New anthraquinone derivatives from the roots of

Berchemia floribunda

Xin Wei, Jian Shuang Jiang, Zi Ming Feng, Pei Cheng Zhang *

Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine (Ministry of Education), Institute of Materia

Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China

Abstract

A new naphthoquinone–anthraquinone dimer named floribundiquinone E (1) and a new anthraquinone 2-acetylphyscion (2)

were isolated from the roots of Berchemia floribunda Brongn. Their structures were elucidated on the basis of spectroscopic

methods.

# 2007 Published by Elsevier B.V. on behalf of Chinese Chemical Society.

Keywords: Berchemia floribunda; Anthraquinone; Floribundiquinone E; 2-Acetylphyscion

The genus Berchemia (Rhamnaceae) comprises about 31 species, occurring mainly in Asian. Eighteen of them have

a wide distribution in the south of China. Its root has been used for treatment of gall-stone, stomach-ache, rheumatism

and lumbago in traditional Chinese medicine [1]. In the course of our chemical studies of the roots of Berchemia

floribunda Brongn, floribundiquinone E (1), a new naphthoquinone–anthraquinone dimer, and a new anthraquinone

(2) were isolated from this plant. Their structures were elucidated on the basis of spectroscopic methods.

Compound 1 [2] was obtained as red powders. The IR spectrum indicated the presence of hydroxyl, carbonyl and

aromatic groups. The HRESIMS of 1 showed a molecular ion peak at m/z 542.1232 corresponding to molecular

formula of C30H22O10. The UV spectrum of 1 showed maxima absorption at 203, 222, 250 (sh), 283 and 435 nm in

MeOH, these data revealed that 1 possesses quinone moieties.

The 1H NMR spectrum of 1 indicated the presence of three phenolic hydroxyl groups at dH 13.08 (s, 1H), 12.27

(s, 1H), and 12.03 (s, 1H), two methoxy groups at dH 3.87 (s, 3H) and 3.84 (s, 3H), and three methyl groups at dH 2.64

(s, 3H), 1.99 (s, 3H), and 2.47 (s, 3H). In addition, the 1H NMR spectrum also showed the presence of four aromatic

protons, two of which were meta coupled (J = 2.0 Hz) at dH 7.10 and 7.67, while the others were sharp singlets at dH

6.09 and 7.52. The 13C NMR spectrum showed 30 carbon signals. Compared the NMR data of 1 with those of the

corresponding signals in physcion [3], data of 1 were similar to those of physcion except the proton signal at C-70 was

absented and the chemical shift of C-70 shifted to downfield. These results were furthermore confirmed by HMBC

(Fig. 1 Fig. 1). In HMBC, the correlations of hydroxyl proton at dH 12.03 (s, 1H) with C-10 at dC 162.8, C-20 at dC 124.8

and C-90a at dC 113.9, hydroxyl proton at dH 12.27 (s, 1H) with C-70 at dC 121.6, C-80 at dC 161.1 and C-80a at dC 111.5,

methyl protons at dH 2.47 (s, 3H) with C-20 at dC 124.8, C-30 at dC 148.9 and C-40 at dC 121.7, and methoxyl protons at

dH 3.87 (s, 3H) with C-60 at dC 163.2 were observed. The remaining NMR data suggested the existence of a

naphthoquinone unit. Additionally, the carbon signals at dC 203.7, 32.3, 17.1, and 56.8 in the 13C NMR spectrum

www.elsevier.com/locate/cclet

Chinese Chemical Letters 18 (2007) 412–414

* Corresponding author.

E-mail address: pczhang@imm.ac.cn (P.C. Zhang).

