Iridoid glycosides from the stems of Pithecoctenium crucigerum (Bignoniaceae)

Article abstract of DOI:10.1016/j.phytochem.2007.02.002

Sixteen crude extracts from six Panamanian plants of the family Bignoniaceae were submitted to rapid TLC tests against DPPH and acetylcholinesterase. Pithecoctenium crucigerum (L.) A.H. Gentry, which showed interesting activity against DPPH, has been studied. The chemical investigation of the methanol extract from the stems afforded the iridoid glycoside theviridoside and three derivatives (6′-O-cyclopropanoyltheviridoside, 10-O-hydroxybenzoyltheviridoside and 10-O-vanilloyltheviridoside), along with five known phenylethanoid glycosides (verbascoside, isoverbascoside, forsythoside B, jionoside D and leucosceptoside B). These last compounds were all active against DPPH. The structures were determined by means of spectrometric and chemical methods, including 1D and 2D NMR experiments and MS analysis.

Full text of DOI:10.1016/j.phytochem.2007.02.002

PHYTOCHEMISTRY
Phytochemistry 68 (2007) 1307–1311
www.elsevier.com/locate/phytochem
Iridoid glycosides from the stems of
Pithecoctenium crucigerum (Bignoniaceae)
a
a
a
Fr e´ d e´ ric Martin , Anne-Emmanuelle Hay , Laura Corno ,
b
a,
*
Mahabir P. Gupta , Kurt Hostettmann
a
Laboratory of Pharmacognosy and Phytochemistry, School of Pharmaceutical Sciences, University of Geneva,
University of Lausanne, Quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
Center for Pharmacognostic Research on Panamanian Flora (CIFLORPAN), College of Pharmacy, University of Panama, Panama
b
Received 20 December 2006; received in revised form 5 February 2007
Available online 23 March 2007
Abstract
Sixteen crude extracts from six Panamanian plants of the family Bignoniaceae were submitted to rapid TLC tests against DPPH and
acetylcholinesterase. Pithecoctenium crucigerum (L.) A.H. Gentry, which showed interesting activity against DPPH, has been studied.
The chemical investigation of the methanol extract from the stems afforded the iridoid glycoside theviridoside and three derivatives
0
(
6 -O-cyclopropanoyltheviridoside, 10-O-hydroxybenzoyltheviridoside and 10-O-vanilloyltheviridoside), along with five known phenyl-
ethanoid glycosides (verbascoside, isoverbascoside, forsythoside B, jionoside D and leucosceptoside B). These last compounds were all
active against DPPH.
The structures were determined by means of spectrometric and chemical methods, including 1D and 2D NMR experiments and MS
analysis.
ꢀ
2007 Elsevier Ltd. All rights reserved.
Keywords: Pithecoctenium crucigerum; Bignoniaceae; Iridoid glycosides; Phenylethanoid glycosides; Cyclopropanoate
1
. Introduction
The genus Pithecoctenium belongs to the tribe Bignonia-
ceae, a large and morphologically diverse clade of neotrop-
ical lianas (Lohmann, 2006). Pithecoctenium crucigerum
(L.) A.H. Gentry is found in Central and South America,
from Mexico to Argentina and Brazil (Woodson et al.,
1973). Only one phytochemical study on P. crucigerum
was made by von Poser et al. in 2000 who isolated the irid-
oid glycosides theviridoside, ipolamiide and strictoloside.
In this work, 16 extracts (DCM and MeOH) from six
Panamanian plants of the Bignoniaceae family were sub-
mitted to rapid TLC tests against DPPH and acetylcholin-
esterase. The methanol extract from the stems of P.
crucigerum was selected due to its good activity observed
against DPPH. This paper describes the isolation and char-
acterization of theviridoside (1), three new iridoid glyco-
sides (2–4), and five known phenylethanoid derivatives.
