Lignan dicarboxylates and terpenoids from the flower buds of cananga odorata and their inhibitory effects on melanogenesis

Article abstract of DOI:10.1021/np401091f

The methanolic extract from the flower buds of Cananga odorata showed an inhibitory effect on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, two new lignan dicarboxylates, canangalignans I and II, three new terpenoids, canangaterpenes I, II, and III, and eight known compounds were isolated. The structures of these compounds were elucidated on the basis of chemical/physicochemical evidence. Several mono- and sesquiterpene analogues significantly inhibited melanogenesis. In particular, canangaterpene I and (3R,3aR,8aS)-3-isopropyl-8a-methyl-8-oxo-1,2,3,3a,6,7,8,8a- octahydroazulene-5-carbaldehyde exhibited a potent inhibitory effect on melanogenesis [inhibition (%): 34.7 ± 4.2 (p < 0.01), 45.5 ± 5.7 (p < 0.01) at 1 μM, respectively] without inducing cytotoxicity. Moreover, the biological effect of these compounds was much stronger than that of the reference compound, arbutin. Thus, these isolated terpenoid derivatives may be promising therapeutic agents for the treatment of several skin disorders.

Full text of DOI:10.1021/np401091f

Article
pubs.acs.org/jnp
Lignan Dicarboxylates and Terpenoids from the Flower Buds of
Cananga odorata and Their Inhibitory Effects on Melanogenesis
Takahiro Matsumoto, Seikou Nakamura, Souichi Nakashima, Katsuyoshi Fujimoto, Masayuki Yoshikawa,
Tomoe Ohta, Keiko Ogawa, and Hisashi Matsuda*
Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan
S
* Supporting Information
ABSTRACT: The methanolic extract from the flower buds of
Cananga odorata showed an inhibitory effect on melanogenesis
in theophylline-stimulated murine B16 melanoma 4A5 cells.
From the methanolic extract, two new lignan dicarboxylates,
canangalignans I and II, three new terpenoids, canangater-
penes I, II, and III, and eight known compounds were isolated.
The structures of these compounds were elucidated on the
basis of chemical/physicochemical evidence. Several mono-
and sesquiterpene analogues significantly inhibited melano-
genesis. In particular, canangaterpene I and (3R,3aR,8aS)-3-
isopropyl-8a-methyl-8-oxo-1,2,3,3a,6,7,8,8a-octahydroazulene-5-carbaldehyde exhibited a potent inhibitory effect on melano-
genesis [inhibition (%): 34.7 4.2 (p < 0.01), 45.5 5.7 (p < 0.01) at 1 μM, respectively] without inducing cytotoxicity.
Moreover, the biological effect of these compounds was much stronger than that of the reference compound, arbutin. Thus, these
isolated terpenoid derivatives may be promising therapeutic agents for the treatment of several skin disorders.
Cananga odorata Hook. f. and Thomson (Annonaceae) is
widely distributed in tropical and subtropical regions. The
flowers have been used as a tonic for the heart and for the
treatment of dizziness and fainting spells. The essential oil from
the flowers has also been used in the field of aromatherapy.
Previous studies have focused on constituents such as
sesquiterpenes,1 monoterpenes,2 and lignans3 from the fruit,
stem, or bark of C. odorata. However, the chemical constituents
of the flowers have not been characterized. In the course of our
studies on bioactive constituents from medicinal flowers.4−14
A
methanolic extract from the flower buds of C. odorata cultivated
in Thailand was shown to have inhibitory effects on
melanogenesis. From the MeOH extract, we have isolated
two new lignan dicarboxylates, canangalignans I (1) and II (2),
three new terpenoid derivatives, canangaterpenes I (5), II (7),
and III (8), and eight known compounds. Herein, we describe
the isolation and structural elucidation of the five new
compounds as well as the inhibitory effects of the isolated
compounds on melanogenesis in theophylline-stimulated B16
melanoma 4A5 cells.
RESULTS AND DISCUSSION
■
A MeOH extract of the dried flower buds of C. odorata
(cultivated in Thailand) showed melanogenesis inhibitory
activity [inhibition (%): 43.8 1.9 (p < 0.01) at 3 μg/mL].
The MeOH extract was partitioned into an EtOAc−H2O (1:1,
v/v) mixture to furnish an EtOAc-soluble fraction (9.8%) and
an aqueous layer. The aqueous layer was extracted with 1-
butanol to give 1-butanol (18.8%) and H2O (10.9%) soluble
fractions. The EtOAc- and the 1-butanol-soluble fractions
Received: December 27, 2013
Published: March 6, 2014
© 2014 American Chemical Society and
American Society of Pharmacognosy
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Journal of Natural Products
Table 1. 13C NMR (125 MHz) Spectroscopic Data for 1 and 2
Article
a
position
1
position
1
position
2
position
2
1
128.1
117.5
146.4
148.7
116.4
124.7
144.4
124.9
169.0
127.6
133.1
116.6
160.6
116.6
133.1
144.1
124.9
169.0
56.1
9″
10″
1‴
2‴
3‴
4‴
5‴
6‴
7‴
146.1
70.2
56.1
75.8
35.7
37.3
25.9
31.2
206.8
110.1
146.1
70.2
104.1
74.5
78.4
71.1
77.8
62.5
104.1
74.5
78.4
71.1
77.8
62.5
1
131.3
124.9
117.1
149.3
145.7
117.1
139.6
124.9
168.5
134.8
129.7
116.2
157.2
116.2
129.7
47.0
9″
10″
1‴
2‴
3‴
4‴
5‴
6‴
7‴
146.2
2
2
69.8
56.2
75.7
35.8
37.3
26.0
31.2
206.8
110.1
146.3
70.1
104.2
74.5
78.5
71.2
77.9
62.6
104.2
74.5
78.5
71.2
77.9
62.6
3
3
4
4
5
5
6
6
7
7
8
8
9
9
1′
2′
3′
4′
5′
6′
7′
8′
9′
1″
2″
3″
4″
5″
6″
7″
8″
8‴
9‴
1′
2′
3′
4′
5′
6′
7′
8′
9′
1″
2″
3″
4″
5″
6″
7″
8″
8‴
9‴
10‴
1⁗
2⁗
3⁗
4⁗
5⁗
6⁗
1⁗′
2⁗′
3⁗′
4⁗′
5⁗′
6⁗′
10‴
1⁗
2⁗
3⁗
4⁗
5⁗
6⁗
1⁗′
2⁗′
3⁗′
4⁗′
5⁗′
6⁗′
49.6
174.5
56.2
75.8
75.8
35.7
35.6
37.3
37.3
26.0
25.9
31.2
31.2
206.8
110.1
206.8
110.1
a
Measured in methanol-d4.
significantly inhibited melanogenesis [inhibition (%): 37.5
3.4 (p < 0.01), 46.9 6.8 (p < 0.01), respectively, at 3 μg/mL],
but the H2O-soluble fraction showed no detectable biological
effect at 3 μg/mL. The EtOAc- and the 1-butanol-soluble
fractions were subjected to normal- and reversed-phase silica
gel column chromatography and repeated HPLC to give two
new lignan dicarboxylates, canangalignans I (1, 0.052%) and II
(2, 0.0015%), three new terpenoid derivatives, canangaterpenes
I (5, 0.0014%), II (7, 0.00087%), and III (8, 0.00061%), the
known lignan (1R,2S)-1,2-dihydro-5,6-dihydroxy-1-(4-hydrox-
yphenyl)-2,3-naphthalenedicarboxylic acid 2,3-bis(10-cananga-
fruiticoside A) ester (3, 0.0038%),3 and eight known terpenoid
derivatives, canangafruiticoside E (4, 0.0039%),3 (E)-
{(1R,3R,5S,6S,8S)-6-hydroxy-1,3-dimethoxy-2-oxaspiro[4.5]-
decan-8-ylmethyl} caffeate (6, 0.0015%),3 15-oxo-α-cadinol (9,
0.0029%),15,16 10β-hydroxyisodauc-6-en-14-al (10, 0.0028%),17
aphanamol II (11, 0.0017%),18 (3R,3aR,8aS)-3-isopropyl-8a-
methyl-8-oxo-1,2,3,3a,6,7,8,8a-octahydroazulene-5-carbalde-
hyde (12, 0.0042%),19 voleneol (13, 0.0019%),20 and
(1R,5E,7S)-4,10-bis(methylene)-7-(1-methylethyl)-5-cyclode-
cen-1-ol (14, 0.0055%).21
data (Table 1) of 1, assigned via various NMR experiments,23
showed resonances assignable to two phenylpropanoid moieties
{two olefinic protons [δ 7.73 (s, H-7), 7.80 (s, H-7′)], seven
aromatic protons [δ 6.68 (d, J = 8.6 Hz, H-5), 6.71 (d, J = 8.6
Hz, H-3′, -5′), 6.92 (dd, J = 8.6, 1.9 Hz, H-6), 7.07 (d, J = 1.9
Hz, H-2), 7.41 (d, J = 8.6 Hz, H-2′, -6′)], and two carbonyl
carbons [δC 169.0, 169.0]}, two monoterpene units {two
oxymethylenes [δ 3.86 (2H, m, H-10″a, -10‴a), 3.96 (2H, m,
H-10″b, -10‴b)], two oxymethines [δ 3.70 (2H, m, H-2″, 2‴)],
four olefinic protons [δ 4.56 (2H, d, J = 6.2 Hz, H-8″, -8‴),
6.42 (2H, d, J = 6.2 Hz, H-9″, -9‴)], two formyl protons [δ
9.76 (2H, s, H-7″, -7‴)]}, and two β-D-glucopyranosyl moieties
[δ 4.46 (2H, d, J = 7.8 Hz, H-1⁗, 1⁗)]. The DQF COSY and
HMBC experiments indicated 1 to be a lignan derivative with
two glucosylated monoterpenoid moieties. The linkages of the
phenylpropenoic acid moieties as well as the locations of the
monoterpene and glucopyranosyl moieties were confirmed by
HMBC spectroscopy. Correlations were observed between H-7
and C-8′, 9; H-7′ and C-8, 9′; H-10″ and C-9; H-10‴ and C-9′;
H-1⁗ and C-9″; and H-1⁗′ and C-9‴. The geometry of the
olefinic bonds of 1 was characterized by NOESY experiments of
lignan 1e derived from 1 (Scheme 1). Specifically, catalytic
reduction of 1 yielded 1a, which upon treatment with NaBH4
afforded 1b. Enzymatic hydrolysis of 1b with hesperidinase
gave 1c, which was treated with trimethylsilyldiazomethane
(TMSCH2N2) followed by ester hydrolysis with NaOMe to
give lignan 1e. NOESY experiments of 1e showed correlations
between H-7 and H-2′, -6′ and between H-7′ and H-2, -6.
