DSpace at VNU: Three new cassane-type furanoditerpenes from the seed of Vietnamese Caesalpinia bonducella

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PHYTOL 965 1–4
Phytochemistry Letters xxx (2015) xxx–xxx

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Phytochemistry Letters
journal homepage: www.elsevier.com/locate/phytol

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Three new cassane-type furanoditerpenes from the seed of vietnamese
Caesalpinia bonducella
Phu Hoang Dang a , Mai Thanh Thi Nguyen a,b , Hai Xuan Nguyen a , Dung Thuy Thi Vu a ,
Son Van Truong a , Nhan Trung Nguyen a,b, *
a
b

Faculty of Chemistry, University of Science, Vietnam National University, Hochiminh City, Viet nam
Cancer Research Laboratory, Vietnam National University, Hochiminh City, Viet nam

A R T I C L E I N F O

A B S T R A C T

Article history:
Received 6 April 2015
Received in revised form 18 May 2015
Accepted 20 May 2015
Available online xxx

Three new cassane-type furanoditerpenes, bonducellpin H (1), bonducellpin I (2), and 7-acetoxycaesalpinin P (3), together with seven known compounds (4–10) have been isolated from the MeOH extract
of the seed kernels of Caesalpinia bonducella from Vietnam. The structures of these compounds were
elucidated by using spectroscopic techniques.
ã2015 Published by Elsevier B.V. on behalf of Phytochemical Society of Europe.

Keywords:
Caesalpiniaceae
Cassane-type furanoditerpenes

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1. Introduction

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Caesalpinia bonducella Flem. (Caesalpiniaceae) is a famous
medicinal plant widely distributed in tropical and subtropical
regions of Southeast Asia. In Vietnam, its seed kernels are used as
anthelmintic, antipyretic, anti-inflammatory, and antimalarial
agent, while decoction of root has been used as a tonic and for
the treatment of rheumatism and backache (Bich, 2003). The
plants belonging to the genus Caesalpinia are rich sources of
cassane-type furanoditerpenes, some of which have been reported
to show antimalaria (Banskota et al., 2003; Linn et al., 2005),

antiviral (Jiang et al., 2001), and anticancer activities (Patil et al.,
1997). Thus, we carried out detail phytochemical investigation of
this plant and isolated three new cassane-type furanoditerpenes,
bonducellpin H (1), bonducellpin I (2), and 7-acetoxycaesalpinin P
(3), together with seven known compounds (4–10) from a MeOH
extract of the seed kernels of this plant from Vietnam. In this paper,
we report the structure elucidation of these new cassane-type
furanoditerpenes.

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2. Results and discussion

Air-dried seed kernels of C. bonducella were extracted with
reluxing MeOH, and the MeOH extract was fractionated with

* Corresponding author at: Faculty of Chemistry, University of Science, Vietnam
National University – Hochiminh City, Viet nam. Tel.: +84 907 426 332;
fax: +84 838 353 659.
E-mail address: (P.H. Dang).

petroleum ether, CHCl3, and EtOAc to yield petroleum ether, CHCl3,
and EtOAc soluble fractions, respectively. The CHCl3 soluble
fraction was subjected to a series of chromatographic separation
and preparative TLC to afford three new cassane-type furanoditerpenes (Fig. 1), bonducellpin H (1), bonducellpin I (2), and 7acetoxycaesalpinin P (3), together with seven known compounds
(4–10) were identified as caesalpin H (4) (Peter et al., 1998),
caesalpinin K (5) (Awale et al., 2006), caesalpinin MP (6) (Kalauni
et al., 2005), caesalpinin E (7) (Kalauni et al., 2004), caesalpinin J
(8) (Awale et al., 2006), 2-acetoxycaesaldekarin E (9) (Kalauni et al.,
2005), norcaesalpinin MC (10) (Kalauni et al., 2004).
Bonducellpin H (1) was isolated as a colorless amorphous solid
and its molecular formula was determined to be C28H38O10 by HRESI-MS m/z 535.2553 [M + H]+. IR absorptions at 3650 and
1730 cmÀ1 indicated the presence of hydroxyl and carbonyl
groups, respectively. The 1H NMR spectrum of 1 (Table 1) displayed
signals corresponding to four methyls (H = 1.12, 1.23, 1.25, 1.36), four
oxymethines (H = 5.24, 5.21, 5.46, 5.52), together with two protons
of a 1,2-disubstituted furan ring (H = 6.17 and 7.22, J = 1.5 Hz), and
four acetyl methyl groups (H = 2.10, 1.96, 2.02, 2.08). On the other
hand, the 13C NMR spectrum of 1 (Table 1) showed four olefinic
carbons (C = 147.8, 122.0, 109.4, 141.2), an oxygenated quaternary
carbon (C = 79.3), four oxygenated methine carbons (C = 75.0, 66.9,
74.8, 74.2), and eight methyl carbons together with four ester
carbonyl carbons (C = 169.0, 170.3, 170.2). These 1H and 13C NMR

