Chantriolide C, a new withanolide glucoside and a new spirostanol saponin from the rhizomes of Tacca chantrieri

Article abstract of DOI:10.1248/cpb.57.1126

A new withanolide, chantriolide C (1) and a new spirostanol saponin, chantrieroside A (2) were isolated from the rhizomes of Tacca chantrieri, together with another five known steroidal compounds. Their structures were established as (22R)-1α,12α-diacetox

Full text of DOI:10.1248/cpb.57.1126

1126
Notes
Chem. Pharm. Bull. 57(10) 1126—1128 (2009)
Vol. 57, No. 10
Chantriolide C, a New Withanolide Glucoside and a New Spirostanol
Saponin from the Rhizomes of Tacca chantrieri
,a
b
c
,b
*
*
Lin ZHANG, Jiang-Yun LIU, Li-Zhen XU, and Shi-Lin YANG
a Zhejiang Provincial Key Laboratory Chinese Medicine Screening, Exploitation & Medicinal Effectiveness Appraise for
Cardio-Cerebral Vascular & Nervous System, The Key Laboratory of Biomedical Engineering Ministry of Education,
China, College of Biomedical Engineering & Instrument Science, Zhejiang University; Hangzhou 310027, China: b School
of Pharmacy, Medical College of Soochow University; Suzhou 215123, China: and c Institute of Medicinal Plant
Development, Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing 100050, China.
Received April 29, 2009; accepted July 4, 2009; published online July 9, 2009
A new withanolide, chantriolide C (1) and a new spirostanol saponin, chantrieroside A (2) were isolated
from the rhizomes of Tacca chantrieri, together with another five known steroidal compounds. Their structures
were established as (22R)-1a,12a-diacetoxy-2a,3a;6a,7a-diepoxy-27-[(b-D-glucopyranosyl)oxy]-5a-hydroxy-
with-24-enolide (1) and (25R)-spirost-5-en-3-yl-O-a-L-rhamnopyranosyl-(1→2)-O-[O-b-D-glucopyranosyl-(1→4)-
a-L-rhamnopyranosyl-(1→3)]-b-D-glucopyranoside (2). The structures of the new saponins were determined by
detailed analysis of their 1 dimensional (1D) and 2D NMR spectra, and chemical evidences.
Key words Tacca chantrieri; Taccaceae; withanolide; spirostanol saponin
Tacca chantrieri ANDRÉ (Taccaceae) is a perennial plant presence of a,b-unsaturated d-ketone moieties. The molecu-
that grows in southeastern China. Its rhizomes have been em- lar formula of 1 was determined to be C38H54O15 by high-
ployed in traditional Chinese medicine for the treatment of resolution (HR)-electrospray ionization (ESI)-MS at m/z
gastric ulcer, enteritis, and hepatitis.1) Previously phytochem- 773.3342 ([MꢁNa]ꢁ, Calcd 773.3360).
1
ical investigations revealed some new diarylheptanoids,
The H- and 13C-NMR spectral data (Table 1) showed
steroidal constituents including the spirostan, furostan, pseu- three methyl singlets (dH 0.81ꢂ2, 2.01; dC 12.4, 16.3, 20.2),
dofurostan, withanolide and pregnane types from T. chantri- a secondary methyl (dH 0.86, d, Jꢃ6.6 Hz; dC 12.4), an a,b-
eri rhizomes.2—5) Besides family Solanaceae, withanolides unsaturated d-lactone [dC 157.0 (C-24), 122.9 (C-25), 166.2
have been first found to distribute in a species of the family (C-26)], two epoxy group (dH 2.80, 3.11; dC 56.2, 54.1, and
Taccaceae. As part of our investigation of bioactive con- dH 3.54, 3.73; dC 55.0, 51.5), two acetoxyl group (dH 2.06,
stituents from Dai medicine, herein we report the isolation 2.11; dC 20.7, 21.4, 170.1, 171.0), and a set of hexose group
and structure elucidation of steroidal compounds from the (dH 4.42, d, Jꢃ7.8 Hz, 3.35—3.82, 5H; dC 102.6, 62.0—
rhizomers of this plant. A new withanoside, chantriolide C 76.4), revealed 1 to be a typical withanolide glycoside bear-
(1) and a new spirostanol saponin, chantrieroside A (2) were ing two acetoxyl group and two epoxy group.
