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A new 9,10-dihydrophenanthrene from Dendrobium moniliforme ab
c
d
d
Ningdong Zhao , Guangyu Yang , Yan Zhang , Lijun Chen & Yegao Chen
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a
School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P.R. China b
Department of Chemistry and Engineering, Wenshan University, Wenshan 663000, P.R. China c
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Yunnan Research Institute of Tobacco Science, Kunming 650106, P.R. China d
School of Pharmacy, Kunming Medical University, Kunming 650500, P.R. China Published online: 01 Jul 2015.
To cite this article: Ningdong Zhao, Guangyu Yang, Yan Zhang, Lijun Chen & Yegao Chen (2015): A new 9,10-dihydrophenanthrene from Dendrobium moniliforme, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2015.1046379 To link to this article: http://dx.doi.org/10.1080/14786419.2015.1046379
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Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2015.1046379
A new 9,10-dihydrophenanthrene from Dendrobium moniliforme Ningdong Zhaoab, Guangyu Yangc, Yan Zhangd, Lijun Chend and Yegao Chena* a School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P.R. China; bDepartment of Chemistry and Engineering, Wenshan University, Wenshan 663000, P.R. China; c Yunnan Research Institute of Tobacco Science, Kunming 650106, P.R. China; dSchool of Pharmacy, Kunming Medical University, Kunming 650500, P.R. China
(Received 28 February 2015; final version received 23 April 2015)
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OH H
MeO OH
OMe OMe
1
A new 9,10-dihydrophenanthrene,1,5-dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) was isolated and identified from the whole plants of Dendrobium moniliforme, as well as 24 known compounds including hircinol (2), (2R*,3S*)-3hydroxymethyl-9-methoxy-2-(40 -hydroxy-30 ,50 -dimethoxyphenyl)-2,3,6,7-tetrahydrophenanthro[4,3-b ]furan-5,11-diol (3), diospyrosin (4), aloifol I (5), moscatilin (6), 3,40 dihydroxy-30 ,4,5-trimethoxybibenzyl (7), gigantol (8), 3,30 -dihydroxy-4,5-dimethoxybibenzyl (9), longicornuol A (10), N-trans-cinnamoyltyramine (11), paprazine (12), N-trans-feruloyl 30 -O-methyldopamine (13), moupinamide (14), dihydroconiferyl dihydro-p-coumarate (15), dihydrosinapyl dihydro-p-coumarate (16), 3-isopropyl-5acetoxycyclohexene-2-one-1 (17), p-hydroxybenzaldehyde (18), vanillin (19), phydroxyphenylpropionic acid (20), vanillic acid (21), protocatechuic acid (22), (þ)syringaresinol (23), b-sitosterol (24) and daucosterol (25). Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and compounds 2, 5, 7, 9 –12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme. Keywords: Dendrobium moniliforme; Orchidaceae; 9,10-dihydrophenanthrene
1. Introduction Dendrobium moniliforme is an Orchidaceae plant widely distributed in China, India, Korea and Japan (Tsai et al. 1999). Previous studies on the chemical constituents of the plants from Dendrobium genus led to the isolation of phenanthrenes, bibenzyls, sesquiterpenoids, alkaloids and polysaccharides, which showed diverse biological activities including anti-tumour, antiinflammatory and platelet anti-aggregation activities (Chen et al. 1994; Ma & Gerald 1998; Moretti et al. 2013; Chaotham 2014). From D. moniliforme, 2 dendrobine-type sesquiterpene alkaloids; 15 sesquiterpenes and their glucosides with picrotoxane, allo-aromadendrane and copacamphane-type skeletons; 5 bibenzyls and their glucosides, 1 9,10-dihydrophenanthrene, 3 phenanthrenequinones, 3 lignans, 2 phenyl propanoids, 3 simple aromatics and 3 sterols were isolated (Lin et al. 2001; Bi et al. 2002, 2004; Zhao, Liu, et al. 2003; Zhao, Ye, et al. 2003; Zhao
*Corresponding author. Email: [email protected] q 2015 Taylor & Francis
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& Zhao 2003; Bae et al. 2004; Lo et al. 2004; Liu et al. 2007). Some of the isolated compounds exhibited potent inhibitory activity on nuclear factor-kappa B by inducing apoptosis via generation of reactive oxygen species in human leukemic cells, on the vaccina open readingframe H1 related protein phosphatase (VHR) dual-specificity protein tyrosine phosphatase by stimulating the proliferation of B cells and inhibiting the proliferation of T cells in vitro, enhancing immunological and anti-inflammatory activities (Lin et al. 2001; Zhao, Liu, et al. 2003; Bae et al. 2004; Sa´nchez-Duffhues et al. 2009). As a part of our research of structurally unique and biologically active compounds from medicinal plants of Yunnan, China, we investigated the plant and isolated a new 9,10-dihydrophenanthrene,1,5-dihydroxy-3,4,7trimethoxy-9,10-dihydrophenanthrene (1), as well as 24 known compounds (Figure 1). Their structures were identified by extensive spectral analysis including 2D NMR and HR-EI-MS.