The Bignoniaceae family includes about 120 genera and
00 species, growing mainly in Africa, Central and South
8
America. Species of the Bignoniaceae are used for many
purposes, such as horticulture, timber, dyes and medicine.
The best-known medicinal use of the Bignoniaceae is the
application of bark preparations of various species of
Tabebuia as cancer cures (Gentry, 1992). Members of the
family have, however, been poorly chemically investigated
(
von Poser et al., 2000).
*
Corresponding author. Tel.: +41 22 379 34 01; fax: +41 22 379 33 99.
E-mail address: Kurt.Hostettmann@pharm.unige.ch (K. Hostett-
mann).
0
031-9422/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.phytochem.2007.02.002

1308
F. Martin et al. / Phytochemistry 68 (2007) 1307–1311
Because the genus Pithecoctenium has been little studied
and the crude methanol extract of the stems exhibited good
radical scavenging activity, a phytochemical investigation of
P. crucigerum was undertaken. The extract was first parti-
tioned between water and EtOAc, then water and n-BuOH.
The latter showed the best activity. A preliminary HPLC/
UV-DAD analysis helped to sort the major and minor
metabolites into two classes. Five compounds showed max-
ima at 200, 215, 250(sh), 290 and 330 nm, the characteristic
pattern of phenylethanoid glycoside derivatives (Li et al.,
2
005). They were isolated from the n-BuOH extract using
ꢁ
MPLC on reversed-phase followed by Lobar chromatog-
raphy with the same C18 phase. Their identity was confirmed
by HR-MS and comparison of their H and C NMR spec-
tra with those of verbascoside, isoverbascoside (Wu et al.,
1
13
2
(
1
004), forsythoside B (Endo et al., 1982), jionoside D
Sasaki et al., 1989) and leucosceptoside B (Miyase et al.,
982). None of these five compounds has ever been
described in the genus Pithecoctenium. Moreover, forsytho-
side B and leucosceptoside B have never been reported in the
Bignoniaceae family. They are all active against DPPH,
which explains the activity of the crude extract.
The second class of compounds (1–4) showed two max-
ima at 200 and 235 nm in the HPLC/UV-DAD analysis.
Compound 1 was identified as theviridoside by comparison
1
13
of its H and C NMR spectra (Tables 2 and 3) with the
literature data (Sticher and Schmid, 1969), in agreement
with the HR-ESI-MS data which indicated a molecular for-
mula of C H O . Furthermore, 1 presented characteris-
2
. Results and discussion
1
7
24 11
Extracts were tested against two targets: DPPH which
tic elements of iridoid glycosides biosynthetically derived
from geniposidic acid, such as the shifts of H-1 (d 5.54),
H-3 (d 7.49). The downfield shift of H-7 (d 5.69) indicated
the presence of a double-bond on the cyclopentane ring
and finally the typical shift of H-10 (d 4.23, 4.11) geminal
to an hydroxyl group (Boros and Stermitz, 1990; Jensen
et al., 2002). Compound 1 was previously isolated from
P. crucigerum (von Poser et al., 2000). Compound 2 had
the same UV spectra profile and the HR-ESI-MS indicated
a molecular formula of C H O . Moreover, the APCI-
reveals a radical scavenging activity, and acetylcholinester-
ase, which is a key enzyme in the pathology of Alzheimer’s
disease. The results are presented in Table 1. Extracts from
roots and stems of Jacaranda caucana Pittier presented
good activities, but the plant has already been studied
before (Ogura et al., 1976, 1977).
Table 1
2
1
28 12
TLC autographical screening of extracts from Bignoniaceae
IT-MS analysis in the negative-ion mode showed a frag-
ment at m/z 241, also observed in the APCI-IT-MS of 1,
corresponding to the same aglycone moiety. Compound 2
thus appeared to be a derivative of 1 with an additional
Botanical species
Extract DPPH
assay
AChE
assay
Callichlamys latifolia (Rich) A.H.
