Jacaranone-derived glucosidic esters from jacaranda glabra and their activity against plasmodium falciparum

Article abstract of DOI:10.1021/np900528m

In a survey of plants from Ecuador with antiprotozoal activity, Jacaranda glabra was found to show promising activity against the Plasmodium falciparum K1 strain. Subsequently, activity-guided isolation of the dichloromethane extract from the leaves of J. glabra afforded four new phenylethanoid glucosides containing jacaranone-type moieties (1-4), named jacaglabrosides A-D. Their chemical structures were identified using NMR spectroscopy and MS techniques. The compounds were found to be active in vitro against the P. falciparum K1 strain (IC₅₀ 1, 1.02; 2, 0.56; 3, 0.56; and 4, 0.55 μg/mL) and generally possessed a low cytotoxicity toward L-6 cells, with the exception of compound 1 (IC₅₀ 1, 8.3; 2, >90; 3, 87; and 4, 85 μg/mL).

Full text of DOI:10.1021/np900528m

J. Nat. Prod. 2010, 73, 553–556
553
Jacaranone-Derived Glucosidic Esters from Jacaranda glabra and Their Activity against
Plasmodium falciparum
M. Salome´ Gachet,† Olaf Kunert,‡ Marcel Kaiser,§ Reto Brun,§ Ricardo A. Mun˜oz,| Rudolf Bauer,† and Wolfgang Schu¨hly*,†
Institute of Pharmaceutical Sciences, Department of Pharmacognosy, Karl-Franzens-UniVersity Graz, UniVersita¨tsplatz 4, 8010 Graz, Austria,
Institute of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, Karl-Franzens-UniVersity Graz, UniVersita¨tsplatz 1,
8010 Graz, Austria, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland, and Laboratorio de Qu´ımica
Orga´nica e InVestigaciones Aplicadas, Escuela Polite´cnica Nacional, Ladro´n de Guebara E11-253, PO Box 17-01-759, Quito, Ecuador
ReceiVed September 22, 2009
In a survey of plants from Ecuador with antiprotozoal activity, Jacaranda glabra was found to show promising activity
against the Plasmodium falciparum K1 strain. Subsequently, activity-guided isolation of the dichloromethane extract
from the leaves of J. glabra afforded four new phenylethanoid glucosides containing jacaranone-type moieties (1-4),
named jacaglabrosides A-D. Their chemical structures were identified using NMR spectroscopy and MS techniques.
The compounds were found to be active in vitro against the P. falciparum K1 strain (IC50 1, 1.02; 2, 0.56; 3, 0.56; and
4, 0.55 µg/mL) and generally possessed a low cytotoxicity toward L-6 cells, with the exception of compound 1 (IC50
1, 8.3; 2, >90; 3, 87; and 4, 85 µg/mL).
The genus Jacaranda (Bignoniaceae) consists of mainly trees,
which are native to Central and South America and the Caribbean
region.1 Jacaranda species are recognized around the world for
the beauty of their flowers as well as for their use in the paper
industry.2,3 Recently, ethnobotanical and pharmacological uses of
Jacaranda species have been reported, emphasizing skin ailments
and protozoal-related diseases.4
Jacaranda glabra (DC.) Bureau & Schumann is a small tree
distributed in Colombia, Ecuador, Peru, Bolivia, and Brazil, growing
at low altitudes (200-1100 m).1 The leaves of J. glabra are used
in traditional folk medicine to treat cutaneous leishmaniasis and
skin illnesses.5,6 The secondary metabolites of J. glabra are as yet
unknown; however, the constituents that have been identified in
the genus include acteoside derivatives, fatty acids, flavonoids, a
neolignan, phenylethanoid glycosides, quinones, and triterpenes.7–20
Among these chemical constituents, the benzoquinone derivative
jacaranone has been described from several Jacaranda species.7,11,12
In an ongoing current project on the evaluation of antiprotozoal
activity of plants traditionally used for medicine in Ecuador, the
dichloromethane extract of the leaves of J. glabra showed promising
activity against the Plasmodium falciparum K1 strain. Antiplas-
modial activity has been previously reported from the methanolic
extract of the leaves of Jacaranda caucana,21 from which eight
compounds have been identified.20 The present article describes
the bioassay-guided isolation, structure elucidation, and antiproto-
zoal evaluation of four new glucosidic esters with phenylacetic and
benzoquinoid moieties (1-4) from J. glabra.
