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6
Chem. Pharm. Bull. 66, 96–100 (2018)
Vol. 66, No. 1
Note
Cyprotuoside C and Cyprotuoside D, Two New Cycloartane Glycosides
from the Rhizomes of Cyperus rotundus
San-qing Lin, Zhong-liu Zhou,* and Chun-Yan Li
School of Chemistry and Chemical Engineering, Lingnan Normal University; 29 Cunjin Road, Zhanjiang 524048,
China.
Received July 27, 2017; accepted November 1, 2017; advance publication released online November 9, 2017
Cyprotuoside C (1) and cyprotuoside D (2), two new cycloartane glycosides were isolated from the
ethanol extract of the rhizomes of Cyperus rotundus. Their structures were identified as 24R-9,10-seco-cyclo-
artan-1(10),9(11)-dien-3β,7β,24,25-tetraol
3-O-β-D-xylopyranosyl-(1→4)-[α-L-arabinopyranosyl-(1→6)]-β-D-
glucopyranosyl-25-O-β-D-glucuronide(1)and9,10-seco-cycloartan-1(10),9(11),23(24)-trien-3β,7β, 25 -triol 3 - O-β-
D-xylopyranosyl-(1→4)-{α-L-arabinopyranosyl-(1→6)-[α-L-rhamnopyranosyl-(1→2)]}-β-D-glucopyranosyl-25-
O-β-D-glucuronide (2) by spectroscopic methods.
Key words Cyperus rotundus; cyprotuoside C; cyprotuoside D; cycloartane glycoside
Cyperus rotundus (C. rotundus), a perennial herb, is Acid hydrolysis of 1 produced a triterpenoid aglycone (1a),
widespread in the tropical and subtropical regions all over and D-glucose, D-xylose, L-arabinose and D-glucuronic acid
the world. The rhizomes of C. rotundus is a kind of tradi- as sugar residues which were identified by comparison with
1
tional Chinese medicine (TCM) named “Xiangfuzi,” which the respective authentic samples by GC analysis. The H-
13
is broadly used in folk medicine as an anti-inflammatory, and C-NMR spectra of 1a confirmed that the structure of
antidepressant, analgesic, and antiemetic remedy for dysentery the aglycone moiety (1a) was the same as secomacrogenin
1–3)
13)
and women’s diseases.
Previous investigations confirmed
B
(Table 1). Thus, the structure of the aglycone of 1
that the phytochemical constituents of C. rotundus contained was determined as 24R-9,10-seco-cycloartan-1(10),9(11)-dien-
4
–6)
1
13
terpenoids, steroids and flavonoids.
Among them, the 3β,7β,24,25-tetraol. Anomeric region in the H- and C-NMR
1)
terpenoids are the characteristic secondary metabolites.
spectra of 1 revealed signals for four anomeric protons at δ
In recent years, we have put our efforts to the discovery of 4.91 (1H, d, J=8.0Hz), 5.03 (1H, d, J=7.6Hz), 5.06 (1H, d,
secondary metabolites with various skeletons, in particular J=7.6Hz) and 5.56 (1H, d, J=7.8Hz) with their correspond-
7
–10)
triterpene glycosides, from TCM.
In our ongoing research ing anomeric carbons at δ 102.6, 105.3, 105.5 and 105.0,
on the triterpene glycosides of this plant, we isolated two new respectively (Table 2). The relative stereochemistry of each
cycloartane glycosides, cyprotuoside C (1) and cyprotuoside monosaccharide was determined as β-D-glucose, β-D-xylose,
D (2) (Fig. 1). This paper reports the isolation and structure α-L-arabinose and β-D-glucuronic acid based on the coupling
13
elucidation of the two new triterpene glycosides.
constants of anomeric protons and C-NMR data of the sugar
moieties. The linkage of the sugar residues was deduced
from the heteronuclear multiple bond correlation (HMBC)
Results and Discussion
Cyprotuoside C (1) was isolated as a white amorphous spectrum. HMBC spectrum showed cross peaks between the
powder. Its molecular formula, C H O , was determined signals at δH 4.91 and δC 78.9 (C-3 of the aglycon), δH 5.56
52
84 23
on the basis of its [M+Na]+ peak (m/z 1099.5303) in the and δC 79.8 (C-4 of the inner glucose), δH 5.06 and δC 68.1
high resolution electrospray ionization (HR-ESI)-MS and (C-6 of the inner glucose) and δ 5.03 and δ 81.2 (C-25 of the
H
C
13
C-NMR data. IR spectrum showed the absorptions for aglycon) (Fig. 2). Therefore, the Xyl-(1→4)-[Ara-(1→6)]-Glc
−1
−1
the hydroxyl (3346cm ) and olefin (1650cm ) functional- structure of the trisaccharide moiety was concluded to be
ities. A distortionless enhancement by polarization transfer linked to C-3 of the aglycone, and the glucuronic acid moiety
(
DEPT) experiment showed that the 52 carbons present in the to the C-25 of the aglycone, respectively. The combined ap-
13
1
1
1
1
C-NMR spectrum consisted of 7 methyl, 11 methylene, 27 plication of H– H correlation spectroscopy ( H– H COSY),
1
methine, and 7 quaternary carbons. The H-NMR spectrum total correlation spectroscopy (TOCSY), heteronuclear single
displayed six methyl singlets at δ 0.76, 0.93, 0.99, 1.02, 1.53, quantum correlation (HSQC) and HMBC experiments allowed
1.58, one methyl doublet at δ 0.94 (3H, d, J=6.4Hz), two ole- the sequential assignments of all resonances for each mono-
finic protons at δ 5.31 (1H, dd, J=4.5, 2.4Hz) and 5.41 (1H, saccharide. The rotating frame Overhauser enhancement spec-
brd, J=5.5Hz), and a pair of diagnostic methylene protons at troscopy (ROESY) correlations among H-7, H-5, H-29, H-28
δ 2.74 (1H, d, J=14.4Hz) and 3.03 (1H, d, J=14.4Hz). Cor- and H-21, and H-3, H-30, H-8 and H-18 established the stereo-
respondingly, seven methyl carbons (δ 15.7, 16.1, 19.2, 24.2, chemistry of H-7α and H-3β (Fig. 3). Based on all above, the
2
4.8, 21.7 and 19.1), four olefinic carbons (δ 120.2, 139.8, structure of 1 was formulated as 24R-9,10-seco-cycloartan-
1
19.3 and 136.9) and an isolated methylene carbon (δ 45.5) 1(10),9(11)-dien-3β,7β,24,25-tetraol
3-O-β-D-xylopyranosyl-
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were exhibited in the C-NMR spectrum (Table 1), respec- (1→4)-[α-L-arabinopyranosyl-(1→6)]-β-D-glucopyranosyl-25-
tively. The above information implied that compound 1 might O-β-D-glucuronide, named cyprotuoside C.
11–13)
possess a 9,10-seco-cycloartane triterpenoid skeleton.
Cyprotuoside D (2) was obtained as a white amorphous
*
©
2018 The Pharmaceutical Society of Japan