Gentry stems
Jacaranda caucana Pittier roots
DCM
MeOH
DCM
MeOH
DCM
MeOH
+
+
+
+
+
ꢀ
+
ꢀ
+
ꢀ
+
+
+
+
+
+
ꢀ
ꢀ
+
ꢀ
+
ꢀ
+
ꢀ
ꢀ
ꢀ
+
ꢀ
ꢀ
ꢀ
+
ꢀ
1
C H O residue. Direct comparison of both H (Table 2)
4
4
1
3
and C (Table 3) NMR spectra of 1 and 2 first showed
additional signals for 2: two more proton signals at d
Jacaranda caucana Pittier stems
0.91 (4H, m) and d 1.65 (1H, m) ppm and four more car-
Mansoa hymenaea (DC.) A.H. Gentry DCM
stems
Mansoa standleyi (Steyerm.) A.H.
Gentry roots
Mansoa standleyi (Steyerm.) A.H.
Gentry stems
Paragonia pyramidata (Rich) Bur.
stems
Pithecoctenium crucigerum (L.) A.H.
Gentry stems
bons at d 8.8, 8.9, 13.6 and 176.5 ppm corresponding to a
MeOH
DCM
MeOH
DCM
MeOH
DCM
MeOH
DCM
carbonyl group. All other shifts were comparable, except
0
for the position 6 for which proton and carbon shifts were
deshielded. This showed that compound 2 was acylated at
0
the 6 -position of the sugar moiety. According to the
00
DEPT data, the carbon at 13.6 ppm (C-2 , d 1.65) corre-
H
0
0
sponded to a methine group and signals at 8.9 ppm (C-3
00
and 4 , d 0.91) were assigned to two methylenic carbons.
The H– H COSY spectrum indicated that protons at d
.65 and 0.91 ppm were on adjacent carbon atoms. Finally,
H
1
MeOH
1
ꢀ, inactive and +, active.
1

F. Martin et al. / Phytochemistry 68 (2007) 1307–1311
1309
Table 2
1
3
H NMR spectra of compounds 1–4 (500 MHz in CD OD)
1
H
1
2
3
4
1
3
6
7
9
1
5.54 d (J = 5.4 Hz)
7.49 s
2.83, 2H, brs
5.69 d (J = 1.5 Hz)
3.03 d (J = 4.8 Hz)
4.23, 4.11 d each (J = 14.2 Hz)
5.36 d (J = 5.9 Hz)
7.49 s
2.82, 2H, dd (J = 17.6, 9.8 Hz)
5.72 d (J = 1.5 Hz)
3.03 d (J = 4.9 Hz)
5.58 d (J = 5.9 Hz)
7.51 s
2.88, 2H, brs
5.86 d (J = 1.5 Hz)
3.09 dd (J = 5.9, 1.0 Hz)
4.93, 2H, d (J = 2.4 Hz)
5.62 d (J = 5.9 Hz)
7.51 s
2.89, 2H, brs
5.87 d (J = 1.5 Hz)
3.10 d (J = 5.9 Hz)
4.94, 2H, s
0
4.18, 2H, dd (J = 25.4, 16.7 Hz)
COOMe
3.73, 3H, s
3.73, 3H, s
4.64 d (J = 7.8 Hz)
3.22 m
3.36 t (J = 9.0 Hz)
3.31 m
3.47 m
4.36 dd (J = 12.0, 2.2 Hz)
4.22 dd (J = 11.7, 5.9 Hz)
1.65 m
3.73, 3H, s
3.73, 3H, s
4.64 d (J = 8.3 Hz)
3.23 m
3.36 t (J = 9.3 Hz)
3.28 m
3.27 m
3.82 m
3.63 dd (J = 12.0, 5.1 Hz)
7.58 d (J = 1.9 Hz)
0
1
2
3
4
5
6
4.62 d (J = 7.8 Hz)
3.21 dd (J = 9.3, 7.8 Hz)
3.37 t (J = 8.8 Hz)
3.28 m
3.28 m
3.87 dd (J = 12.0, 1.7 Hz)
4.64 d (J = 8.3 Hz)
3.23 dd (J = 9.3, 7.8 Hz)
3.37 t (J = 9.3 Hz)
3.28 m
0
0
0
0
3.27 m
0
3.83 dd (J = 12.0, 1.2 Hz)
3.63 dd (J = 11.7, 5.3 Hz)
7.91 d (J = 8.8 Hz)
6.83 d (J = 8.8 Hz)