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2. Results and discussion Compound 1 was obtained as brown amorphous powder. Its molecular formula was established as C17H18O5 by HR-EI-MS analysis at m/z 302.1147 [M]þ (calcd 302.1154), implying nine degrees of unsaturation. Its IR absorptions at 3385, 1598 and 1426 cm21 inferred the presence of hydroxyls and aromatic rings, respectively. The 1H NMR of 1 showed four methylene protons [d 2.49 (4H, s, H-9 and H-10)], which are typical of the protons of the two benzylic methylene groups of a 9,10-dihydrophenanthrene derivative. Furthermore, the 1H NMR exhibited three aromatic proton signals consisting of one isolated aromatic proton [d 6.44 (1H, s, H-2)], and a pair of meta-coupled aromatic protons [d 6.37 (1H, d, J ¼ 2.8 Hz, H-8) and 6.32 (1H, d, J ¼ 2.8 Hz, H-6)]. In addition, three aromatic methoxyls at d 3.69, 3.68 and 3.49 (each 3H, s) were displayed. These observations suggested the presence of two hydroxyl groups in 1, which was confirmed by the 13C NMR and DEPT spectra of 1. The 13C NMR spectrum displayed 17 carbons including three methoxyls, two aromatic methylenes, three aromatic methines and nine quaternary aromatic carbons (including five oxygenated quaternary aromatic carbons). The HMBC spectrum showed that both of the meta-coupled aromatic protons, H-6 and H-8, correlated with the same oxygenated aromatic carbon C-7 (d 161.7) (Figure S1 and Table S1), and H-8 had 3J correlation with C-9 (d 32.4). C-7 had a more downfield shift as a methoxyl (d 3.69) had a 3J correlation with C-7. Therefore, C-7 was methoxylated and C-5 was hydroxylated, which was supported by the observation of the correlation peak between 7-OMe and H-6, and H-8 in ROESY spectrum (Figure S2). In another aromatic ring, the isolated aromatic proton H-2 displayed HMBC correlation with three oxygenated aromatic carbons (C-1, C-3, C-4), and a NOE correlation between 3-OMe (d 3.68) and H-2 was observed, suggesting hydroxylation of C-1. It followed that C-3 and C-4 must be methoxylated, which was supported by the observation of the correlation peaks from 3-OMe to C-3, and 4-OMe to C-4 in the HMBC spectrum. Thus, the structure of 1 was elucidated as 1,5-dihydroxy-3,4,7-trimethoxy-9,10dihydrophenanthrene. By comparison of the physical and spectral data with literature values, the 24 known compounds (2– 25) were identified, respectively, as hircinol (2) (Honda & Yamaki 2001), (2R*,3S*)-3-hydroxymethyl-9-methoxy-2-(40 -hydroxy-30 ,50 -dimethoxyphenyl)-2,3,6,7-tetrahydro-phenanthro[4,3-b ]furan-5,11-diol (3) (Leong & Harrison 2004), diospyrosin (4) (Ma et al. 2008), aloifol I (5) (Hu et al. 2008), moscatilin (6) (Majumder & Sen 1987), 3,40 -dihydroxy30 ,4,5-trimethoxybibenzyl (7) (Chen et al. 2010), gigantol (8) (Leong et al. 1997), 3,30 dihydroxy-4,5-dimethoxybibenzyl (9) (Chen et al. 2010), longicornuol A (10) (Hu et al. 2008), N-trans-cinnamoyltyramine (11) (Guan et al. 2009), paprazine (12) (Li et al. 2010), N-transferuloyl 30 -O-methyldopamine (13) (Cutillo et al. 2003), moupinamide (14) (Guan et al. 2009), dihydroconiferyl dihydro-p-coumarate (15) (Zhang et al. 2006), dihydrosinapyl dihydrop-coumarate (16) (Grabber et al. 1996), 3-isopropyl-5-acetoxycyclohexene-2-one-1 (17)
