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New spermidine alkaloids from Capparis spinosa roots
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Phytochemistry Letters 1 (2008) 59–62 www.elsevier.com/locate/phytol
New spermidine alkaloids from Capparis spinosa roots Xiao Pu Fu a, Tao Wu a, Miriban Abdurahim b, Zhen Su a, Xue Ling Hou a, Haji Akber Aisa a,*, Hankui Wu a a
Xinjiang Key Laboratory of Plant Resources and Natural Products Chemistry, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 Beijing South Road, Urumqi 830011, China b Pharmaceutical Institute, Xinjiang Medical University, Urumqi 830054, China Received 6 November 2007; received in revised form 8 January 2008; accepted 9 January 2008 Available online 6 February 2008
Abstract Three new spermidine alkaloids capparispine (1), capparispine 26-O-b-D-glucoside (2) and cadabicine 26-O-b-D-glucoside hydrochloride (3) were isolated from the roots of Capparis spinosa. Their structures were established on the basis of spectroscopic analysis, including 1D and 2D NMR experiments (1H–1H COSY, HSQC, HMBC). # 2008 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. Keywords: Capparis spinosa; Capparidaceae; Spermidine alkaloids; Capparispine; Capparispine 26-O-b-D-glucoside; Cadabicine 26-O-b-D-glucoside hydrochloride
1. Introduction The traditional uses of the medicinal plant Capparis spinosa L. (Capparidaceae) as an effective herbal drug for the treatment of rheumatism (Fu, Aisa, Abdurahim, & Yili, 2007) have attracted our interest to investigate its secondary metabolites. The plant is widely distributed in Xinjiang Uighur Autonomous Region, China. It has been used since ancient times in traditional medicine especially for the treatment of rheumatism and gout. In an earlier research, we have isolated and identified the alkaloids from C. spinosa fruits (Fu et al., 2007). As a part of ongoing research, we have investigated the roots of C. spinosa. The present paper reports the isolation and characterization of three novel spermidine alkaloids. 2. Results and discussion Compound 1 was obtained as an amorphous white solid, positive to Dragendorff’s test, and exhibited a molecular formula of C25H29N3O4 as determined by HRESIMS. The IR spectrum of 1 presented absorptions at 1653 and 1616 cm1 for a- and b-unsaturated amides and at 1601 and 1504 cm1 for * Corresponding author. Tel.: +86 991 3835679; fax: +86 991 3835679. E-mail address: [email protected] (H.A. Aisa).
aromatic rings. The UV spectrum displayed maximum at 217.0 and 284.8 nm which were very close to those of cadabicine (Ahmad, Amber, Arif, Chen, & Clardy, 1985) and isocodonocarpine (Ahmad, Ismail, & Amber, 1989). In the 1H NMR spectrum of compound 1 (Table 1), two doublets at dH 7.07 (d, 2H, J = 9.0 Hz) and 7.62 (d, 2H, J = 9.0 Hz) with orthocoupling constants showed the presence of a para-substituted benzene ring. A typical ABX system at dH 6.86 (d, 1H, J = 9.0 Hz), 7.09 (d, 1H, J = 1.8 Hz) and 6.81 (dd, 1H, J = 8.4, 1.8 Hz) suggested the existence of a 1,2,4-trisubstituted benzene ring. In addition, resonances at dH 7.36 (d, 1H, J = 15.6 Hz) and 6.55 (d, 1H, J = 15.6 Hz) showed the presence of two protons belonging to a double bond in the E configuration. In comparison with the literature data (Tawil, Zhu, Plantini, & Hese, 1989), resonances at dH 6.37 (d, 1H, J = 12.6 Hz) and 5.70 (d, 1H, J = 2.6 Hz) due to the presence of two protons belonging to a double bond in the Z configuration. Doublet at dH 6.86 (d, 1H, J = 8.4 Hz), which showed only ortho- but not meta-coupling, was assigned to H-25. A doublet at dH 7.09, which showed only a meta-coupling (J = 1.8 Hz), was due to H-27. Another doublet at dH 6.81 with an ortho- and a meta-coupling (J = 8.4, 1.8 Hz) was attributed to H-24. Resonances at dC 125.9, 147.8 and 116.1 were assigned to C-24, C-25 and C-27 by HSQC spectrum, respectively. Long-range HMBC correlation from the olefinic protons at dH 6.37 (d, 1H, J = 12.6 Hz) to aromatic carbons at dC 116.7 (C-24) and 125.9
