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Journal of Chemistry, Vol. 45 (Special issue), P. 131 - 135, 2007 A new derivative of furancarboxaldehyde from Chlorophytum laxum R. Br. (Athericaceae) Received 21 March 2007 1 nguyen thi hoai , pham thanh ky1, chau van minh2, Phan Van Kiem2 1 Hanoi Institute of Pharmacy, Ministry of Health 2 Institute of Natural Products Chemistry, Vietnamese Academy of Science and Technology SUMMARY From the methanol extract of the leaves of Chlorophytum laxum R. Br. (Athericaceae), a new (1) and two known (2, 3) derivatives of furancarboxaldehyde, and a derivative of anthraquinone (4) were isolated by various chromatography methods. Their structures were elucidated as 5(ethoxymethyl)-2-furancarboxaldehyde (1), 5-hydroxymethyl-2-furancarboxaldehyde (2) and cirsiumaldehyde (3) and 1,5-dihydroxy-3-hydroxymethylanthraquinone (4) by analyses of the NMR (1D-, 2D-NMR), EI-MS and ESI-MS spectra. This is the first report of 2, 3, and 4 from C. laxum. I - INTRODUCTION In previous paper, we have reported the isolation and structural elucidation of one new and three known flavone glycosides from Chlorophytum laxum, which is used in folk medicine. As a part of our work on phytochemical and bioactive components from this plant [4], we report herein the isolation and structural determination of a new (1) and two known (2, 3) derivatives of furancarboxaldehyde together with a derivative of anthraquinone (4) isolated from C. laxum. II - Experimental 1. General experimental procedures The Electronspray Ionization (ESI) mass spectrum was obtained using a 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 using TMS as the internal standard. Column chromatography (CC) was performed on silica gel (Kieselgel 60, 70-230 mesh and 230 - 400 mesh, Merck) or YMC RP8 resins (30 - 50 µm, Fujisilisa Chemical Ltd). Thin layer chromatography (TLC) was performed on DC-Alufolien 60 F254 (Merck 1.05715) or RP18 F254s (Merck) plates. 2. Plant material The roots of Chlorophytum laxum R. Br. (Athericaceae) were collected in A Roang, A Dot, A Luoi, Thua-Thien-Hue, in September, 2006 and were identified by Dr Duong Duc Huyen, Institute of Ecology and Biological Resources, VAST. An authentic sample was deposited at this Institute. 3. Extraction and isolation The roots (1.0 kg) of C. laxum were washed, dried and powdered, then extracted repeatedly with hot MeOH (three times). The combined solutions were evaporated under reduced pressure to give MeOH extract (15.0 g), which was suspended in water and then partitioned with n-hexane, chloroform, ethyl acetate, nbutanol to give the n-hexane (1.5 g), chloroform 131 crystals. Compound 4 (22 mg) was obtained as orange crystals from the ethyl acetate extract (2.6 g) after repeated chromatography on silica gel columns. (5.5 g), ethyl acetate (2.6 g), n-butanol 2.0 (g) extracts and water layer. The chloroform extract (5.5 g) was