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OH MeO
R1
10a
8a
8
OH
10
9
R4
4b 4a
7 5
6
O
HO
1 2
R3
MeO
MeO
HO
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4
H
O H
O
OMe R2
OH
CHO
1 R1= R2= OMe, R3= H, R4= OH 2 R1= R2= R4 = H, R3= OH
MeO
OMe
3
4
MeO R3
HO
R1O R4
HO
CH2OH O
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R2 R5 5 R1= R4= R5= H, R2= OMe, R3= OH 6 R1= R5= H, R2= R3= OMe, R4 = OH 7 R1= Me, R2= R4 = OH, R3= OMe, R5= H 8 R1= R2= R4 = H, R3= OH, R5= OMe 9 R1= Me, R2= R3= OH, R4 = R5= H
OMe OMe MeO
OH
10
O R3 NH
R1
H3CO O
OH R2
HO
11 R1~ R3=H 12 R1= OH, R2= R3= H 13 R1= OH, R2= R3= OMe 14 R1= OH, R2= OMe, R3= H
CH2CH2CH2 O C
CH2CH2
R1 15 R1= H 16 R1= OMe OCH3 OH
R1
O OCH3
O H3C C O
H
R2
H
OH CH3
O CH3 17
18 R1= CHO, R2= H 19 R1= CHO, R2= OMe 20 R1= CH2CH2COOH, R2= H 21 R1= COOH, R2= OMe 22 R1= COOH, R2= OH
RO 24 R= H 25 R= Glc
Figure 1. Structures of compounds 1 – 25.
H
H3CO O HO OCH3 23
OH
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(Kong et al. 2004), p-hydroxybenzaldehyde (18), vanillin (19) (Zhang et al. 2006), p-hydroxyphenylpropionic acid (20), vanillic acid (21) (Li et al. 2010), protocatechuic acid (22) (Ye & Zhao 2002), (þ )-syringaresinol (23) (Song et al. 2008), b-sitosterol (24) and daucosterol (25). Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and compounds 2, 5, 7, 9 –12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme.
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3. Experimental 3.1. Apparatus and reagents IR was measured on a Perkin-Elmer 241 polarimeter. MS was obtained on a VG Auto Spec-3000 spectrometer. NMR spectra were recorded on a Bruker DRX-400 spectrometer at 400 MHz for 1 H and 100 MHz for 13C using standard pulse sequence programs. All chemical shifts were recorded with respect to tetramethylsilane as an internal standard. Column chromatography was carried out on silica gel (200 –300 mesh, Qingdao Marine Chemical Co., Qingdao, China) and MCI gel CHP 20P (75 –150 mm, Mitsubishi Chemical Corp., Japan). Thin Layer Chromatography (TLC) was performed on silica gel GF254 (Yantai Jiangyou Silica Gel Co. Ltd, Yantai, China). Semi-preparative HPLC was carried out using a system composed of a Waters 600 pump, with an Agilent 1100 detector and Sunfire C18 reversed-phase column (10 £ 150 mm, detected at UV of 254 nm). The solvents were of industrial purity and distilled prior to use. 3.2. Plant material The whole plants of D. moniliforme were collected from Pingbian County of Yunnan Province, China in April 2006 and identified by Mr Yongxing Chu, a botanist of Daweishan National Natural Reserve, Pingbian, China and the voucher specimen (no. 0604002) is deposited at the herbarium of School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, China. 