1874-3900/$ – see front matter # 2008 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.phytol.2008.01.001
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X.P. Fu et al. / Phytochemistry Letters 1 (2008) 59–62
Table 1 1 H and 13C NMR data for compounds 1–3 (in DMSO-d6), d in ppm, J in Hz 1
1 3 4, 28 5, 29 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 10 20 30 40 50 60
2
3
dH
dC
dH
dC
dH
dC
– – 7.07 7.62 – 7.36 6.55 – 8.50 3.29 1.58 2.59 – 2.35 1.23 1.18 2.58 7.87 – 5.70 6.37 – 6.81 6.86 – 7.09
145.4 156.5 120.8 129.2 130.8 137.3 122.4 165.4 – 38.7 26.6 47.5 – 48.1 28.1 26.8 39.5 – 166.0 122.2 134.0 126.7 125.9 116.1 147.8 116.7
– – 7.10 d (8.4) 7.64 d (8.4) – 7.38 d (15.6) 6.56 d (15.6) – 8.47 t (4.8) 3.3 m 1.59 m 2.63 m – 2.36 m 1.28 m 1.21 m 2.63 m 7.87 t (4.8) – 5.79 d (12.6) 6.45 d (12.6) – 6.91 dd (7.8, 1.8) 7.16 d (8.4) – 7.09 d (1.8) 5.06 d (7.2) 3.3 m 3.3 m 3.19 m 3.3 m 3.69 dd (10.2, 3.6) 3.48 m
146.9 156.1 121.2 129.2 131.1 137.3 122.4 165.2 – 38.7 26,8 47.4 – 48.0 28.0 26.6 38.8 – 165.6 123.4 133.9 129.2 125.1 115.6 146.9 116.4 99.3 73.1 76.8 69.6 77.1 60.6
– – 7.22 d (8.4) 7.73 d (8.4) – 7.50 d (15.6) 6.67 d (15.6) – 8.23 t (6.0) 3.40 m 1.85 m 2.85 m 9.00 brs 2.85 m 1.66 m 1.40 m 3.16 m 8.15 t (5.4) – 5.90 d (15.6) 7.25 d (15.6) – 7.06 dd (8.4, 1.8) 7.19 d (8.4) – 6.36 d (1.8) 5.10 d (7.2) 3.3,m 3.3,m 3.17 t (9.0) 3.3 m 3.69 dd (10.8, 1.0) 3.49 dd (10.8, 6.0)
150.0 155.6 122.9 129.8 133.5 138.0 124.7 165.3 – 36.0 25.8 44.1 – 46.3 23.0 25.6 38.7 – 164.8 120.2 138.0 128.6 125.3 116.2 147.7 110.2 99.9 73.3 77.1 69.8 77.3 60.8
d (9.0) d (9.0) d (15.6) d (15.6) t (4.8) m m m t (7.2) m m m t (5.4) d (12.6) d (12.6) dd (8.4, 1.8) d (9.0) d (1.8)
(C-27) suggested the (Z)-olefin was attached to the 1,2,4trisubstituted benzene ring. HMBC cross-peak between aromatic protons at dH 7.36 and (E)-olefinic carbon at dC 137.3 confirmed that the (E)-olefin was adjacent to the paradisubstituted benzene ring. In addition, the HMBC spectra showed that the (Z)-olefinic proton at dH 6.37 and amide proton at dH 7.87 (t, 1H, J = 5.4 Hz) were correlated with a carboxyl carbon at dC 166.00. (E)-olefinic proton at dH 7.36 and amide proton at dH 8.50 (t, 1H, J = 4.8 Hz) were correlated with a carboxyl carbon at dC 165.4. This information established that the resonances at dH 7.87 (t, 1H, J = 5.4 Hz) and 8.50 (t, 1H, J = 4.8 Hz) were assigned to H-19 and H-10, respectively. 1 H–1H COSY spectra indicated that the methylene protons at dH 3.29 (m, 2H, H-11) was coupled with the amide proton on 10-N at dH 8.50 (t, 1H, J = 4.8 Hz) as well as methylene signal at dH 1.58 (m, 2H, H-12). Downfiled signal at dH 2.59 (m, 2H, H-13) coupled with H-12 supported that methylene on C-13 was attached to N-14. The exact attachment of spermidine moiety with the rest of the molecule was confirmed according to analysis of the 1H–1H COSYand HMBC spectrum. On the basis of the above results, compound 1 was established as a novel spermidine alkaloid which has a Z configuration olefin and named capparispine (Fig. 1).