isolated out, and their structures were established as (22R)-
The oxymethine proton signal at d 3.73 (1H, dd, Jꢃ4.8,
1a,12a-diacetoxy-2a,3a;6a,7a-diepoxy-27-[(b-D-glucopy- 3.6 Hz, H-2) was correlated to the other two oxymethine pro-
ranosyl)oxy]-5a-hydroxywith-24-enolide (1) and (25R)- tons at d 4.62 (1H, d, Jꢃ4.8 Hz, H-1) and 3.54 (m, H-3) in
spirost-5-en-3-yl-O-a-L-rhamnopyranosyl-(1→2)-O-[O-b-D- the H–1H correlation spectroscopy (COSY) spectrum, sug-
1
glucopyranosyl-(1→4)-a-L-rhamnopyranosyl-(1→3)]-b-D- gested a 2a,3a-epoxy moiety. A heteronuclear multiple bond
glucopyranoside (2), on the basis of detailed analysis of their connectivity (HMBC) correlation from H-1 to an acetyl car-
1 dimensional (1D) and 2D NMR spectra and chemical evi- bonyl carbon signal at d 170.1 indicated that an acetoxyl
dences. Another five known steroidal compounds, chantri- group was attached to C-1. Long-range HMBC correlations
olide A (3),6) taccalonolide O (4),7) taccalonolide P (5),7) from H-2, H-4eq (d 2.38), and Me-19 to the quaternary car-
polyphyllin C (6)8) and collettiside IV(7)8) were also isolated bon signal at d 70.1 gave evidence for the presence of a hy-
and identified by comparison of their spectra data with refer- droxyl group at C-5. Thus, the C-1 acetoxy, C-2/C-3 epoxy,
ences.
and C-5 hydroxy functionalities were assigned for ring A.
Long-range HMBC correlations from H-6 (d 2.80) to C-5 at
d 70.1 indicated another C-6/C-7 epoxy ring. The presence
Results and Discussion
The EtOH extract of T. chantrieri rhizomes was suspended of another acetoxyl group was atributed to C-12 from the
in water, followed by partition between petrol ester, CHCl3 HMBC correlation between the signals of the H-12 oxyme-
and n-BuOH successively. The CHCl3 fraction was enriched thine proton at d 4.96 (1H, br s) and the carbonyl carbon at d
with steroidal ingredients, which was subjected to multiple 170.5.
chromatographic steps over Si gel and octadecylsilanized
(ODS) Si gel, giving compounds 1 (30 mg) and 2 (11 mg), ety at d 4.42 (d, Jꢃ7.8 Hz) showed a long-range correlation
together with other known compounds 3—7. with the C-27 carbon resonance at d 63.0 in the HMBC spec-
The anomeric proton signal of a b-D-glucopyranosyl moi-
Compound 1 was isolated as white plates. The IR spec- trum, and the presence of D-glucose was also evidenced by
trum of 1 displayed absorption bands of hydroxyl (3440 results of acid hydrolysis. Accordingly, the planar structure
cmꢀ1), ketone (1733 cmꢀ1), and a,b-unsaturated d-ketone of 1 was determined as shown in Fig. 1.