Results and Discussion
The dichloromethane extract of the leaves of J. glabra was
subjected to several chromatographic separation steps, which led
finally to the isolation of four new glucosidic ester derivatives
and the monosodiated ion at m/z 739.2025 [M + Na]+, suggesting
a molecular formula of C38H36O14 (calcd m/z 716.217). The 1H and
HSQC spectra indicated the presence of a highly substituted
saccharide unit, and the triplet couplings of the proton resonances
of H-2, H-3, and H-4, in combination with large three-bond
homonuclear coupling constants, were consistent with the presence
of glucopyranose in the ꢀ-form. The sign of optical rotation of the
hydrolyzed sugar demonstrated that the glucose belongs to the D
series. Two substituents were identified as phenylacetate moieties,
while the other units were found to be jacaranone acid moieties.
HMBC correlations between H-1 and C-8′, H-2 and C-8′′, H-3 and
C-8′′′, and H-6 and C-8′′′′ led to the structural assignment of
(1-4), along with their degradation products 5 and 6. Combined
NMR and MS analysis allowed identification of these compounds.
Jacaglabroside A (1) was isolated as pale yellow oil. The positive
ESIMS of 1 showed a molecular ion peak at m/z 717.01 corre-
sponding to [M + H]+, with the ion at m/z 734.2462 [M + NH4]+
* To whom correspondence should be addressed. Tel: +43-316-380 5527.
Fax: +43-316-380 9860. E-mail: wolfgang.schuehly@uni-graz.at.
† Department of Pharmacognosy, University of Graz.
‡ Department of Pharmaceutical Chemistry, University of Graz.
§ Swiss Tropical Institute.
| Escuela Polite´cnica Nacional, Quito.
10.1021/np900528m  2010 American Chemical Society and American Society of Pharmacognosy
Published on Web 03/22/2010

554 Journal of Natural Products, 2010, Vol. 73, No. 4
Gachet et al.
molecular formula of C30H29O11. LC-ESIMS and HPLC-DAD
analysis of the isolated compounds from a fresh plant extract
confirmed that free jacaranone (5), phenylacetic acid (6), and the
artifacts did not occur in the original CH2Cl2 extract of J. glabra.
Similar chemical structures to those of compounds 1-4 have
been identified from Forsythia suspensa (Oleaceae; forsythensides
A and B)20 and Senecio scandens (Compositae; mixtures of C-1
epimeric glucose derivatives).21 Both investigators reported instabil-
ity problems during the structure elucidation process, which could
be attributed to the use of MeOH during isolation and for the NMR
measurements. Therefore, it could be speculated that these reported
compounds are actually degradation products of more highly
substituted parent compounds, as described in the present work.
Data on the in vitro antiplasmodial activity and cytotoxicity
against L-6 cells for compounds 1-6 are presented in Table 2.
Compounds 2-4 showed similar IC50 values in both assays
(moderate antiplasmodial activity and low cytotoxicity). In contrast,
the IC50 value of 1 against L-6 cells was found to be approximately
1 order of magnitude lower than for 2-4. Regarding jacaranone
(5), the results were in agreement with known reports on unselective
toxicity.11,12,22,23 Phenylacetic acid (6) was not found to be active
in either in vitro assay.
Recently, Martin et al. described phenylethanoid glycosides from
J. caucana,24 which were reported to have activity against P.
falciparum.25 These compounds share certain characteristics with
those described in this paper, including the presence of ꢀ-glucose
and of moieties structurally similar to jacaranone, namely, cyclo-
hexanone and cyclohexanol moieties, which are attached to the
central saccharide unit. It would be worthwhile, therefore, to
determine the antiplasmodial potential of these compounds isolated
from J. caucana.24
Figure 1. Relevant HMBC correlations of compound 1.
jacaglabroside A (1) (Figure 1). The different shift values for the
chemically equivalent positions in the quinoid moietiy and the
benzylic moieties attached to C-1, C-2, and C-3 of the saccharide
unit, respectively, indicated a hindered rotation of these substituents.
1
The H and 13C NMR data for compound 1 data are presented in
Table 1. The representative fragment ion at m/z 548.94 [M -
C8H7O4 + H]+ pointed to the loss of one jacaranone acid moiety.
Compound 2 showed a molecular ion peak of m/z 599.1767 [M
+ H]+ by positive-mode ESIMS, indicating a molecular formula
of C30H30O13 (calcd m/z 598.1679). Other representative ions were
at m/z 616.2028 [M + NH4]+ and m/z 431.00 [M - C8H7O4 +
H]+. The 1H, 13C, and HSQC NMR spectra shared the same
characteristic data as for compound 1, i.e., ꢀ-glucopyranose
substituted by one phenylacetate and two jacaranone acid moieties.