Compound 2, a white amorphous powder, exhibited in ESIMS a quasi-molecular ion peak at m/z 598 [M + 1]+ and 436 [M + 1–162]+, in accordance with the molecular formula C31H39N3O9. IR spectrum showed absorptions at 3382 (OH, NH), 1645, 1615 (a,b-unsaturated amides) and 1577, 1506 cm1 (aromatic ring). Its UV absorptions maxima were observed at 285.2 and 213.6 nm. The resonances of the 1H NMR and 13C NMR at dH 5.06 (d, 1H, J = 7.2 Hz) and dC 99.3, 73.1, 76.8, 69.6, 60.6, 77.1 suggested the presence of a bglucopyransol unit. Comparing the NMR data of 2 with those of 1 allowed the identification of the aglycon in capparispine. HMBC correlation of the glucose proton at dH 5.06 with C-26 at dC 146.9 suggested this glucose moiety was attached to C-26. Major HMBC correlations were shown in Fig. 2. All of the above arguments determined the structure of 2 as capparispine 26-O-b-D-glucoside. Compound 3 was a water-soluble amorphous white solid. Its HRESIMS exhibited a pseudo-molecular ion peak at m/z 598.27309 [M + 1]+ ascribable to a molecular formula C31H40N3O9. The IR and UV spectra were close to those of cadabicine. The structure of 3 was identified to be composed of cadabicine and b-glucose moiety by comparison of its 1H and 13 C NMR spectral data with those of cadabicine (Ahmad et al.,
X.P. Fu et al. / Phytochemistry Letters 1 (2008) 59–62
61
Fig. 1. Structures of the isolated compounds from Capparis spinosa roots.
1985). In the HMBC spectrum, cross-peak between H-10 at dH 5.10 and aromatic carbon at dC 158.4 confirmed that the glucose moiety was linked at C-26. Exchangeable protons at dH 9.00 (2H, brs) which showed coupling correlation with resonances at dH 2.85 (m, 4H, H-13, 15) in COSY spectrum were assigned to 14-NH2. All of the assignments based on a series of 2D NMR experimental (COSY, HSQC and HMBC) supported the structure of 3 for cadabicine 26-O-b-D-glucoside hydrochloride. 3. Experimental 3.1. Extraction and isolation The roots of C. spinosa were collected from Turpan, Xinjiang Uighur Autonomous Region, China, in June 2004 and identified as C. spinosa L. (family: Capparidaceae) by Prof. Shiming Duan from Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, where a voucher specimen has been deposited. Air-dried, powdered roots of C. spinosa (1.8 kg) were homogenized with 70% EtOH (4 6 L) and kept overnight at RT. After removal of solvent, the residue was suspended in H2O (1 L) and acidified with 5% H2SO4 to pH
Fig. 2. Selective HMBC correlations for 2.
