Highly glycosylated flavonoids from the pods of Bobgunnia madagascariensis

Article abstract of DOI:10.1016/j.tetlet.2010.07.013

Methanolic extracts of the pods of Bobgunnia madagascariensis (Leguminosae) yielded four pentaglycosylated flavonoids, including the 3-O-α-l- rhamnopyranosyl(1→3)-α-l-rhamnopyranosyl(1→2) [α-l-rhamnopyranosyl(1→6)]-β-d-glucopyranoside-7-O-α-l- rhamnopyranosides of 3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-benzopyran-4-one (kaempferol) and 3,5,7-trihydroxy-2-(3,4-dihydroxyphenyl)-4H-benzopyran-4-one (quercetin), which were characterized by a novel O-linked branched tetrasaccharide. Spectroscopic and chemical methods were used to determine the structures of the latter, which co-occurred with the corresponding β-d-galactopyranosyl isomers, and two saponins. Conformational isomerism of quercetin 3-O-α-l-rhamnopyranosyl(1→3)-α-l- rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)] -β-d-glucopyranoside-7-O-α-l-rhamnopyranoside was detected in solution by NMR, a phenomenon previously associated only with C-glycosylflavonoids.

Full text of DOI:10.1016/j.tetlet.2010.07.013

Tetrahedron Letters 51 (2010) 4727–4730
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Highly glycosylated flavonoids from the pods of Bobgunnia madagascariensis
a,b,*
c
a
Philip C. Stevenson
, Stephen P. Nyirenda , Nigel C. Veitch
a
Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK
Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK
Department of Agricultural Research Services, PO Box 59, Mzuzu, Malawi
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Methanolic extractsofthepodsofBobgunniamadagascariensis(Leguminosae) yieldedfourpentaglycosylated
flavonoids, including the 3-O- -rhamnopyranosyl(1?3)- -rhamnopyranosyl(1?2)[ -rhamnopyr-
anosyl(1?6)]-b- -glucopyranoside-7-O- -rhamnopyranosides of 3,5,7-trihydroxy-2-(4-hydroxyphenyl)-
H-benzopyran-4-one (kaempferol) and 3,5,7-trihydroxy-2-(3,4-dihydroxyphenyl)-4H-benzopyran-4-one
quercetin), which were characterized by a novel O-linked branched tetrasaccharide. Spectroscopic and
chemical methods were used to determine the structures of the latter, which co-occurred with the
corresponding b- -galactopyranosyl isomers, and two saponins. Conformational isomerism of quercetin
-O- -rhamnopyranosyl(1?3)- -rhamnopyranosyl(1?2)[ -rhamnopyranosyl(1?6)]-b- -gluco-
pyranoside-7-O- -rhamnopyranoside was detected in solution by NMR, a phenomenon previously
associated only with C-glycosylflavonoids.
Received 19 April 2010
Revised 16 June 2010
Accepted 2 July 2010
Available online 7 July 2010
a
-
L
a-L
a-L
D
a-L
4
(
Keywords:
Bobgunnia
Swartzia
Tribe Swartzieae
Leguminosae
flavonol pentaglycosides
saponins
D
3
a
-
L
a
-
L
a
-
L
D
a
-L
Ó 2010 Elsevier Ltd. All rights reserved.
Bobgunnia madagascariensis (Desv.) J. H. Kirkbr. & Wiersema
Leguminosae) is a small tree or shrub found in deciduous forests
for 24 h at room temperature. The filtered and evaporated MeOH
extract was redissolved in MeOH and analyzed by LC–ESI-MS
(Waters Alliance system with ZQ LC–MS detector) using a Phenom-
(
throughout tropical and southern Africa, although it is primarily
associated with Miombo woodland.1 It was previously classified
in section Fistuloides of the genus Swartzia, together with Bobgun-
nia fistuloides (Harms) J. H. Kirkbr. & Wiersema, which occurs in
western tropical Africa.2 Evidence supporting the segregation of
both species into the separate genus Bobgunnia came initially from
differences in morphology and pollen type, compared to neo-
enex Luna C18(2) column (150 ꢀ 4.0 mm i.d.; 5
operating under gradient conditions (solvents A = MeOH, B = H
C = 1% HCO H in MeCN; A = 0%, B = 90% at t = 0 min; A = 90%,
lm particle size)
2
O,
2
B = 0% at t = 20 min; A = 90%, B = 0% at t = 30 min; A = 0%, B = 90%
at t = 31 min; Method 1) at a flow rate of 0.5 mL/min at 30 °C.