data closely resembled those of caesalpinin K (Awale et al., 2006),
except for the appearance of signals due to three more acetoxyl
groups and downfield shifted signal of proton H-7 (H = 5.52) and
carbon C-7 (C = 74.2) due to additional acetoxyl group attached to

/>1874-3900/ ã 2015 Published by Elsevier B.V. on behalf of Phytochemical Society of Europe.

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bonducella. Phytochem. Lett. (2015), />
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Fig. 1. Chemical structures of three new cassane-type furanoditerpenes.
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C-7. The location of the acetoxyl substituents were determined to
be at C-1, C-2, C-6, and C-7, based on the HMBC correlations
observed between the oxymethine protons (H-1, H-2, H-6 and H-7)
and the acetyl carbonyl carbons respectively (Fig. 2). The relative
stereochemistry of 1 was determined on the basis of coupling
constants and the results of ROESY spectrum (Fig. 3). The
correlations from H3-20 to H-1, H-2, H-6, and Hax-11; from H2 to Heq-3, and H3-19 indicated that b-orientation of H-1, H-2, H319, H3-20, and H-6; and rings A and B have a chair conformation
with a trans-fused junctions. Moreover, the small coupling
constant 3J1,2 = 3J2,3eq = 3.0 Hz indicated the acetoxyl substituents
at C-1 and C-2 to be in the a-axial and a-equatorial orientation,
respectively. Similarly, the large coupling constant 3J6,7 = 3J7,8 = 9.0
Hz indicated the acetoxyl substituent at C-6 and C-7 to be in the
a-equatorial and b-equatorial orientation, respectively. The ROESY
correlations from H-7 to H-9 and H3-17 also suggested the 17-Me

group to be in the a-axial orientation. Thus, the relative structure
of bonducellpin H was assigned as 1 (Fig. 3).
Bonducellpin I (2) was isolated as a colorless amorphous solid
and its molecular formula was determined to be C25H30O9 by HRESI-MS m/z 475.1989 [M + H]+. IR absorptions at 1730 and
1710 cmÀ1 indicated the presence of carbonyl groups. The 1H
NMR spectrum of 2 (Table 1) displayed signals corresponding to
three methyls (H = 1.46, 1.11, 1.53), two oxymethines (H = 5.66 and
5.27), together with two protons of a 1,2-disubstituted furan ring
(H = 6.11 and 7.22, J = 2.0 Hz), two acetyl methyls (H = 1.96 and 2.01),
and a methoxyl groups (H = 3.71). Moreover, the 13C NMR spectrum

of 2 (Table 1) showed 25 carbon signals including four olefinic
carbons (C = 150.4, 112.6, 108.2, 141.6), two oxygenated quaternary
carbons (C = 65.8, 71.3), two oxygenated methine carbons (C = 68.3,
75.1), and five methyl carbons, together with a ketone carbonyl
carbon (C = 208.2), three ester carbonyl carbons (C = 174.0, 170.0,

Table 1
The NMR data of compounds 1–3 in CDCl3 ( in ppm, multiplicities, J in Hz).a
Position

1
1

H

2
13

C

1
2

5.24 (1H, d, 3.0)
5.21 (1H, m)

75.0
66.9

3

1.36 (1H, dd, 16.0, 3.0)
2.02 (1H, m)

37.4

4
5
6

5.46 (1H, dd, 9.0, 1.5)

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10
11

5.52 (1H, t, 9.0)
2.10 (1H, m)
2.70 (1H, m)