3.64 dd (J = 12.0, 5.6 Hz)
0
0
0
0
0
0
0
0
0
0
2
3
4
5
6
0.91, 4H, m
6.83 d (J = 8.8 Hz)
7.91 d (J = 8.8 Hz)
6.86 d (J = 8.3 Hz)
7.60 dd (J = 8.3, 1.9 Hz)
OMe
3.90, 3H, s
00
lent 4 -carbones (8.8 and 8.9 in 2 vs 9.4 and 9.5 ppm in car-
nitine). Alkaline hydrolysis of 2 (Cogne et al., 2005) yielded
a mixture of two compounds. The presence of 1 was con-
firmed by HPLC-UV-DAD, and the cyclopropanecarboxy-
lic acid was identified using GC/MS and comparison with a
Table 3
1
3
3
C NMR spectra of compounds 1–4 (125 MHz in CD OD)
1
3
C
1
2
3
4
1
3
4
5
6
7
8
9
1
1
96.9
97.6
97.6
97.5
154.0
114.5
76.4
153.9
114.7
76.6
154.0
114.6
76.5
154.0
114.6
76.5
0
standard. Thus the structure of 2 was 6 -O-cyclopropanoyl-
theviridoside. This is the first description of an iridoid
esterified with cyclopropanecarboxylic acid. Among the
rare natural products with such a substituent is rubesanide
from Fagara rubescens (Dadson and Minta, 1976).
46.9
47.1
47.3
47.3
126.7
142.0
56.7
61.0
168.2
126.9
142.1
56.7
130.1
137.3
57.4
63.3
167.9
130.4
137.2
57.5
63.5
167.9
The HR-ESI-MS of 3 gave a molecular formula of
C H O , differing from 1 by a C H O residue. The
0
1
61.1
2
4
28 13
7
4
2
168.2
NMR spectra of 1 and 3 (Tables 2 and 3) were very similar.
However, significant downfield shifts of the signals corre-
sponding to H-10 (ca. 0.8 ppm), and C-10 (2 ppm), and
an upfield one for C-8 (5 ppm) could be observed. These
shifts suggested that in 3 the C-10 oxygen was esterified.
COOMe
51.6
100.2
74.6
77.6
71.5
78.5
62.7
51.7
100.2
74.5
77.4
71.5
75.7
64.5
176.5
13.6
8.9
51.6
100.3
74.6
77.7
71.5
51.7
100.3
74.6
77.7
71.5
0
1
2
0
0
0
0
0
3
4
5
6
1
2
3
4
5
6
7
1
78.4
62.8
78.2
62.8
Moreover, the aromatic signals in the H NMR spectrum
at d 7.91 (2H, d, J = 8.8 Hz) and d 6.83 ppm (2H, d,
J = 8.8 Hz) suggested that the ester residue was a symmet-
0
0
0
0
0
0
0
0
120.7
132.9
116.2
162.0
116.2
132.9
167.9
122.5
113.8
148.9
152.8
116.1
125.3
168.2
0
0
0
0
0
0
1
3
ric moiety. The C NMR spectra corroborated this infor-
8.8
mation and showed the presence of a carbonyl carbon at d
00
00
1
67.9 (C-7 ) ppm and a phenolic carbon at d 162.0 (C-4 )
ppm. These elements indicated that C-10 was esterified by
a p-hydroxybenzoyl group. Thus, the new structure 3 was
named 10-O-p-hydroxybenzoyltheviridoside. The analogue
OMe
56.5
10-O-benzoyltheveside has been reported from Cerbera
long-range correlations observed on the HMBC spectrum
manghas L. (Apocynaceae) (Yamauchi et al., 1990).
