A New Compound from Cymbaria dahurica

Article abstract of DOI:10.1007/s10600-019-02770-z

A new compound, named cymbadahoside A (1), was isolated from the EtOAc extract of Cymbaria dahurica. The structure of cymbadahoside A was identified by UV, IR, ESI-MS, and 1D and 2D NMR.

Full text of DOI:10.1007/s10600-019-02770-z

DOI 10.1007/s10600-019-02770-z
Chemistry of Natural Compounds, Vol. 55, No. 4, July, 2019
A NEW COMPOUND FROM Cymbaria dahurica
Qing-hu Wang,* Wen-qiang Bao, Bi-li-ge-tu-lan Pa,
and Na-ren-chao-ke-tu Han
A new compound, named cymbadahoside A (1), was isolated from the EtOAc extract of Cymbaria dahurica.
The structure of cymbadahoside A was identified by UV, IR, ESI-MS, and 1D and 2D NMR.
Keywords: Cymbaria dahurica, Orobanchaceae, cymbadahoside A, NMR.
Cymbaria dahurica L. (Orobanchaceae) is a perennial herb, densely covered with white sericeous leaves, making the
plant silver gray, which grows up to 20–30 cm high with large yellow flowers. It is found predominantly in hills, gullies, and
grasslands of Ximeng, Inner Mongolia. The aerial parts of C. dahurica are used as folk medicine for impetigo, toxic liver
diseases, skin itch, and vaginal pruritus [1]. Flavonoids [2] and nonglycosidic iridoids [3, 4] have been isolated from this plant.
Further phytochemical study of the EtOAc extract from the aerial parts of C. dahurica resulted in the isolation of a new
compound, named cymbadahoside A (1).
Compound 1 was obtained as a white solid. The molecular formula was established as C H O based on the
29 36 15
–
HR-ESI-MS at m/z 623.5787 [M – H] (calcd 623.5792). The IR spectrum exhibited stretching bands for hydroxyl, carbonyl,
–1
1
and aromatic groups at 3424, 1691, 1586, and 1481 cm . The H NMR spectrum of 1 (Table 1) exhibited two olefinic
hydrogens at δ 7.61 (1H, d, J = 15.5 Hz, H-7), and 6.30 (1H, d, J = 15.5 Hz, H-8), which were verified by the HMBC
correlations (Fig. 1) from H-7 to C-2 (δ 113.7), C-6 (δ 121.8), and C-9 (δ 166.9), and H-8 to C-1 (δ 126.2) and C-9 (δ 166.9).
Moreover, the signals of six aromatic protons at δ 6.96 (1H, dd, J = 8.0, 2.0 Hz, H-6), 6.79 (1H, d, J = 8.0 Hz, H-5), and 7.04
(1H, d, J = 2.0 Hz, H-2), and 6.58 (1H, dd, J = 8.0, 2.0 Hz, H-6′), 6.70 (1H, d, J = 2.0 Hz, H-2′), and 6.68 (1H, d, J = 8.0 Hz,
H-5′) indicated the presence of two ABC systems. The HMBC correlations observed from H-6 to C-4 (δ 148.4), C-2 (δ 113.7)
and C-7 (δ 146.6), from H-5 to C-1 (δ 126.2) and C-3 (δ 145.4), from H-2 to C-4 (δ 148.4), C-6 (δ 121.8), and C-7 (δ 146.6),
from H-6′ to C-2′ (δ 115.7), C-4′ (δ 143.3), and C-7′ (δ 35.1), from H-5′ to C-1′ (δ 129.9) and C-3′ (δ 144.7), and from H-2′ to
C-4′ (δ 143.3), C-6′ (δ 119.8), and C-7′ (δ 35.1) further supported the presence of two ABC systems.
13
The C NMR signals (Table 1) also proved the presence of one trans olefinic group and two trisubstituted aromatic
rings. Except for the aglycone carbons, there were 12 carbon signals, which were assigned to the sugar moiety. Acid hydrolysis
[5, 6] of compound 1 afforded sugar components identified as D-glucose and L-rhamnose by GC analysis. The anomeric
proton appearing at δ 4.39 (1H, d, J = 8.0 Hz, H-1′′′) and its corresponding carbon resonating at δ 102.8 (C-1′′′) from the
HSQC experiment also suggested the presence of a β-D-glucose. The remaining signals at 101.7 (C-1′′), 80.9 (C-2′′), 70.6 (C-3′′),
1
1
72.4 (C-4′′), 69.0 (C-5′′), and 17.0 (C-6′′) belong to the L-rhamnose. In the H– H COSY spectrum, the mutual couplings
observed between H-1′′ (δ 5.20) and H-2′′ (δ 3.93), H-6′′ (δ 1.10) and H-5′′ (δ 3.56), H-5′′ and H-4′′ (δ 3.31), H-4′′ and H-3′′
(δ 3.58), H-1′′′ and H-2′′′ (δ 3.41), H-2′′′ and H-3′′′ (δ 3.85), H-3′′′ and H-4′′′ (δ 4.89), and H-4′′′ and H-5′′′ (δ 3.58) also
confirmed the presence of a β-D-glucose and L-rhamnose.
The structure of 1 was determined further by long-range correlations of H-1′′′ of the β-D-glucose to C-8′ (δ 70.8) of
the aglycon, H-1′′ (δ 5.20) of the L-rhamnose to C-3′′′ (δ 80.2) of the β-D-glucose, and H-2′′ (δ 3.93) of the L-rhamnose to
C-9 (δ 166.9) of the aglycon. The anomeric configuration in the L-rhamnose was determined as α according to the singlet
peak. Thus, the structure of compound 1 was elucidated and named cymbadahoside A.
College of Traditional Mongolian Medicine, Inner Mongolia University for Nationalities, 028000, Tongliao,
P. R. China, fax: +86 0475 831424, e-mail: wqh196812@163.com. Published in Khimiya Prirodnykh Soedinenii, No. 4,
July–August, 2019, pp. 560–561. Original article submitted May 25, 2018.
0009-3130/19/5504-0651 ©2019 Springer Science+Business Media, LLC
651

