New flavone and isoflavone glycoside from

Belamcanda chinensis

Li Jin a, Hai Sheng Chen a,*, Zhao Bao Xiang a,b, Shuang Liang a,Yong Sheng Jin a, Jian Guo Liu a

a College of Pharmacy, Second Military Medical University, Shanghai 200433, Chinab College of Bio-information, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

Received 31 August 2006

Abstract

The new flavone, 5,40-dihydroxy-6,7-methylenedioxy-30-methoxyflavone, and one new isoflavone glycoside, 30,50-dimethoxy

irisolone-40-O-b-D-glucoside were isolated from the rhizomes of Belamcanda chinensis. Their structures were established based on

the spectroscopic methods.

# 2007 Hai Sheng Chen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Keywords: Belamcanda chinensis; Flavone; Isoflavone glycoside

The dried rhizomes of Belamcanda chinensis (L.) DC (Iridaceae) have been used as folk medicine for the treatment

of coughing and pharyngitis in China [1]. As for the chemical constituents of the plant, the occurrence of iridal-type

triterpenoids [2–4] and isoflavonoids [5–11] in the rhizomes, and phenols, benzoquinones and benzofurans [3,12] in

the seeds was reported. In the course of further studies, a new flavone and a new isoflavone glycoside have been

isolated from the rhizomes. We report herein the structure elucidation of these new compounds.

The plant material was purchased in October 2000 from Bozhou, Anhui province and identified as the rhizome of B.

chinensis (L.) DC by Professor Zhen Han Chen, College of Pharmacy, Second Military Medical University. A voucher

specimen has been deposited in the herbarium of School of Pharmacy, Second Military Medical University, Shanghai

(No. 20001022).

The dried rhizomes were chopped and extracted with 80% EtOH three times under reflux and concentrated in

vacuum. The residue was further suspended in water and partitioned with CHCl3 and EtOAc, successively. The CHCl3layer was concentrated and repeatedly subjected to column chromatography on silica gel with various solvent systems,

and Sephadex LH-20 with CHCl3–MeOH to give a new flavone, 5,40-dihydroxy-6,7-methylenedioxy-30-methoxyflavone (1). The EtOAc layer was concentrated and chromatographed over silica gel and ODS gel and

Sephadex LH-20 to afford a new isoflavone glycoside, 30,50-dimethoxy irisolone-40-O-b-D-glucoside (2) (Fig. 1).

Compound 1, a yellow powder, exhibited a [M � H]� ion peak at m/z 327 in EI-MS and the molecular formula

C17H12O7 was determined by HRESI-MS (m/z 327.0502 [M � H]�, calcd. for C17H11O7: 327.0505). The 13C NMR

www.elsevier.com/locate/cclet

Chinese Chemical Letters 18 (2007) 158–160

* Corresponding author.

E-mail address: haishengc@hotmail.com (H.S. Chen).

1001-8417/$ – see front matter # 2007 Hai Sheng Chen. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

doi:10.1016/j.cclet.2006.12.031

(DMSO-d6, 500 MHz) spectrum revealed the signals of a carbon skeleton of flavone, one methoxyl group and one

methylenedioxy group. The 1H NMR (DMSO-d6, 500 MHz) spectrum showed a typical three substituents in ring B

and three protons signals were at d 7.56 (d, J = 2 Hz), d 6.93 (d, J = 9 Hz), d 7.57 (dd, J = 9, 2 Hz), which were assigned

to H-20, H-50, H-60 of ring B, respectively. One-proton singlet at d 6.95 was ascribable to C-3. The extreme downfield

characteristic signal at d 13.03 could be assigned to 5-OH, due to intramolecular hydrogen bonding. The appearance of

RDA fragment ions at m/z 180 and 148 in the mass spectrum indicated the presence of one methylenedioxy in ring A

and one methoxyl and one hydroxyl in ring B. The positions of the methoxyl group at C-30 and hydroxyl group at C-40

in the ring B were ascertained by the NOESY spectrum, which showed a clear correlation between the methoxyl signal

(d 3.90) and H-20 signal (d 7.56, d, J = 2 Hz). The methylenedioxy group was positioned at C-6, C-7 on account of the

downfield proton signal at d 6.96 (H-8) and the upfield carbon signal at d 89.76 (C-8). All the C and H assignments

could be further confirmed by HMBC spectrum (see Fig. 2). Consequently, compound 1 was deduced to be 5,40-dihydroxy-6,7-methylenedioxy-30-methoxyflavone.

