxyl groups
Fig. 1. Key HMBC correlations of 1.
J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946
945
Fig. 2. Structure of juglanin A (1).
were located by the correlations of the methoxy protons at d 61.6 with C-2 (d 139.7), and the protons of C-17-OCH3 (d 56.1) with C-17 (d 146.5). Thus, the structure of juglanin A was proposed as 1 (Fig. 2). Juglanin B (2) was also isolated as colorless needle, mp 181–183 8C, ½a20 D þ 6 (c 0.5, MeOH). Its molecular formula was assigned as C20H22O3 on basis of the HR-ESIMS (m/z = 311.1676 [M + H]+, calcd. for C20H23O3, 311.1647). The UV spectrum of 2 showed absorption maxima at 256 (log e = 3.96), 286 (log e = 3.85) and 298 (log e = 3.81), meanwhile, the IR spectrum showed strong absorptions at nmax 3382, 2931, 1619 and 1595 cm1 indicative of a hydroxyl group and an aromatic ring systems. Analysis of the 1H and 13C NMR spectra (Table 1) of 2 indicated that juglanin B also was a cyclic diarylheptanoid closely related to myricarborin which was isolated from Myrica arborea [5], but differing in the upfield chemical shift at C-11 d 67.3 (d 77.8 in myricarborin). In the 1H NMR spectrum of 2, five aromatic proton signals were observed as two broad singlets at d 6.75 (s, 1H, H-5) and 6.77 (s, 1H, H-19) of benzene ring A, and as an ABX system at d 7.02 (dd, 1H, J = 7.2, 2.4 Hz, H-15), 6.82 (d, 1H, J = 7.2 Hz, H16) and 7.21 (s, 1H, J = 2.4 Hz, H-18) of benzene ring B [6]; additionally, a methoxyl group at d 3.83 (s) were also confirmed in the 1H NMR spectrum. The correlations of the aliphatic protons in the 1H-1H COSY spectrum displayed the connectivities from C-7 to C-13; the correlation of H-13 [d 2.91 (m, 1H), 2.80 (m, 1H)] with H-12 [d 2.22 (m, 1H), 1.70(m, 1H)] in 1H-1H COSY spectrum and the HMBC correlation of H-13 with C-11 (d 67.2) revealed the location of a hydroxyl group at C-11 position. The linkage of two benzene rings on the alkyl chain were established by the HMBC correlations of H-7 with C-5, 6, 19, and H-13 with C-14, 15, C-18, respectively; the biaryl macrocycle skeleton structure of 2 was also confirmed through the HMBC correlations of H-18 with C-2, 14, 17 and H- 19 with C-1, 3, 5; the methyoxyl group was located by the HMBC correlations of the methyoxy protons (d 55.6) with C-4 (d 148.0); the
Fig. 3. Key NOESY correlations of 2.
Fig. 4. Structure of juglanin B (2).
946
J.X. Liu et al. / Chinese Chemical Letters 18 (2007) 943–946
ether function between C-3 and C-17 was located by the downfield chemical shift at d 151.4 (d 150.3 in myricarborin). This proposed structure was further supported by NOESY spectrum (Fig. 3) in which the key correlation were observed between H-11 and H-18, H-12 and H-18, H-13 and H-15; meanwhile, the correlation from the proton of hydroxyl group at C-11 to H-11 was also supported the location of the ether function between C-3 and C-17. The absolute configuration (R) of the hydroxyl group at C-11 was determined through comparison the optical rotations data with those literatures [3,5,7] and the negative Cotton effects at 252(43.4), 297 nm(38.0) and the positive one at 206(+32.9), 225 nm(+15.9) in the CD spectrum (c = 0.0005, MeOH) [6,7]. In conclusion the structure of juglanin B was determined as 2 (Fig. 4). Acknowledgments This work was supported by the Great Research Project of CAS (KGCX2-SW-213-08) and the ‘‘Hundreds of Talents Program’’ of CAS. References [1] [2] [3] [4] [5] [6] [7]
K.S. Lee, G. Li, S.H. Kim, J. Nat. Prod. 65 (2002) 1707. M. Morihara, N. Sakurai, T. Inoue, Chem. Pharm. Bull. 45 (1997) 820. G. Li, M.L. Xu, H.G. Choi, Chem. Pharm. Bull. 51 (2003) 262. Z.H. Jiang, T. Tanaka, C. Inutsuka, Chem. Pharm. Bull. 49 (2001) 737. M. Tene, H.K. Wabo, P. Kamnaing, Phytochemistry 54 (2000) 975. Y. Takeda, T. Fujita, T. Shingu, Chem. Pharm. Bull. 35 (1987) 2569. B.S. Joshi, W. Pelletier, J. Nat. Prod. 59 (1996) 759.