(1701, 1690 cmꢀ1) functions. The UV spectrum of 1 showed
The stereo configuration of 1 was further convinced by nu-
absorption at lmax (MeOH) 217 nm, which also implied the clear Overhauser effect (NOEs). NOE correlations from H-1,
© 2009 Pharmaceutical Society of Japan
∗ To whom correspondence should be addressed. e-mail: zxxtjk@gmail.com; yangshilin@suda.edu.cn

October 2009
1127
Table 1. 1H- (600 MHz) and 13C-NMR (125 MHz) Chemical Shift Assign-
ments of Compounds 1 (in CDCl3) and 2 (in C5D5N)
1
2
Position
Position
dC
dH
dC
dH
1
2
71.7 4.62(1H, d, Jꢃ4.8 Hz)
51.5 3.73 (1H, dd,
Jꢃ4.8, 3.6 Hz)
1
2
37.5 1.70, 0.95 (1H each, m)
30.1 2.06, 1.84 (1H each, m)
3
55.0 3.54 (1H, m)
32.6 2.38 (1H, br d, Jꢃ15.0 Hz)
2.03 (1H, m)
3
4
77.8 3.90 (1H, m)
4-eq
ax
38.7 2.74, 2.68(1H, br d)
5
70.1
5
6
140.7
6
56.2 2.80 (1H, d, Jꢃ3.6 Hz)
54.1 3.11 (1H, br s)
36.0 1.74 (1H, m)
28.0 2.03 (1H, m)
39.8
121.8 5.30 (1H, d, Jꢃ3.6 Hz)
32.3 1.43 (1H, m, overlap)
31.8 1.64 (1H, m)
50.3 0.88 (1H, m)
37.1
7
7
8
8
9
9
10
10
11
11-eq
ax
24.6 1.57 (1H, m)
1.51 (1H, m,)
21.1 1.42 (1H, m)
12
75.3 4.96 (1H, br s)
46.1
12
13
14
15
39.8 1.68 (1H, m, overlap)
40.5
Fig. 1. Structures of Chantriolide C (1) and Chantrieroside A (2)
13
14
44.3 2.02 (1H, m)
22.7 1.90 (1H, m)
1.33 (1H, m)
56.6 1.05 (1H, m)
32.2 1.43 (2H, m, overlap)
15-eq
ax
16-eq
ax
26.5 1.76 (1H, m)
1.43 (1H, m)
16
81.1 4.82 (1H, m)
17
43.5 1.72 (1H, m)
12.4 0.81 (3H, s)
16.3 0.81 (3H, s)
38.1 1.95 (1H, m)
12.4 0.86 (3H, d, Jꢃ6.6 Hz)
78.2 4.42 (1H, m)
29.8 2.46 (1H, m)
2.03 (1H, m)
17
18
19
20
21
22
23
62.2 1.80 (1H m)
16.3 0.81 (3H, s)
19.4 1.09 (3H, s)
42.0 1.94 (1H, m)
15.0 0.69 (3H, d, Jꢃ4.8 Hz)
109.2
18
19
20
21
22
Fig. 2. Key HMBC Correlations Observed in 1
23-eq
ax
31.7 2.01, 1.86 (1H each, m)
24
157.0
24
25
26
27
29.3 1.56 (2H, m)
H-2, H-3, H-6, and H-7 to Me-19, from H-12 to Me-18 were
consistent with the 1a, 2a, 3a, 6a, 7a and 12a. The corre-
lations from H-14, H-17 to Me-21 indicated C-20 to be S
configuration, and the conclusion was also confirmed by
comparisons of chemical shift data at C-17, C-20, C-21, C-
22 of compound 1 with those of analogues ((ꢁ)-6a,7a-
epoxy-5a-hydroxy-1-oxowitha-2,24-dienolide).5) The abso-
lute configuration at the C-22 chiral center was elucidated as
R by a positive Cotton effect at 251.7 nm in the CD spec-
trum.6) The fully assignments of all NMR signals of 1 were
25
122.9
30.6 1.57 (1H, m)
26
166.2
66.9 3.59, 3.50 (1H each, m)
17.3 1.30 (3H, d, Jꢃ7.2 Hz)
27a
27b
28
63.0 4.62 (1H, d, Jꢃ10.8 Hz)
4.42 (1H, d, Jꢃ10.8 Hz)
20.2 2.01 (3H, s)
Glc-1ꢄ 102.6 4.42 (1H, d, Jꢃ7.8 Hz)
99.9 4.90 (1H, d, Jꢃ7.8 Hz)
78.6 4.08 (1H, dd,
Jꢃ9.1, 7.8 Hz)
2ꢄ
73.3 3.37 (1H, dd,
Jꢃ8.8, 7.8 Hz)
3ꢄ
4ꢄ
76.4 3.54 (1H, m)
70.1 3.54 (1H, m)
75.8 3.35 (1H, m)
62.0 3.82 (2H, m)
86.4 4.19 (1H, m)
69.7 4.08 (1H, m)
78.0 3.74 (1H, m)
62.6 4.44 (2H, m)
102.6 5.81 (1H, br s)
72.5 4.72 (1H, br s)
72.8 4.51 (1H, m)
73.8 4.33 (1H, m)
69.9 4.86 (1H, m)
18.7 1.75 (3H, d, Jꢃ6.6 Hz)
103.2 5.75 (1H, br s)
72.1 4.80 (1H, m)
72.4 4.57 (1H, m)
84.6 4.44 (1H, m)
68.7 4.83 (1H, m)
18.3 1.68 (3H, d, Jꢃ6.6 Hz)
106.6 5.24 (1H, d, Jꢃ7.8 Hz)
76.4 4.08 (1H, m)
78.6 4.19 (1H, m)
71.4 4.33 (1H, m)
78.4 3.74 (1H, m)
62.9 4.33 (2H, m)
5ꢄ
6ꢄ
1
carried out by H–1H COSY, HMQC, HMBC and ROESY
Rha-1ꢅ
2ꢅ
experiments (Table 1), in agreements with those of previ-
ously reported withanolide glucosides chantriolides A (3)
and B,6) the fully assignments of all NMR signals of 1 were
3ꢅ
4ꢅ
1
carried out by H–1H COSY, HMQC, HMBC and ROESY
5ꢅ
6ꢅ
experiments (Table 1). They all process the similar structure,
with slight differences in C-16 substitute group.