3.3. Extraction and isolation The air-dried powdered whole plants (3 kg) were extracted with MeOH at room temperature (six times, each 25 l) and the concentrated extract was added with H2O (1.5 l) and then extracted with EtOAc and n-BuOH successively. Evaporation of the respective solvents gave the EtOAc (99 g) extract and n-BuOH extract (74 g). As the EtOAc extract usually contain bioactive phenanthrenes, bibenzyls, sesquiterpenoids and alkaloids, it was chosen for further isolation. The EtOAc extract was subjected to column chromatography (silica gel, gradient petroleum ether: EtOAc 1:0, 20:1, 10:1, 8:1, 8:2, 7:3, 1:1 and 0:1) to obtain seven fractions monitored by TLC. Fr. 2 (18.7 g) was separated on column chromatography (silica gel, petroleum ether: EtOAc 15:1, 10:1, 8:1, 8:2, 7:3, 1:1 and 0:1) to yield seven sub-fractions. Compound 24 (0.6 g) was crystallised from sub-fr. 3 (2 g) by petroleum ether. Sub-frs 4 (1.5 g), 5 (1.2 g), 6 (2.1 g) and 7 (0.7 g) were subjected separately to columns (MCI gel, H2O-MeOH 10:0, 1:1, 2:8, 1:9 and 0:10; Sephadex LH-20, CHCl3:MeOH 3:2), and then purified by semi-preparative HPLC (MeOH:H2O 75 –70%, 3 ml/min) to give 1 (12 mg), 2 (7 mg), 5 (7 mg), 18 (7 mg) and 19 (12.7 mg). Fr. 3 (6.0 g) was subjected to columns (MCI gel, H2O:MeOH 10:0, 1:1, 2:8, 1:9 and 0:10; Sephadex LH-20, CHCl3:MeOH 3:2), and then purified by semi-preparative HPLC (MeOH:H2O 65 –60%, 3 ml/min) to afford 6 (45 mg), 7 (22 mg), 8 (6 mg), 9 (9 mg), 15 (52 mg), 20 (129 mg) and 21 (48 mg). Fr. 4 (6.6 g) was isolated similarly and then purified by semipreparative HPLC (MeOH:H2O 55 –40%, 3 ml/min) to obtain 11 (5 mg), 16 (35 mg), 17 (8 mg) and 22 (40 mg). Fr. 6 (7.8 g) was treated similarly and then purified by semi-preparative HPLC
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(MeOH:H2O 50– 40%, 3 ml/min) to yield 3 (15 mg), 4 (87 mg), 10 (47 mg), 12 (2 mg), 13 (5 mg), 14 (8 mg) and 23 (5 mg). Compound 25 (1.2 g) was obtained by the treatment of Fr.7 (14.9 g) with acetone.
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3.3.1. 1,5-Dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) Brown amorphous powder; IR (KBr) nmax cm21: 3385, 3181, 1623, 1598, 1426, 1330; EI-MS: 302 [M]þ, HR-EI-MS m/z 302.1147 [M]þ (calcd for C17H18O5, 302.1154); 1H NMR (CD3OD, 400 MHz): d 6.44 (1H, s, H-2), 6.37 (1H, d, J ¼ 2.8, H-8), 6.32 (1H, d, J ¼ 2.8, H-6), 3.69 (3H, s, OMe-7), 3.68 (3H, s, OMe-3), 3.49 (3H, s, OMe-4), 2.49 (4H, s, H-9 and H-10); 13C NMR (CDCl3, 100 MHz): d 161.7 (s, C-7), 156.5 (s, C-5), 154.7 (s, C-3), 150.0 (s, C-1), 144.1 (s, C-8a), 137.6 (s, C-4), 128.2 (s, C-4a), 120.1 (s, C-10a), 114.4 (s, C-4b), 107.7 (d, C-8), 103.1 (d, C-6), 99.8 (d, C-2), 32.4 (t, C-9), 22.7 (t, C-10), 62.2 (q, OMe-4), 56.3 (q, OMe-3), 55.6 (q, OMe-7). 4. Conclusion In our research, chemical constituents of D. moniliforme were investigated and 25 compounds were isolated and characterised. 1,5-Dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) is a new compound. Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and 2, 5, 7, 9– 12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme. Supplementary material Supplementary material relating to this article is available online at http://dx.doi. org/10.1080/14786419.2015.1046379. Disclosure statement No potential conflict of interest was reported by the authors.
Funding This work was supported by the Natural Science Foundation of China [grant number 30860346]; and from Yunnan Province of China [grant number 2009CC018] for basic research in social development.