Therefore, the geometries of both olefinic groups were E. In
addition, the known monoterpene glucoside 1h3 was obtained
from 1b by methylation and ester hydrolysis, hence defining the
structure of the monoterpenoid moiety. Collectively, the data
Canangalignan I (1) was isolated as an amorphous powder
with a positive specific rotation ([α]25D +25, in MeOH). Its IR
spectrum showed absorption bands at 3400, 1703, 1682, 1601,
1512, and 1075 cm−1 ascribable to hydroxy, ester, formyl,
aromatic ring, and ether functionalities, respectively. FABMS in
the positive-ion mode revealed a quasimolecular ion [M + Na]+
at m/z 1053, from which the molecular formula C50H62O23 was
determined via HRMS and 13C NMR data. Acid hydrolysis of 1
with 5% aqueous H2SO4−1,4-dioxane yielded D-(+)-glucose,
which was identified by HPLC of the chiral tolylthiocarbamoyl
thiazolidine derivative.22 The H (methanol-d4) and 13C NMR
1
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Scheme 1
permitted assignment of the structure of canangalignan I (1) as
shown.
Canangaterpene I (5) was isolated as an amorphous powder
with a negative specific rotation ([α]25 −2, in MeOH). Its IR
D
spectrum showed absorption bands at 3400, 1716, and 1508
cm−1 ascribable to hydroxy, ester, and aromatic ring
functionalities, respectively. EIMS revealed a molecular ion
[M]+ at m/z 408, from which the molecular formula C21H28O8
Canangalignan II (2), obtained as an amorphous powder
with a positive specific rotation ([α]25 +33 in MeOH),
D
showed absorption bands due to hydroxy, ester, formyl,
aromatic ring, and ether functionalities in the IR spectrum.
Positive-ion FABMS revealed a quasimolecular ion [M + Na]+
at m/z 1053, from which the molecular formula C50H62O23 was
determined via HRMS and 13C NMR data. Acid hydrolysis of 2
1
was determined via HRMS and 13C NMR data. The H NMR
(methanol-d4) and 13C NMR data (Table 2) of 523 showed
resonances assignable to a caffeoyl group [δ 6.23 (d, J = 15.5
Hz, H-8), 6.76 (d, J = 8.3 Hz, H-5), 6.92 (d, J = 8.3 Hz, H-6),
7.03 (s, H-2), 7.51 (d, J = 15.5 Hz, H-7)] and a monoterpenoid
moiety {an oxymethylene [δ 4.03 (2H, m, H2-11′)], three
oxymethines [δ 3.39 (m, H-6′), 4.89 (s, H-1′), 5.07 (dd, J = 4.2,
6.2 Hz, H-3′)], and two methoxy groups [δ 3.37 (s, 3′-OMe),
3.38 (s, 1′-OMe)]}. As shown in Figure 1 the DQF COSY
experiments indicated the presence of partial structures
(written in bold), and in the HMBC experiments, correlations
were observed between H-2 and C-7, -3; H-6 and C-7, -1, -4;
H-7 and C-2; H-1′ and C-5′; H-3′ and C-5′; H-6′ and C-8′; H-
7′ and C-9′, -11′; H-8′ and C-6′; H-9′ and C-11′; H-10′ and C-
5′; H-11′ and C-9; and OCH3 × 2 and C-1′, -3′. The molecular
structure was the same as that of the known compound 6. The
relative configuration of the monoterpenoid moiety 5 was
characterized by NOESY (Figure 2). Correlations were
observed between H-4′β and H-3′; H-6′ and H-4′β, -7′α, -8′;
and H-8′ and H-7′α, -9′α. On the basis of all this evidence,
canangaterpene I (5) was characterized to be a monoterpene
analogue possessing a rare oxaspiro[4.5]decane skeleton similar
to 6. Compound 6 might be formed from an oxaspiro[4.5]-
yielded D-(+)-glucose.22 The H (methanol-d4) and 13C NMR
1
data (Table 1) of 2, assigned via various NMR experiments,23
showed resonances assignable to a lignan moiety {two methines
[δ 3.80 (d, J = 2.2 Hz, H-8′), 4.37 (d, J = 2.2 Hz, H-7′)], an
olefinic proton [δ 7.52 (s, H-7)], and six aromatic protons [δ
6.46 (s, H-3), 6.59 (d, J = 8.5 Hz, H-3′, -5′), 6.78 (d, J = 8.5 Hz,
H-2′, -6′), 6.80 (s, H-6)], and two carbonyl carbons [δC 168.5,
174.5]} together with a monoterpene glucoside unit. The
proton and carbon resonances in the 1H and 13C NMR data of
2 were superimposable on those of 3, except for the resonances
around C-3 and C-5 of 2. The DQF COSY and HMBC
experiments indicated 2 to be a lignan derivative with the same
monoterpene glucoside moieties as 1. The absolute config-
urations at C-7′ and C-8′ in 2 were confirmed by electronic
circular dichroism (ECD). The ECD spectrum (MeOH) of 2
was identical to that of the known compound 3.24 Both 2 and 3
showed a positive Cotton effect at 257 nm indicative of a (7′R,
8′S) absolute configuration. Thus, the structure of canangali-
gnan II (2) was defined as shown.
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C22H30O3 was determined via HRMS and 13C NMR data. The
1H (CDCl3) and 13C NMR (Table 2) data of 723 showed
resonances assignable to three methyl groups [δ 0.96 (3H, s, H-
15), 0.98 (3H, s, H-14), 1.11 (3H, s, H-13)], two oxymethines
[δ 3.34 (1H, m, H-9), 5.09 (1H, dd, J = 6.2, 8.2 Hz, H-2)], and
five aromatic protons [δ 7.43 (2H, dd, J = 7.6, 7.6 Hz, H-3′,
-5′), 7.55 (1H, t, J = 7.6 Hz, H-4′), 8.03 (2H, d, J = 7.6 Hz, H-
2′, -6′)]. The DQF COSY and HMBC experiments indicated 7
to be a clovane-type sesquiterpene with a benzoyl group. The
C-2 location of the benzoate group was confirmed by the
HMBC correlations between H-2 and the carbonyl carbon. The
relative configuration was characterized by the observed NOE
correlations between H-2 and H-3β, -5; H-3α and H3-14; H-5
and H-11β, -13; H-9 and H-11α, -12β, -15; and H-11α and H-
12β (Figure 2). The C-9 absolute configuration was determined
by application of the modified Mosher’s method. Treatment of
7 with (−)-α-methoxy-α-(trifluoromethyl)phenylacetyl chlor-
ide [(−)-MTPA-Cl] in pyridine yielded the (S)-MTPA ester
7a. The (R)-MTPA ester 7b was derived from 7 by treatment
with (+)-MTPA-Cl in pyridine. As shown in Figure 2, the
resonances due to the C-10 and C-11 protons in 7a were
deshielded compared to those of 7b [Δδ: positive], while the
resonances due to the protons C-6, C-7, C-12, and C-15 of the
(S)-MTPA ester (7a) were shielded compared to those of the
(R)-MTPA ester (7b) [Δδ: negative]. Thus, the C-9 absolute
configuration in 7 was defined as R. Thus, the structure of
canangaterpene II (7) was defined as (1R,2S,5R,8S,9R)-2-
benzoylclovan-2,9-diol.
