5-O-caffeoylquinic acid and cinamic acid from Gleditschia australis Hemsl (Caesalpiniaceae)

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Journal of Chemistry, Vol. 45 (Special issue), P. 127 - 130, 2007 5-O-caffeoylquinic acid and cinamic acid from Gleditschia australis Hemsl., (Caesalpiniaceae) Received 15 October 2007 NGUYEN THI HONG VAN, PHAN VAN KIEM, CHAU VAN MINH, NGUYEN THE DUNG Institute of Natural Products Chemistry, Vietnamese Academy of Science and Technology SUMMARY From the methanolic extract of the leaves of Gleditschia australis Hemsl., (Caesalpiniaceae) 5-O-caffeoylquinic acid (1) and cinnamic acid (2) have been isolated. Their structures were deduced from the spectral evidence and comparison with the literature. I - INTRODUCTION Gleditschia australis Hemsl., belongs to family Caesalpiniaceae and is wildly distributed in Vietnam. The fruits are used to produce soaps, shampoo, medicinal drugs, and local people can sell them for income. It has been used in traditional medicine for various diseases such as inflammation, kidney stone, and diabetes mellitus…[1, 2]. The fruits contain numbers of triterpenes and flavonoids [2]. However, no studies on chemical constituents and bioactivity of the leaves has been carried out. As a part of our study on this plant [3, 4], we report herein the isolation and the structural elucidation of 5-O-caffeoylquinic acid (1) and cinnamic acid (2) from the leaves. II - EXPERIMENTAL 1. Plant material The leaves of G. australis Hemsl. were collected in Tam Dao Mountain, Vinh Phuc province, Vietnam and was identified by Dr Tran Huy Thai, Institute of Ecology and Biological Resources, VAST. A voucher of specimen was deposited at Institute of Natural Products Chemistry (INPC), VAST. 2. General experimental procedures Melting points were determined using an Electro thermal IA-9200. The IR spectra were obtained on a Hitachi 270-30 type spectrometer with KBr discs. Optical rotations were determined on a Jasco DIP-1000 KUY polarimeter. The electrospray ionization (ESI) mass spectra were obtained using an AGILENT 1100 LC-MSD Trap spectrometer. The 1H-NMR (500 MHz) and 13C-NMR (125 MHz) spectra were recorded on a Bruker AM500 FT-NMR spectrometer and TMS was used as an internal standard. Column chromatography (CC) was performed on silica gel (Kieselgel 60, 70 - 230 mesh and 230 - 400 mesh, Merck) and YMC RP-18 resins. 3. Extraction and isolation Dried leaves of G. australis (5.0 kg) were powdered and then extracted three times with MeOH. The MeOH extract (70 g) was suspended in water and partitioned in turn with n-hexane, chloroform, ethyl acetate, and nBuOH to obtain n-hexane, chloroform, ethyl acetate, and n-BuOH fraction. The n-BuOH fraction (8.0 g) was chromatographed on silica gel column using CHCl3-MeOH-H2O (30:10:1) and on YMC column using MeOH-H2O (2:1) to yield compounds 1 (18 mg) and 2 (65 mg). 127 5-O-caffeoylquinic acid (1): Colorless needles; IR (KBr) max cm-1: 3440 (OH), 1725 (C=O), 1445 (C=C), 1055 (C-O-C); ESI-MS m/z: 355 [M+H]+; 353 [M-H]- (C16H18O9); 1HNMR (500 MHz, CD3OD+D2O) and 13C-NMR (125 MHz, CD3OD+D2O): see Table 1. Cinnamic acid (2): Colorless needles; IR (KBr) max cm-1: 3432 (OH), 1714 (C=O), 1445 (C=C); ESI-MS m/z: 149 [M+H]+; 353 [M-H](C9H8O2); 1H-NMR (500 MHz, CDCl3+CD3OD) and 13C-NMR (125 MHz, CDCl3+CD3OD), see table 1. III - RESULTS AND DISCUSSION Repeated column chromatography on silica gel and YMC RP-18 of the n-BuOH fraction of G. australis give compounds 1 and 2 as colorless needles. The IR spectrum of 1 exhibited the presence of OH, C =O and C=C, C-O-C groups at 3440, 1725, 1445 and 1055 cm-1, respectively. The 1H-NMR showed a 1,2,3-substituted benzene ring at 6.70 (1H, dd, J = 2.0, 9.0 Hz), 6.85 (1H, d, J = 9.0 Hz) and 7.11 (1H, d, J = 2.0 Hz); a double bond with trans configuration at 6.32 (1H, d, J = 16.0 Hz) and 7.62 (1H, d, J = 16.0 Hz), and a quinic acid at 2.00-5.37 ppm. The 13C-NMR showed