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13
14
15
16
17
18
19

20
1-OCOCH3
1-OCOCH3
2-OCOCH3
2-OCOCH3
6-OCOCH3
6-OCOCH3
7-OCOCH3
7-OCOCH3
5-OH
17-OCH3
a

1

The H and

40.6
79.3
74.8

2.41 (1H, m)

74.2
39.8
31.6
46.2
22.6

2.70 (1H, m)

6.17 (1H, d, 1.5)
7.22 (1H, d, 1.5)
1.12 (1H, d, 7.0)

147.8
122.0
27.8
109.4
141.2
16.9

1.23 (3H, s)
1.25 (3H, s)
1.36 (3H, s)
2.10 (3H, s)
1.96 (3H, s)
2.02 (3H, s)
2.08 (3H, s)

30.7
25.8
17.1
20.9
169.0
20.8
170.2
21.0
170.3
21.5
170.3

1

H

2.04 (1H, dd, 13.0, 5.0)
2.75 (1H, dd, 13.0, 8.0)
2.34 (1H, d, 8.0)

5.66 (1H, d, 10.5)
5.27 (1H, d, 10.5)
2.68 (1H, t, 10.5)
2.43 (1H, m)
2.43 (1H, m)
2.96 (1H, d, 12.0)

3.50 (1H, d, 10.5)
6.11 (1H, d, 2.0)
7.22 (1H, d, 2.0)

1.46 (3H, s)
1.11 (3H, d, 7.0)
1.53 (3H, s)

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13

C

1

H

2.01 (3H, s)

C

208.2
41.1

4.90 (1H, brs)
5.60 (1H, m)

75.3
75.6

35.8

1.12 (1H, m)
1.80 (1H, m)

32.4

65.8
71.3
68.3
75.1
39.6
36.7
50.8

23.8
150.4
112.6
45.1
108.2
141.6
174.0
18.0
17.0
18.0

1.80 (1H, m)
1.91 (1H, m)
5.60 (1H, m)
2.74 (1H, m)
2.74 (1H, m)
2.42 (1H, dd, 16.5, 4.5)
2.60 (1H, dd, 16.5, 10.5)

6.42 (1H, d, 2.0)
7.24 (1H, d, 2.0)
4.95 (1H, s)
5.09 (1H, s)
1.17 (3H, s)
1.16 (3H, s)
1.31 (3H, s)
2.11 (3H, s)
1.97 (3H, s)

1.96 (3H, s)

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20.5
170.0
21.1
169.6

2.08 (3H, s)

38.6
79.3
22.1
75.2
41.7
38.1
44.6
23.3
150.6
119.8
138.6
106.5
142.0
105.6
30.7
25.0
17.1
21.4
169.1
21.3

170.8

21.7
170.8

2.95 (1H, d, 1.5)
3.71 (3H, s)

52.1

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C NMR spectra were measured at 500 and 125 MHz, respectively.

Please cite this article in press as: Dang, P.H., et al., Three new cassane-type furanoditerpenes from the seed of vietnamese Caesalpinia
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Fig. 2. Key HMBC and 1H-1H COSY correlations of three new compounds 1–3.

Fig. 3. ROESY correlations of compounds 1 and 2.
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169.6), and a methoxyl carbon (C = 52.1). The partial structure C(2)
H2–C(3)H–C(19)H3 was deduced by HMBC correlations of the
secondary methyl proton at 1.11 (H3-19) with C-2, C-3, and C4 together with 1H–1H COSY correlations of H2-2, H-3 and H319 indicated that 2 should be a rare rearranged cassane-type
furanoditerpene having one of the two methyl groups at C4 migrated to C-3. The molecular formula and the 13C NMR
chemical shifts of C-4 (C = 65.8) and C-5 (C = 71.3) indicated that 2
might contain an epoxide ring between C-4 and C-5. The 1H and 13C
NMR data of 2 were similar to those of caesalpinin (Peter et al.,
1997), except for the presence of the signals due to a carbomethoxyl group assigned to C-17 and lack of the signals due to a 17-Me
group and an oxygenated quaternary carbon in caesalpinin. The