1001-8417/$ – see front matter # 2007 Published by Elsevier B.V. on behalf of Chinese Chemical Society.

doi:10.1016/j.cclet.2007.02.001

revealed that a methyl, a methoxyl, a hydroxyl and an acetyl groups exist in the naphthoquinone unit [4]. While the

positions of the methyl and acetyl groups in the naphthoquinone unit located at C-6 and C-7, respectively, confirmed

by the HMBC spectrum, which exhibited the correlations of dH 2.64 (s, 3H) with C-6 at dC 138.1 and C-11 at dC 203.7,

and dH 1.99 (s, 3H) with C-6 at dC 138.1, C-7 at dC 143.4 and C-8 at dC 128.5, and the positions of hydroxy and methoxy

located at C-2 and C-5, respectively. The HMBC spectrum, exhibited the correlations of dH 3.84 (s, 3H) with C-2 at dC

161.0 and dH 13.08 (s, 1H) with C-5 at dC 158.3, C-6 at dC 138.1 and C-10 at dC 113.7. So, compound 1 is a combination

of two sub-units physcion and naphthoquinone. The biaryl connectivity was determined at the C-8 and C-70 positions

on the basis of the facts that C-70and C-8 were quaternary carbons and their chemical shifts were in downfield. On the

other hand, in HMBC spectrum, the C-8 terminus of biaryl bond at dC 128.5 correlated over three bonds with H-13 at

dH 1.99, and C-70at the other end of the biaryl bond at dC 121.6 correlated with H-50 at dH 7.52. Therefore, the structure

of compound 1 was elucidated as depicted and was named floribundiquinone E.

Compound 2 [5] was obtained as a yellow powder, The IR spectrum of 2 showed the presence of hydroxyl groups,

conjugated carbonyl and aromatic rings. The HRESIMS of 2 showed a positive ion peak at m/z 327.0863,

corresponding to molecular formula C18H15O6. In the UV spectrum of 2, it gave the maxima absorption at 209, 227,

288 and 436 nm, suggesting the existence of the skeleton of anthraquinone. The 13C NMR spectrum of 2 showed 18

carbon signals. Except for 14 carbon signals of the anthraquinone skeleton, two methyl carbon signals, one methoxyl

signal and one carbonyl signal were observed. The 1H NMR spectrum of 2 showed three aromatic protons signals, of

which two at dH 6.71 (d, 1H, J = 2.5 Hz) and 7.39 (d, 1H, J = 2.5 Hz) were meta coupled and a singlet signal at dH 7.66

(s, 1H). In addition, two methyl signals at dH 2.39 (s, 3H) and 2.61 (s, 3H), one methoxyl signal at dH 3.95 (s, 3H), and

two aromatic hydroxyl signals at dH 12.19 (s, 1H) and 12.49 (s, 1H) were presented in the 1H NMR spectrum. Thus, an

anthraquinone with five substitutions can be deduced, in which one of the benzene rings was di-substituted, while the

other benzene ring was tri-substituted. Furthermore, the positions of these groups were given by the detailed HMBC

analysis (Fig. 1). In the HMBC spectrum, correlations between aromatic protons at dH 7.66 (s, 1H) and 7.39 (d, 1H,

J = 2.5 Hz) with the carbonyl carbon at dC 181.5 were present, while dH 7.39 (d, 1H, J = 2.5 Hz) and 6.71 (d, 1H,

J = 2.5 Hz) were meta coupled. All of these suggested that dH 7.66 (s, 1H) was located at C-4, dH 7.39 and 6.71 were

located at C-5 and C-7. Additionally, in view of the correlations between hydroxyl proton at dH 12.49 (s, 1H), methyl

proton at dH 2.61 (s, 3H) and aromatic proton at dH 7.66 with C-2 at dC 136.3, dH 12.49 (s, 1H) with C-9a at dC 114.1, dH

2.61 (s, 3H) with carbonyl carbon at dC 203.0, dH 7.66 with the methyl at dC 20.1, it was deduced that the hydroxyl must

locate at C-1, acetyl located at C-2 and methyl located at C-3. Combined all the above information, the structure of 2

was identified as 2-acetyl-1, 8-dihydroxy-6-methoxy-3-methyl-anthraquinone.

References

[1] S. Inoshiri, M. Sasaki, Y. Hirai, H. Kohda, H. Otsuka, K. Yamasaki, Chem. Pharm. Bull. 34 (1) (1986) 1333.

