A new derivative of butanenitrile from euphorbia hirta L

JOURNAL OF SCIENCE OF HNUE DOI: 10.18173/2354-1059.2016-0055 Natural Sci. 2016, Vol. 61, No. 9, pp. 48-52 This paper is available online at 48 A NEW DERIVATIVE OF BUTANENITRILE FROM Euphorbia hirta L. Le Thi Thu Huong, Nguyen Thi My Hanh, Ngo Van Khue, Vu Hai My and Nguyen Nhu Ngoc Faculty of Chemistry, Ho Chi Minh City University of Pedagogy Abstract. From the ethyl acetate extract of Euphorbia hirta L. collected in Vietnam, four isolated compounds were gallic acid (1), blumenol C glucoside (2), corchoionoside C (3) and 3,4-dihydroxy-2-methylenebutanenitrile 4-O--D-glucopyranoside (4). The structures of these compounds were elucidated by spectroscopic data and compared with the literature. The results showed that 3,4-dihydroxy-2-methylenebutanenitrile 4-O--D-glucopyranoside is a new derivative which has not been reported yet. Keywords: Euphorbiaceae, Euphorbia hirta, butane nitrile. 1. Introduction Euphorbia hirta L. belongs to the plant family Euphorbiaceae. The medicinal uses include anti-diarrheal, anti-spasmodic, anti-inflammatory, and diuretic. It promotes wound healing, and it is also used in treating coughs, chronic bronchitis and other pulmonary disorders, tumors, gonorrhoea, jaundice, dysentery, and boils [1]. Some phytochemical studies on the plant have revealed the presence of triterpenoids [2], flavonoids, phenolic [3] and megastigmane glucoside [4]. In this study, we mentioned the isolation and structure of four compounds: gallic acid (1), blumenol C glucoside (2), corchoionoside C (3) and a new 3,4-dihydroxy-2- methylenebutanenitrile 4-O--D-glucopyranoside (4). Gallic acid (1), blumenol C glucoside (2), corchoionoside C (3) and 3,4-dihydroxy-2-methylenebutanenitrile 4-O--D-glucopyranoside (4) Received October 4, 2016. Accepted November 25, 2016. Contact Le Thi Thu Huong, e-mail address: huonghctn@yahoo.com A new derivative of butanenitrile from Euphorbia hirta L. 49 2. Content 2.1. Experiment 2.1.1. Materials and equipments The aerial part of Euphorbia hirta was collected in Dong Nai province, Vietnam in July 2013. The scientific name was identified by Dr. Pham Van Ngot, Faculty of Biology Ho Chi Minh City University of Pedagogy (HCMUP). The voucher specimen (EH01) was deposited at the Faculty of Chemistry, HCMUP. TLC was carried out on pre-coated Silica gel GF254 (Merck Co., Germany). NMR spectra were recorded on a Brucker Avance 500 (500 MHz for 1 H NMR and 125 MHz for 13 C NMR). The chemical shift () values were given in ppm with TMS as the internal standard, coupling J in Hz. The high resolution ESI-MS was performed on APEX III FTICR mass spectrometer equipped with a 7 Tesla super-conducting magnet. 2.1.2. Extraction and isolation The powder of dried aerial part of E. hirta (12 kg) was extracted three times with 96% ethanol (20 L × 3) at room temperature for one week, and then concentrated to 3 L in vacuum. The concentrated extract was washed with petroleum ether (5 L, 60 g), ethyl acetate (6 L, 335 g) and butanol (2 L, 100 g). The ethyl acetate fraction (335 g) was sequentially submitted to column chromatography (silica gel, petroleum ether/ethyl acetate (1:1 - 0:1) to afford five fractions (from EA1 to EA5). The EA1 fraction (petroleum ether/ethyl acetate 1:1, 60 g) was chromatographed to give a compound named 1 with the weight of 50 mg. The EA3 fraction (petroleum ether/ethyl acetate 3:7, 50 g) was separated by comprising silica gel column chromatography and preparative thin-layer chromatography (ethyl acetate-methanol). Finally, compounds named 2, 3, 4 with the weight of 15 mg, 63 mg and 30 mg, respectively, were obtained from the EA3 fraction. Compound 1: white powder, 1 H NMR (acetone-d6), H: 7.14 (2H, s, H-2 and H-6). 