2–3. The precipitate was filtered and the acidified aqueous solution was treated with saturated water solution of ammonium reineckate to precipitate all of the alkaloids. The precipitate was filtered, washed with water and dried. Dissolved the dried precipitates in acetone, and then filtered. Excess of Ag2SO4 saturated water solution was added to the acetone filtration and the precipitate was filtered off. Equal molecular solution of BaCl2 was added to the filtrate and the precipitate was filtered off. The aqueous solution was evaporated to yield a crude alkaloids hydrochloride (25 g). The material was subjected to silica gel CC and eluted sequentially with CHCl3–MeOH–NH4OH (7:2:0.2) and CHCl3–MeOH (1:1, 1:2) to give three fractions. Fr.1 was purified by neutral Al2O3 CC and eluted sequentially with CHCl3–MeOH (20:1, 5:1) and then eluted with CHCl3–MeOH–diethylamine (4:1:0.05), to give compounds 1 (15 mg). Fr.2 was fractionated by ODS CC with H2O–MeOH (20:80) as elucidation and then purified on silica gel CC with CHCl3–MeOH (6:4) as elucidation to give compound 2 (12 mg). Fr.3 was applied sequentially on silica gel CC with CHCl3–MeOH (3:1, 1:1) as elution and ODS CC with H2O to afford compound 3 (140 mg). Capparispine (1), amorphous white solid, mp 263 8C (decomp); UV lmax (MeOH) nm (log e): 284.8 (3.18), 217.0 1 (3.14); IR vKBr max cm : 3347, 3250 (OH, NH), 1653 (a,bunsaturated amide), 1558, 1541, 1506 (aromatic ring). ESIMS: m/z 436 [M + 1]+, m/z 458 [M + Na]+, HRESIMS: m/z 436.22533 [M + 1]+ (calcd. for 436.22363); ESIMS: m/z (ref. int.): 419 (40), 362 (12), 348 (100), 320 (8), 291 (39), 265 (44), 202 (12), 172 (33); 1H, 13C NMR, see Table 1. Capparispine 26-O-b-D-glucoside (2), amorphous white solid, mp 168–170 8C; [a]D20 29.4 (c 0.63, MeOH); UV lmax 1 (MeOH) nm (log e): 285.2 (4.37), 213.0 (4.38); IR vKBr max cm : 3382 (OH, NH), 1645, 1615 (a,b-unsaturated amides), 1577, 1506 (aromatic ring); ESIMS: m/z 598 [M + 1]+, m/z 436 [M + 1-glu]+; HRESIMS: m/z 598.27724 [M + 1]+ (calcd. for 598.27645); 1H, 13C NMR, see Table 1. Cadabicine 26-O-b-D-glucoside hydrochloride (3), amorphous white solid, mp 179 8C (decomp); [a]D20 23.6 (c 0.64, MeOH); UV lmax (MeOH) nm (log e): 280.2 (4.49), 217.6 1 (4.39); IR vKBr max cm : 3377 (OH, NH), 1659 (a,b-unsaturated amide), 1581, 1506 (aromatic ring); ESIMS: m/z 598 [M + 1]+,
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X.P. Fu et al. / Phytochemistry Letters 1 (2008) 59–62
m/z 436 [M + 1-glu]+; HRESIMS: m/z 598.27309 [M + 1]+ (calcd. for 598.27645); 1H, 13C NMR, see Table 1. Acknowledgements This research was supported by the funds of National Natural Science Foundation of China (no. 30560190). Biological activities were completed by the National Center for Drug Screening, Shanghai Institute of Material Medical, Chinese Academy of Sciences.