The molecular formula of 4, deduced from HR-ESI-MS
was C H O , with an additional CH O residue when
compared to 3. The H and C spectra (Tables 2 and 3)
of the theviridoside moieties in the two compounds were
almost identical, showing that the difference must reside
in the ester parts of the molecules. Analysis of the spectra
of 4 indicated that the acyl moiety was a vanilloyl group,
00
for the carbonyl carbon C-1 (d 176.5) with the methylenic
0
00
00
protons H-6 (d 4.22 and 4.36) and H-3 /H-4 (d 0.91)
H
25 30 14
2
0
1
13
suggested the presence of a 6 -cyclopropanoate moiety.
Kawagishi et al. (2006) isolated carnitine esterified with
the same cyclopropanoate group from the mushroom Suil-
1
13
lus laricinus. The H and C NMR shifts for this group
were similar in both compounds, such as the non-equiva-

1
310
F. Martin et al. / Phytochemistry 68 (2007) 1307–1311
13
1
and this was corroborated by the long-range H– C corre-
lation observed in the HMBC spectrum between the meth-
oxy group (d 3.90) and C-3 (d 148.9). Thus compound 4
was 10-O-vanilloyltheviridoside, a new natural product.
to 60:40 in 5% steps) to afford 41 fractions. This separation
yielded 181 mg of compound 1 (fraction 9), 16 mg of 2
(fraction 15), 272 mg of verbascoside (fraction 18) and
54 mg of isoverbascoside (fraction 20).
00
Fractions 17, 23, and 24 were purified by low pressure
liquid chromatography (LPLC) with a MeOH–H O step
2
3
. Experimental
gradient yielding, respectively, 12 mg of forsythoside B,
3
mg of 3, 3 mg of jionoside D, 5 mg of leucosceptoside
3
.1. General
B, and 3 mg of 4.
1
13
H and C NMR: Varian Unity Inova NMR instru-
3.4. Radical scavenging activity (DPPH) TLC assay
1
13
ment, Palo Alto, CA, USA. H and C NMR spectra were
recorded in CD OD at 500 and 125 MHz, respectively.
3
A TLC autographic assay of radical scavenging activity
TMS: int. standard. UV: Perkin-Elmer-Lambda-20 UV–
VIS spectrophotometer. UV spectra were recorded in
using the DPPH radical was employed for extract screen-
ing. After application of 100 lg of the samples on a silica
gel 60 F254 Al sheet (Merck), the TLC plate was developed
in hexane–EtOAc 1:1 for the dichloromethane extracts, or
CH Cl –MeOH–H O 13:7:1 for the methanol extracts, and
MeOH. [a] : Perkin-Elmer-241 polarimeter. TLC: silica
D
gel 60 F254 Al sheets (Merck) using EtOAc–formic acid–gla-
cial acetic acid–water 100:11:11:26. MPLC: RP-18 LiChro-
prep (40–63 lm; 460 · 50 mm i.d.; Merck). LPLC: Lobar
RP-18 column (LiChroprep 40–63 lm, 310 · 25 mm i.d.;
Merck). EI-MS: Finnigan MAT TSQ-700 triple stage quad-
rupole instrument, in negative mode. APCI-MS: Finnigan
MAT LCQ ion-trap instrument, in negative mode. HRMS:
Micromass LCT Premier, in negative mode. GC–MS with a
Varian 3400 gas chromatograph coupled to a Finnigan
MAT TSQ-70 triple stage quadrupole mass spectrometer
in the EI mode. A Chrompak (CP Select CB for FAME)
capillary column (100 m · 0.25 mm i.d.; 0.25 lm) was used
at 80 ꢂC (He column head pressure: 25 psi). HPLC-UV-
DAD was carried out on a HP1100 (Agilent) with a
Nova-Pak RP-18 column (4 lm; 150 · 3.9 mm i.d.; Waters)
2
2
2
then thoroughly dried for complete removal of solvents. A
solution of 2,2-diphenyl-1-picryl-hydrazyl radical (DPPH,
2
mg/ml in MeOH) was then sprayed. Inhibitors appeared
as yellow spots against a purple background.