Two pairs of polar constituents eluting between t 5–7 min had
R
3
4
tropical Swartzia, and later from DNA sequence analysis. Local
uses for B. madagascariensis have been documented for most parts
of the plant, but those relating to the pods are of particular interest,
since in crushed and powdered form they can be effective as fish
UV spectra typical of O-glycosides of quercetin (1a and 1b; 255,
266 sh, 355 nm) and kaempferol (2a and 2b; 265, 349 nm).8 In
each case, a broad valley observed between bands I and II and
the lack of a shoulder at ca. 300 nm indicated that the flavonols
were glycosylated at both C-3 and C-7. The earlier eluting querce-
tin glycosides 1a and 1b exhibited identical mass spectra charac-
terized by a protonated molecule at m/z 1049 [M+H]+ and
fragments generated in-source at m/z 903, 757, 611, 449, and
303. Similarly, the kaempferol glycosides 2a and 2b gave proton-
1,5
poisons, insecticides, and molluscicidal agents. The latter activity
6
has been associated with saponins, but little is known about other
chemical constituents.7 Herein we report on highly glycosylated
flavonoids present in MeOH extracts of the pods, including two
new examples characterized by a novel O-linked branched tetra-
saccharide, and the first evidence for conformational isomerism
of O-glycosylated flavonols in solution.
+
ated molecules at m/z 1033 [M+H] and fragments generated in-
source at m/z 887, 741, 595, 433, and 287. These results suggested
that each flavonol 3,7-di-O-glycoside comprised four deoxyhexose
residues and one hexose residue. Two less polar constituents that
eluted late in the chromatogram and without appreciable absor-
Pods of B. madagascariensis were collected near Mzuzu, north-
ern Malawi, and a voucher specimen deposited in the Herbarium,
Royal Botanic Gardens Kew (STVP 1017). For initial analyses, 5 g
of pods were ground to a powder and extracted in 50 mL of MeOH
bance above 210 nm were detected as sodiated molecules
+
[
M+Na] at m/z 1095 (3), and 963 (4).
Compounds 1a, 1b, 2a, 2b, 3, and 4 were purified by semi-pre-
parative HPLC using a Waters system (LC600 pump and controller,
96 photodiode array detector, and 717 Plus autosampler). A dried
*
Corresponding author. Tel.: +44 2083325377; fax: +44 2083325310.
E-mail addresses: p.stevenson@kew.org, p.c.stevenson@gre.ac.uk (P.C. Steven-
9
son).
0
040-4039/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2010.07.013

4
728
P. C. Stevenson et al. / Tetrahedron Letters 51 (2010) 4727–4730
MeOH extract derived from 10 g of powdered pods of B. madaga-
scariensis was redissolved in 2 mL of MeOH, and aliquots (100 L)
injected successively onto a LiChrospher 100 RP-18 column
250 ꢀ 10.0 mm i.d.; 10 m particle size). Gradient conditions
were selected to give baseline separation of the four flavonol glyco-
sides (A = MeOH, B = H O; A = 20% at t = 0 min; A = 44% at
t = 16 min; A = 100% at t = 20 min; flow rate of 4.7 mL/min at
0 °C; Method 2), which were obtained in yields of 3.4 mg (1a,
R1
3'
l
CH3
OH
HO
HO
HO
α-Rha IV
4'
2
α-Rha I
(
l
O
9
O
2
O
1'
OH
7
O
CH3
1
3
1
2
10
O
OH
1
5
4
O
3
O
OH
O
1
O
3
OH
CH
O
t
R
= 11.3 min), 1.4 mg (1b,
t
R
= 11.9 min), 25.0 mg (2a,
OH
3
t
R
= 12.7 min), and 2.6 mg (2b, t
R