References Ahmad, V. U., Amber, A. R., Arif, S., Chen, M. H. M., & Clardy, J. (1985). Cadabicine, an alkaloid from Cadaba farinose. Phytochemistry, 24, 2709– 2711. Ahmad, V. U., Ismail, N., & Amber, A. R. (1989). Isocodonocarpine from Capparis decidua. Phytochemistry, 28, 2493–2495. Fu, X. P., Aisa, H. A., Abdurahim, M., & Yili, A. (2007). Chemical constitution of Capparis spinosa fruits. Chemistry of Natural Compounds, 43, 181–183. Tawil, B. F., Zhu, J.-P., Plantini, U., & Hese, M. (1989). New spermine alkaloids from Aphelandra tetragona (Vahl) Nees. Helvetica Chimica Acta, 72, 180– 184.
Phytochemistry Letters 1 (2008) 59–62 www.elsevier.com/locate/phytol
New spermidine alkaloids from Capparis spinosa roots Xiao Pu Fu a, Tao Wu a, Miriban Abdurahim b, Zhen Su a, Xue Ling Hou a, Haji Akber Aisa a,*, Hankui Wu a a
Xinjiang Key Laboratory of Plant Resources and Natural Products Chemistry, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 40-1 Beijing South Road, Urumqi 830011, China b Pharmaceutical Institute, Xinjiang Medical University, Urumqi 830054, China Received 6 November 2007; received in revised form 8 January 2008; accepted 9 January 2008 Available online 6 February 2008
Abstract Three new spermidine alkaloids capparispine (1), capparispine 26-O-b-D-glucoside (2) and cadabicine 26-O-b-D-glucoside hydrochloride (3) were isolated from the roots of Capparis spinosa. Their structures were established on the basis of spectroscopic analysis, including 1D and 2D NMR experiments (1H–1H COSY, HSQC, HMBC). # 2008 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. Keywords: Capparis spinosa; Capparidaceae; Spermidine alkaloids; Capparispine; Capparispine 26-O-b-D-glucoside; Cadabicine 26-O-b-D-glucoside hydrochloride
1. Introduction The traditional uses of the medicinal plant Capparis spinosa L. (Capparidaceae) as an effective herbal drug for the treatment of rheumatism (Fu, Aisa, Abdurahim, & Yili, 2007) have attracted our interest to investigate its secondary metabolites. The plant is widely distributed in Xinjiang Uighur Autonomous Region, China. It has been used since ancient times in traditional medicine especially for the treatment of rheumatism and gout. In an earlier research, we have isolated and identified the alkaloids from C. spinosa fruits (Fu et al., 2007). As a part of ongoing research, we have investigated the roots of C. spinosa. The present paper reports the isolation and characterization of three novel spermidine alkaloids. 2. Results and discussion Compound 1 was obtained as an amorphous white solid, positive to Dragendorff’s test, and exhibited a molecular formula of C25H29N3O4 as determined by HRESIMS. The IR spectrum of 1 presented absorptions at 1653 and 1616 cm1 for a- and b-unsaturated amides and at 1601 and 1504 cm1 for * Corresponding author. Tel.: +86 991 3835679; fax: +86 991 3835679. E-mail address: [email protected] (H.A. Aisa).