3.5. Acetylcholinesterase (AChE) TLC assay
The bioautographic assay developed by Marston et al.
(2002) was used in this work. After application of the sam-
ples on a silica gel 60 F254 Al sheet (Merck), the TLC plate
was developed in hexane–EtOAc 1:1 for the dichlorometh-
ane extracts, or CH Cl –MeOH–H O 13:7:1 for the meth-
2
2
2
anol extracts, and then thoroughly dried for complete
removal of solvents. The plate was then sprayed with a
solution of acetylcholinesterase (1500 U) and bovine serum
albumin (225 mg) dissolved in 500 ml of a Tris–hydrochlo-
ric acid buffer at pH 7.8 and incubated at 37 ꢂC for 15 min
in polystyrene boxes with a moist atmosphere. Then, a
solution (1:4) of naphthyl acetate (250 mg in 100 ml EtOH)
using an acetonitrile + 0.05%TFA-H O + 0.05% TFA gra-
2
dient (2:98–40:60) in 40 min. The detection was performed
at 210, 254, 280 and 360 nm.
3
.2. Plant material
The stems of P. crucigerum (L.) A.H. Gentry were col-
and Fast Blue B salt (50 mg in 20 ml H O) was sprayed
2
lected in March 2003 in Soberania National Park, Panama
and identified by Prof. Mireya Correa, Director of the Her-
barium of the University of Panama. Vouchers are depos-
ited at the University of Panama (FLORPAN 5890) and at
the Laboratory of Pharmacognosy and Phytochemistry,
Geneva, Switzerland (No. 2005003).
onto the plate to give a purple coloration after 1–2 min.
Inhibitors appeared as white spots against a purple
background.
0
3.6. 6 -O-Cyclopropanoyltheviridoside (2)
2
D
5
3
.3. Extraction and isolation
Pale yellow amorphous solid. ½aꢁ ꢀ27.3ꢂ (MeOH, c
1
.0), UV (MeOH) k
(loge) 200 (4.04), 231 (3.79), 282
max
(3.13), 324 (3.01); H and C NMR: see Tables 2 and 3,
HR-ESI-MS: m/z 517.1536 (C22H O14: [M+formiate]
29
1
13
The air-dried powdered stems of P. crucigerum (820 g)
ꢀ
were first extracted at room temperature with dichloro-
methane, then with methanol affording, respectively, 3.0
and 37.5 g of extracts. Methanol extract (30.0 g) was parti-
tioned by LLE between EtOAc and water (500 ml of each).
The aqueous fraction was then partitioned with n-BuOH
requires 517.1557).
Basic hydrolysis: To 5.0 mg of 2, 0.5 ml of diethylamine,
4.0 ml of MeOH and 0.5 ml of water were added. The
mixture was stirred at 35 ꢂC for 17 h. The reaction was
monitored by TLC. To confirm the presence of cyclopro-
panecarboxylic acid, a GC–MS analysis was performed
using a standard from Sigma–Aldrich (D-89555, Stein-
heim, Germany).