= 13.4 min). Additional constitu-
R2
HO
HO
CH3
ents isolated using the same column but with method 1 above
and a flow rate of 4.7 mL/min comprised a mixture of 3 and 4
6
R3
HO
α-Rha III
O
α-Rha II
O
HO
(
R R
4.3 mg, t = 20.2 min), and 4 (8.0 mg, t = 20.7 min), as white
1
amorphous solids, and the common flavonoid aglycones, eri-
odictyol (1.6 mg), and luteolin (1.3 mg).9 The structures of the
compounds were determined by NMR, MS, and in the case of the
flavonoid glycosides, by sugar analysis. NMR spectra were acquired
in MeOH-d at 30 °C on a Bruker Avance II+ 700 MHz instrument
4
equipped with a TCI-cryoprobe or on a Bruker Avance 400 MHz
HO
1
2
3
1
1
2
2
a R = R = OH, R = H
1
3
2
b R = R = OH, R = H
1
3
2
a R = R = H, R = OH
1
2
3
b R = R = H, R = OH
instrument. Standard pulse sequences and parameters were used
1
13
to obtain 1D H, 1D C, 1D selective NOE, COSY, TOCSY, HSQC,
and HMBC spectra. Chemical shift referencing was carried out
2
8
using the internal solvent resonances at d
H
3.31 and d
C
49.1 (cali-
2
COOR
brated to TMS at 0.00 ppm). The absolute configurations of the
constituent monosaccharides of 1a, 1b, 2a, and 2b released by acid
hydrolysis (0.1–0.5 mg in 0.5 mL of 2 M HCl; 100 °C, 1.5 h) were
determined by GC–MS of their trimethylsilylated thiazolidine
derivatives prepared using an established method.10 Conditions
for GC were: capillary column, DB5-MS (30 m ꢀ 0.25 mm ꢀ
3
O
O
HOOC
OR1
2
HO
O
3
1
2
3
R = β-Xyl, R = β-Glc
4 R = H, R = β-Glc
0
.25
tion temp., 350 °C; carrier gas, He at 1 mL/min. The acid hydroly-
sates of 1a and 2a each gave -rhamnose and -galactose,
whereas 1b and 2b gave -rhamnose and -glucose ( -rhamnose,
-galactose and -glucose at t = 10.3, 12.4 and 12.2 min, respec-
lm), oven temp. programme, 180–300 °C at 6 °C/min; injec-
H C
1
3
HO
O
1
2
HO
L
D
OH
L
D
L
D
D
R
Figure 1. Flavonol pentaglycosides and saponins from the pods of Bobgunnia
madagascariensis (b-Glc = b-glucopyranosyl, a-Rha = a-rhamnopyranosyl, b-Xyl = b-
tively; identical to authentic standards).
xylopyranosyl).
Flavonol glycosides 1a and 2a were identified from NMR and
MS data as the known 3-O-
rhamnopyranosyl(1?2)[ -rhamnopyranosyl(1?6)]-b-
pyranoside-7-O- -rhamnopyranosides of quercetin (cordylasin
A), and kaempferol (cordylasin B), respectively (Fig. 1). Com-
pounds 1b and 2b were thus hexosyl isomers of the latter; they
had UV and MS spectra identical to those of 1a and 2a, respectively,
a
-
L
-rhamnopyranosyl(1?3)-
a-L-
a-L
D-galacto-
a
-L
downfield shift to C-3 of Rha I, and confirmed by connectivities de-
tected from H-3 of Rha I to C-1 of Rha II at d 104.1, and H-1 of Rha
II to C-3 of Rha I at d 80.2. Thus a branched tetrasaccharide was O-
linked at C-3, and a single -rhamnopyranosyl residue (Rha IV)
O-linked at C-7. Compound 1b was therefore quercetin 3-O-
rhamnopyranosyl(1?3)- -rhamnopyranosyl(1?2)[ -rhamno-
-glucopyranoside-7-O- -rhamnopyranoside
11
C
C
a
-L
but on hydrolysis afforded
-galactose and -rhamnose. For 1b, a yellow amorphous solid
ꢂ88.0 (c 0.038, MeOH)), the molecular formula C45
D
-glucose and
L
-rhamnose rather than
a-L-
D
L
a
-
L
a-L
2
D
2
(½
a
ꢁ
H
60
O
28
pyranosyl(1?6)]-b-
D
a-L
+
was established by HRESIMS (m/z 1049.3336 [M+H] , calcd for
(Fig. 1).