aromatic rings. The UV spectrum displayed maximum at 217.0 and 284.8 nm which were very close to those of cadabicine (Ahmad, Amber, Arif, Chen, & Clardy, 1985) and isocodonocarpine (Ahmad, Ismail, & Amber, 1989). In the 1H NMR spectrum of compound 1 (Table 1), two doublets at dH 7.07 (d, 2H, J = 9.0 Hz) and 7.62 (d, 2H, J = 9.0 Hz) with orthocoupling constants showed the presence of a para-substituted benzene ring. A typical ABX system at dH 6.86 (d, 1H, J = 9.0 Hz), 7.09 (d, 1H, J = 1.8 Hz) and 6.81 (dd, 1H, J = 8.4, 1.8 Hz) suggested the existence of a 1,2,4-trisubstituted benzene ring. In addition, resonances at dH 7.36 (d, 1H, J = 15.6 Hz) and 6.55 (d, 1H, J = 15.6 Hz) showed the presence of two protons belonging to a double bond in the E configuration. In comparison with the literature data (Tawil, Zhu, Plantini, & Hese, 1989), resonances at dH 6.37 (d, 1H, J = 12.6 Hz) and 5.70 (d, 1H, J = 2.6 Hz) due to the presence of two protons belonging to a double bond in the Z configuration. Doublet at dH 6.86 (d, 1H, J = 8.4 Hz), which showed only ortho- but not meta-coupling, was assigned to H-25. A doublet at dH 7.09, which showed only a meta-coupling (J = 1.8 Hz), was due to H-27. Another doublet at dH 6.81 with an ortho- and a meta-coupling (J = 8.4, 1.8 Hz) was attributed to H-24. Resonances at dC 125.9, 147.8 and 116.1 were assigned to C-24, C-25 and C-27 by HSQC spectrum, respectively. Long-range HMBC correlation from the olefinic protons at dH 6.37 (d, 1H, J = 12.6 Hz) to aromatic carbons at dC 116.7 (C-24) and 125.9
1874-3900/$ – see front matter # 2008 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.phytol.2008.01.001
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X.P. Fu et al. / Phytochemistry Letters 1 (2008) 59–62
Table 1 1 H and 13C NMR data for compounds 1–3 (in DMSO-d6), d in ppm, J in Hz 1
1 3 4, 28 5, 29 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 10 20 30 40 50 60
2
3
dH
dC
dH
dC
dH
dC
– – 7.07 7.62 – 7.36 6.55 – 8.50 3.29 1.58 2.59 – 2.35 1.23 1.18 2.58 7.87 – 5.70 6.37 – 6.81 6.86 – 7.09
145.4 156.5 120.8 129.2 130.8 137.3 122.4 165.4 – 38.7 26.6 47.5 – 48.1 28.1 26.8 39.5 – 166.0 122.2 134.0 126.7 125.9 116.1 147.8 116.7
– – 7.10 d (8.4) 7.64 d (8.4) – 7.38 d (15.6) 6.56 d (15.6) – 8.47 t (4.8) 3.3 m 1.59 m 2.63 m – 2.36 m 1.28 m 1.21 m 2.63 m 7.87 t (4.8) – 5.79 d (12.6) 6.45 d (12.6) – 6.91 dd (7.8, 1.8) 7.16 d (8.4) – 7.09 d (1.8) 5.06 d (7.2) 3.3 m 3.3 m 3.19 m 3.3 m 3.69 dd (10.2, 3.6) 3.48 m
146.9 156.1 121.2 129.2 131.1 137.3 122.4 165.2 – 38.7 26,8 47.4 – 48.0 28.0 26.6 38.8 – 165.6 123.4 133.9 129.2 125.1 115.6 146.9 116.4 99.3 73.1 76.8 69.6 77.1 60.6
– – 7.22 d (8.4) 7.73 d (8.4) – 7.50 d (15.6) 6.67 d (15.6) – 8.23 t (6.0) 3.40 m 1.85 m 2.85 m 9.00 brs 2.85 m 1.66 m 1.40 m 3.16 m 8.15 t (5.4) – 5.90 d (15.6) 7.25 d (15.6) – 7.06 dd (8.4, 1.8) 7.19 d (8.4) – 6.36 d (1.8) 5.10 d (7.2) 3.3,m 3.3,m 3.17 t (9.0) 3.3 m 3.69 dd (10.8, 1.0) 3.49 dd (10.8, 6.0)
150.0 155.6 122.9 129.8 133.5 138.0 124.7 165.3 – 36.0 25.8 44.1 – 46.3 23.0 25.6 38.7 – 164.8 120.2 138.0 128.6 125.3 116.2 147.7 110.2 99.9 73.3 77.1 69.8 77.3 60.8
d (9.0) d (9.0) d (15.6) d (15.6) t (4.8) m m m t (7.2) m m m t (5.4) d (12.6) d (12.6) dd (8.4, 1.8) d (9.0) d (1.8)