(
500 ml). This LLE yielded 1.6 g of EtOAc, 7.0 g of n-
BuOH, and 21.8 g of water extracts. The n-BuOH extract
5.8 g) was separated by medium pressure liquid chroma-
tography (MPLC) with MeCN–H O step gradient (5:95
(
2

F. Martin et al. / Phytochemistry 68 (2007) 1307–1311
1311
3
.7. 10-O-Hydroxybenzoyltheviridoside (3)
Gentry, A.H., 1992. A synopsis of Bignoniaceae ethnobotany and
economic botany. Ann. Mo. Bot. Gard. 79, 53–64.
2
D
5
Jensen, S.R., Franzyk, H., Wallander, E., 2002. Chemotaxonomy of the
Oleaceae: iridoids as taxonomic markers. Phytochemistry 60, 213–231.
Kawagishi, H., Murakami, H., Sakai, S., Inoue, S., 2006. Carnitine-esters
from the mushroom Suillus laricinus. Phytochemistry 67, 2676–2680.
Li, L., Tsao, R., Liu, Z., Liu, S., Yang, R., Young, J.C., Zhu, H., Deng,
Z., Xie, M., Fu, Z., 2005. Isolation and purification of acteoside and
isoacteoside from Plantago psyllium L. by high-speed counter-current
chromatography. J. Chromatogr. A 1063, 161–169.
Pale yellow amorphous solid. ½aꢁ ꢀ31.8ꢂ (MeOH, c
1
3
.0), UV (MeOH) k
nm (loge): 201 (4.22), 253 (3.91),
25 (3.32); H and C NMR: see Tables 2 and 3, HR-
max
13
1
ꢀ
ESI-MS: m/z 523.1438 (C H O : [MꢀH] requires
2
4
27 13
5
23.1452).
3
.8. 10-O-Vanilloyltheviridoside (4)
Lohmann, L.G., 2006. Untangling the phylogeny of neotropical lianas
(
Bignonieae, Bignoniaceae). Am. J. Bot. 93, 304–318.
25
Pale yellow amorphous solid. ½aꢁ ꢀ26.6ꢂ (MeOH, c
Marston, A., Kissling, J., Hostettmann, K., 2002. A rapid TLC bioau-
tographic method for the detection of acetylcholinesterase and
butyrylcholinesterase inhibitors in plants. Phytochem. Anal. 13, 51–54.
Miyase, T., Koizumi, A., Ueno, A., Noro, T., Kuroyanagi, M.,
Fukushima, S., Akiyama, Y., Takemoto, T., 1982. Studies on the acyl
glycosides from Leucoseptrum japonicum (Miq.) Kitamura et Murata.
Chem. Pharm. Bull. 30, 2732–2737.
D
2
2
.0), UV (MeOH) k
nm (loge): 202 (4.31), 220 (4.16),
max
1
13
54 (3.85), 292 (3.68), 327 (3.46); H and C NMR: see
Tables 2 and 3, HR-ESI-MS: m/z 553.1541 (C H O :
2
5
29 14
ꢀ
[
MꢀH] requires 553.1557).
Ogura, M., Cordell, G.A., Farnsworth, N.R., 1976. Potential anticancer
agents. III. Jacaranone, a novel phytoquinoid from Jacaranda caucana.
Lloydia 39, 255–257.
Acknowledgment
Ogura, M., Cordell, G.A., Farnsworth, N.R., 1977. Potential anticancer
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The authors thank the Swiss National Science Founda-
tion for financial support of this work (Grant No. 200020-
Sasaki, H., Nishimura, H., Chin, M., Chen, Z., Mitsuhashi, H., 1989.
Chemical and biological studies on Rehmanniae radix. Part 2.
Hydroxycinnamic acid esters of phenethyl alcohol glycosides from
Rehmannia glutinosa var. purpurea. Phytochemistry 28, 875–879.
Sticher, O., Schmid, H., 1969. Theviridoside, an iridoid glucoside from
Thevetia peruviana. Helv. Chim. Acta 52, 478–481.
1
07775/1 to Prof. K. Hostettmann).
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