signals of 16 carbons including 9 carbons of the OH O 9' O OH 6 5 7 4 O 2 1 OH caffeoyl unit and 7 carbons of the quinic acid. The substituted benzene ring was confirmed at 115.56, 116.82, 123.14, 127.81, 146.81 and 149.19, a double bond at 116.69 and 146.99 and a carboxyl carbon at 169.55. The presence of a quinic acid unit was confirmed at 181.03 (C=O), 72.31, 72.40, 74.79 (CH), 38.84 and 40.38 (CH2), and a tertiary carbon bearing oxygen atom at 77.77. These evidence suggested the molecular formula of 1 as C16H18O9, which was further confirmed by the ESI-MS with the appearance of the quasi ion peaks at 355 [M+H]+ (positive); 353 [M-H](negative). All the NMR assignments were deduced from HSQC and HMBC spectra and shown in table 1. The key HMBC correlations of 1 were shown in Fig. 2. In the HMBC spectrum, H-5 ( 5.37) correlated to C-9' ( 169.55). This evidence confirmed that the caffeoyl unit linked to C-5 of the quinic acid by ester linkage. Furthermore, the NMR data of 1 were compared to those of 5-O-caffeoylquinic acid and found to match well [5]. This compound had been reported to have insecticide activity, inhibits development of Spodoptera litura larvae, inhibitor of glucose 6-phosphate translocase, shows antiviral (HSV-1), antioxidant activities and scavenging effect on DPPH radical. 8' 7' 2' 3' 1' 4' 6' 8 OH 5' 7 4 OH 9 COOH 1 2 3 2 OH 1 Figure 1: Structures of 1 and 2 The 1H-NMR spectrum of 2 displayed the resonances due to the signals of a benzene ring ( 7.37-7.53, 5H) and a trans double bond at 6.43 (1H, J = 16.0 Hz) and 7.71 (1H, J = 16.0 Hz). The 13C-NMR spectrum showed the signals of 9 carbons, including a benzene ring at 134.31 (C), 128.12 (2 x CH), 128.84 (2 x CH) and 128 130.33 (CH), a carbonyl carbon and the double bond were assigned at 169.56, 117.91 and 145.74, respectively. These evidence together with the appearance of the quasi ion peaks at 149 [M+H]+ and 147 [M-H]- in the ESI-MS led to the structure of 2 as cinnamic acid, which was reported as an anaesthetic, anthelmintic, phytotoxic, cell differentiation inducer, and protein isoprenylation inhibitor. OH O O 9' OH 6 7 O 2 4 5 3 8' 2' 7' 3' 1' 4' 6' OH 5' OH 1 OH OH H C Figure 2: HMBC correlations of 1 Table 1: The NMR data of 1 and 2 C 1 2 3 4 5 6 7 1' 2' 3' 4' 5' 6' 7' 8' 9' 1 a,b C 77.77 38.84 72.82 74.79 72.67 40.38 181.03 127.81 115.31 146.41 149.19 115.48 123.14 146.99 116.69 169.55 2 a,c d,b C H 2.11 (m); 2.14 (m) 4.17 (dd, J = 6.5, 3.5 Hz) 3.74 (dd, J = 3.5, 10.0 Hz) 5.37 (m) 2.00 (m); 2.18 (m) 7.11 (d, J = 2.0 Hz) 6.85 (d, J = 9.0 Hz) 6.70 (dd, J = 2.0, 9.0 Hz) 7.62 (d, J = 16.0 Hz) 6.32 (d, J = 16.0 Hz) - 134.31 128.12 128.84 130.33 128.84 128.12 145.74 117.91 169.56 d,c H 7.53 (m) 7.38 (m)* 7.38 (m)* 7.38 (m)* 7.53 (m) 7.72 (d, J = 16.0 Hz) 6.43 (d, J = 16.0 Hz) - a Measured in CD3OD&D2O, b125 MHz, c500 MHz, dMeasured in CDCl3&CD3OD; Chemical shift ( ) in ppm, *Overlapped signals. Acknowledgments: The authors would like to thank Dr Tran Huy Thai, Institute of Ecology and Biological Resources, VAST for the plant identification. REFERENCES 1. V. V. Chi, Vietnamese Medical Plant Dictionary. Medicinal Publishing House, (1997). 2. D. H. Bich, D. Q. Trung, B. X. Chuong, N. T. Dong, D. T. Dam, P. V. Hien, V. N. Lo, P. D. Mai, P. K. Man, D. T. Nhu, N. Tap, and T. Toan, The medicinal plants and animals of Vietnam, Hanoi Science and 129 Technology Publisher, 1st edition, Hanoi, Vol. II. pp. 635 - 636 (2004). 3. P. V. Kiem, N. T. H. Van, P. K. Tiep, C. V. Minh, L. M. Huong, N. D. Tomasi, A. Braca. Journal of Pharmacy (Vietnamese), Vol. 372 (4), 33 - 36 (2007). 4. N. T. H. Van, P. V. Kiem, C. V. Minh, N. T. 130 Dung. Flavonoid constituents from Gleditschia australis Hemsl., (Caesalpiniaceae), Journal of Pharmacy (Vietnamese), submitted (2007). 5. L. C. Lin, Y. C. Kuo, and C. J. Chou. Journal of Natural Products, Vol. 62(3), 405 - 408 (1999).
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