(C-27) suggested the (Z)-olefin was attached to the 1,2,4trisubstituted benzene ring. HMBC cross-peak between aromatic protons at dH 7.36 and (E)-olefinic carbon at dC 137.3 confirmed that the (E)-olefin was adjacent to the paradisubstituted benzene ring. In addition, the HMBC spectra showed that the (Z)-olefinic proton at dH 6.37 and amide proton at dH 7.87 (t, 1H, J = 5.4 Hz) were correlated with a carboxyl carbon at dC 166.00. (E)-olefinic proton at dH 7.36 and amide proton at dH 8.50 (t, 1H, J = 4.8 Hz) were correlated with a carboxyl carbon at dC 165.4. This information established that the resonances at dH 7.87 (t, 1H, J = 5.4 Hz) and 8.50 (t, 1H, J = 4.8 Hz) were assigned to H-19 and H-10, respectively. 1 H–1H COSY spectra indicated that the methylene protons at dH 3.29 (m, 2H, H-11) was coupled with the amide proton on 10-N at dH 8.50 (t, 1H, J = 4.8 Hz) as well as methylene signal at dH 1.58 (m, 2H, H-12). Downfiled signal at dH 2.59 (m, 2H, H-13) coupled with H-12 supported that methylene on C-13 was attached to N-14. The exact attachment of spermidine moiety with the rest of the molecule was confirmed according to analysis of the 1H–1H COSYand HMBC spectrum. On the basis of the above results, compound 1 was established as a novel spermidine alkaloid which has a Z configuration olefin and named capparispine (Fig. 1).
Compound 2, a white amorphous powder, exhibited in ESIMS a quasi-molecular ion peak at m/z 598 [M + 1]+ and 436 [M + 1–162]+, in accordance with the molecular formula C31H39N3O9. IR spectrum showed absorptions at 3382 (OH, NH), 1645, 1615 (a,b-unsaturated amides) and 1577, 1506 cm1 (aromatic ring). Its UV absorptions maxima were observed at 285.2 and 213.6 nm. The resonances of the 1H NMR and 13C NMR at dH 5.06 (d, 1H, J = 7.2 Hz) and dC 99.3, 73.1, 76.8, 69.6, 60.6, 77.1 suggested the presence of a bglucopyransol unit. Comparing the NMR data of 2 with those of 1 allowed the identification of the aglycon in capparispine. HMBC correlation of the glucose proton at dH 5.06 with C-26 at dC 146.9 suggested this glucose moiety was attached to C-26. Major HMBC correlations were shown in Fig. 2. All of the above arguments determined the structure of 2 as capparispine 26-O-b-D-glucoside. Compound 3 was a water-soluble amorphous white solid. Its HRESIMS exhibited a pseudo-molecular ion peak at m/z 598.27309 [M + 1]+ ascribable to a molecular formula C31H40N3O9. The IR and UV spectra were close to those of cadabicine. The structure of 3 was identified to be composed of cadabicine and b-glucose moiety by comparison of its 1H and 13 C NMR spectral data with those of cadabicine (Ahmad et al.,
X.P. Fu et al. / Phytochemistry Letters 1 (2008) 59–62
61
Fig. 1. Structures of the isolated compounds from Capparis spinosa roots.
1985). In the HMBC spectrum, cross-peak between H-10 at dH 5.10 and aromatic carbon at dC 158.4 confirmed that the glucose moiety was linked at C-26. Exchangeable protons at dH 9.00 (2H, brs) which showed coupling correlation with resonances at dH 2.85 (m, 4H, H-13, 15) in COSY spectrum were assigned to 14-NH2. All of the assignments based on a series of 2D NMR experimental (COSY, HSQC and HMBC) supported the structure of 3 for cadabicine 26-O-b-D-glucoside hydrochloride. 3. Experimental 3.1. Extraction and isolation The roots of C. spinosa were collected from Turpan, Xinjiang Uighur Autonomous Region, China, in June 2004 and identified as C. spinosa L. (family: Capparidaceae) by Prof. Shiming Duan from Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, where a voucher specimen has been deposited. Air-dried, powdered roots of C. spinosa (1.8 kg) were homogenized with 70% EtOH (4 6 L) and kept overnight at RT. After removal of solvent, the residue was suspended in H2O (1 L) and acidified with 5% H2SO4 to pH
Fig. 2. Selective HMBC correlations for 2.