Table 2. 13C NMR (125 MHz) Spectroscopic Data for 5, 7,
and 8
a
b
b
position
5
position
7
position
8
1
127.7
115.1
146.8
149.6
116.6
123.0
146.9
115.2
169.2
106.7
107.6
44.8
1
45.1
82.8
1
45.8
19.6
22.5
140.7
154.8
35.9
43.8
19.6
34.5
71.9
27.3
21.4
15.6
29.5
194.5
2
2
2
3
3
44.5
3
4
4
38.4
4
5
5
50.4
5
6
6
20.9
6
7
7
33.1
7
8
8
34.6
8
9
9
74.8
9
1′
3′
4′
5′
6′
7′
8′
9′
10
11
12
13
14
15
1′
2′
3′
4′
5′
6′
27.5
10
11
12
13
14
15
26.6
35.5
53.2
31.6
76.8
25.4
36.3
28.2
37.5
130.8
129.7
128.3
132.7
128.3
129.7
166.3
27.3
10′
11′
7′-OMe
9′-OMe
32.4
69.6
55.5
55.7
1′-COO
a
b
Measured in methanol-d4. CDCl3.
Canangaterpene III (8), obtained as a white powder with a
decane with hydroxy groups at C-1′ and C-3′ during extraction
with MeOH.3
positive specific rotation ([α]25 +25 in MeOH), showed
D
absorption bands due to hydroxy and formyl functionalities in
the IR spectrum. EIMS revealed a molecular ion [M]+ at m/z
236, from which the molecular formula C151H24O2 was
determined via HRMS and 13C NMR data. The H (CDCl3)
and 13C NMR data (Table 2) of 823 showed resonances
Canangaterpene II (7), obtained as colorless crystals with a
positive specific rotation ([α]25 +25 in MeOH), showed
D
absorption bands due to hydroxy, ester, and aromatic ring
functionalities in the IR spectrum. EIMS revealed a molecular
ion [M]+ at m/z 342, from which the molecular formula
Figure 1.
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Figure 2.
assignable to three methyl groups [δ 0.91, 0.95 (3H each, both
d, J = 6.7 Hz, H3-12, -13), 1.25 (3H, s, H3-14)], an olefinic
proton [δ 6.96 (1H, d, J = 5.7 Hz, H-5)], and a formyl proton
[δ 9.44 (1H, s, H-15)]. DQF COSY and HMBC experiments
indicated 8 to be similar to the cadinane-type sesquiterpenes
15-oxo-α-cadinol (9) and 15-oxo-T-muurolol. The relative
configuration of 8 was characterized by NOESY correlations
between H-1 and H-6, H3-14 and between H-6 and H-11, H3-
12, -13 (Figure 2). Therefore, the structure of canangaterpene
III (8) was defined as shown.
Melanin production, which is principally responsible for skin
color, is a major defense mechanism against the harmful
ultraviolet rays in sunlight. However, excess production of
melanin after long periods of exposure to the sun can cause
dermatological disorders such as melasma, freckles, post-
inflammatory melanoderma, and solar lentigo. We previously
reported that several constituents from natural medicines and
medicinal foods inhibited melanogenesis in theophylline-
stimulated B16 melanoma 4A5 cells.8,9,11−13,25−29 As a
continuation of these studies, the inhibitory effects of
constituents from the flower buds of C. odorata on melano-
genesis were examined (Table 3). Terpenoid derivatives 5, 6, 8,
9, and 11−14 inhibited melanogenesis [inhibition: 28.9−45.5%
(p < 0.01) at 1 μM]. In particular, compounds 5 (IC50 = 3.6
μM) and 12 (IC50 = 2.5 μM) exhibited considerable inhibitory
effects on melanogenesis without inducing cytotoxicity [cell
viability: more than 95.2% at 30 μM]. Indeed, 5 and 12
displayed greater potency for inhibiting melanogenesis than the
control, arbutin (IC50 = 174 μM). Compounds 9 and 12, with a
trans-fused ring junction, showed stronger inhibitory effects
than compounds 8 and 11, with a cis-fused junction.
Compound 12, with a C-2 carbonyl, displayed a stronger
inhibitory effect than compound 10, with a C-2 hydroxy group.
By contrast, lignan 1c, derived from 1, showed moderate
inhibitory activity. However, lignans 1a, 1b, 1d, and 1e
displayed either no inhibitory action or only a very weak
inhibitory effect on melanogenesis. These findings indicate that
a catechol moiety and structures lacking glucosyl moieties are
important for the melanogenesis inhibitory activity of the
lignans studied here.
In conclusion, two new lignan carboxylates, canangalignans I
(1) and II (2), and three new terpenoids, canangaterpenes I
(5), II (7), and III (8), were isolated from the dried flower buds
of C. odorata cultivated in Thailand. Compounds 5 and 12
exhibited significant inhibitory effects on melanogenesis
without inducing cytotoxicity. Therefore, compounds 5 and
12 are potential therapeutic agents for the treatment of several
skin disorders. Further structure activity relationship studies
and elucidation of the inhibitory mechanism are warranted.
EXPERIMENTAL SECTION
■
General Experimental Procedures. The following instruments
were used to obtain physical data: optical rotations, a Horiba SEPA-
300 digital polarimeter (l = 5 cm); IR spectra, a Shimadzu FTIR-8100
spectrometer; ECD spectra, a JASCO J-720WI spectrometer; FABMS
and HRFABMS, a JEOL JMS-SX 102A mass spectrometer; EIMS and
HREIMS, a JEOL JMS-GCMATE mass spectrometer; 1H NMR
spectra, a JEOL JNM-LA 500 (500 MHz); 13C NMR spectra, a JEOL
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Table 3. Inhibitory Effects of Constituents and Their Derivatives from the Flower Buds of Cananga odorata on Melanogenesis
a
in B16 Melanoma 4A5 Cells
inhibition (%)
10 μM
IC50
control
1 μM
3 μM
30 μM
100 μM
(μM)
b
c
1
2
3
4
5
6
7
8
9
0.0 2.1
0.0 4.0
0.0 5.2
0.0 4.2
0.0 6.8
0.0 5.4
0.0 1.3
0.0 4.4
0.0 5.0
0.0 3.5
0.0 6.9
0.0 7.8
0.0 4.8
0.0 7.3
0.0 4.9
0.0 4.7
0.0 2.5
0.0 1.5
0.0 5.1
0.0 4.1
0.0 1.3
0.0 2.1
28.6 1.6**
9.2 3.8
30.2 2.2**
8.7 2.1
31.8 1.1**
3.6 5.8
34.8 1.8**
2.9 4.1
16.7 1.9**
8.7 4.6
>100
>100
>100
>100
3.6
c
12.8 3.7
14.9 2.8
9.4 5.0
8.4 3.7
−27.9 5.9
12.2 5.6
b
b
c
−3.8 3.0
−8.5 4.1
42.8 2.2**
16.9 3.7**
40.2 1.4**
29.9 4.1**
45.5 1.0**
9.2 5.6
9.3 5.5
11.4 3.4
62.8 0.8**
60.0 0.8**
34.7 4.2**
13.5 2.3*
45.3 1.1**
19.2 3.8**
25.0 3.1**
−4.4 11.3
37.6 6.3**
45.5 5.7**
42.3 4.5**
28.9 2.5**
8.1 5.1
65.2 2.6**
36.4 2.6**
66.7 0.8**
35.8 1.0**
64.0 2.7**
14.7 3.1
66.8 0.5**
81.2 0.6**
19.3
ca. 3
26.2
5.1
e
c
50.8 1.7**
65.9 3.0**
37.7 4.2**
28.3 7.8**
68.5 1.9**
54.7 1.9**
61.2 5.2**
24.2 1.0**
32.3 4.7**
49.8 2.0**
−19.9 6.7
35.9 2.5**
51.6 1.2**
−9.2 7.2
66.3 1.5**
48.8 1.4**
58.8 1.3**
42.1 2.6**
80.6 2.6**
59.2 2.4**
62.2 1.6**
29.8 1.9**
25.3 3.7**
44.2 1.3**
−15.7 5.0
11.5 2.8
c
c
10
11
12
13
14
57.5
>100
2.5
d
b
d
b
34.3 6.9**
50.3 2.1**
39.7 4.2**
30.5 3.0**
18.0 5.0*
27.2 3.9*
45.0 3.2*
24.1 2.3*
48.4 12.3
55.1 1.8**
20.2 3.1*
17.9 3.2*
32.9 7.7**
57.6 3.7**
53.8 2.7**
40.6 2.3**
18.4 1.9*
27.3 2.1*
59.0 1.7**
8.1 5.4
8.4
17.3
>100
>100
ca. 5
b
1a
c
1b
22.3 1.7**
36.1 3.8**
34.4 2.5**
49.0 4.6**
45.0 1.5**
14.8 5.6
b
1c
e
1d
d
1e
43.6 1.4**
55.9 2.5**
8.9 2.6
b
1f
25.6 5.5
ca. 2
b
1g
1h
−21.8 4.7
−9.4 3.8
c
16.1 7.1
15.3 5.0
−2.5 6.5
inhibition (%)
100 μM
38.1 0.9**
IC50
(μM)
174
control
0.0 1.4
10 μM
10.6 0.6**
30 μM
300 μM
1000 μM
f
arbutin
20.4 0.5**
61.5 0.6**
83.7 0.5**
a
Each value represents the mean SEM (n = 4). Significantly different from the control group, *p < 0.05, **p < 0.01. IC50 values were determined
graphically. The cell viabilities at 30 μM are more than 95.2%. The cell viabilities at 30 μM are more than 80.3%. The cell viabilities at 30 μM are
more than 74.5%. Cytotoxicity was observed [cell viabilities: 7: 75.9% at 10 μM, 7.9% at 30 μM; 1d: 82.0% at 10 μM, 68.8% at 30 μM]. Reference
b
c
d
e
f
compound.