HMBC correlations between H-1 and C-8′, H-2 and C-8′′, and H-6
and C-8′′′′ assisted in the structure determination of 2 (jacaglabro-
side B) as shown. (1H and 13C NMR chemical shifts are shown in
Table 1).
ESIMS (positive mode) of 3 and 4 yielded molecular ion peaks
at m/z 733.2148 and 733.2157 [M + H]+, respectively, and very
similar fragmentation patterns (e.g., m/z 750.2424 and 750.2392
[M + NH4]+, 564.97 and 565.02 [M - C8H7O4 + H]+, respec-
tively), which confirmed the molecular formula, C38H36O15 (calcd
Experimental Section
General Experimental Procedures. Optical rotations were measured
in MeOH on a Perkin-Elmer polarimeter 341. UV-vis spectra were
recorded on a UV-160A spectrophotometer (Shimadzu). IR spectra were
taken as KBr pellets on a Perkin-Elmer 281 spectrophotometer. All 1D
(1H and 13C) and 2D (COSY, HMBC, and HSQC) NMR spectra were
recorded at 298 K on a Varian UNITY INOVA-600 MHz spectrometer
using (CD3)2CO as solvent with TMS as internal standard. EIMS were
recorded on a Hewlett-Packard HP 7890 instrument fitted with a HP 7890
detector. ESIMS were measured in the positive mode on a Thermo
Finnigan LQ Deca XPPLUS mass spectrometer with autosampler using a
SB-C18 Zorbax column (3.5 µm; 150 × 2.1 mm; Agilent Technologies),
with a guard column, at a flow rate of 300 µL/min using an acetonitrile
gradient in water. High-resolution ESIMS spectra were recorded on a
MALDI Synapt HDMS system (Waters, Milford, MA) in positive ion time-
of-flight mode using a LockSpray dual electrospray ion source. Leu-
enkephalin was used for lock-mass correction.
1
732.2047). For both compounds the H, 13C, and HSQC NMR
spectra of these isomers showed the same characteristic pattern
described for compound 1, which included two jacaranone acid
and phenylacetate substituents (i.e., the observed three-bond HMBC
correlations for positions H-1, H-2, H-3, and H-6). In contrast to
compound 1, one of the two phenylacetate moieties in 3 and 4
showed the presence of a hydroxy group in the para-position, as
indicated by the carbon shifts at C-4′′, C-3/5′′, and C-1′′ in
compound 3 and at C-4′′′, C-3/5′′′, and C-1′′′ in compound 4,
respectively. Thus the structures of the two compounds, jacagla-
brosides C (3) and D (4), were assigned as shown. The 1H and 13
C
NMR chemical shifts are given in Table 1.
According to observations made in the present study, the four
isolated quinoid glucosidic esters (1-4) were found to be unstable
in MeOH to different degrees. This phenomenon became evident
during the NMR analysis of compounds 2 and 4 in CD3OD, the
first solvent chosen. During the measurement of compound 2 using
2D NMR experiments, two compounds could be observed forming
a mixture within a few hours. These degradation products cor-
responded to compound 2 after the loss of a jacaranone acid moiety
at the anomeric carbon of the glucose, which was confirmed by
MS data (m/z 448.98 [M + H]+), resulting in a mixture of epimeric
compounds. The free jacaranone acid was also identified in the
NMR spectra. However, the loss of this moiety did not alter the
antiplasmodial activity (see below), as demonstrated by the fact
that the IC50 values of the artifacts were comparable to that for
compound 2 (data not shown). Compound 4 was apparently even
less stable, as shown by the recognition of several artifacts in both
the NMR spectra and HPLC chromatograms, which made the
elucidation difficult in CD3OD. However, the main two artifacts
of compound 4 showed a molecular mass of m/z 564.97 [M + H]+,
which suggested the loss of one jacaranone acid (C8H7O4) and a
Semipreparative and analytical HPLC separations were performed
using an Agilent 1100 series instrument equipped with a diode-array
detector. Compound mixtures were separated on a LiChrosorb RP-18
(7 µm, 250 × 10 mm, Merck, Darmstadt) HPLC preparative column.