2–3. The precipitate was filtered and the acidified aqueous solution was treated with saturated water solution of ammonium reineckate to precipitate all of the alkaloids. The precipitate was filtered, washed with water and dried. Dissolved the dried precipitates in acetone, and then filtered. Excess of Ag2SO4 saturated water solution was added to the acetone filtration and the precipitate was filtered off. Equal molecular solution of BaCl2 was added to the filtrate and the precipitate was filtered off. The aqueous solution was evaporated to yield a crude alkaloids hydrochloride (25 g). The material was subjected to silica gel CC and eluted sequentially with CHCl3–MeOH–NH4OH (7:2:0.2) and CHCl3–MeOH (1:1, 1:2) to give three fractions. Fr.1 was purified by neutral Al2O3 CC and eluted sequentially with CHCl3–MeOH (20:1, 5:1) and then eluted with CHCl3–MeOH–diethylamine (4:1:0.05), to give compounds 1 (15 mg). Fr.2 was fractionated by ODS CC with H2O–MeOH (20:80) as elucidation and then purified on silica gel CC with CHCl3–MeOH (6:4) as elucidation to give compound 2 (12 mg). Fr.3 was applied sequentially on silica gel CC with CHCl3–MeOH (3:1, 1:1) as elution and ODS CC with H2O to afford compound 3 (140 mg). Capparispine (1), amorphous white solid, mp 263 8C (decomp); UV lmax (MeOH) nm (log e): 284.8 (3.18), 217.0 1 (3.14); IR vKBr max cm : 3347, 3250 (OH, NH), 1653 (a,bunsaturated amide), 1558, 1541, 1506 (aromatic ring). ESIMS: m/z 436 [M + 1]+, m/z 458 [M + Na]+, HRESIMS: m/z 436.22533 [M + 1]+ (calcd. for 436.22363); ESIMS: m/z (ref. int.): 419 (40), 362 (12), 348 (100), 320 (8), 291 (39), 265 (44), 202 (12), 172 (33); 1H, 13C NMR, see Table 1. Capparispine 26-O-b-D-glucoside (2), amorphous white solid, mp 168–170 8C; [a]D20 29.4 (c 0.63, MeOH); UV lmax 1 (MeOH) nm (log e): 285.2 (4.37), 213.0 (4.38); IR vKBr max cm : 3382 (OH, NH), 1645, 1615 (a,b-unsaturated amides), 1577, 1506 (aromatic ring); ESIMS: m/z 598 [M + 1]+, m/z 436 [M + 1-glu]+; HRESIMS: m/z 598.27724 [M + 1]+ (calcd. for 598.27645); 1H, 13C NMR, see Table 1. Cadabicine 26-O-b-D-glucoside hydrochloride (3), amorphous white solid, mp 179 8C (decomp); [a]D20 23.6 (c 0.64, MeOH); UV lmax (MeOH) nm (log e): 280.2 (4.49), 217.6 1 (4.39); IR vKBr max cm : 3377 (OH, NH), 1659 (a,b-unsaturated amide), 1581, 1506 (aromatic ring); ESIMS: m/z 598 [M + 1]+,
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m/z 436 [M + 1-glu]+; HRESIMS: m/z 598.27309 [M + 1]+ (calcd. for 598.27645); 1H, 13C NMR, see Table 1. Acknowledgements This research was supported by the funds of National Natural Science Foundation of China (no. 30560190). Biological activities were completed by the National Center for Drug Screening, Shanghai Institute of Material Medical, Chinese Academy of Sciences.
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