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Natural Product Research: Formerly Natural Product Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gnpl20
A new 9,10-dihydrophenanthrene from Dendrobium moniliforme ab
c
d
d
Ningdong Zhao , Guangyu Yang , Yan Zhang , Lijun Chen & Yegao Chen
a
a
School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P.R. China b
Department of Chemistry and Engineering, Wenshan University, Wenshan 663000, P.R. China c
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Yunnan Research Institute of Tobacco Science, Kunming 650106, P.R. China d
School of Pharmacy, Kunming Medical University, Kunming 650500, P.R. China Published online: 01 Jul 2015.
To cite this article: Ningdong Zhao, Guangyu Yang, Yan Zhang, Lijun Chen & Yegao Chen (2015): A new 9,10-dihydrophenanthrene from Dendrobium moniliforme, Natural Product Research: Formerly Natural Product Letters, DOI: 10.1080/14786419.2015.1046379 To link to this article: http://dx.doi.org/10.1080/14786419.2015.1046379
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
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Natural Product Research, 2015 http://dx.doi.org/10.1080/14786419.2015.1046379
A new 9,10-dihydrophenanthrene from Dendrobium moniliforme Ningdong Zhaoab, Guangyu Yangc, Yan Zhangd, Lijun Chend and Yegao Chena* a School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P.R. China; bDepartment of Chemistry and Engineering, Wenshan University, Wenshan 663000, P.R. China; c Yunnan Research Institute of Tobacco Science, Kunming 650106, P.R. China; dSchool of Pharmacy, Kunming Medical University, Kunming 650500, P.R. China
(Received 28 February 2015; final version received 23 April 2015)
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OH H
MeO OH
OMe OMe
1
A new 9,10-dihydrophenanthrene,1,5-dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) was isolated and identified from the whole plants of Dendrobium moniliforme, as well as 24 known compounds including hircinol (2), (2R*,3S*)-3hydroxymethyl-9-methoxy-2-(40 -hydroxy-30 ,50 -dimethoxyphenyl)-2,3,6,7-tetrahydrophenanthro[4,3-b ]furan-5,11-diol (3), diospyrosin (4), aloifol I (5), moscatilin (6), 3,40 dihydroxy-30 ,4,5-trimethoxybibenzyl (7), gigantol (8), 3,30 -dihydroxy-4,5-dimethoxybibenzyl (9), longicornuol A (10), N-trans-cinnamoyltyramine (11), paprazine (12), N-trans-feruloyl 30 -O-methyldopamine (13), moupinamide (14), dihydroconiferyl dihydro-p-coumarate (15), dihydrosinapyl dihydro-p-coumarate (16), 3-isopropyl-5acetoxycyclohexene-2-one-1 (17), p-hydroxybenzaldehyde (18), vanillin (19), phydroxyphenylpropionic acid (20), vanillic acid (21), protocatechuic acid (22), (þ)syringaresinol (23), b-sitosterol (24) and daucosterol (25). Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and compounds 2, 5, 7, 9 –12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme. Keywords: Dendrobium moniliforme; Orchidaceae; 9,10-dihydrophenanthrene
1. Introduction Dendrobium moniliforme is an Orchidaceae plant widely distributed in China, India, Korea and Japan (Tsai et al. 1999). Previous studies on the chemical constituents of the plants from Dendrobium genus led to the isolation of phenanthrenes, bibenzyls, sesquiterpenoids, alkaloids and polysaccharides, which showed diverse biological activities including anti-tumour, antiinflammatory and platelet anti-aggregation activities (Chen et al. 1994; Ma & Gerald 1998; Moretti et al. 2013; Chaotham 2014). From D. moniliforme, 2 dendrobine-type sesquiterpene alkaloids; 15 sesquiterpenes and their glucosides with picrotoxane, allo-aromadendrane and copacamphane-type skeletons; 5 bibenzyls and their glucosides, 1 9,10-dihydrophenanthrene, 3 phenanthrenequinones, 3 lignans, 2 phenyl propanoids, 3 simple aromatics and 3 sterols were isolated (Lin et al. 2001; Bi et al. 2002, 2004; Zhao, Liu, et al. 2003; Zhao, Ye, et al. 2003; Zhao
*Corresponding author. Email: [email protected] q 2015 Taylor & Francis
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& Zhao 2003; Bae et al. 2004; Lo et al. 2004; Liu et al. 2007). Some of the isolated compounds exhibited potent inhibitory activity on nuclear factor-kappa B by inducing apoptosis via generation of reactive oxygen species in human leukemic cells, on the vaccina open readingframe H1 related protein phosphatase (VHR) dual-specificity protein tyrosine phosphatase by stimulating the proliferation of B cells and inhibiting the proliferation of T cells in vitro, enhancing immunological and anti-inflammatory activities (Lin et al. 2001; Zhao, Liu, et al. 2003; Bae et al. 2004; Sa´nchez-Duffhues et al. 2009). As a part of our research of structurally unique and biologically active compounds from medicinal plants of Yunnan, China, we investigated the plant and isolated a new 9,10-dihydrophenanthrene,1,5-dihydroxy-3,4,7trimethoxy-9,10-dihydrophenanthrene (1), as well as 24 known compounds (Figure 1). Their structures were identified by extensive spectral analysis including 2D NMR and HR-EI-MS.