Analytical HPLC-DAD analysis was performed using a SB-C18 Zorbax
column (3.5 µm; 150 × 2.1 mm; Agilent Technologies), equipped with
a guard column, at a flow rate of 300 µL/min and a gradient elution
program. Fractionation was performed on a fast centrifugal partition
chromatograph (FCPC) with a rotor of 200 mL capacity, a 0.025-25
mL/min high-pressure pump, and an injection loop of 10 mL, coupled
to a UV-vis detector with a flow cell and a fraction collector (FCPC-
Kromaton-201, AlphaChrom OHG). For TLC analysis, precoated Si60
F254 plates (Merck) were used. Detection was performed under UV
light at 254 and 366 nm, with visualization by spraying with vanillin-
sulfuric acid reagent and heating.
Plant Material. Leaves of Jacaranda glabra were collected in
August 2006 at the Estacio´n Cient´ıfica Jatun Sacha in the Province of
Napo in the Ecuadorian Amazon. The plant was identified by Carlos
Morales Cabrera, and a voucher (No. 227457) has been deposited at
the Herbario Nacional del Ecuador in Quito.
Plasmodium falciparum in Vitro Assay. Antiplasmodial activity
was determined using the K1 strain of P. falciparum (resistant to

Jacaranone-DeriVed Glucosidic Esters
Journal of Natural Products, 2010, Vol. 73, No. 4 555
Table 1. 1H and 13C NMR Data of Compounds 1-4 (600 and 150 MHz, in (CD3)2CO)
1
2
3
4
δH mult. (J, Hz)
δC
δH mult. (J, Hz)
δC
δH mult. (J, Hz)
δC
δH mult. (J, Hz)
δC
ꢀ-glucose
1
2
3
4
5
6
5.82 d (8.4)
4.98 t (9.0)
5.28 t (9.0)
3.76 t (9.6)
3.89 m
92.6 d
71.5 d
75.8 d
69.0 d
75.5 d
63.8 t
5.67 d (8.4)
4.90 t (9.0)
3.74 m
3.51 t (9.0)
3.70 m
93.0 d
73.6 d
75.3 d
71.1 d
75.7 d
64.2 t
5.81 d (8.4)
4.97 t (8.4)
5.27 t (9.0)
3.75 s
3.89 m
a 4.25 dd (5.4, 12.0)
b 4.42 d (12.0)
92.7 d
71.3 d
75.8 d
69.0 d
75.5 d
63.8 t
5.81 d (8.4)
4.97 t (8.4)
5.26 t (9.6)
3.74 t (9.6)
3.89 m
92.7 d
71.5 t
75.7 d
69.0 d
75.6 d
63.9 t
a 4.25 dd (5.4, 11.4)
b 4.42 d (11.4)
a 4.19 dd (5.4, 10.8)
b 4.43 d (10.8)
a 4.24 dd (5.4, 12.0)
b 4.42 d (12.0)
jacaranone acid
1′
67.6 s
150.9 d
128.3 d
185.5 s
150.8 d
45.1 t
67.7 s
150.9 d
128.3 d
185.5 s
151.0 d
45.2 t
67.5 s
150.8 d
128.1 d
185.5 s
150.8 d
45.2 t
67.6 s
151.0 d
128.3 da
185.5 s
150.8 d
45.1 t
2′a
3/5′
4′
7.03 d (10.2)
6.09 m
6.99 m
6.08 d (10.8)
7.02 m
6.08 d (11.4)
7.02 m
6.08 m
6′a
7′
7.01 d (10.2)
a 2.60 d (15.0)
b 2.70 d (15.0)
6.99 m
a 2.55 d (15.0)
b 2.67 d (15.0)
7.02 m
a 2.64 d (15.0)
b 2.71 d (15.0)
7.02 m
a 2.59 d (15.0)
b 2.70 d (15.0)
8′
167.8 s
168.0 s
167.8 s
p-hydroxyphenylacetate
125.5 d
167.8 s
phenylacetate
1′′
134.9 s
130.3 d
129.2 d
127.7 d
41.2 t
135.3 s
130.2 d
129.2 d
127.7 d
41.4 t
134.9 s
130.2 d
129.3 d
127.9 d
41.2
2/6′′b
3/5′′c
4′′d
7.20 d (7.2)
7.30 n.d.