Finally, the structure of 1 was established as (22R)-
1a,12a-diacetoxy-2a,3a;6a,7a-diepoxy-27-[(b-D-glucopy-
ranosyl)oxy]-5a-hydroxywith-24-enolide.
Compound 2 was obtained as white needles. The IR spec-
trum of 2 displayed absorption bands of hydroxyl (3347
cmꢀ1) and C–O bands (1047 cmꢀ1) functions. The molecular
formula of 2 was determined to be C51H82O21 by HR-ESI-MS
at m/z 1053.5208 ([MꢁNa]ꢁ, Calcd 1053.5410).
Rha-1ꢆ
2ꢆ
3ꢆ
4ꢆ
5ꢆ
6ꢆ
Glc-1ꢅꢅ
2ꢅꢅ
3ꢅꢅ
4ꢅꢅ
5ꢅꢅ
6ꢅꢅ
*CO
The 1H- and 13C-NMR spectral data of 2 (Table 1) showed
two methyl singlets (dH 0.81, 1.09; dC 16.3, 19.4), four sec-
ondary methyl [(dH 0.69, d, Jꢃ4.8 Hz; dC 15.0), (dH 1.68, d,
Jꢃ6.6 Hz; dC 18.3), (dH 1.75, d, Jꢃ6.6 Hz; dC 18.7), and
(dH 1.30, d, Jꢃ7.2 Hz; dC 17.3)], a methene [dH 5.30,
d, Jꢃ3.6 Hz; dC 121.8 (C-6), dC 140.7 (C-5)], and four
171.0
170.1
*CH3CO 20.7 2.11(3H, s)
21.4 2.06 (3H, s)

1128
Vol. 57, No. 10
Union Medical College. A voucher specimen has been deposited in the Insti-
tute of Medicinal Plant Development, Chinese Academy of Medical Sci-
ences and Peking Union Medical College (voucher No. TC-2003-10-08).
Extraction and Isolation The plant material (dry weight, 13.0 kg) was
extracted with 95% EtOH (100 lꢂ2) and 50% EtOH (100 lꢂ1) under reflux.
The EtOH extract (1.5 kg) was suspended in water, extracted with petrol
ester, CHCl3, n-BuOH successively. The CHCl3 part (220 g) was chro-
matographed on a silica gel column with a stepwise gradient mixture of
CHCl3–MeOH (9 : 1, 4 : 1, 3 : 1, 2 : 1, and 1 : 1; 4 l of each), and each fraction
was monitored by TLC, and combined to 10 fractions.
Fig. 3. Important NOE Correlations of 1
Fraction 6 was further chromatographed on a silica gel MPLC column
with gradient CHCl3–MeOH (100 : 0—90 : 10) as eluent, and further purified
with Sephadex LH-20 column to give 4 (22 mg) and 5 (39 mg). Fraction 7
was further chromatographed on an ODS column with gradient MeOH–H2O
(4 : 6—6 : 4) as eluent, and further purified with Sephadex LH-20 column to
give 1 (30 mg). Fraction 8 was recrystalized with 95% EtOH to give 3
(25 mg). Fraction 9 was separated by preparative HPLC using CH3CN–H2O
(25 : 75) to give 6 (11 mg) and 7 (21 mg). Fraction 10 was separated by
preparative HPLC using CH3CN–H2O (25 : 75) to give 2 (11 mg).
