Chemical constituents in leaves of Rubus alceaefolius Poir. (rosaceae) growing in Quang Ninh province

Four compounds as B-sitosterol, 1,8-dihydroxy-3-methoxy- 6-methylanthraquinone (physcion), ursolic acid and 2α,3α,19- trihydroxyurs-12-ene-28-oic acid (euscaphic acid) were isolated from the ethanolic extract of the Rubus alceaefolius leaves growing in Vietnam. Their chemical structures were identified by IR, ESI-MS, 1D and 2D NMR spectral.
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Chemical constituents in leaves of Rubus alceaefolius Poir. (rosaceae) growing in Quang Ninh province JOURNAL OF SCIENCE OF HNUE Natural Sci., 2010, Vol. 55, No. 6, pp. 71-77 CHEMICAL CONSTITUENTS IN LEAVES OF Rubus alceaefolius Poir. (ROSACEAE) GROWING IN QUANG NINH PROVINCE Nguyen Quyet Tien, Pham Thi Hong Minh Institute of Chemistry, VAST Nguyen Thi Tam, Doan Thanh Tuong(∗) Hanoi National University of Education (∗) E-mail: doantuong58@gmail.com Abstract. Four compounds as β-sitosterol (1), 1,8-dihydroxy-3-methoxy- 6-methylanthraquinone (physcion) (2), ursolic acid (3) and 2α,3α,19- trihydroxyurs-12-ene-28-oic acid (euscaphic acid) (4) were isolated from the ethanolic extract of the Rubus alceaefolius leaves growing in Vietnam. Their chemical structures were identified by IR, ESI-MS, 1D and 2D NMR spec- tral. Keywords: Rubus alceaefolius, triterpenoids, anthraquinone.1. Introduction Rubus alceaefolius Poir. plants (Rosaceae) are widely distributed in the Northof Vietnam and used to treat several diseases such as anorexia, dyspepsia... inthe Vietnamese folk medicines [1]. In the last papers [2-5], isolation of the somecompounds as ellagic acid 3-(2,3,4-trihydroxyphenyl) ether; sanguiin H2 ethyl es-ter; 2,3,19,23-tetrahydroxyurs-12-ene-28-oic acid 3,23-O-isopropylidene; 2,3,19,23-tetrahydroxyurs-12-ene-28-oic acid 3-O-(4-hydroxy-3-methoxy-E-cinnamoyl); 7-O-(4-hydroxycinamoyl)-astragalin; 3-O-rhamnopyranosylquercetrin; ellagic acid 3-methylether-7-α-D-rhamnopyranoside; icariside E4; sericic acid; euscaphic acid; rosamutinand ziyu-glycoside I from the leaves of R. Alceaefolius was reported. Further studyon the chemical constituents of this plant growing in Cam Pha, Quang Ninh provinceled to the isolation of β-sitosterol (1), physcion (2), ursolic acid (3) and euscaphicacid (4). Their structures were elucidated by the IR, ESI-MS, 1D and 2D NMRspectral data and comparison with the spectral data of the known compounds. 71 Nguyen Quyet Tien, Pham Thi Hong Minh, Nguyen Thi Tam and Doan Thanh Tuong2. Content2.1. Materials and methods2.1.1. Plant material The sample (leaves) of Rubus alceaefolius Poir. was collected in Cam Pha,Quang Ninh province, in Dec. 2007 and identified by Dr. Ninh Khac Ban, Instituteof Ecology and Biological Resources, VAST.2.1.2. General experimental procedures Melting points were determined using an Electrothermal IA-9200 apparatus.IR spectra were obtained by an IMPACT 410 type spectrometer in KBr disks. TheElectronspray Ionization Mass spectra (ESI/MS) were obtained by using AGILENT1100 LC-MSD Trap spectrometer. 1 H-NMR (500 MHz) and 13 C-NMR (125 MHz)spectra were recorded by a Bruker AM500 FT-NMR spectrometer and TMS wasused as internal standard. Column chromatography (CC) was performed on silicagel (Kieselgel 60, 70-230 mesh and 230-400 mesh, Merck).2.1.3. Extraction and Isolation The powdered sample of Rubuis alceaefolius Poir. (1.6 kg) were extracted threetimes with hot ethanol (at 600 C). The combined extracts were then evaporated togive the ethanolic residue (150.6 g), which was suspended in water and extractedsequentially with n-hexane, ethyl acetate and methanol. β-Sitosterol (25.6 mg)was obtained from the n-hexane extract (26.3 g) by column chromatography. Theethyl acetate extract residue (47.3 g) was subjected to chromatography on a silicagel column, using chloroform and chloroform-methanol (9:1) as eluents to yield sixfractions (fractions A-F). Fraction C (1.6 g) and the combined fractions D-E (2.3g) were separated on column silica gel using CHCl3 -MeOH (9:1) as eluent. Threecompounds: physcion (2) (12.10 mg) from fraction C; ursolic acid (3) (35.2 mg)and euscaphic acid (4) (11.8 mg) were isolated from fraction E-D. * β-Sitosterol (1): White needle crystals, mp. 136 - 1380 C, Rf = 0.50(soltvents n-hexane-EtOAc/5:1). 1 H-NMR (500 MHz, CDCl3 ); δ (ppm): 0.68 (3H, s, Me-18); 1.01 (3H, s, 19-Me); doublet-doublet - δH 0.81/0.88 (2×3H, d, J 7.7 Hz, 26-CH3 and 27-CH3 ); 0.83(3H, t, 7.32 Hz, 29-CH3 ); 0.92 (3H, d, J 10 Hz, 21-CH3 ); 3.52 (1H, m, H-3α); 5.35(1H, d, J 5 Hz, H-6). 13 C-NMR (125 MHz, CDCl3 ); δ (ppm): 37.3 (t, C-1); 31.7 (t, C-2); 71.8 (d,C-3); 42.3 (t, C-4); 140.8 (s, C-5); 121.7 (d, C-6); 31.9 (t, C-7); 33.9 (d, C-8); 50.2(d, C-9); 36.5 (s, C-10); 21.1 (t, C-11); 39.8 (t, C-12); 37.8 (s, C-13); 56.8 (d, C-14);24.3 (t, C-15); 28.3 (t, C-16); 56.1 (d, C-17); 11.9 (q, C-18); 19.4 (q, C-19); 36.2 (d,C-20); 18.8 (q, C-21); 29.5 (t, C-22); 26.2 (t, C-23); 45.9 (d, C-24); 29.2 (d, C-25);72 Chemi ...