7.25 n.d.
a 3.41 d (15.6)
b 3.49 d (15.0)
7.30 m
7.30 m
7.24 m
a 3.67 s
b 3.67 s
7.02 m
6.77 d (8.4)
131.2 d
116.1 d
157.4 s
40.4 t
7.20 d (7.2)
7.29 d (7.2)
7.25 m
a 3.41 d (15.0)
b 3.47 d (15.0)
7′′
a 3.30 d (15.0)
b 3.37 d (15.0)
8′′
170.7 s
170.9 s
171.1 s
170.7 s
p-hydroxyphenylacetate
125.8 s
phenylacetate
1′′′
135.1 s
130.3 d
129.3 d
127.9 d
41.3 t
135.2 s
130.3 d
129.2 d
127.7 d
41.3 t
2/6′′′b
3/5′′′c
4′′′d
7′′′
7.24 d (7.8)
7.30 n.d.
7.25 n.d.
a 3.52 d (15.6)
b 3.59 d (15.6)
7.24 m
7.31 dd (6.6, 13.8)
7.26 m
a 3.51 d (16.2)
b 3.58 d (16.2)
7.07 d (11.4)
6.78 d (8.4)
131.3 d
116.1 d
128.1 s
40.5
a 3.41 d (13.2)
b 3.48 d (15.6)
8′′′
171.3 s
171.3 s
171.7 s
jacaranone acid
1′′′′
67.8 s
151.3 d
128.1 d
185.6 s
45.7 t
67.9 s
151.4 d
128.1 d
185.6 s
45.8 t
67.9 s
151.3 d
128.4 d
185.6 s
45.7 t
67.8 s
151.4 d
128.4 da
185.6 s
45.8 t
2/6′′′′
3/5′′′′
4′′′′
7.08 d (10.2)
6.09 m
7.08 d (10.6)
6.10 d (10.6)
7.06 n.d.
6.10 d (10.2)
7.08 d (13.2)
6.10 d (9.6)
7′′′′
2.81 s
2.79 s
2.81 s
2.81 s
8′′′′
169.4 s
169.4 s
169.4 s
169.4 s
a Interchangeable signals. n.d. ) not determined.
Cytotoxicity Assay on L-6 Cells. The rat skeletal myoblast cell
Table 2. Activities of Compounds 1-4 against P. falciparum
line (L-6 cells) was used to assess cytotoxicity. The cells were grown
in RPMI 1640 medium supplemented with 1% L-glutamine (200 nM)
and 10% fetal bovine serum at 37 °C in 5% CO2 in air. The assay was
performed in 96-well microtiter plates, each well receiving 100 µL of
culture medium with ca. 4 × 104 cells. After 24 h, the medium was
removed from all wells, and serial drug dilutions were prepared covering
a range from 90 to 0.123 µg/mL. After 72 h of incubation, the plates
were inspected under an inverted microscope to ensure growth of the
controls and sterile conditions. Then, 10 µL of Alamar blue (12.5 mg
of resazurin dissolved in 100 mL of distilled water) was added to each
well, and the plates were incubated for another 2 h, with the plates
evaluated with a Spectramax Gemini XS microplate fluorometer
(Molecular Devices Corporation, Sunnyvale, CA) using an excitation
wavelength of 536 nm and an emission wavelength of 588 nm. IC50
values were determined using the microplate reader software Softmax
Pro (Molecular Devices). Each sample was tested in two independent
assays. A third assay was performed if the calculated IC50 values
differed by more than a factor of 2.
Extraction and Isolation. The dried and powdered leaves (480 g)
of J. glabra were extracted sequentially with CH2Cl2 and MeOH by
percolation, to yield residues of 37 and 42 g, respectively. The CH2Cl2
extract, which showed activity against the P. falciparum K1 strain, was
chosen for further purification. A portion (9 g) of the crude CH2Cl2
extract was fractionated on silica gel (VLC) using a gradient of
n-hexane-EtOAc (each of 500 mL) from 100% n-hexane (F-1), with
gradient steps of 5-10%, to 100% EtOAc (F-12), then with a final
elution by 100% MeOH (F-13). The activity was found to be in fractions
F-11 (840 mg) and F-12 (3.3 g), corresponding to 80% and 100%
EtOAc, respectively.
and L-6 Cells
compound
IC50 (P. falc. K1)
IC50 (L-6 cells)
jacaglabroside A (1)
jacaglabroside B (2)
jacaglabroside C (3)
jacaglabroside D (4)
jacaranone (5)
1.02 ( 0.29a
8.3 ( 4.8a
>90
0.56
0.56
0.55
1.32
>5
0.06
87.0
84.8
1.06
>90
phenylacetic acid (6)
chloroquineb
podophyllotoxinc
0.007
a Each sample was tested in two independent assays. Replicate values
are within a factor of 2. Data are expressed in µg/mL. b n ) 8.
c Positive control.
