A new cyclopeptide from Dianthus caryophyllus

Fei Li, Feng Mei Zhang, Ya Bin Yang, Xue Qiong Yang, Qiu E. Cao,Zhong Tao Ding *

Key Laboratory of Medicinal Chemistry for Nature Resource, Ministry of Education, School of Chemical Science

and Technology, Yunnan University, # 2 Green Lake North Road, Kunming 650091, China

Received 19 September 2007

Abstract

A new cyclopeptide as well as a known cyclopeptide were isolated from the whole plants of Dianthus caryophyllus. Their

structures were elucidated as cyclo (-Thr-Gly-Pro-Tyr-Phe-) (1) and cyclo (-Ala-Gly-Ser-IIe-Phe-Phe-) (2) by means of chemical

and spectroscopic methods including MS, 1D and 2D NMR techniques.

# 2007 Zhong Tao Ding. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Keywords: Caryophyllaceae; Dianthus caryophyllus; Cyclopeptide; Caryophllusin A

Dianthus caryophyllus L. (Caryophyllaceae), a famous flower also called as carnation, is widely distributed all over

the world [1]. There is no report about its cyclopeptide. As a series of investigation on Caryophyllaceae-type

homocyclopeptides [2–6], from the ethanol extract, a new cyclopeptide named caryophllusin A (1) and a known

cyclopeptide as cyclo (-Ala-Gly-Ser-IIe-Phe-Phe-) (2) [7] were isolated. In this paper, the isolation and structural

elucidation of compound 1 were described.

The air-dried whole plants of D. caryophyllus L. (16.5 kg) were extracted with 70% ethanol for three times. The

concentrated extract was suspended in water, and then extracted with petroleum ether, ethyl acetate and n-BuOH,

respectively. The n-BuOH residue (200.0 g) was subjected to SPD-100 column chromatography using H2O–MeOH

gradient system (1:0–0:1). The fraction eluted with 50% MeOH was further subjected to silica gel column

chromatograph, Pharmadex LH-20 and RP-18 to yield compound 1 (14 mg) and compound 2 (16 mg) as white powders.

Caryophllusin A (1), ½a�23D �34.8 (c. 0.008, MeOH), was negative to ninhydrin reagent but positive after hydrolyzed

with 6 mol/L HCl [8]. Based on the HR ESI-MS ([M + H]+ at m/z 566.6269; calcd. 566.6299), its molecular formula was

established as C29H35N5O7, indicated 15 degrees of unsaturation. IR spectrum (KBr) exhibited intense N–H and C O

absorption at 3300 and 1650 cm�1, respectively. The 13C NMR and 1H NMR spectra showed the presence of five amide

carbonyl signals in the range (d 173.1–178.5) and four NH signals in the range (d 7.38–8.61), respectively. The results

mentioned above suggested 1 was a cyclopeptide. By analysis of 1H–1H COSY, HMBC and HMQC spectra, the amino

acid residues consisted of compound 1 were proved to be one threonine, one tyrosine, one glycine, one phenylalanine and

one proline, which were supported by standard amino acid analysis of the hydrolysate prepared from compound 1. These

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Chinese Chemical Letters 19 (2008) 193–195

* Corresponding author.

E-mail address: ztding@ynu.edu.cn (Z.T. Ding).

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

doi:10.1016/j.cclet.2007.12.010

amino acid residues accounted for the molecular weight observed in ESI-MS of 1. The sequence of amino acid residues

for compound 1 was elucidated from the HMBC spectrum. HMBC spectrum exhibited the correlations between NHGly

and C OThr, d-HPro and C OGly, NHTyr and C OPro, a-HPhe and C OTyr, respectively (Fig. 1). Therefore, the structure of

compound 1 was established to be cyclo (-Thr-Gly-Pro-Tyr-Phe-). The complete assignments for the 1H and 13C NMR

signal of compound 1 in pyridine-d5 were accomplished using a combination of 2D NMR experiments (Table 1).

Up to now, about 170 Caryophyllaceae-type homocyclopeptides were obtained from plants. They mainly consisted

of six to nine protein amino acids, only eight cyclopeptides consisting of five amino acids were obtained [9].

Acknowledgments

This work was financially supported by the Natural Science Foundation of Ynunan Province (No. 2007B021M) and

Yunnan University (No. 2003Q008A).

References

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F. Li et al. / Chinese Chemical Letters 19 (2008) 193–195194

Fig. 1. The structure of caryophllusin A, arrows show selected HMBC correlations (H! C).

Table 11H NMR (500 MHz) and 13C (125 MHz) NMR data of caryophllusin A in pyridine-d5 (d ppm, J Hz)

CO Ca Cb Cg Cd HN Ha Hb Hg Hd

Thr 173.7 62.87 72.16 21.83 7.96(br.s) 5.13(m) 5.18(m) 1.43(d, J = 7.7)

Gly 173.9 45.50 7.99(br.s) 5.09(d, J = 18.6),

3.82(d, J = 18.6)

Pro 178.5 63.89 35.16 23.50 52.05 4.71(m) 2.06(m),

1.92(m)

1.49(m) 3.77(m), 3.53(m)

Tyr 177.7 59.13 38.16 128.7 132.9, 118.7, 160.2,

118.7, 132.9

8.61(d, J = 6.7) 5.01(m) 3.21(m) 7.05 (br.s)

Phe 173.1 60.67 37.32 142.4 132.1, 131.9,

128.9, 131.9, 132.1

7.38(br.s) 4.12(m) 3.89(m),

3.46(m)

7.36(d, J = 7.4),

7.60(m),

7.08(d, J = 7.4)

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