13 C NMR (acetone-d6), C: 167.6 (COOH), 146.0 (C-3 and C-5), 138.6 (C-1), 122.1 (C-4), 110.1 (C-2 and C-6). Compound 1 was characterized as gallic acid by comparing spectral data with that reported in the literature [5]. Compound 2: amorphous and colourless solid, []D 25 +39 (c, 0.1, MeOH), 1 H NMR (DMSO- d6), H: 5.71 (1H, s, H-4), 4.15 (1H, d, 8.0, H-1’), 3.72 (1H, m, H-9), 3.65 (1H, br d, 13.0, H-6’), 3.41 (1H, dd, 12.5, 5.5, H-6’), 3.10 (1H, m, H-3’), 3.06 (1H, m, H-4’), 3.03 (1H, m, H-5’), 2.91 (1H, m, H-2’), 2.37 (1H, d, 17.0, H-2), 1.96 (3H, s, H-13), 1.87 (1H, d, 17.0, H-2), 1.87 (1H, m, H-6), 1.70 (1H, m, H-7), 1.53 (1H, m, H-7), 1.53 (2H, m, H-8), 1.15 (3H, d, 6.0, H-10), 1.00 (3H, s, H-11), 0.94 (3H, s, H-12); 13 C NMR (DMSO-d6), 198.1 (C-3), 165.4 (C-5), 124.1 (C-4), 102.3 (C-1’), 76.9 (C-5’), 76.7 (C-3’), 74.7 (C-9), 73.5 (C-2’), 70.2 (C-4’), 61.0 (C-6’), 50.4 (C-6), 47.1 (C-2), 36.1 (C-1), 35.5 (C-8), 28.7 (C-12), 26.7 (C-11), 24.8 (C-7), 24.0 (C-13), 21.6 (C-10). 1 H NMR and 13 C NMR spectra agreed with the data given in the literature for blumenol C glucoside [6]. Compound 3: amorphous and colourless solid, []D 25 +25 (c, 0.25, MeOH), 1 H NMR (DMSO-d6), H: 5.76 (1H, m, H-4), 5.94 (1H, d, 15.5, H-7), 5.64 (1H, dd, 15.5, 6.5, H-8), 4.42 (1H, m, H-9), 4.09 (1H, d, 7.5, H-1’), 3.63 (1H, m, H-6’), 3.42 (1H, m, H-6’), 3.03 (1H, m, H- Le Thi Thu Huong, Nguyen Thi My Hanh, Ngo Van Khue, Vu Hai My and Nguyen Nhu Ngoc 50 3’), 3.03 (1H, m, H-4’), 2.95 (1H, m, H-2’), 2.95 (1H, m, H-5’), 2.54 (1H, d, 17.0, H-2), 2.05 (1H, d, 17.0, H-2),1.82 (3H, d, 1.0, H-13), 1.18 (3H, d, 6.5, H-10), 0.93 (3H, s, H-11), 0.91 (3H, s, H-12); 13 C NMR (DMSO-d6), 197.4 (C-3), 163.8 (C-5), 131.7 (C-7), 131.5 (C-8), 125.6 (C-4), 100,0 (C-1’), 78.0 (C-6), 77.2 (C-5’), 77.0 (C-3’), 73,3 (C-2’), 72.1 (C-9), 70.1 (C-4’), 61.1 (C-6’), 49.4 (C-2), 40.9 (C-1), 24.1 (C-12), 23.1 (C-11), 22.1 (C-10), 18.7 (C-13). 1 H NMR and 13 C NMR spectra agreed with data given in the literature for corchoionoside C [7]. Compound 4: amorphous powder, 1 H NMR and 13 C NMR (MeOD): see Table 1. The key HMBC correlations of compound 4: see Figure 2; The high resolution ESI-FTICR-MS: (positive mode) m/z 298.0923 [M+Na] + (calcd. for C11H17NO7, 298.0897) (see Figure 3). 2.2. Results and discussion Compound 4 was isolated as an amorphous powder. Its molecular formula determined by electro-spray ionization (ESI-FTICR-MS) was C11H17NO7. 1 H NMR spectrum showing the presence of one group of methylene, two of oxymethylene and six of oxymethine. 13 C NMR spectrum exhibited eleven carbons: two of alkene, one of nitrile at C 118.1, two of oxymethylene and six of oxymethine (Table 1). Table 1. NMR data of the compound 4 (MeOD) Position H (ppm) (J = Hz) C (ppm) HMBC ( 1H→13C) 1 118.1 2 125.1 3 4.47 (1H, m) 72.0 1, 2, 4, 5 4 4 4.04 (1H, dd, 10.5, 4.0) 3.67 (1H, dd, 10.8, 7.5) 73.1 1’, 2, 3 5 5 6.19 (1H, d, 1.5) 6.13 (1H, d, 1.0) 132.9 1, 2, 3 1’ 4.36 (1H, d, 8.0) 104.7 2’, 3’, 4 2’ 3.24 (1H, t, 8.0) 75.0 1’, 3’, 4’ 3’ 3.39 (1H, dd, 9.5, 8.5) 77.8 2’, 5’ 4’ 3.33 (1H, m) 71.5 2’, 3’, 5’, 6’ 5’ 3.33 (1H, m) 78.0 3’, 4’, 6’ 6’ 6’ 3.90 (1H, br d, 11.5) 3.70 (1H, m) 62.6 4’, 5’ A new derivative of butanenitrile from Euphorbia hirta L. 51 Figure 2. Key HMBC correlations of 4 Figure 3. The HR-ESI-MS of 4 HMBC spectrum showed correlations between olefinic proton signals H-5 at H 6.19, 6.13 and the signals at C 118.1 (C-1), 125.1 (C-2), 72.0 (C-3). Further, the oxymethine proton at H 4.47 (H-3) also correlated to C-1, C-2, C-4 and C-5. Similarly, the oxymethylene proton H-4 at H 4.04 and 3.67 was coupled to C-1’, C-2, C-3. Thus, the aglycone of compound 4 was 3, 4- dihydroxy-2-methylenebutannitrile. A combination of 1 H NMR, 13 C NMR spectra with DEPT mode measurement showed the presence of a -D-glucopyranosyl moiety from the signals at C 104.7 and H 4.36. The exact location of the sugar was determined by HMBC method with the correlation between H-1’ anomeric and C-4 peaks. Therefore, the structure of compound 4 was established as 3, 4- dihydroxy-2-methylenebutanenitrile 4-O--D-glucopyranoside which was a new compound in nature [8]. However, in this study, the absolute configurations of compound 4 have not been determined yet. 3. Conclusion From Euphorbia hirta L. collected in Dong Nai, Vietnam, by using basic separation and isolation techniques in laboratory, four compounds were successfully isolated. All the structure of these compounds was elucidated by modern spectroscopic methods. 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