chloroquine and pyrimethamine). A modification of the [3H]-hypox-
anthine incorporation assay was used.26 Briefly, infected human red
blood cells in RPMI 1640 medium with 5% Albumax were exposed to
serial drug dilutions in microtiter plates. After 48 h of incubation at 37
3
°C in a reduced oxygen atmosphere, 0.5 µCi of H-hypoxanthine was
added to each well. Cultures were incubated for a further 24 h before
they were harvested onto glass-fiber filters and washed with distilled
water. The radioactivity was counted using a Betaplate liquid scintil-
lation counter (Wallac, Zurich, Switzerland). The results were recorded
as counts per minute per well at each drug concentration and expressed
as percentages of the untreated controls. From the sigmoidal inhibition
curves, IC50 values were calculated. Each sample was tested in two
independent assays. A third assay was performed if the calculated IC50
values differed by more than a factor of 2.

556 Journal of Natural Products, 2010, Vol. 73, No. 4
Gachet et al.
Fraction F-11 was partitioned by FCPC (dual mode) using i-PrOH-n-
hexane-EtOAc-MeOH (4:4:1:1:0.5) in the ascending mode (switching
volume 360 mL, 1000 rpm, 4 mL/min flow rate). On the basis of UV
detection at λ 254 nm and TLC analysis, 14 fractions were combined.
Fractions F-11-H (465 mg) and F-11-I (110 mg) contained the same
main compound. F-11-H was fractionated using the FCPC dual mode
with i-PrOH-n-hexane-EtOAc-MeOH (4:4:1:4:0.5), in ascending
mode (260 mL, 1000 rpm, 4 mL/min), to yield seven fractions, including
F-11-H-5 (300 mg). A portion of F-11-H-5 (20.8 mg) was further
purified by preparative HPLC (CH3CN-H2O, 45:55, 2.5 mL/min, tR
18.2 min) to yield compound 1 (12.7 mg). Fraction F-11-I-5 yielded
also 7 mg of jacaranone (5) (tR 5.6 min). From fraction F-11-E (70
mg), phenylacetic acid (6) (18 mg) was isolated using preparative HPLC
(CH3CN-H2O, 57:43; 2.5 mL/min, tR 6.4 min).
A portion of VLC fraction F-12 (1 g) was separated by FCPC (dual
mode) using n-hexane-EtOAc-MeOH-H2O (3:7:4:6) in the descend-
ing mode (131 mL, 800 rpm., 1 mL/min), to yield six fractions.
Fractions F-12-B (520 mg), F-12-D (220 mg), and F-12-E (861 mg)
were further fractionated using preparative HPLC. F-12-B (36 mg) was
fractionated using a CH3CN-H2O gradient (10:90 to 30:70 in 10 min,
then isocratic for 20 min at 30:70, flow rate 2.5 mL/min, tR 20.3 min)
to yield compound 2 (12.7 mg). F-12-D (100 mg) was fractionated
using isocratic conditions (CH3CN-H2O, 45:55, 2.5 mL/min, tR 18.2
min) to yield 1 (15.2 mg). F-12 E (75 mg) was separated using a
CH3CN-H2O gradient (25:75 to 35:65 in 10 min, then isocratic for 21
min at 35:65, flow rate 2.5 mL/min, tR 29.5 min (3) and tR 27.5 min
(4), to yield compounds 3 (22.5 mg) and 4 (8.9 mg).
[M + NH4]+ (calcd for C38H40O15N, 750.2392), m/z 755.1994 [M +
Na]+ (calcd for C38H36O15Na, 755.1946), m/z 565.1713 [M - C8H8O4
+ H]+ (calcd for C30H29O11, 565.1704).
2,5-Cyclohexadiene-1-acetic acid, 1-hydroxy-4-oxo-, methyl ester
1
or jacaranone (5): yellow oil; H and 13C NMR in CDCl3 compared
with ref 12; GC EIMS C9H10O4 m/z 182 [M]+ (4), 109 in [M -
CH2COOCH3]+ (100).
Phenylacetic acid (6): yellow powder; 1H NMR (400 CH3OD, 400
MHz) δ 3.57 (3H, s), 7.28 (1H, m), 7.21 (1H, m), 7.26 (1H, m); 13C
NMR (CD3OD, 100 MHz) δ 175.2 (C s), 41.6 (C t), 135.8 (C s), 128.7
(C d), 127.0 (C d), 129.5 (C d); GC EIMS C8H8O2 m/z 136 [M]+ (46),
91 [M - CO2 - H]+ (100).
