The traditional medicinal plant Euphorbia sororia A. Schrenk (Euphorbiaceae) is distributed mainly in northwestern China and certain regions of Central Asia. Seeds of E. sororia are used for treating chest pain, stomach stress, skin diseases, and stroke in addition to increasing mental capabilities and appetite [1]. Previous investigations of the aerial part of E. sororia isolated several sphingolipids, flavonoids, and coumarins [2–5].

Herein we report data on triterpenoids isolated from the slightly polar fraction of the MeOH extract of the whole plant. Chromatography and rechromatography of the fraction over a column of silica gel using various solvent systems isolated six triterpenoids 1–6. PMR and 13C NMR spectra in addition to DEPT experiments and two-dimensional HSQC and HMBC (Tables 1 and 2) and IR and electrospray positive- and negative-ion mass spectra (MS ES PI and NI) were interpreted to identify the isolated compounds as β-amyrin acetate (1) [6], β-amyrin (2) [7], oleanolic acid (3) [8], maslinic acid (4) [9], friedelin (5) [10], and cycloart-23Z-en-3β,25-diol (6) [11].

Table 1 Chemical Shifts of C and H Atoms of 1–4. DEPT, HSQC, HMBC Data (CDCl3, C5D5N, δ, ppm, J/Hz, 0 = TMS)
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Table 2 Chemical Shifts of C and H Atoms of 5, 6. DEPT, HSQC, HMBC Data (CDCl3, C5D5N, δ, ppm, J/Hz, 0 = TMS)
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Chemical shifts of C-24, C-26, and C-29 in the 13C NMR spectrum of maslinic acid (4) were revised relative to those published [9].

All triterpenoids described herein were isolated for the first time from E. sororia. Maslinic acid was found for the first time in the genus Euphorbia.

General Comments. PMR and 13C NMR spectra in CDCl3 or C5D5N were recorded on an INOVA-400 (Varian) spectrometer with TMS internal standard. 13C NMR spectra were obtained with full C–H decoupling and under DEPT conditions; 2D spectra, using standard Varian programs.

IR spectra in KBr disks were recorded on a Shimadzu FTIR-8400s spectrophotometer; electrospray positive- and negative-ion mass spectra, in a VG autospec-3000 mass spectrometer.

Column chromatography used silica gel (200–300 mesh, Qingdao Haiang Chemical Co., Ltd.) and MCI-gel (CHP 20P, 75–150 μm).

E. sororia was grown in 2007 in Jimsaer (Xinjiang Uygur Autonomous Region, P. R. China) and was identified by Dr. G. M. Shen (Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences). A specimen with a voucher (XJIPC0236) was stored at Xinjiang Technical Institute of Physics and Chemistry, Academy of Sciences of the PRC.

Isolation and Separation of Isoprenoids fromE. sororia. Air-dried ground whole plant (28 kg) was extracted exhaustively with MeOH (5 × 50 L) at room temperature. MeOH was evaporated from the total extracted substances, which were suspended in water and extracted with petroleum ehter. Solvent was evaporated to afford extract (2 kg) that was separated into two fractions by chromatography over a column of silica gel with elution by petroleum ether (fraction A) and MeOH (fraction B). Fraction B was rechromatographed over a column of MCI-gel CHP 20P with elution first by MeOH:H2O (9:1) and then MeOH. The fraction eluting with MeOH:H2O was evaporated (fraction C, 400 g) and rechromatographed over a column of silica gel with elution successively by petroleum ether and solvent systems petroleum ether:acetone (100:1→100:10), CHCl3, and CHCl3:acetone (100:1→0:100). Elution with petroleum ether:acetone (100:2) isolated β-amyrin acetate (1, 15 mg) and friedelin (5, 13 mg). Fractions eluted by petroleum ether:acetone (100:5) produced β-amyrin (2, 4 mg). Petroleum ether:acetone (100:7) eluted a cycloartane triterpenoid (6, 12 mg). Then, elution of the column by CHCl3 isolated oleanolic acid (3, 21 mg). Continued elution of the column by CHCl3:acetone (100:5) isolated maslinic acid (4, 42 mg).