HMBC correlations of H3-20 and H2-2 with a ketone carbonyl
carbon (C = 208.2) indicated the location of the ketone carbonyl
carbon to be C-1. The HMBC correlations of the methine proton H14 and methoxyl proton with an ester carbonyl carbon indicated
the carbomethoxyl group should be at C-14. The location of the
acetoxyl groups were determined to be C-6 and C-7, based on the
analysis of the COSY, HSQC, and HMBC spectra (Fig. 2). The relative
stereochemistry of 2 was determined on the basis of coupling
constant and ROESY correlations (Fig. 3). The ROESY correlations
between Hb -2 and H3-19 and H3-20 and the coupling constant
3
J2a,3 = 5.0 Hz and 3J2b,3 = 8.0 Hz suggesting H3-20 and H3-19 were
all on the same side and to be b-oriented. Since the C-5 hydroxyl
substituent is biogenetically a-oriented in cassane-type diterpenes of the Caesalpinia species, the epoxide ring between C-4 and
C-5 should be a-oriented (Ming et al., 2011). This was supported by
the ROESY correlations of H3-18 with Hb-2, H3-19, and H3-20.
Furthermore, the ROESY correlations between H3-20 with H6 suggested the a-equatorial orientation of the C-6 acetoxyl
substituent, while the large coupling constant 3J6,7 = 3J7,8 = 10.5 Hz,
together with the ROESY correlation between H-7 and H-9,
suggested the acetoxyl substituent at C-7 to be b-equatorial
oriented. Similarly, the configuration of carbomethoxyl group at C14 to be b-orientation from the ROESY correlation between H-

14 and H-7 and large coupling constant 3J8,14 = 10.5 Hz. Thus, the
structure of bonducellpin I was determined as 2 (Fig. 3).
7-Acetoxycaesalpinin P (3) was isolated as a colorless amorphous
solid and their IR spectra indicated the presence of hydroxyl and
ester carbonyl groups, respectively. Its molecular formula was
determined to be the same C26H34O8 by HR-ESI-MS m/z 417.2285
[M + H]+. The 1H and 13C NMR spectra of 3 were also similar to those
of caesalpinin P, except for the presence of the signals due to an
additional acetoxyl group. Analysis of COSY, HSQC, and HMBC

showed the downfield shifted signal of proton H-7 (H = 5.60),
compared to that of caesalpinin P (H-7; 1.70), suggesting the
location of an acetoxyl substituent to be at C-7. This was further
confirmed by HMBC correlations of the proton at H 5.60 (H-7) with
the ester carbonyl carbon at C 170.8 (7-OCO) (Fig. 2). The relative
structure of 3 was suggested by comparision with NMR data of
caesalpinin P (Awale et al., 2006). Because of the lack of amount of 3,
the ROESY experiment was not recorded. Furthermore, the acetoxyl
substituent at C-7 is biogenetically b-oriented in cassane-type
diterpenes of the Caesalpinia species (Ming et al., 2011). So, the
structrure of 7-acetoxycaesalpinin P was concluded as 3 (Fig. 2).
In this research, we reported the structures of three new
diterpenes, bonducellpin H (1), bonducellpin I (2), and 7acetoxycaesalpinin P (3). Among the isolated compounds, 1 and
3 are cassane-type furanoditerpenes, and 2 represents a rearranged cassane-type furanoditerpene in which one of the C4 methyl groups has migrated, which are the characteristic
structural features of diterpenes isolated from the plant of
Caesalpinia genus.

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3. Experimental

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3.1. General experimental procedures

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IR spectra were measured with a Shimadzu IR-408 spectrophotometer in CHCl3 solutions. NMR spectra were taken on a Bruker
Avance III 500 MHz spectrometer with tetramethylsilane (TMS) as

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Please cite this article in press as: Dang, P.H., et al., Three new cassane-type furanoditerpenes from the seed of vietnamese Caesalpinia
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P.H. Dang et al. / Phytochemistry Letters xxx (2015) xxx–xxx

an internal standard, and chemical shifts are expressed in values.
HR-ESI-MS was performed on the Agilent 6310 Ion Trap mass
spectrometer. The HPLC experiments were carried out on the HPLC
Agilent 1100 series with UV detector. Analytical and preparative
TLC was carried out on precoated Merck Kieselgel 60F254 or RP18F254 plates (0.25 or 0.5 mm thickness).
3.2. Chemicals

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The purity of isolated compounds from C. bonduccella ranged
90.3–96.5% as determined by HPLC with UV detection. Other
chemicals were of the highest grade available.