JNM-LA (125 MHz) spectrometer with TMS as internal standard;
1HNMR spectra, JEOL JNM-ECA600 (600 MHz) spectrometers; and
HPLC, SPD-10Avp fitted with UV−vis detectors. The following
columns from Nacalai Tesque (Kyoto, Japan) were used: (i) for
analytical purposes, a COSMOSIL 5C18-MS-II 250 × 4.6 mm (5 μm
i.d.) and (ii) for preparative purposes, a COSMOSIL 5C18-MS-II 250
× 20 mm (5 μm i.d.). The following experimental conditions were
used for chromatography: ordinary-phase silica gel column chroma-
tography (CC), silica gel BW-200 (Fuji Silysia Chemical, Ltd., Kasugai,
Japan; 150−350 mesh); reversed-phase silica gel CC, Chromatorex
ODS DM1020T (Fuji Silysia Chemical, Ltd., 100−200 mesh); TLC,
precoated TLC plates with silica gel 60F254 (Merck, Darmstadt,
Germany; 0.25 mm) (ordinary phase) and silica gel RP-18 F254S
(Merck, 0.25 mm) (reversed phase); reversed-phase HPTLC,
precoated TLC plates with silica gel RP-18 WF254S (Merck, 0.25
mm). Detection was achieved by spraying with 1% Ce(SO4)2−10%
aqueous H2SO4 followed by heating.
→ 5:1 → 1:1 → 1:2, v/v) → MeOH] to give nine fractions [Fr.B1
(1.4 g), Fr.B2 (6.2 g), Fr.B3 (1.2 g), Fr.B4 (6.6 g), Fr.B5 (8.4 g), Fr.B6
(6.2 g), Fr.B7 (30.1 g), Fr.B8 (6.8 g), Fr.B9 (2.3 g)]. Fraction B7 (30.1
g) was further separated by reversed-phase silica gel column
chromatography [1 kg, MeOH−H2O (3:7 → 4:6 → 5:5 → 6:4 →
7:3, v/v) → MeOH] to give eight fractions [Fr.B7-1, Fr.B7-2, Fr.B7-3
(6.2 g), Fr.B7-4 (573 mg), Fr.B7-5, Fr.B7-6, Fr.B7-7, Fr.B7-8].
Fraction B7-3 (6.2 g) was purified by reversed-phase silica gel column
chromatography [180.0 g, MeOH−H2O (1:9 → 2:8 → 3:7 → 4:6 →
5:5, v/v) → MeOH] to give six fractions [Fr.B7-3-1, Fr.B7-3-2, Fr.B7-
3-3, Fr.B7-3-4, Fr.B7-3-5 (1.5 g), Fr.B7-3-6]. Fraction B7-3-5 (1.5 g)
was purified by HPLC [mobile phase: H2O−MeOH (80:20, v/v)] to
give 1 (275.5 mg), 2 (8.1 mg), 3 (20.5 mg), and 4 (21.3 mg). A part of
the EtOAc-soluble fraction (50.0 g) was subjected to normal-phase
silica gel column chromatography [3.0 kg, n-hexane → n-hexane−
CHCl3 (5:1 → 2:1, v/v) → CHCl3−MeOH (200:1 → 100:1 → 50:1
→ 10:1 → 3:1, v/v) → MeOH] to give seven fractions [Fr.E1 (7.5 g),
Fr.E2 (3.9 g), Fr.E3 (3.6 g), Fr.E4 (27.6 g), Fr.E5 (6.6 g), Fr.E6 (16.8
g), Fr.E7 (10.0 g)]. Fraction E4 (27.6 g) was separated by reversed-
phase silica gel column chromatography [900.0 g, MeCN−H2O (4:6
→ 5:5 → 6:4 → 7:3 → 8:2 → 9:1, v/v) → MeCN] to give seven
fractions [Fr.E4-1, Fr.E4-2 (0.73g), Fr.E4-3 (1.0 g), Fr.E4-4 (0.84g),
Fr.E4-5, Fr.E4-6 (1.5 g), Fr.E4-7]. Fraction E4-2 (0.73 g) was purified
by HPLC [mobile phase: H2O−MeCN−HOAc (650: 350: 3, v/v/v)]
to give 13 (10.0 mg). Fraction E4-3 (1.0 g) was purified by HPLC
[mobile phase: H2O−MeOH−HOAc (800:200:3, v/v/v)] to give 8
(6.3 mg), 9 (15.2 mg), 10 (14.8 mg), and 11 (8.9 mg). Fraction E4-4
(0.84 g) was purified by HPLC [mobile phase: H2O−MeOH−HOAc
(500:500:3, v/v/v)] to give 12 (22.3 mg) and 14 (29.2 mg). Fraction
E4-6 (1.5 g) was purified by HPLC [mobile phase: H2O−MeOH−
HOAc (320:680:3, v/v/v)] to give 7 (8.9 mg). Fraction E5 (6.6 g) was
Plant Material. Flower buds of C. odorata cultivated in Thailand
were purchased from Mae Chu Co. Ltd. (Nara, Japan) in 2012 and
identified by one of the authors (M.Y.). A voucher specimen is on file
in our laboratory (KPU CO-2012-1).
Extraction and Isolation. The dried flower buds (4 kg) were
extracted three times with MeOH under reflux for 3 h. Evaporation of
the solvent under reduced pressure provided a MeOH extract (1575 g,
39.4%). A part of the MeOH extract (210 g) was partitioned into an
EtOAc−H2O (1:1, v/v) mixture to furnish an EtOAc-soluble fraction
(52 g, 9.8%) and an aqueous phase. The aqueous phase was further
extracted with 1-butanol to give a 1-butanol-soluble fraction (100 g,
18.8%) and an H2O-soluble fraction (58 g, 10.9%). The 1-butanol-
soluble fraction (100 g) was subjected to normal-phase silica gel
column chromatography [2.5 kg, CHCl3−MeOH (1:0 → 50:1 → 10:1
995
dx.doi.org/10.1021/np401091f | J. Nat. Prod. 2014, 77, 990−999

Journal of Natural Products
Article
separated by reversed-phase silica gel column chromatography [500.0
g, MeCN−H2O (1:9 → 2:8 → 3:7 → 4:6 → 5:5 → 6:4 → 7:3 → 8:2
→ 9:1, v/v) → MeCN] to give seven fractions [Fr.E5-1, Fr.E5-2,
Fr.E5-3, Fr.E5-4, Fr.E5-5 (40.7 mg), Fr.E5-6, Fr.E5-7]. Fraction E6
(16.8 g) was separated by reversed-phase silica gel column
chromatography [500 g, MeOH−H2O (1:9 → 2:8 → 3:7 → 4:6 →
5:5 → 6:4 → 7:3 → 8:2 → 9:1, v/v) → MeOH] to give seven
fractions [Fr.E6-1, Fr.E6-2, Fr.E6-3, Fr.E6-4 (1.2 g), Fr.E6-5, Fr.E6-6
(1.6 g), Fr.E6-7]. Fraction E6-4 (1.2 g) was separated by normal-phase
silica gel column chromatography [1.2 g, n-hexane−EtOAc (2:1 → 1:1
→ 1:2, v/v) → EtOAc−MeOH (1:1, v/v) → MeOH] to give five
fractions [Fr.E6-4-1, Fr.E6-4-2, Fr.E6-4-3 (130 mg), Fr.E6-4-4 (225
mg), Fr.E6-4-5 (399 mg)]. Fraction E6-4-5 (399 mg) was purified by
HPLC [H2O−MeCN−HOAc (670:330:3, v/v/v)] to give 5 (14.0
mg) and 6 (8.2 mg).
-6′); 13C NMR (CDCl3, 125 MHz) δ given in Table 2; EIMS m/z 342
[M]+; HREIMS m/z 342.21981 (calcd for C22H30O3 [M]+,
342.21948).
Canangaterpene III (8): white powder; [α]25D −21 (c 0.5, MeOH);
IR (film) νmax 3410, 1684, 1509 cm−1; 1H NMR (CDCl3, 500 MHz) δ
0.91 (3H, d, J = 6.7 Hz H-12), 0.95 (3H, d, J = 6.7, H-13), 1.25 (3H, s,
H-14), 1.39 (1H, m, H-7), 1.46 (2H, m, H-2β, -8β), 1.51 (1H, m, H-
9α), 1.52 (2H, m, H-2α, -8α), 1.63 (1H, m, H-9β), 1.75 (1H, m, H-1),
1.96 (1H, m, H-11), 2.43 (1H, dd, J = 5.7, 17.6 Hz, H-3α), 2.47 (1H,
m, H-3β), 2.76 (1H, m, H-6), 6.96 (1H, d, J = 5.7 Hz, H-5), 9.44 (1H,
s, H-15); 13C NMR (CDCl3, 125 MHz) δ given in Table 2; EIMS m/z
236 [M]+; HREIMS m/z 236.1780 (calcd for C15H24O2 [M]+,
236.1776).