β-Amyrin acetate (1), C32H52O2, colorless needle-like crystals, mp 238–240°C (MeOH). IR spectrum (KBr, νmax, cm–1): 2960, 2846, 1735, 1456, 1366, 1241, 1032, 900. MS ES PI (m/z): 469 [M + H]+. PMR spectrum (400 MHz, CDCl3, δ, ppm, J/Hz, 0 = TMS): 0.81 (s, CH3-28), 0.85 (s, CH3-23), 0.85 (s, CH3-24), 0.94 (s, CH3-29), 0.94 (s, CH3-30), 0.98 (s, CH3-25), 0.98 (s, CH3-26), 1.13 (s, CH3-27), 2.04 (s, CH3COO), 4.45 (dd, 3J1 = 9, 3J2 = 6, H-3), 5.16 (t, 3J1 = 3J2 = 3.5, H-12) [6]. Table 1 lists the 13C NMR spectrum.

β-Amyrin (2), C30H50O, colorless needle-like crystals, mp 196–198°C (MeOH). IR spectrum (KBr, νmax, cm–1): 2958, 2868, 1456, 1382. MS ES PI (m/z): 427 [M + H]+. PMR spectrum (400 MHz, CDCl3, δ, ppm, J/Hz, 0 = TMS): 0.80, 0.86, 0.88, 0.89, 0.94, 0.98, 1.02, 1.11 (all s, 8 × CH3), 3.15 (dd, 3J1 = 10.4, 3J2 = 5.4, H-3), 5.16 (t, 3J1 = 3J2 = 3.5, H-12) [7]. Table 1 lists the 13C NMR spectrum.

Oleanolic acid (3), C30H48O3, colorless needles, mp 303-305°C (MeOH). IR spectrum (KBr, νmax, cm–1): 3403, 2930, 1691, 1455, 1380, 1275, 1053, 812. MS ES NI (m/z): 455 [M –H]–. PMR spectrum (400 MHz, CDCl3, δ, ppm, J/Hz, 0 = TMS): 0.78, 0.79, 0.90, 0.91, 0.92, 1.00, 1.15 (all s, 7 × CH3), 2.81 (dd, 3J1 = 9, 3J2 = 6.2, H-18), 3.22 (dd, 3J1 = 9.1, 3J2 = 4.7, H-3), 5.30 (t, 3J1 = 3J2 = 3.5, H-12) [8]. Table 1 lists the 13C NMR spectrum.

Maslinic acid (4), C30H48O4, white powder. IR spectrum (KBr, νmax, cm–1): 3415, 3280, 2945, 1697, 1462, 1050. MS ES PI (m/z): 495 [M + Na]+ [9]. Table 1 lists the PMR and 13C NMR spectra.

Friedelin (5), C30H50O, colorless needles recrystallized from MeOH. IR spectrum (KBr, νmax, cm–1): 2925, 2865, 1715, 1460, 1385. MS ES PI (m/z): 427 [M + H]+. PMR spectrum (400 MHz, CDCl3, δ, ppm, J/Hz, 0 = TMS): 0.72 (s, CH3-24), 0.87 (s, CH3-25), 0.89 (d, 3J = 6.8, CH3-23), 0.95 (s, CH3-30), 1.00 (s, CH3-29), 1.01 (s, CH3-26), 1.05 (s, CH3-27), 1.18 (s, CH3-28), 2.24 (m, H-4), 2.30 (m, H-2), 2.38 (ddd, 2J = 16, 3J1 = 3.6, 3J2 = 1.6, H-2′) [10]. Table 2 lists the 13C NMR spectrum.

Cycloart-23Z-en-3β,25-diol (6), C30H50O2, colorless needles crystallized from CHCl3:CH3OH. IR spectrum (KBr, νmax, cm–1): 3655, 3324, 3038, 2970, 2931, 2866, 1467, 1377, 1358, 1224, 1163, 1104, 1051, 971, 890. MS ES PI (m/z): 443 [M + H]+ [11]. Table 2 lists the PMR and 13C NMR spectra.