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3.3. Plant material

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The seed kernels of C. bonducella Flem was collected at Khanh
Hoa province, Vietnam, in October 2009 and was identified by Ms.
Hoang Viet, Faculty of Biology, University of Science, National
University-Ho Chi Minh City. A voucher sample has been deposited
with the number AN-2813 at the Deparment of Analytical
Chemistry of the University of Science, National University-Ho
Chi Minh City, Vietnam.

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3.4. Extraction and isolation

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Air-dried seed kernels of C. bonducella (2.1 kg) were extracted
with MeOH (15 L, reflux, 3 h  3) to yield a MeOH extract (400 g).
The MeOH extract was suspended in H2O and successively
partitioned with petroleum ether, CHCl3, and EtOAc to yield

petroleum ether (100 g), CHCl3 (40 g), EtOAc (40 g) soluble
fractions and remaining aqueous fraction (220 g), respectively.
The CHCl3 fraction (40 g) was subjected to silica gel column
(8 cm  80 cm) chromatography eluted with increasing polarity of
EtOAc/petroleum ether (0–100%) and then MeOH/CHCl3 (0–30%) to
give eight fractions: Fr.1–Fr.8.
Fr.2 (1.2 g) was subjected to silica gel with EtOAc/petroleum
ether (0–30%) to yield four sub-fractions Fr.2.1–4. Fr.3.3 and
Fr.3.4 were chromatographed on silica gel column with EtOAc/
petroleum ether (20%) to give 4 (11 mg), 9 (5 mg), 10 (7 mg). Fr.3
(3.1 g) was chromatographed on silica gel column (3 cm  70 cm)
with EtOAc/petroleum ether (0–30%) to yield five sub-fractions
Fr.3.1–5. Fr.3.2 and Fr.3.3 were recrystallized with MeOH/CHCl3 led
to 1 (35 mg) and 6 (12 mg). Fr.3.4 was subjected to silica gel with
EtOAc/petroleum ether (20%) and followed by normal-phase
preparative TLC with EtOAc/petroleum ether (15%) to give 3
(18 mg). Fr.4 (1.8 g) was subjected to silica gel with MeOH/CHCl3
(20%) to obtain 5 (23,3 mg). Fr.5 (2.8 g) was chromatographed on
silica gel column with MeOH/CHCl3 (0–30%) to yield four subfractions Fr.5.1–4. Fr.5.2 and Fr.5.3 were applied to normal-phase
preparative TLC with EtOAc/petroleum ether (35%) to gain 7
(10 mg) and 8 (8 mg).
Fr.6 (1.3 g) was chromatographed on ODS with H2O/MeOH
(60%) and then purified by reversed-phase preparative TLC with
H2O/MeOH/CH3CN (4:3:3) to afford 2 (12 mg).

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3.4.1. Bonducellpin H (1)
Colorless amorphous solid; mp 252.4  C; IR (CHCl3) cmÀ1: 3650,
1730; NMR data (CDCl3) see Table 1; HR-ESI-MS: m/z 535.2553
[M + H]+, calcd. for C28H39O10 535.2543.

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3.4.2. Bonducellpin I (2)
Colorless amorphous solid; mp 180.2  C; IR (CHCl3) cmÀ1: 1730,
1710; NMR data (CDCl3) see Table 1; HR-ESI-MS: m/z 475.1989
[M + ]+, calcd. for C25H31O9 475.1968.

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3.4.3. 7-Acetoxycaesalpinin P (3)
Colorless amorphous solid; IR (CHCl3) cmÀ1: 3575, 1730; NMR
data (CDCl3) see Table 1; HR-ESI-MS: m/z 417.2285 [M + ]+, calcd. for
C26H35O8 417.2277.

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Acknowledgements

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This work was supported by Department of Science and
Technology, Hochiminh City.

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Appendix A. Supplementary data

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Supplementary data associated with this article can be found, in
the
online
version,
at
/>phytol.2015.05.018.

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Please cite this article in press as: Dang, P.H., et al., Three new cassane-type furanoditerpenes from the seed of vietnamese Caesalpinia
bonducella. Phytochem. Lett. (2015), />
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