Acknowledgment. We would like to thank the Austrian Exchange
¨
Service (OAD) for research funding, C. Morales Cabrera for the help
with the identification of the botanical material, and Dr. S. Crockett
for the help with editing. We kindly thank M. Zehl (University of
Vienna) for recording the HRESIMS and G. Allmaier and W. Winkler
(Vienna University of Technology) for facilitating the measurements
of the HRESI mass spectra.
Supporting Information Available: NMR spectra of compounds
1-4. This information is available free of charge via the Internet at
http://pubs.acs.org.
References and Notes
(1) Gentry, A. H. Flora Neotropica, Monograph 25; New York Botanical
Garden: New York, 1992; pp 52-105.
(2) Willis, J. C. A Dictionary of the Flowering Plants and Ferns;
Cambridge University Press: Cambridge, UK, 1966; pp 134-135.
(3) Parker, T. Trees of Guatemala; The Tree Press: Austin, TX, 2008; pp
86-87, 90-91.
To determine the sugar configuration, 15 mg of compound 1 was
dissolved and hydrolyzed in dioxane (1 mL) and 2 N H2SO4 (1 mL)
and left stirring overnight. The aglycone was extracted with Et2O from
the sugar dissolved in H2O. The H2O was removed and the specific
rotation was measured in MeOH.
(4) Gachet, M. S.; Schu¨hly, W. J. Ethnopharmacol. 2009, 121, 14–27.
(5) Bourdy, G.; DeWalt, S. J.; Chavez de Michel, L. R.; Roca, A.; Deharo,
E.; Munoz, V.; Balderrama, L.; Quenevo, C.; Gimenez, A. J.
Ethnopharmacol. 2000, 70, 87–109.
Jacaglabroside A [1,6-bis(1-hydroxy-4-oxo-2,5-cyclohexadiene-
1-acetyl)-2,3-bis(benzeneacetyl)-ꢀ-glucopyranoside] (1): slightly yel-
low oil; [R]20 -3.2 (c 0.19, CH3OH); UV (CH3CN) λmax (log ε) 211
D
(6) De la Torre, L.; Navarrete, H.; Muriel, P. M.; Mac´ıa, M. J.; Balslev,
(4.7) nm; IR (KBr) νmax 3425, 1745, 1671, 1625, 1152, 1076, 1014,
861, 714 cm-1; 1H and 13C NMR data, see Table 1; ESIMS m/z 717.01
[M + H]+ (4), 733.94 [M + NH4]+ (100), 740.07 [M + Na]+ (10),
´
H. Plantas Utiles del Ecuador; Pontificia Universidad Cato´lica del
Ecuador, Universidad de Aarhus: Quito, 2007; pp 243-244.
(7) Ogura, M.; Cordell, G. A.; Farnsworth, N. R. Lloydia 1977, 40, 157–
168.
548.94 [M + H - C8H7O4]+ (45), 430.94 [M + H - C8H7O3
-
C8H7O2]+; HRESIMS m/z 717.2198 [M + H]+ (calcd for C38H37O14,
717.2178), m/z 734.2462 [M + NH4]+ (calcd for C38H40O14N, 734.2443),
m/z 739.2025 [M + Na]+ (calcd for C38H36O14Na, 739.1997), m/z
549.1753 [M - C8H8O4 + H]+ (calcd for C30H29O10, 549.1755).
Jacaglabroside B [1,6-bis(1-hydroxy-4-oxo-2,5-cyclohexadiene-
1-acetyl)-2-benzeneacetyl-ꢀ-glucopyranoside] (2): slightly yellow oil;
[R]20D +1.9 (c 0.16, CH3OH); UV (CH3CN) λmax (log ε) 220 (4.4) nm;
IR (KBr) νmax 3422, 1738, 1671, 1626, 1398, 1261, 1152, 1079, 1012,
863, 715 cm-1; 1H and 13C NMR data, see Table 1; ESIMS m/z 598.93
[M + H]+ (5), 615.92 [M + NH4]+ (100), 431.00 [M + H - C8H7O4]+
(77); HRESIMS m/z 599.1767 [M + H]+ (calcd for C30H31O13,
599.1759), m/z 616.2028 [M + NH4]+ (calcd for C30H34O13N, 616.2025),
m/z 621.1595 [M + Na]+ (calcd for C30H30O13Na, 621.1579), m/z
431.1336 [M - C8H8O4 + H]+ (calcd for C22H23O9, 431.1337).