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2. Results and discussion Compound 1 was obtained as brown amorphous powder. Its molecular formula was established as C17H18O5 by HR-EI-MS analysis at m/z 302.1147 [M]þ (calcd 302.1154), implying nine degrees of unsaturation. Its IR absorptions at 3385, 1598 and 1426 cm21 inferred the presence of hydroxyls and aromatic rings, respectively. The 1H NMR of 1 showed four methylene protons [d 2.49 (4H, s, H-9 and H-10)], which are typical of the protons of the two benzylic methylene groups of a 9,10-dihydrophenanthrene derivative. Furthermore, the 1H NMR exhibited three aromatic proton signals consisting of one isolated aromatic proton [d 6.44 (1H, s, H-2)], and a pair of meta-coupled aromatic protons [d 6.37 (1H, d, J ¼ 2.8 Hz, H-8) and 6.32 (1H, d, J ¼ 2.8 Hz, H-6)]. In addition, three aromatic methoxyls at d 3.69, 3.68 and 3.49 (each 3H, s) were displayed. These observations suggested the presence of two hydroxyl groups in 1, which was confirmed by the 13C NMR and DEPT spectra of 1. The 13C NMR spectrum displayed 17 carbons including three methoxyls, two aromatic methylenes, three aromatic methines and nine quaternary aromatic carbons (including five oxygenated quaternary aromatic carbons). The HMBC spectrum showed that both of the meta-coupled aromatic protons, H-6 and H-8, correlated with the same oxygenated aromatic carbon C-7 (d 161.7) (Figure S1 and Table S1), and H-8 had 3J correlation with C-9 (d 32.4). C-7 had a more downfield shift as a methoxyl (d 3.69) had a 3J correlation with C-7. Therefore, C-7 was methoxylated and C-5 was hydroxylated, which was supported by the observation of the correlation peak between 7-OMe and H-6, and H-8 in ROESY spectrum (Figure S2). In another aromatic ring, the isolated aromatic proton H-2 displayed HMBC correlation with three oxygenated aromatic carbons (C-1, C-3, C-4), and a NOE correlation between 3-OMe (d 3.68) and H-2 was observed, suggesting hydroxylation of C-1. It followed that C-3 and C-4 must be methoxylated, which was supported by the observation of the correlation peaks from 3-OMe to C-3, and 4-OMe to C-4 in the HMBC spectrum. Thus, the structure of 1 was elucidated as 1,5-dihydroxy-3,4,7-trimethoxy-9,10dihydrophenanthrene. By comparison of the physical and spectral data with literature values, the 24 known compounds (2– 25) were identified, respectively, as hircinol (2) (Honda & Yamaki 2001), (2R*,3S*)-3-hydroxymethyl-9-methoxy-2-(40 -hydroxy-30 ,50 -dimethoxyphenyl)-2,3,6,7-tetrahydro-phenanthro[4,3-b ]furan-5,11-diol (3) (Leong & Harrison 2004), diospyrosin (4) (Ma et al. 2008), aloifol I (5) (Hu et al. 2008), moscatilin (6) (Majumder & Sen 1987), 3,40 -dihydroxy30 ,4,5-trimethoxybibenzyl (7) (Chen et al. 2010), gigantol (8) (Leong et al. 1997), 3,30 dihydroxy-4,5-dimethoxybibenzyl (9) (Chen et al. 2010), longicornuol A (10) (Hu et al. 2008), N-trans-cinnamoyltyramine (11) (Guan et al. 2009), paprazine (12) (Li et al. 2010), N-transferuloyl 30 -O-methyldopamine (13) (Cutillo et al. 2003), moupinamide (14) (Guan et al. 2009), dihydroconiferyl dihydro-p-coumarate (15) (Zhang et al. 2006), dihydrosinapyl dihydrop-coumarate (16) (Grabber et al. 1996), 3-isopropyl-5-acetoxycyclohexene-2-one-1 (17)