Compound 2 was obtained as a yellow amorphous powder. Its molecular formula C25H26O13 was determined by

HRESI-MS (m/z 557.1264 [M + Na]+, calcd. for C25H26O13 Na: 557.1271). The 1H and 13C NMR spectra (DMSO-d6,

500 MHz) of 2 showed a number of signals characteristic of sugar and isoflavone moieties. In the 1H NMR spectrum

the characteristic isoflavone signals for H-2 was observed at d 8.34 together with only one aromatic proton signal at d

7.02 (H-8), indicating that three substituents were linked to the A-ring. Two singlets at d 6.86 (H-20, 60), indicated a

symmetric trisubstituted B-ring. The spectrum also revealed the presence of three methoxyl groups (d 3.91, d 3.80, d

3.80) and a methylenedioxy (d 6.19) in the compound. Thus, the singlet at d 3.80 six-protons for two methoxyl group

could be assigned to C-30, 50, while the methylenedioxy group must be located on ring A. The signal of the anomeric

proton of the sugar moiety appeared at d 4.97 (J = 7 Hz) as a doublet along with other characteristic signals indicated

the existence of b-D-glucose. In the NOESY spectrum, the third methoxyl group (d 3.91) showed a correlation with the

methylenedioxy group, suggesting the ortho disposition to each other in ring A. According to the substitution of ring A

and B, the position, which can be glucosylation, was at 40-OH. The structure of 2 was finally confirmed by HMBC

technique (see Fig. 2). On the basis of the above evidences, compound 2 was identified as 3,5-dimethoxy irisolone-4-

O-b-D-glucoside (Table 1).

The total isoflavones (the content of isoflavones was about 65%) from Belamcanda chinensis showed estrogenic

effect on estrogen-deficiency rats and anti-estrogenic effect on high-estrogen-level ones.

L. Jin et al. / Chinese Chemical Letters 18 (2007) 158–160 159

Fig. 1. Structures of compounds 1 and 2.

Fig. 2. Key HMBC and NOESY correlations of 1 and 2.

References

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L. Jin et al. / Chinese Chemical Letters 18 (2007) 158–160160

Table 11H and 13C NMR data for compounds 1 and 2 (500 MHz, DMSO-d6, d ppm)a

Position 1 2

dC dH dC dH

2 164.01, s 152.06, d 8.34 (s)

3 103.04, d 6.95(s) 127.28, s

4 182.50, s 173.72, s

5 153.70, s 140.48, s

6 129.46, s 135.91, s

7 152.57, s 152.62, s

8 89.76, d 6.96 (s) 93.54, d 7.02 (s)

9 141.13, s 153.83, s

10 106.65, s 113.15, s

10 121.32, s 123.89, s

20 110.31, d 7.56 (d, J = 2 Hz) 107.85, d 6.86 (s)

30 148.06, s 152.20, s

40 150.89, s 134.43, s

50 115.80, d 6.93 (d, J = 9 Hz) 152.20, s

60 120.40, d 7.57 (dd, J = 9, 2 Hz) 107.85, d 6.86 (s)

Glc-100 102.61, d 4.97 (d, J = 7 Hz)

200 74.12, d 3.41 (m)

300 77.15, d 3.49 (m)

400 69.82, d 3.34 (m)

500 76.50, d 3.30 (m)

600a 60.71, t 3.75 (m)

600b 3.58 (m)

6,7-(OCH2O) 102.70, t 6.17 (s) 102.55, t 6.19 (s)

5-OMe 60.74, q 3.91 (s)

30-OMe 56.02, q 3.90 (s) 56.54, q 3.80(s)

50-OMe 56.54, q 3.80(s)

5-OH 13.03 (s)

40-OH 9.99 (s)

a Recorded on JOEL FX-400 spectrometer; TMS was used as an internal standard.