Catalytic Hydrogenation of Canangalignan I (1). Canangali-
gnan I (1) (178 mg, 0.17 mmol) was dissolved in MeOH (16 mL) and
reduced with 10% Pd−C (10 mg) under a H2 atmosphere for 18 h at
room temperature. The mixture was filtered, and the filtrate
evaporated to give 1a (178 mg, quant.).
Canangalignan I (1): amorphous powder; [α]25 +25 (c 0.6,
D
MeOH); UV (MeOH) λmax 200.0 nm (log ε 4.20), 314.0 nm (log ε
1
4.22); IR (KBr) νmax 3400, 1703, 1682, 1601, 1512, 1075 cm−1; H
NMR (methanol-d4, 600 MHz) δ 1.21 (2H, m, H-6″α, -6‴α), 1.28
(2H, m, H-5″β, -5‴β), 1.62 (2H, m, H-4″, -4‴), 1.76 (2H, m, H-3″α,
-3‴α), 2.29 (2H, dd-like, H-6″β, -6‴β), 3.24 (2H, m, H-2⁗, -2⁗′),
3.30 (4H, m, H-5″α, -5‴α, -4⁗, -4⁗′), 3.34 (4H, m, H-3″β, -3‴β, -5⁗,
-5⁗′), 3.70 (2H, m, H-2″, -2‴), 3.84 (4H, d, J = 12.4 Hz, H-6⁗, -6⁗′),
3.86 (2H, m, H-10″a, -10‴a), 3.96 (2H, m, H-10″b, -10‴b), 4.46 (2H,
d, J = 7.8, H-1⁗, -1⁗′), 4.56 (2H, d, J = 6.2 Hz, H-8″, -8‴), 6.42 (2H,
d, J = 6.2, H-9″, -9‴), 6.68 (1H, d, J = 8.6 Hz, H-5), 6.71 (2H, d, J =
8.6 Hz, H-3′, -5′), 6.92 (1H, dd, J = 1.9, 8.6 Hz, H-6), 7.07 (1H, d, J =
1.9 Hz, H-2), 7.41 (2H, d, J = 8.6 Hz, H-2′, -6′), 7.73 (1H, s, H-1),
7.80 (1H, s, H-7′), 9.76 (2H, s, H-7″, -7‴); 13C NMR (methanol-d4,
125 MHz) δ given in Table 1; positive-ion FABMS m/z 1053 [M +
Na]+; HRFABMS m/z 1053.3580 (calcd for C50H62O23Na [M + Na]+,
1053.3574).
1a: amorphous powder; [α]25 −27 (c 0.2, MeOH); UV (MeOH)
D
λmax 207.0 nm (log ε 4.22), 316.0 nm (log ε 4.33); 1H NMR
(methanol-d4, 500 MHz) δ 1.02 (2H, m, H-5″β, -5‴β), 1.06 (2H, m,
H-8″a, -8‴a), 1.08 (2H, m, H-6″α, -6‴α), 1.18 (2H, m, H-5″α, -5‴α),
1.48 (2H, m, H-4″, -4‴), 1.69−1.72 (4H, m, H-3″α, -3‴α, -H-8″b,
-8‴b), 1.90 (2H, m, H-6″β, -6‴β), 2.12 (2H, m, H-3″β, -3‴β), 3.05
(2H, t, J = 9.0 Hz, H-2⁗, -2⁗′), 3.16−3.18 (4H, m, H-3⁗, -3⁗′, -4⁗,
-4⁗′), 3.25 (2H, m, H-5⁗, -5⁗′), 3.46 (2H, m, H-9″a, -9‴a), 3.51
(2H, m, H-2″, -2‴), 3.55 (2H, m, H-6⁗a, -6⁗′a), 3.76 (4H, m, H-6⁗b,
-6⁗′b, -10″a, -10‴a), 3.84−3.90 (4H, m, H-9″b, -9‴b, -10″b, -10‴b),
4.12 (2H, d, J = 7.75 Hz, H-1⁗, -1⁗′), 6.61 (1H, d, J = 8.6 Hz, H-5),
6.62 (2H, d, J = 8.6 Hz, H-3′, -5′), 6.84 (1H, dd, J = 2.1, 8.6 Hz, H-6),
6.97 (1H, d, J = 2.1 Hz, H-2), 7.33 (2H, d, J = 8.6 Hz, H-2′, -6′), 7.63
(1H, s, H-7), 7.70 (1H, s, H-7′), 9.71 (2H, s, H-7″, -7‴); 13C NMR
(methanol-d4, 125 MHz) δ 128.1 (C-1), 117.5 (C-2), 146.5 (C-3),
149.3 (C-4), 116.4 (C-5), 124.7 (C-6), 144.5 (C-7), 124.9 (C-8, -8′),
169.0 (C-9, -9′), 127.6 (C-1′), 133.1 (C-2′, -6′), 116.6 (C-3′, -5′),
160.7 (C-4′), 144.1 (C-7′), 59.3 (C-1″, -1‴), 75.1 (C-2″, -2‴), 35.6
(C-3″, -3‴), 37.5 (C-4″, -4‴), 26.2 (C-5″, -5‴), 30.1 (C-6″, -6‴),
210.0 (C-7″, -7‴), 36.6 (C-8″, -8‴), 66.5 (C-9″, -9‴), 70.1 (C-10″,
-10‴), 104.4 (C-1⁗, -1⁗′), 75.1 (C-2⁗, -2⁗′), 78.1 (C-3⁗, -3⁗′),
71.6 (C-4⁗, -4⁗′), 77.9 (C-5⁗, -5⁗′), 62.8 (C-6⁗, -6⁗′); positive-ion
FABMS m/z 1057 [M + Na]+; HRFABMS m/z 1057.3885 (calcd for
C50H66O23Na [M + Na]+, 1057.3893).
Canangalignan II (2): amorphous powder; [α]25 +33 (c 0.5,
D
MeOH); UV (MeOH) λmax 226.0 nm (log ε 4.20), 331.0 nm (log ε
1
4.33); IR (KBr) νmax 3400, 1701, 1685, 1508, 1075 cm−1; H NMR
(methanol-d4, 500 MHz) δ 1.21 (2H, m, H-6″α, -6‴α), 1.27 (2H, m,
H-5″β, -5‴β), 1.62 (2H, m, H-4″, -4‴), 1.87 (2H, m, H-3″α, -3‴α),
2.27 (2H, m, H-6″β, -6‴β), 3.22 (2H, m, H-2⁗, -2⁗′), 3.27 (4H, m,
H-5″α, -5‴α, -4⁗, -4⁗′), 3.30 (4H, m, H-3″β, -3‴β, -5⁗, -5⁗′), 3.60
(2H, m, H-2″, -2‴), 3.80 (4H, d, J = 10.4 Hz, H-6⁗, -6⁗′), 3.82 (2H,
m, H-10″b, -10‴b), 3.86 (2H, m, H-10″a, -10‴a), 4.42 (2H, d, J = 7.8,
H-1⁗, -1⁗′), 4.56 (2H, d, J = 6.5 Hz, H-8″, -8‴), 6.38 (2H, d, J = 6.5,
H-9″, -9‴), 6.46 (1H, s, H-3), 6.59 (2H, d, J = 8.5 Hz, H-3′, -5′), 6.78
(2H, d, J = 8.5 Hz, H-2′, -6′), 6.80 (1H, s, H-6), 7.52 (1H, s, H-7),
9.74, 9.77 (2H, s, H-7″, -7‴); 13C NMR (methanol-d4, 125 MHz) δ
given in Table 1; ECD Δε (nm) −1.6 (203), −2.1 (230), +2.2 (257),
−0.2 (293), +0.1 (311), −2.7 (340) (c 8.00 × 10−5 m, MeOH);
positive-ion FABMS m/z 1053 [M + Na]+; HRFABMS m/z
1053.3573 (calcd for C50H62O23Na [M + Na]+, 1053.3574).
NaBH4 Reduction of 1a. To a solution of 1a (174 mg, 0.17
mmol) in MeOH (16 mL) was added NaBH4 (13 mg, 0.34 mmol),
and the mixture was stirred for 2 h at room temperature. Saturated
aqueous NH4Cl was added, and the solution was evaporated. The
residue was subjected to normal-phase silica gel column chromatog-
raphy [CHCl3−MeOH] and purified by HPLC [mobile phase: H2O−
MeOH (50:50, v/v)] to give 1b (115 mg, 66%).