[2] Floribundiquinone E, red powder; mp 144–146 8C, [a]D20 + 16 (c 0.10, CHCl3), UV (MeOH) lmax 203, 222, 250 (sh), 283, 435 nm; IR (KBr) n

3477, 3334, 2976, 1709, 1635, 1626, 1597, 1558, 1485, 1423, 1383, 1209, 1115, 758 cm�1; 1H NMR (500 MHz, CDCl3, d ppm): 6.09 (s, 1H,

H-3), 13.08 (s, 1H, H-5), 2.64 (s, 3H, H-12), 1.99 (s, 3H, H-13), 3.84 (s, 3H, 2-OMe), 12.03 (s, 1H, H-10), 7.10 (d, 1H, J = 2.0 Hz, H-20), 7.67 (d,

1H, J = 2.0 Hz, H-40), 7.52 (s, 1H, H-50), 12.27 (s, 1H, H-80), 2.47 (s, 3H, 30-Me) and 3.87 (s, 3H, 60-OMe); 13C NMR data (125 MHz, CDCl3, d

ppm): 179.4 (C-1), 161.0 (C-2), 108.8 (C-3), 191.0 (C-4), 158.3 (C-5), 138.1 (C-6), 143.4 (C-7), 128.5 (C-8), 127.2 (C-9), 113.7 (C-10), 203.7

(C-11), 32.3 (C-12), 17.1 (C-13), 56.8 (2-OMe), 162.8 (C-10), 124.8 (C-20), 148.9 (C-30), 121.7 (C-40), 133.4 (C-40a), 103.8 (C-50), 163.2 (C-60),

X. Wei et al. / Chinese Chemical Letters 18 (2007) 412–414 413

Fig. 1. The structures and key HMBC of 1 and 2.

121.6 (C-70), 161.1 (C-80), 111.5 (C-80a), 191.5 (C-90), 113.9 (C-90a), 182.3 (C-100), 135.0 (C-100a), 22.4 (30-Me), 56.9 (60-OMe); EIMS m/z 542,

511, 439, 331, 171, 115, HREIMS m/z 542.1232 (calcd. for 542.1213 corresponding to C30H22O10).

[3] K. Danielsen, D.W. Aksnes, G.W. Francis, Magn. Reson. Chem. 30 (6) (1992) 359.

[4] M.C. Steven, R.D. Peter, R.H. Clive, Phytochemistry 26 (4) (1987) 979.

[5] 2-Acetylphyscion, yellow powder; UV (MeOH) lmax 209, 227, 288, 436 nm; IR (KBr) n 3363, 2919, 2850, 1736, 1701, 1613, 1469, 1444, 1403,

1267, 1208, 1165, 1102, 1066, 900, 843, 778, 764, 721, 603 cm�1; 1H NMR data (500 MHz, CDCl3, d ppm): 12.49 (s, 1H, H-1), 7.66 (s, 1H, H-

4), 7.39 (d, 1H, J = 2.5 Hz, H-5), 6.71 (d, 1H, J = 2.5 Hz, H-7), 12.19 (s, 1H, H-8), 2.61 (s, 3H, H-12), 2.39 (s, 3H, H-13), 3.95 (s, 3H, H-14); 13C

NMR data (125 MHz, CDCl3, d ppm): 159.3 (C-1), 136.3 (C-2), 144.6 (C-3), 122.1 (C-4), 133.0 (C-4a), 108.8 (C-5), 166.9 (C-6), 106.9 (C-7),

165.4 (C-8), 110.2 (C-8a), 190.7 (C-9), 114.1 (C-9a), 181.5 (C-10), 135.0 (C-10a), 203.0 (C-11), 31.8 (C-12), 20.1 (C-13), 56.2 (C-14); ESIMS

[M + H]� m/z 325.4, HRESIMS [M + H]+ m/z 327.0863 (calcd. for 327.0869 corresponding to C18H15O6).

X. Wei et al. / Chinese Chemical Letters 18 (2007) 412–414414