Compound 1: White plates, mp 224—226 °C (MeOH); [a]D25 ꢁ66.8°
(cꢃ0.10, CHCl3); CD (MeOH) lmax (De) 251.7 nm (ꢁ15.0); IR (film) nmax
1
3440 (OH), 1733 ((CꢃO), 1701, 1690 (a,b-unsaturated d-ketone); H- and
13C-NMR (CDCl3), see Table 1; HR-ESI-MS m/z: 773.2224 (Calcd for
C38H54O15Na, 773.3360).
Compound 2: White needle, mp 260—261 °C (MeOH); [a]D25 ꢀ93.6°
Fig. 4. Key HMBC Correlations Observed in 2
1
(cꢃ0.10, MeOH); IR (film) nmax 3440 (OH), 2934 (CH), 1635 (CꢃC); H-
and 13C-NMR (C5D5N), see Table 2; HR-ESI-MS m/z: 1053.5208 [MꢁNa]ꢁ
(Calcd for C51H82O21Na, 1053.5210).
anomeric protons and carbons of four monosaccharides (dH
4.90, d, Jꢃ7.8 Hz, dC 99.9; dH 5.24, d, Jꢃ7.8 Hz, dC 106.6;
dH 5.75, s, dC 103.2; dH 5.81, s, dC 102.6), suggested 2 to be
Acid Hydrolysis of 1 and 2 Compounds 1 and 2 (3 mg, each) were dis-
solved in 2 M CF3COOH (2 ml) and heated to 120 °C in a sealed tube for 2 h.
After extraction with CHCl3, the aqueous layer was concentrated to dryness
using N2 gas. The residue was dissolved in H2O (1 ml) and filtrated, which
was then analyzed by HPLC under the following conditions: column, Cos-
mosil sugar-D (4.6 mm i.d.ꢂ250 mm, 5 mm); solvent, MeCN–H2O (80 : 20);
flow rate, 1.0 ml/min; detection, ELSD and OR. Identification of D-glucose
for 1, L-rhamnose and D-glucose for 2 were carried out by comparison of
their retention time and optical rotation with those of authentic samples: tR
(min) 6.3 (L-rhamnose, negative optical rotation), 11.7 (D-glucose, positive
optical rotation).
a steroidal glycoside. By comparisons of the H- and 13C-
1
NMR data with those reported,3,9,10) the signals of C-24, C-
25, C-26, C-27 (dC 29.3, 30.6, 66.9, 17.3) revealed Me-27 in
an equatorial position rather than in axial position (dC 25.8,
26.0, 65.0, 16.1). Thus, the aglycone of 2 was deduced as
diosgenin ((25R)-spirost-5-en-3b-ol).9,11)
Results of acid hydrolysis gave only D-glucose and L-
rhamnose. In HMBC spectrum, correlations were observed
from dH 4.90 (H-1ꢄ) to dC 77.8 (C-3), from dH 5.81 (H-1ꢅ) to
dC 78.6 (C-2ꢄ), from dH 5.75 (H-1ꢆ) to dC 86.4 (C-3ꢄ), and
from dH 5.24 (H-1ꢅꢅ) to dC 84.6 (C-4ꢆ). By comparision its
NMR data with (25S)-spirost-5-en-3-yl-O-a-L-rhamnopy-
ranosyl-(1→2)-O-[O-b -D-glucopyranosyl-(1→4)-a -L-
rhamnopyranosyl-(1→3)]-b-D-glucopyranoside,3) 2 has the
same sugar sequences with the known one. Thus, 2 was iden-
tified as (25R)-spirost-5-en-3-yl-O-a-L-rhamnopyranosyl-
(1→2)-O-[O-b-D-glucopyranosyl-(1→4)-a-L-rhamnopyra-
nosyl-(1→3)]-b-D-glucopyranoside.
Acknowledgments The authors thank L. P. Shi of the Shanghai Institute
of Materia Medica, Chinese Academy of Sciences, China, for measurements
of NMR spectra.
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