Chemical Constituents of Euphorbia sororia

Abstract

Euphorbia sororia Schrenk, an annual herbaceous plant of the genus Euphorbia L. (Euphorbiaceae), is distributed mainly in Central Asia and the Hetian region of Xinjiang in China. Having diuretic, antihypertensive, antiasthmatic, and purgative properties, it is a commonly used medicinal material of Uighur doctors and has been recorded in the pharmacography of Uighur [1]. In this work, we report on the chemical constituents of the aerial parts of E. sororia. The 95% EtOH extracts of the plant were partitioned with EtOAc and n-BuOH, and the corresponding residues, submitted to different chromatographic techniques, such as silica gel, Sephadex LH-20, and MCI-gel columns, led to the isolation and identification of nine chemical compounds. Their structures were identified as astragalin (1), kaempferol-3-O-D-galactoside (2), rutin (3), 24-methylene cycloartanol (4), heptacosanol (5), octacosanol (6), adenosine (7), -sitosterol (8), and daucosterol (9), respectively. Compounds 1, 4–6 are reported from the plant for the first time [2, 3]. All the purified compounds were identified by spectral analysis (1H and 13C NMR, EI-MS) and by comparison with the literature data [2–8]. Plant Material. The plant materials were collected in the Tacheng region of Xinjiang (June 2004) and authenticated by Prof. Zhang Yan Fu (Xinjiang Institute of Materia Medica, China) for E. sororia. Extraction and Isolation. The air-dried aerial parts of E. sororia (10 kg) were extracted three times with 95% aqueous ethanol (v/v) (50 L 3 h) at reflux to give a crude extract (1.8 kg) after concentration at reduced pressure. The extract was suspended in water and extracted with petroleum ether, EtOAc, and n-BuOH successively. The petroleum ether fraction (45 g) was subjected to repeated silica gel column chromatography and eluted with petroleum ether–EtOAc gradient to give compounds 4–7. The EtOAc fraction (45 g) was subjected to repeated silica gel column chromatography and eluted with petroleum ether–EtOAc–MeOH gradient to give compounds 8 and 9. The n-BuOH fraction (30 g) was chromatographed over an AB-8 macroporous absorbent resin column with gradient elution by water, 10% EtOH, and 30% EtOH successively. The 30% EtOH fraction (10 g) was chromatographed over Sephadex LH-20 and MCI gel columns and eluted with H2O–CH3OH in a gradient manner to afford compounds 1–3. Astragalin (1). C21H20O11, light yellow needles (MeOH), mp 163–165 C. HCl-Mg reducion reaction is positive. 1H NMR (600 MHz, CD3OD, , ppm, J/Hz): 8.05 (2H, d, J = 8.4, H-2 , 6 ), 6.88 (2H, d, J = 8.4, H-3 , 5 ), 6.20 (1H, d, J = 1.2, H-6), 6.40 (1H, d, J = 1.2, H-8), 5.35 (1H, d, J = 6.8, H-1 ). 13C NMR (150 MHz, CD3OD, , ppm): 156.6 (C-2), 133.4 (C-3), 177.0 (C-4), 160.1 (C-5), 98.2 (C-6), 164.2 (C-7), 93.7 (C-8), 156.6 (C-9), 104.2 (C-10), 120.9 (C-1 ), 131.0 (C-2 , 6 ), 115.1 (C-3 , 5 ), 160.1 (C-4 ), 101.1 (C-1 ), 74.5 (C-2 ), 76.4 (C-3 ), 71.9 (C-4 ), 76.6 (C-5 ), 60.9 (C-6 ). Kaempferol-3-O-D-galactoside (2). C21H20O11, yellow powder (MeOH), mp 231–232 C. IR (KBr, , cm–1): 3455, 3173, 1656, 1590, 1558, 149, 1302, 1264, 1081, 798. 1H NMR (600MHz, CD3OD, , ppm, J/Hz): 12.50 (H, s, 5-OH), 8.08 (2H, d, J = 9.0, H-6 ), 6.84 (2H, d, J = 9.0, H-3 , 5 ), 6.40 (1H, d, J = 1.2, H-8), 6.20 (1H, d, J = 1.2, H-6), 5.35 (1H, d, J = 7.2, H-1 ). 13C NMR (150 MHz, CD3OD, , ppm, J/Hz): 176.6 (C-4), 164.2 (C-7), 160.1 (C-5), 159.1 (C-4 ), 156.3 (C-9), 156.3 (C-2), 133.2 (C-3), 131.4 (C-2 , 6 ), 120.2 (C-1 ), 114.6 (C-3 , 5 ), 104.4 (C-10), 102.0 (C-1 ), 98.2 (C-6), 93.7 (C-8), 75.7 (C-5 ), 73.9 (C-3 ), 71.7 (C-2 ), 68.0 (C-4 ), 60.1 (C-6 ). 24-Methylene Cycloartanol (4). C41H52O, white amorphous powder (CHCl3), mp 122–123 C. EI-MS m/z 441 [M + H]+. 1H NMR (600 MHz, CDCl3, , ppm, J/Hz): 0.33, 0.55 (each 1H, d, J = 4.2, H2-19), 0.81 (3H, s, H3-30), 0.90 (3H, s, H3-28), 0.90, (3H, d, J = 6.5, H3-21), 0.97 (6H, s, H3-18, 29), 1.02 (3H, d, J = 6.9, H3-27), 1.03 (3H, J = 6.9, H3-26), 4.62, 4.67 (each 1H, br.s, H2-31). 13C NMR (150 MHz, CDCl3, , ppm, J/Hz): 32.0 (C-1), 30.40 (C-2), 78.9 (C-3), 40.5 (C-4), 47.1