Canangaterpene I (5): amorphous powder; [α]25 −2 (c 0.4,
1b: amorphous powder; [α]25D −13 (c 0.1, M.eOH); UV (MeOH)
λmax 204.2 nm (log ε 4.26),316.2 nm (log ε 4.36); 1H NMR
(methanol-d4, 500 MHz) δ 1.02 (2H, m, H-5″β, -5‴β), 1.07 (2H, m,
H-6″α, -6‴α), 1.25 (4H, m, H-3″α, -3‴α, -5″α, -5‴α), 1.27 (2H, m,
H-6″β, -6‴β), 1.28 (2H, m, H-4″, -4‴), 1.65 (2H, m, H-3″β, -3‴β),
1.81 (2H, m, H-8″a, -8‴a), 1.88 (H-8″b, -8‴b), 3.16 (2H, t, J = 7.7 Hz,
H-2⁗, -2⁗′), 3.28−3.29 (4H, m, H-3⁗, -3⁗′, -4⁗, -4⁗′), 3.34 (2H, m,
H-5⁗, -5⁗′), 3.54 (2H, m H-9″b, -9‴b), 3.54−3.58 (4H, m, H-7″,
-7‴), 3.56 (2H, m, H-2″, -2‴), 3.65 (2H, d-like, J = 11.6 Hz, H-6⁗a,
-6⁗′a), 3.81 (2H, m H-9″a, -9‴a), 3.86 (2H, d-like, J = 11.6 Hz, H-
6⁗b, -6⁗′b), 3.91 (2H, m, H-10″a, -10‴a), 3.96 (2H, m, H-10″b,
-10‴b), 4.28 (2H, d, J = 7.75 Hz, H-1⁗, -1⁗′), 6.70 (1H, d, J = 8.0 Hz,
H-5), 6.71 (2H, d, J = 8.0 Hz, H-3′, -5′), 6.92 (1H, dd, J = 2.1, 8.0 Hz,
H-6), 7.07 (1H, d, J = 2.1 Hz, H-2), 7.41 (2H, d, J = 8.0 Hz, H-2′, -6′),
7.74 (1H, s, H-7), 7.81 (1H, s, H-7′); 13C NMR (methanol-d4, 125
MHz) δ 128.2 (C-1), 117.5 (C-2), 146.5 (C-3), 149.1 (C-4), 116.4
(C-5), 124.9 (C-6), 144.5 (C-7), 124.9 (C-8, -8′), 169.0 (C-9, -9′),
127.6 (C-1′), 133.1 (C-2′, -6′), 116.7 (C-3′, -5′), 160.7 (C-4′), 144.1
(C-7′), 42.0 (C-1″, -1⁗), 76.4 (C-2″, -2‴), 34.5 (C-3″, -3‴), 37.8 (C-
4″, -4‴), 25.1 (C-5″, -5‴), 31.6 (C-6″, -6‴), 76.4 (C-7″, -7‴), 37.1 (C-
8″, -8‴), 63.4 (C-9″, -9‴), 70.3 (C-10″, -10‴), 104.2 (C-1⁗, -1⁗′),
D
MeOH); IR (film) νmax 3400, 1716, 1508, 1456 cm−1; 1H NMR
(methanol-d4, 500 MHz) δ 1.11 (m, H-9′β), 1.26 (m, H-10′α), 1.33
(m, H-7′β), 1.52 (m, H-9′α), 1.68 (dd, J = 4.2, 6.2 Hz, H-4′α), 1.84
(m, H-8′), 1.91 (m, H-7′α), 2.12 (m, H-10′β), 2.22 (dd, J = 4.2, 6.2
Hz, H-4′β), 3.37 (s, 3′-OMe), 3.38 (s, 1′-OMe), 3.39 (m, H-6′), 4.03
(dd, J = 4.2, 6.2 Hz, H-11′), 4.89 (s, H-1′), 5.07 (dd, J = 4.2, 6.2 Hz,
H-3′), 6.23 (d, J = 15.5 Hz, H-8), 6.76 (d, J = 8.3 Hz, H-5), 6.92 (d, J
= 8.3 Hz, H-6), 7.03 (s, H-2), 7.51 (d, J = 15.5 Hz, H-7); 13C NMR
given in Table 1; EIMS m/z 408 [M]+; HREIMS m/z 408.1788 (calcd
for C21H28O8 [M]+: m/z 408.1784).
Canangaterpene II (7): colorless crystals (n-hexane−CHCl3); mp
181−185 °C; [α]25 +25 (c 0.5, MeOH); IR (film) νmax 3400, 1716,
D
1
1508 cm−1; H NMR (CDCl3, 500 MHz) δ 0.96 (3H, s, H-15), 0.98
(3H, s, H-14), 1.11 (3H, s, H-13), 1.26 (1H, m, H-10β), 1.40 (1H, m,
H-6β), 1.46 (1H, m, H-7β), 1.53 (1H, m, H-6α), 1.58 (1H, m, H-
12α), 1.59 (1H, m, H-5), 1.64 (1H, m, H-11α), 1.65 (1H, m, H-12β),
1.68 (1H, m, H-3α), 1.69 (1H, m, H-10α), 1.92 (1H, dd, J = 6.2, 8.2
Hz, H-3β), 2.03 (1H, m, H-11β), 2.30 (1H, m, H-7α), 3.34 (1H, m,
H-9), 5.09 (1H, dd, J = 6.2, 8.2, H-2), 7.43 (2H, dd, J = 7.6, 7.6 Hz, H-
3′, -5′), 7.55 (1H, dd, J = 7.6, 7.6, H-4′), 8.03 (2H, t, J = 7.6 Hz, H-2′,
996
dx.doi.org/10.1021/np401091f | J. Nat. Prod. 2014, 77, 990−999

Journal of Natural Products
Article
75.1 (C-2⁗, -2⁗′), 78.2 (C-3⁗, -3⁗′), 71.7 (C-4⁗, -4⁗′), 78.0 (C-5⁗,
-5⁗′), 62.9 (C-6⁗, -6⁗′); positive-ion FABMS m/z 1061 [M + Na]+;
HRFABMS m/z 1061.4202 (calcd for C50H70O23Na [M + Na]+,
1061.4206).
s, 3-OCH3), 3.70 (6H, s, H-9-OCH3, 9′-OCH3), 3.77 (3H, s, 4′-
OCH3), 3.80 (3H, s, 4-OCH3), 6.84 (2H, d, J = 8.7 Hz, H-3′, -5′), 6.88
(1H, d, J = 8.7 Hz, H-5), 7.08 (1H, dd, J = 2.0, 8.7 Hz, H-6), 7.14 (1H,
d, J = 2.0 Hz, H-2), 7.45 (2H, d, J = 8.7 Hz, H-2′, -6′), 7.81 (1H, s, H-
7), 7.85 (1H, s, H-7′); 13C NMR (methanol-d4, 150 MHz) δ 128.9 (C-
1), 113.3 (C-2), 150.2 (C-3), 152.2 (C-4), 112.5 (C-5), 125.9 (C-6),
143.8 (C-7), 125.6 (C-8, -8′), 169.3 (C-9), 128.5 (C-1′), 132.8 (C-2′,
-6′), 115.2 (C-3′, -5′), 162.7 (C-4′), 143.6 (C-7′), 168.4 (C-9′), 56.2
(3-OCH3), 56.3 (4-OCH3), 55.8 (4′-OCH3), 52.8 (9, 9′-O-CH3);
positive-ion EIMS m/z 412 [M]+; HREIMS m/z 412.1525 (calcd for
C23H24O7 [M]+, 412.1522). 1f: amorphous powder; [α]25D −34 (c 0.1,
MeOH); 13C NMR (methanol-d4, 125 MHz) δ 42.6 (C-1), 77.6 (C-
2), 34.7 (C-3), 40.9 (C-4), 25.2 (C-5), 32.4 (C-6), 62.0 (C-7), 41.9
(C-8), 58.9 (C-9), 68.1 (C-10); positive-ion CIMS m/z 205 [M +
H]+; HRCIMS m/z 205.1442 (calcd for C10H22O4 [M + H]+,
205.1440).
Enzymatic Hydrolysis of 1b. To a solution of 1b (75 mg, 0.072
mmol) in 20 mM acetate buffer (20 mL, pH = 3.70) was added
hesperidinase (10 mg, from Penicillium sp. Sigma-Aldrich), and the
mixture was stirred for 12 h at 37 °C. EtOH was the added to each
mixture, and the solution was centrifuged at 4000 rpm for 10 min. The
supernatant solution was concentrated under vacuum to give a residue,
which was subjected to HPLC [mobile phase: H2O−MeCN (70:30, v/
v)] to give 1c (13.5 mg).