Jacaglabroside C [1,6-bis(1-hydroxy-4-oxo-2,5-cyclohexadiene-
1-acetyl)-2-(para-hydroxybenzeneacetyl)-3-benzeneacetyl-ꢀ-glucopy-
(8) Ali, R. M.; Houghton, P. J. Planta Med. 1999, 65, 455–457.
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16, 286–287.
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Gayral, P.; Kunesch, G. Phytother. Res. 1993, 7, 167–171.
(12) Ogura, M.; Cordell, G. A.; Farnsworth, N. R. Lloydia 1976, 39, 255–
257.
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210, 289–292.
(14) Varanda, E. M.; Zuniga, G. E.; Salatino, A.; Roque, N. F.; Corcuera,
L. J. J. Nat. Prod. 1992, 55, 800–803.
(15) Ferguson, N. M.; Lien, E. J. J. Nat. Prod. 1982, 45, 523–524.
(16) Sankara-Subramanian, S.; Nagarajan, S.; Sulochana, N. Phytochemistry
1972, 11, 1499.
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1973, 12, 220–221.
(18) Moharram, F. A.; Marzouk, M. S. A. Z. Naturforsch. 2007, 62, 1213–
1220.
(19) Chisholm, M. J.; Hopkins, C. Y. J. Org. Chem. 1962, 27, 3137–3139.
(20) Ming, D.-S.; Yu, D.-Q.; Yu, S.-S. J. Nat. Prod. 1998, 61, 377–379.
(21) Tian, X.-Y.; Wang, Y.-H.; Yang, Q.-Y.; Liu, X.; Fang, W.-S.; Yu,
S.-S. J. Asian Nat. Prod. Res. 2005, 8, 125–132.
(22) Yvin, J. C.; Chevolot, L.; Chevolot-Magueur, A. M.; Cochard, J. C.
J. Nat. Prod. 1985, 48, 814–816.
(23) Xu, H.; Zhang, N.; Casida, J. E. J. Agric. Food Chem. 2003, 51, 2544–
2547.
(24) Martin, F.; Hay, A.-E.; Quinteros Condoretty, V. R.; Cressend, D.;
Reist, M.; Gupta, M. P.; Carrupt, P.-A.; Hostettmann, K. J. Nat. Prod.
2009, 72, 852–856.
ranoside] (3): slightly yellow oil; [R]20 +2.2 (c 0.20, CH3OH); UV
D
(CH3CN) λmax (log ε) 220 (4.6) nm; IR (KBr) νmax 3421, 1746, 1671,
1
1625, 1517, 1398, 1230, 1152, 1076, 1014, 862, 714 cm-1; H- and
13C NMR data, see Table 1; ESIMS m/z 732.87 [M + H]+ (5), 749.99
[M + NH4]+ (100), 564.97 [M + H - C8H7O4]+ (61); HRESIMS m/z
733.2148 [M + H]+ (calcd for C38H37O15, 733.2127), m/z 750.2424
[M + NH4]+ (calcd for C38H40O15N, 750.2392), m/z 755.1987 [M +
Na]+ (calcd for C38H36O15Na, 755.1946), m/z 565.1713 [M - C8H8O4
+ H]+ (calcd for C30H29O11, 565.1704).
Jacaglabroside D [1,6-bis(1-hydroxy-4-oxo-2,5-cyclohexadiene-
1-acetyl)-2-benzeneacetyl-3-(para-hydroxybenzeneacetyl)-ꢀ-glucopy-
ranoside] (4): slightly yellow oil; [R]20 +3.5 (c 0.16, CH3OH); UV
(25) Weniger, B.; Robledo, S.; Arango, G. J.; Deharo, E.; Aragon, R.;
Munoz, V.; Callapa, J.; Lobstein, A.; Anton, R. J. Ethnopharmacol.
2001, 78, 193–200.
(26) Matile, H.; Pink, J. R. L. In Immunological Methods; Lefkovits, I.,
Pernis, B., Eds.; Academic Press: San Diego, 1990; pp 221-234.
D
(CH3CN) λmax (log ε) 223 (4.6) nm; IR (KBr) νmax 3423, 1750, 1671,
1625, 1517, 1232, 1152, 1076, 1018, 862, 714 cm-1; 1H and 13C NMR
data, see Table 1; ESIMS m/z 733.01 [M + 1]+ (5), 749.96 [M +
NH4]+ (100), 565.02 [M + 1 - C8H7O4]+ (61); HRESIMS m/z
733.2157 [M + H]+ (calcd for C38H37O15, 733.2127), m/z 750.2423
NP900528M