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OH MeO
R1
10a
8a
8
OH
10
9
R4
4b 4a
7 5
6
O
HO
1 2
R3
MeO
MeO
HO
3
4
H
O H
O
OMe R2
OH
CHO
1 R1= R2= OMe, R3= H, R4= OH 2 R1= R2= R4 = H, R3= OH
MeO
OMe
3
4
MeO R3
HO
R1O R4
HO
CH2OH O
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R2 R5 5 R1= R4= R5= H, R2= OMe, R3= OH 6 R1= R5= H, R2= R3= OMe, R4 = OH 7 R1= Me, R2= R4 = OH, R3= OMe, R5= H 8 R1= R2= R4 = H, R3= OH, R5= OMe 9 R1= Me, R2= R3= OH, R4 = R5= H
OMe OMe MeO
OH
10
O R3 NH
R1
H3CO O
OH R2
HO
11 R1~ R3=H 12 R1= OH, R2= R3= H 13 R1= OH, R2= R3= OMe 14 R1= OH, R2= OMe, R3= H
CH2CH2CH2 O C
CH2CH2
R1 15 R1= H 16 R1= OMe OCH3 OH
R1
O OCH3
O H3C C O
H
R2
H
OH CH3
O CH3 17
18 R1= CHO, R2= H 19 R1= CHO, R2= OMe 20 R1= CH2CH2COOH, R2= H 21 R1= COOH, R2= OMe 22 R1= COOH, R2= OH
RO 24 R= H 25 R= Glc
Figure 1. Structures of compounds 1 – 25.
H
H3CO O HO OCH3 23
OH
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(Kong et al. 2004), p-hydroxybenzaldehyde (18), vanillin (19) (Zhang et al. 2006), p-hydroxyphenylpropionic acid (20), vanillic acid (21) (Li et al. 2010), protocatechuic acid (22) (Ye & Zhao 2002), (þ )-syringaresinol (23) (Song et al. 2008), b-sitosterol (24) and daucosterol (25). Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and compounds 2, 5, 7, 9 –12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme.
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3. Experimental 3.1. Apparatus and reagents IR was measured on a Perkin-Elmer 241 polarimeter. MS was obtained on a VG Auto Spec-3000 spectrometer. NMR spectra were recorded on a Bruker DRX-400 spectrometer at 400 MHz for 1 H and 100 MHz for 13C using standard pulse sequence programs. All chemical shifts were recorded with respect to tetramethylsilane as an internal standard. Column chromatography was carried out on silica gel (200 –300 mesh, Qingdao Marine Chemical Co., Qingdao, China) and MCI gel CHP 20P (75 –150 mm, Mitsubishi Chemical Corp., Japan). Thin Layer Chromatography (TLC) was performed on silica gel GF254 (Yantai Jiangyou Silica Gel Co. Ltd, Yantai, China). Semi-preparative HPLC was carried out using a system composed of a Waters 600 pump, with an Agilent 1100 detector and Sunfire C18 reversed-phase column (10 £ 150 mm, detected at UV of 254 nm). The solvents were of industrial purity and distilled prior to use. 3.2. Plant material The whole plants of D. moniliforme were collected from Pingbian County of Yunnan Province, China in April 2006 and identified by Mr Yongxing Chu, a botanist of Daweishan National Natural Reserve, Pingbian, China and the voucher specimen (no. 0604002) is deposited at the herbarium of School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, China. 