then repeated chromatographed on silica gel columns to get 1 (15 mg), 2 (45 mg) as white needles, and 3 (17 mg) as pale yellow 4 8 2 5 6 7 4 3 H3CH 2COH 2C 1 6 CHO O 3 2 5 HOH 2C O 1 2 O 3' 4 4' 5' 1' OHC 6' O 6 2 5 1 O O OH 3 8 2' 1 CHO CHO 7 6 5 OH 3 10 9 14 13 1 11 2 12 4 3 15 CH2OH O 4 Figure 1: The structures of 1 - 4 5-(ethoxymethyl)-2-furancarboxaldehyde (1): White needles. EI-MS: m/z: 154 [M]+•(C8H10O3). IR (KBr) max (cm-1): 3447.6 (OH), 2981.4, 2866.6(C-H), 1677.5 (C=O), 1097.2 (C-O-C).1H-NMR (500 MHz, CDCl3) and 13C-NMR (125 MHz, CDCl3): see tables 1 and 2. 5-hydroxymethyl-2-furancarboxaldehyde (2): White needles. EI-MS m/z: 126 [M]+• (C6H6O3). 1H-NMR (500 MHz, CDCl3) and 13CNMR (125 MHz, CDCl3): see tables 1 and 2. Cirsiumaldehyde (3): Pale yellow crystals. ESI-MS m/z: 235 [M+H]+ (C12H10O5). Mp 115116oC, IR (KBr) max (cm-1): 3325.7 (OH), 2931.2, 2852.3 (C-H), 1667.2 (C=O), 1045.5 (C-O-C). 1H-NMR (500 MHz, CDCl3) and 13CNMR (125 MHz, CDCl3): see tables 1 and 2. 1,5-dihydroxy-3hydroxymethylanthraquinone (4): Orange crystal, mp. 233-235oC. ESI-MS m/z: 271 [M+H]+ (C15H10O5). 1H-NMR (500 MHz, CDCl3) and 13C-NMR (125 MHz, CDCl3), see table 3. 132 III - RESULTS AND DISCUSSION Compound 1 was obtained as white needles from the methanolic extract of the roots of C. laxum. The 1H-NMR spectrum of 1 showed a singlet signal at 9.62 (1H) of the aldehydic proton, two doublets at 7.21 (1H, J = 3.5 Hz) and 6.51 (1H, J = 3.5 Hz) suggesting the presence of a furano ring [2], a singlet of the methylene group bearing oxygen atom at 4.53 (2H). The ethylene group bearing to oxygen atom was confirmed at 3.59 (2H, q, J = 7.0 Hz) and at 1.24 (3H, t, J = 7.0 Hz). The 13CNMR spectrum of 1 exhibited signals of 8 carbons including an aldehydic carbon at 177.71, the furan ring at 158.80, 152.61, 121.84 and 110.96 [2], a methylene carbon at 64.67 and a ethylene group at 66.63 and 15.05. The chemical shift assignments of protons and carbons of 1 were elucidated from its HSQC and HMBC spectra. In the HSQC spectrum, a singlet at H 9.62 coupled with signal at C 177.71, proton at 7.21 coupled with carbon at 152.61, H-4 at 6.51 linked to C-4 at 110.96, a singlet at H 4.53 coupled with carbon at 64.77, as well as signals at 3.59 and 1.24 coupled with carbon signals at 66.63 and 15.05, respectively. Table 1: The 1H-NMR data of 1 - 3 1 C a,b H 1 3 4 6 7 8 6-OH 1' 2' 3' 4' 5' 6' (J, Hz) 2 HMBC 9.62 (br s) 7.21 (d, 3.5) 6.51 (d, 3.5) 4.53 (s) 3.59 (q, 7.0) 1.24 (t, 7.0) 2, 4, 5 2, 3, 5 4, 5, 7 6 7 a,b 3 (J, Hz) HMBC 9,53 (br s) 7.22 (d, 3,5) 6.51 (d, 3,5) 4.65 (d, 3,5) 2 2, 4, 5 2, 3, 5 4, 5 H a,b H (J, Hz) HMBC 9.63 (br s) 7.20 (d, 3.5) 6.56 (d, 3.5) 4.63 (s) 2, 3 1, 2, 4, 5 2, 3, 5, 6 4, 5, 6' 9.63 (br s) 7.20 (d, 3.5) 6.56 (d, 3.5) 4.63 (s) 2', 3' 1', 2', 4', 5' 2', 3', 5', 6' 4', 5', 6 3.87 (br s) a Measured in CDCl3, b500 MHz. Comparing the NMR data of 1 to those of 5hydroxymethyl-2-furancarboxaldehyde [2] led to suggest the structure of 1 as 5(ethoxymethyl)-2-furancarboxaldehyde (Fig. 1), which was further confirmed by HMBC and MS spectra. In the HMBC spectrum, the H-6 proton ( 4.53) correlated with C-5 ( 158.80)/C-4 ( 110.96)/C-7 ( 66.63), the H-4 ( 6.51) correlated with C-2 ( 152.61)/C-3 ( 121.84)/C-6 ( 64.77). This evidence confirmed the presence of a furancarboxaldehyde structure [2] and the ethylene group linked to C-6 by an ether linkage. Furthermore, the EI mass spectrum of 1 exhibited an ion peak at m/z 154 [M]+, corresponding to molecular formula C8H10O3. From the above data, compound 1 was determined to be 5-(ethoxymethyl)-2furancarboxaldehyde, which was first isolated from nature. The NMR spectra of 2 and 3 were very similar to those of 1, except for the absence of the ethylene signals in the NMR spectra of 2 and 3. This evidence as well as the exhibition of an ion peak at m/z 126 (corresponding to the molecular formula of C6H6O3) in the EI mass spectrum of 2, and a quasi ion peak at m/z 235 [M+H]+• (corresponding to the molecular formula of C12H10O5) in the ESI mass spectrum of 3 led to identify compounds 2 and 3 as 5hydroxymethyl-2-furancarboxaldehyde and cirsiumaldehyde, respectively [2]. These compounds showed antibacterial activity [2]. The NMR data of compound 4 was compared to those of 1,5-dihydroxy-3hydroxymethylanthraquinone and found to match [3]. In addition, all its NMR assignments were reconfirmed by HMQC, HMBC spectra as shown in table 3. 133 Table 2: The 13C-NMR data of 1 - 3 2 1 C 3 a.b C a.b C 1 177.71 # 178.2 177.74 * 177.7 177.69 2 152.61 152.2 152.08 152.9 152.79 3 121.84 124.1 123.23 121.7 121.78 4 110.96 110.2 109.90 111.8 111.82 5 158.80 161.6 161.02 157.3 157.21 6 64.77 57.1 57.26 64.6 64.60 7 66.63 8 15.05 1' 177.7 177.69 2' 152.9 152.79 3' 121.7 121.78 4' 111.8 111.82 5' 157.3 157.21 64.6 64.60 C 6' a Measured in CDCl3, b125 MHz, # C C of 5-hydroxymethyl-2-furancarboxaldehyde [2], * C of cirsiumaldehyde [2]. Table 3: The NMR data of 4 C 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a a,b C 161.32 120.66 153.65 117.05 161.61 124.37 137.27 119.28 133.31 181.43 114.43 133.09 191.58 115.87 62.03 DEPT CH CH CH CH CH CH2 a,c H 7.28 (1H, d, J = 1.0 Hz) 7.68 (1H, d, J = 1.0 Hz) 7.37 (1H, dd, J = 8.0, 1.0 Hz) 7.80 (1H, dd, J = 8.0, 8.0 Hz) 7.70 (1H, dd, J = 8.0, 1.0 Hz) 4.62 (2H, s) Measured in DMSO-d6, b125 MHz, c500 MHz. 134 HMBC C-1, C-4, C-14, C-15 C-2, C-14, C-15, C-6 C-7, C-8, C-10, C-11 C-8, C-9. C-11, C-12 C-9. C-12, C-7, C-13 C-2, C-3, C-4 REFERENCES 1. Vo Van Chi. Vietnamese Medical Plant Dictionary, Hanoi Medicine Pub. (1997). 2. Yue-mao Shen and Quan-zhang Mu. Planta Medica, Vol. 56, 472 - 474 (1990). 3. Sedat Imre, Sezen Sar and Ronald H. Thomson. Phytochemistry, Vol. 15, 317 320 (1976). 4. Nguyen Thi Hoai, Pham Thanh Ky, Chau Van Minh, Phan Van Kiem. Pharmaceutical Journal, Vol. 372 (4), 29 - 32 (2007). 135