1c: amorphous powder; [α]25 −5 (c 0.5, MeOH); UV (MeOH)
D
λmax 208.4 nm (log ε 4.19),316.4 nm (log ε 4.36); 1H NMR
(methanol-d4, 500 MHz) δ 0.95 (2H, m, H-6″α, -6‴α), 1.06 (2H, m,
H-5″β, -5‴β), 1.22 (4H, m, H-3″α, -3‴α, -5″α, -5‴α), 1.57 (2H, m, H-
4″, -4‴), 1.64 (2H, m, H-8″a, -8‴a), 1.65 (2H, m, H-3″β, -3‴β), 1.71
(2H, m, H-6″β, -6‴β), 1.78 (H-8″b, -8‴b), 3.43 (2H, m, H-2″, -2‴),
3.57 (2H, d-like, J = 11.6 Hz, H-7″a, -7‴a), 3.65 (2H, d-like, J = 11.6
Hz, H-6″a, -6‴a), 3.67 (2H, m H-9″a, -9‴a), 3.72 (2H, m H-9″b,
-9‴b), 3.79 (2H, d-like, J = 11.6 Hz, H-7″b, -7‴b), 3.94 (2H, m, H-
10″a, -10‴a), 4.00 (2H, m, H-10″b, -10‴b), 6.68 (1H, d, J = 8.3 Hz, H-
5), 6.70 (2H, d, J = 8.7 Hz, H-3′, -5′), 6.92 (1H, dd, J = 2.1, 8.3 Hz, H-
6), 7.07 (1H, d, J = 2.1 Hz, H-2), 7.41 (2H, d, J = 8.7 Hz, H-2′, -6′),
7.74 (1H, s, H-7), 7.81 (1H, s, H-7′); 13C NMR (methanol-d4, 125
MHz) δ 128.0 (C-1), 117.5 (C-2), 146.6 (C-3), 149.4 (C-4), 116.4
(C-5), 124.8 (C-6), 144.4 (C-7), 124.9 (C-8, -8′), 169.2 (C-9, -9′),
127.6 (C-1′), 133.1 (C-2′, -6′), 116.7 (C-3′, -5′), 160.8 (C-4′), 144.1
(C-7′), 42.4 (C-1″, -1‴), 77.2 (C-2″, -2‴), 34.4 (C-3″, -3‴), 37.8 (C-
4″, -4‴), 25.1 (C-5″, -5‴), 32.2 (C-6″, -6‴), 62.1 (C-7″, -7‴), 41.7 (C-
8″, -8‴), 58.9 (C-9″, -9‴), 70.4 (C-10″, -10‴); positive-ion FABMS
m/z 737 [M + Na]+; HRFABMS m/z 737.3145 (calcd for
C38H50O13Na [M + Na]+, 737.3149).
Methylation of 1b. The procedure was the same as that used for
the preparation of 1d. Compound 1g (14.2 mg) was obtained from 1b
(20 mg) using trimethylsilyldiazomethane (2 M in diethyl ether, 0.2
mL). The crude product was purified by reversed-phase ODS open
column chromatography [1.0 g, MeOH−H2O (2:8 → 3:7 → 4:6 →
1:0, v/v)].
1g: amorphous powder; [α]25 −21 (c 0.2, MeOH); UV (MeOH)
D
λmax 204.2 nm (log ε 4.31), 313.0 nm (log 4.41); 1H NMR (methanol-
d4, 500 MHz) δ 1.05 (2H, m, H-5″β, -5‴β), 1.08 (2H, m, H-6″α,
-6‴α), 1.25 (2H, m, H-3″α, -3‴α), 1.26 (2H, m, H-5″α, -5‴α), 1.29
(2H, m, H-4″, -4‴), 1.29 (2H, m, H-6″β, -6‴β), 1.62 (2H, m, H-3″β,
-3‴β), 1.81 (2H, m, H-8″a, -8‴a), 1.88 (H-8″b, -8‴b), 3.16 (2H, t, J =
7.7 Hz, H-2⁗, -2⁗′), 3.27−3.28 (4H, m, H-3⁗, -3⁗′, -4⁗, -4⁗′), 3.34
(2H, m, H-5⁗, -5⁗′), 3.55 (2H, m H-9″b, -9‴b), 3.55−3.57 (4H, m,
H-7″, -7‴), 3.56 (2H, m, H-2″, -2‴), 3.69 (3H, s, 3-OCH3), 3.66 (2H,
d-like, J = 11.6 Hz, H-6⁗a, -6⁗′a), 3.77 (3H, s, 4′-OCH3), 3.83 (3H, s,
4-OCH3), 3.81 (2H, m H-9″a, -9‴a), 3.85 (2H, d-like, J = 11.6 Hz, H-
6⁗b, -6⁗′b), 3.91 (2H, m, H-10″a, -10‴a), 3.96 (2H, m, H-10″b,
-10‴b), 4.27 (2H, d, J = 8.0 Hz, H-1⁗, -1⁗′), 6.90 (1H, d, J = 9.0 Hz,
H-5), 7.49 (2H, d, J = 9.0 Hz, H-3′, -5′), 7.12 (1H, dd, J = 2.0, 9.0 Hz,
H-6), 7.18 (1H, d, J = 2.0 Hz, H-2), 6.86 (2H, d, J = 9.0 Hz, H-2′, -6′),
7.83 (1H, s, H-7), 7.87 (1H, s, H-7′); 13C NMR (methanol-d4, 125
MHz) δ 143.5 (C-7), 126.0 (C-8), 126.1 (C-8′), 143.5 (C-7′), 168.8
(C-9), 168.9 (C-9′), 129.0 (C-1), 113.5 (C-2), 150.3 (C-3), 152.3 (C-
4), 112.6 (C-5), 125.9 (C-6), 128.6 (C-1′), 132.9 (C-2′, -6′), 115.3
(C-3′, -5′), 162.7 (C-4′), 42.0 (C-1″, -1‴), 76.4 (C-2″, -2‴), 34.6 (C-
3″, -3‴), 37.8 (C-4″, -4‴), 25.1 (C-5″, -5‴), 31.6 (C-6″, -6‴), 76.5 (C-
7″, -7‴), 37.2 (C-8″, -8‴), 63.3 (C-9″, -9‴), 70.5 (C-10″, -10‴), 104.2
(C-1⁗, -1⁗′), 75.1 (C-2⁗, -2⁗′), 78.2 (C-3⁗, -3⁗′), 71.7 (C-4⁗,
-4⁗′), 78.1 (C-5⁗, -5⁗′), 62.9 (C-6⁗, -6⁗′), 56.3 (3-OCH3), 56.4 (4-
OCH3), 55.9 (4′-OCH3); positive-ion FABMS m/z 1103 [M + Na]+;
HRFABMS m/z 1103.4668 (calcd for C53H76O23Na [M + Na]+,
1103.4675).
Methylation of 1c. A solution of 1c (12.0 mg) in dry MeOH (1.0
mL) was treated with trimethylsilyldiazomethane (2 M in diethyl
ether, 0.3 mL), and the mixture was stirred for 15 h at room
temperature. Removal of the solvent under reduced pressure gave a
residue, which was purified by HPLC [mobile phase: H2O−MeCN
(70:30, v/v)] to give 1d (11.5 mg).
1d: amorphous powder; [α]25 −3 (c 0.2, MeOH); UV (MeOH)
D
λmax 207.0 nm (log ε 4.14),312.8 nm (log ε 4.19); 1H NMR
(methanol-d4, 500 MHz) δ 0.91 (2H, m, H-6″α, -6‴α), 1.01 (2H, m,
H-5″β, -5‴β), 1.21 (2H, m, H-5″α, -5‴α), 1.24 (2H, m, H-3″α, -3‴α),
1.57 (2H, m, H-4″, -4‴), 1.65 (2H, m, H-8″a, -8‴a), 1.65 (2H, m, H-
3″β, -3‴β), 1.71 (2H, m, H-6″β, -6‴β), 1.78 (H-8″b, -8‴b), 3.39 (2H,
m, H-2″, -2‴), 3.59 (2H, m, H-7″a, -7‴a), 3.60 (2H, m H-9″b, -9‴b),
3.62 (3H, s, 3-OCH3), 3.69 (2H, m H-9″a, -9‴a), 3.71 (3H, s, 4′-
OCH3), 3.74 (3H, s, 4-OCH3), 3.81 (2H, d-like, J = 11.6 Hz, H-7″b,
-7‴b), 3.94 (2H, m, H-10″a, -10‴a), 3.97 (2H, m, H-10″b, -10‴b),
6.79 (2H, d, J = 8.7 Hz, H-3′, -5′), 6.83 (1H, d, J = 8.7 Hz, H-5), 7.06
(1H, dd, J = 2.0, 8.7 Hz, H-6), 7.12 (1H, d, J = 2.0 Hz, H-2), 7.43 (2H,
d, J = 8.7 Hz, H-2′, -6′), 7.77 (1H, s, H-7), 7.80 (1H, s, H-7′); 13C
NMR (methanol-d4, 125 MHz) δ 128.6 (C-1), 113.5 (C-2), 150.3 (C-
3), 152.3 (C-4), 112.6 (C-5), 125.9 (C-6), 143.7 (C-7), 125.9 (C-8),
168.9 (C-9), 129.0 (C-1′), 132.9 (C-2′, -6′), 115.3 (C-3′, -5′), 162.7
(C-4′), 143.5 (C-7′), 126.1 (C-8′), 168.7 (C-9′), 42.4 (C-1″, -1‴),
77.1 (C-2″, -2‴), 34.5 (C-3″, -3‴), 37.8 (C-4″, -4‴), 25.0 (C-5″, -5‴),
32.2 (C-6″, -6‴), 61.9 (C-7″, -7‴), 41.7 (C-8″, -8‴), 58.9 (C-9″, -9‴),
70.5 (C-10″, -10‴), 56.3 (3-OCH3), 56.4 (4-OCH3), 55.9 (4′-OCH3);
positive-ion FABMS m/z 779 [M + Na]+; HRFABMS m/z 779.3615
(calcd for C41H56O13Na [M + Na]+, 779.3619).