1
13
TABLE 1. H and C NMR Spectral Assignments of Compound 1 (CD OD, δ, ppm, J/Hz)
3
C atom
C atom
δC
δH
δC
δH
1
2
3
4
5
6
7
8
9
1′
2′
3′
4′
5′
6′
126.2 (C)
113.7 (CH)
145.4 (C)
–
35.1 (CH2)
70.8 (CH2)
2.81 (m)
4.06 (dd, J = 16.0, 8.5)
3.72 (dd, J = 16.0, 8.5)
5.20 (s)
7′
7.04 (d, J = 2.0)
′
8
–
–
148.4 (C)
101.7 (CH)
80.9 (CH)
70.6 (CH)
72.4 (CH)
69.0 (CH)
17.0 (CH3)
102.8 (CH)
74.8 (CH)
80.2 (CH)
69.1 (CH)
74.6 (CH)
60.9 (CH2)
′′
1
115.1 (CH)
121.8 (CH)
146.6 (CH)
113.2 (CH)
166.9 (C)
129.9 (C)
115.7 (CH)
144.7 (C)
143.3 (C)
6.79 (d, J = 8.0)
6.96 (dd, J = 8.0, 2.0)
7.61 (d, J = 15.5)
6.30 (d, J = 15.5)
3.93 (m)
3.58 (m)
3.31 (m)
3.56 (m)
2′′
′′
3
4′′
5′′
6′′
1′′′
2′′′
3′′′
4′′′
5′′′
6′′′
–
–
1.10 (d, J = 6.0)
4.39 (d, J = 8.0)
3.41 (t, J = 9.0)
3.85 (t, J = 9.0)
4.89 (m)
6.70 (d, J = 2.0)
–
–
114.8 (CH)
119.8 (CH)
6.68 (d, J = 8.0)
6.58 (dd, J = 8.0, 2.0)
3.58 (m)
3.64 (m); 3.53 (m)
OH
3'
HO
1'
7'
8'
OH
6'''
O
O
1'''
O
5'
OH
HO
OH
3'''
1''
3
OH
4
1
9
O
O
7
O
3''
6''
OH
OH
1
Fig. 1. Selected HMBC correlations for 1.
EXPERIMENTAL
General. IR spectra were recorded on a Thermo Nicolet 200 double-beam spectrophotometer. HR-ESI-MS spectra
were measured on Waters Xeve C2-S QTOF. The LC system consisted of a LC-20AT pump (Shimadzu, Kyoto, Japan), Shimadzu
1
13
1
1
SPD-20A detector, and Shimadzu CBM-20A software for data processing. H NMR, C NMR, H– H COSY, HSQC, and
HMBC spectra were recorded in CD OD using a 500 Hz Bruker NMR Avance spectrometer.
3
Plant Material. The aerial parts of C. dahurica were collected in Tongliao, Inner Mongolia of China, in June 2016,
and identified by Prof. Buhebateer (Inner Mongolia University for Nationalities). Avoucher (No. 20160526) has been deposited
in the School of Traditional Mongolian Medicine of Inner Mongolia University for Nationalities.
Extraction and Isolation. After extraction with 2000 mL of CH Cl , the ground-dried aerial parts of C. dahurica
2
2
(2.0 kg) were extracted with EtOAc (5.0 L) under reflux. The EtOAc extract (85.0 g) was separated with CHCl –CH OH
3
3
(50:1 to 10:1) using silica gel column chromatography to give three fractions (Frs. 1–3). Fraction 3 (760 mg) was isolated by
HPLC (CH OH–H O, 45:55) to give 1 (31 mg).
3
2
ACKNOWLEDGMENT
We acknowledge financial support from the National Science and Technology Support Program of China
(2012BA128B00).
652

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