3.3. Extraction and isolation The air-dried powdered whole plants (3 kg) were extracted with MeOH at room temperature (six times, each 25 l) and the concentrated extract was added with H2O (1.5 l) and then extracted with EtOAc and n-BuOH successively. Evaporation of the respective solvents gave the EtOAc (99 g) extract and n-BuOH extract (74 g). As the EtOAc extract usually contain bioactive phenanthrenes, bibenzyls, sesquiterpenoids and alkaloids, it was chosen for further isolation. The EtOAc extract was subjected to column chromatography (silica gel, gradient petroleum ether: EtOAc 1:0, 20:1, 10:1, 8:1, 8:2, 7:3, 1:1 and 0:1) to obtain seven fractions monitored by TLC. Fr. 2 (18.7 g) was separated on column chromatography (silica gel, petroleum ether: EtOAc 15:1, 10:1, 8:1, 8:2, 7:3, 1:1 and 0:1) to yield seven sub-fractions. Compound 24 (0.6 g) was crystallised from sub-fr. 3 (2 g) by petroleum ether. Sub-frs 4 (1.5 g), 5 (1.2 g), 6 (2.1 g) and 7 (0.7 g) were subjected separately to columns (MCI gel, H2O-MeOH 10:0, 1:1, 2:8, 1:9 and 0:10; Sephadex LH-20, CHCl3:MeOH 3:2), and then purified by semi-preparative HPLC (MeOH:H2O 75 –70%, 3 ml/min) to give 1 (12 mg), 2 (7 mg), 5 (7 mg), 18 (7 mg) and 19 (12.7 mg). Fr. 3 (6.0 g) was subjected to columns (MCI gel, H2O:MeOH 10:0, 1:1, 2:8, 1:9 and 0:10; Sephadex LH-20, CHCl3:MeOH 3:2), and then purified by semi-preparative HPLC (MeOH:H2O 65 –60%, 3 ml/min) to afford 6 (45 mg), 7 (22 mg), 8 (6 mg), 9 (9 mg), 15 (52 mg), 20 (129 mg) and 21 (48 mg). Fr. 4 (6.6 g) was isolated similarly and then purified by semipreparative HPLC (MeOH:H2O 55 –40%, 3 ml/min) to obtain 11 (5 mg), 16 (35 mg), 17 (8 mg) and 22 (40 mg). Fr. 6 (7.8 g) was treated similarly and then purified by semi-preparative HPLC
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(MeOH:H2O 50– 40%, 3 ml/min) to yield 3 (15 mg), 4 (87 mg), 10 (47 mg), 12 (2 mg), 13 (5 mg), 14 (8 mg) and 23 (5 mg). Compound 25 (1.2 g) was obtained by the treatment of Fr.7 (14.9 g) with acetone.
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3.3.1. 1,5-Dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) Brown amorphous powder; IR (KBr) nmax cm21: 3385, 3181, 1623, 1598, 1426, 1330; EI-MS: 302 [M]þ, HR-EI-MS m/z 302.1147 [M]þ (calcd for C17H18O5, 302.1154); 1H NMR (CD3OD, 400 MHz): d 6.44 (1H, s, H-2), 6.37 (1H, d, J ¼ 2.8, H-8), 6.32 (1H, d, J ¼ 2.8, H-6), 3.69 (3H, s, OMe-7), 3.68 (3H, s, OMe-3), 3.49 (3H, s, OMe-4), 2.49 (4H, s, H-9 and H-10); 13C NMR (CDCl3, 100 MHz): d 161.7 (s, C-7), 156.5 (s, C-5), 154.7 (s, C-3), 150.0 (s, C-1), 144.1 (s, C-8a), 137.6 (s, C-4), 128.2 (s, C-4a), 120.1 (s, C-10a), 114.4 (s, C-4b), 107.7 (d, C-8), 103.1 (d, C-6), 99.8 (d, C-2), 32.4 (t, C-9), 22.7 (t, C-10), 62.2 (q, OMe-4), 56.3 (q, OMe-3), 55.6 (q, OMe-7). 4. Conclusion In our research, chemical constituents of D. moniliforme were investigated and 25 compounds were isolated and characterised. 1,5-Dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (1) is a new compound. Compounds 3, 4, 13, 16, 17 and 20 were isolated from the Dendrobium genus for the first time, and 2, 5, 7, 9– 12, 14, 15, 18, 21 and 22 were originally obtained from D. moniliforme. Supplementary material Supplementary material relating to this article is available online at http://dx.doi. org/10.1080/14786419.2015.1046379. Disclosure statement No potential conflict of interest was reported by the authors.
Funding This work was supported by the Natural Science Foundation of China [grant number 30860346]; and from Yunnan Province of China [grant number 2009CC018] for basic research in social development.
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