Hydrolysis of 1g. The procedure was the same as that used for the
preparation of 1e and 1f. Compound 1e (2.2 mg) and the known
dihydrocanangafruticoside A 7-ol (1h, 3.7 mg) were obtained from 1g
(11.2 mg) using NaOCH3 (0.1 M in MeOH, 4 mL). The crude
product was purified by reversed-phase ODS open column
chromatography [1.0 g, MeOH−H2O (1:9 → 2:8 → 5:5 → 7:3, v/
1
v)]. Compound 1h was identified by comparison of H NMR data
with the reported data.
1
1h: amorphous powder; [α]25 −2 (c 0.7, MeOH); H NMR data
D
were the same as the reported data;3 13C NMR data (methanol-d4, 125
MHz) δ 42.3 (C-1), 76.9 (C-2), 34.9 (C-3), 40.9 (C-4), 25.3 (C-5),
31.9 (C-6), 76.9 (C-7), 37.4 (C-8), 63.4 (C-9), 68.1 (C-10), 104.3 (C-
1′), 75.2 (C-2′), 78.2 (C-3′), 71.8 (C-4′), 78.1 (C-5′), 62.9 (C-6′);
positive-ion FABMS m/z 389 [M]+; HRFABMS m/z 389.1795 (calcd
for C16H30O9Na [M + Na]+, 389.1788).
Hydrolysis of 1d. A solution of 1d (9.3 mg) in dry MeOH (1.0
mL) was treated with NaOCH3 (0.1 M in MeOH, 3 mL), and the
mixture was stirred for 3 h at room temperature. Removal of the
solvent under reduced pressure gave a residue, which was subjected to
normal-phase silica gel column chromatography [1.0 g, EtOAc−
MeOH (2:1 → 1:1 → 1:2 → 0:1, v/v)] to give 1e (2.7 mg) and 1f
(2.0 mg).
Preparation of the (S)- and (R)-MTPA Esters (7a and 7b) of 7.
A solution of 7 (2.0 mg, 0.0059 mmol) in pyridine (0.5 mL) was
treated with (−)-MTPA-Cl (0.02 mL), and the mixture was stirred at
rt for 12 h. Removal of the solvent from the reaction mixture under
reduced pressure furnished a residue, which was subjected to reversed-
phase silica gel column chromatography [H2O → MeOH] to give the
1e: amorphous powder; UV (MeOH) λmax 207.0 nm (log ε 4.16),
311.6 nm (log ε 4.32); 1H NMR (methanol-d4, 600 MHz) δ 3.67 (3H,
997
dx.doi.org/10.1021/np401091f | J. Nat. Prod. 2014, 77, 990−999

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(S)-MTPA ester (7a, 1.7 mg). Employing a similar procedure, the (R)-
MTPA ester (7b, 1.3 mg) was obtained from 7 (2.0 mg, 0.0059 mmol)
using (+)-MTPA-Cl.
and a test compound for 70 h, the cells were washed with PBS. After 2
h further in culture with 100 μL of DMEM (4.5 g/L glucose) and 10
μL of WST-8 solution (Cell Counting Kit-8), the optical density of the
water-soluble formazan produced by the cells was measured with a
microplate reader (SH-1000, Corona Electric Co.) at 450 nm
(reference: 655 nm). The test compound was dissolved in DMSO.
The final concentration of DMSO in the medium was 0.1%. Inhibition
of proliferation was calculated using the following formula, where A
and B indicate the optical density of vehicle- and test compound-
treated groups, respectively.
(S)-MTPA ester (7a): 1H NMR (CDCl3, 500 MHz) δ 0.75 (s, H-15),
1.26 (m, H-6β), 1.27 (m, H-10α), 1.36 (m, H-7α), 1.45 (m, H-10β),
1.56 (m, H-12b), 1.69 (m, H-12a), 2.09 (m, H-7β), 2.10 (m, H-11α);
FABMS m/z 581 [M + Na]+; HRFABMS m/z 581.2498 (calcd for
C32H37O5F3Na [M + Na]+, m/z 581.2491).
1
(R)-MTPA ester (7b): H NMR (CDCl3, 500 MHz) δ 0.88 (s, H-
15), 1.27 (m, H-6β), 1.10 (m, H-10α), 1.57 (m, H-7α), 1.32 (m, H-
10β), 1.68 (m, H-12b), 1.83 (m, H-12a), 2.31 (m, H-7β), 2.04 (m, H-
11α); FABMS m/z 581 [M + Na]+; HRFABMS m/z 581.2498 (calcd
for C32H37O5F3Na [M + Na]+, m/z 581.2491).
Inhibition (%) = [(A − B)/A] × 100
Acid Hydrolysis and Monosaccharide Composition of
Canangalignans I (1) and II (2). To determine the absolute
configurations of the constituent monosaccharide of 1 and 2, the
reported method22 by Tanaka et al. was used with slight modifications
as follows. Compounds 1 and 2 (each 1.0 mg) were dissolved in 5%
aqueous H2SO4−1,4-dioxane (1:1, v/v, 1.0 mL), and each solution was
heated at 90 °C for 3 h. After extraction with EtOAc (3 × 3 mL), the
aqueous layer was neutralized by dropwise addition of 5% NaHCO3.
After drying in vacuo, the residue was dissolved in pyridine (0.1 mL)
containing L-cysteine methyl ester hydrochloride (0.5 mg) and heated
at 60 °C for 1 h. A solution of o-tolylisothiocyanate (0.5 mg) in
pyridine (0.1 mL) was added, and the mixture heated at 60 °C for 1 h.
The mixture was analyzed by reversed-phase HPLC [column:
COSMOSIL 5C18-AR-II (Nacalai Tesque), 250 × 4.6 mm i.d. (5
μm); mobile phase: MeCN−H2O in 1% AcOH (18:82, v/v);
detection: UV (250 nm); flow rate: 0.8 mL/min; column temperature:
35 °C] to identify the derivatives of constituent D-glucose in 1 and 2
by comparison of their retention times with those of authentic samples
(tR: D-glucose, 56.0 min; L-glucose, 50.3 min).
ASSOCIATED CONTENT
■
S
* Supporting Information
The NMR spectra [1H (solvent: methanol-d4, CDCl3), 13C
NMR (solvent: methanol-d4, CDCl3)] for the new compounds
are available free of charge via the Internet at http://pubs.acs.
org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: matsuda@mb.kyoto-phu.ac.jp. Tel: +81-75-595-4633.
Notes
■
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This research was supported in part by a Ministry of Education,
Culture, Sports, Science and Technology (MEXT)-Supported
Program for the Strategic Research Foundation at Private
Universities, by a Grant-in-Aid for Young Scientists (B) from
the Japan Society for the Promotion of Science (JSPS).
Reagents for Bioassays. Dulbecco’s modified Eagle’s medium
(DMEM, 1 or 4.5 g/L glucose) was purchased from Sigma-Aldrich (St.
Louis, MO, USA); the Cell Counting Kit-8 was from Dojindo Lab.
(Kumamoto, Japan); fetal bovine serum (FBS), amphotericin B,
penicillin, and streptomycin were purchased from Gibco (Invitrogen,
Carlsbad, CA, USA); the Pierce BCA protein assay kit was from
Takara Bio Inc. (Shiga, Japan); all other chemicals were purchased
from Wako Pure Chemical Co., Ltd. (Osaka, Japan).
REFERENCES
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Cell Culture. Murine B16 melanoma 4A5 cells (RCB0557)30 were
obtained from Riken Cell Bank (Tsukuba, Japan). The cells were
grown in DMEM (4.5 g/L glucose) supplemented with 10% FBS,
streptomycin (100 μg/mL), and penicillin (100 units/mL) at 37 °C in
5% CO2/air and harvested by incubation in phosphate-buffered saline
(PBS) containing 1 mM EDTA and 0.25% trypsin for ca. 2 min at 37
°C. The cells were used for the bioassays.
Melanogenesis. Screening for melanogenesis with B16 melanoma
4A5 cells was performed as described previously27 with slight
modifications. The melanoma cells were seeded into 24-well
multiplates (2.0 × 104 cells/400 μL/well). After 24 h of culture, a
test compound and 1 mM theophylline were added and incubated for
72 h. The cells were harvested by treatment with PBS containing 1
mM EDTA and 0.25% trypsin and washed with PBS. The cells were
treated with 1 M NaOH (120 μL/tube, 80 °C, 30 min) to obtain a
lysate. An aliquot (100 μL) of the lysate was transferred to a 96-well
microplate. The optical density of each well was measured with a
microplate reader (SH-1000, Corona Electric Co., Hitachinaka, Japan)
at 405 nm. The test compound was dissolved in DMSO, and the final
concentration of DMSO in the medium was 0.1%. Inhibition (%) was
calculated using the following formula, where A and B indicate the
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