1
C
45
H
61
O
28, 1049.3344). The H NMR spectrum of 1b included reso-
nances for anomeric protons of O-linked sugars at d 5.62 (d,
J = 7.7 Hz, d 100.5), corresponding to -glucose, and 5.55 (d,
100.0), 5.22 (d, J = 1.8 Hz, 102.6), 5.03 (d,
104.1), and 4.50 (d, J = 1.8 Hz, d 102.2), corresponding
The kaempferol pentaglycoside 2b was a yellow amorphous so-
2
D
2
H
lid ((½
of C45
61
calcd for C45H O
a
ꢁ
ꢂ121.2 (c 0.085, MeOH)) for which a molecular formula
+
C
D
H
60
O
27 was obtained by HRESIMS (m/z 1033.3389 [M+H] ,
27, 1033.3395). It had a glycosylation profile iden-
J = 1.9 Hz,
d
C
d
C
J = 1.8 Hz, d
C
C
tical to that of 1b. In comparison with the latter, the same pattern
of connectivities defining linkages between the glycosyl residues
and the aglycone, and between the glycosyl residues themselves,
1
13
to four L-rhamnose residues. Full assignment of the H and C res-
onances of each sugar was achieved using standard 2D NMR data-
sets (Table 1), and their anomeric configurations defined from the
1
was observed in HMBC data. NMR assignments for the H and
3
12
13
magnitudes of JH-1,H-2 coupling constants. The sites of glycosyl-
ation of the quercetin aglycone of 1b were determined from long
C resonances of the glycosyl residues of 2b were almost identical
to those of 1b (Table 1). Compound 2b was therefore kaempferol
range connectivities detected in the HMBC spectrum between d
.62 (H-1 of Glc) and C-3 (d 134.7), and d 5.55 (H-1 of 7-O-
Rha) and C-7 (d 163.4). The b- -glucopyranosyl residue was there-
fore the primary sugar O-linked at C-3. Both C-2 and C-6 of the lat-
H
3-O-
a
-
L
-rhamnopyranosyl(1?3)-
a
-
L
-rhamnopyranosyl(1?2)[
a-L-
5
C
H
rhamnopyranosyl(1?6)]-b-
pyranoside (Fig. 1).
Two sets of resonances corresponding to the protons of the
quercetin B-ring of 1b were observed in the H NMR spectrum ac-
quired in MeOH-d
those of the 3-O-b-
anosyl (Rha III) residues, was detectable, although with less differ-
entiation in chemical shift between the two forms. The extent of
D
-glucopyranoside-7-O- -rhamno-
a-L
C
D
13
1
ter were shifted downfield in the
glycosylated by -rhamnopyranosyl residues (Rha I and Rha III,
respectively), according to the HMBC connectivities detected from
Glc H-2 to C-1 of Rha I at d 102.6, H-1 of Rha I to Glc C-2 at d 80.1,
Glc 6-CH to C-1 of Rha III at d 102.2, and H-1 of Rha III to Glc C-6
at d 68.2. An additional site of glycosylation was suggested by the
C NMR spectrum, and
a-
L
4
, and duplication of other resonances, including
Glc
D
-glucopyranosyl and 6 -O-a-L-rhamnopyr-
C
C
2
C
1
3
C
the differences noted for the C resonances of 1b was greatest

P. C. Stevenson et al. / Tetrahedron Letters 51 (2010) 4727–4730
4729
Table 1
1
H and 13C NMR spectroscopic data for 1b, 1bàa and 2b (700 MHz, CD
3
OD, 30 °C)
1
b
1bà
2b
d 1H (J in Hz)
d 13
C
d 1H (J in Hz)
d 13
C
d 1H (J in Hz)
d 13
C
Aglycone
2
3
4
5
6
7
8
9
159.5
134.7
179.5
162.9
100.5
163.4
95.6
158.0
107.6
123.1
117.3
146.2
150.2
116.2
123.6
161.2
134.0
179.3
163.1
100.3
163.3
95.6
158.0
107.5
121.0
110.0
153.2
157.2
109.1
122.8
159.7
134.7
179.6
163.1
100.6
163.5
95.8
158.2
107.7
122.8
132.4
116.5
161.9
116.5
132.4
6.46 (d, 2.1)
6.72 (d, 2.2)
6.45 (d, 2.1)
6.72 (d, 2.1)
6.47 (d, 2.2)
6.73 (d, 2.2)
1
1
2
3
4
5
6
0
0
0
0
0
0
0
7.61 (d, 2.1)
7.44 (d, 2.0)
6.69 (d, 8.2)
8.05 (d, 8.9)
6.90 (d, 8.9)
6.88 (d, 8.4)
7.64 (dd, 8.4, 2.1)
6.90 (d, 8.9)
8.05 (d, 8.9)
7.52 (dd, 8.2, 2.1)
3-O-b-Glc
1
2
3
4
5
6
5.62 (d, 7.7)
3.67 (dd, 9.4, 7.8)
3.56 (t, 9.1)
3.28 (m)
3.34 (ddd, 9.7, 6.3, 1.8)
3.81 (m)
100.5
80.1
79.0
71.9
77.1
68.2
5.66 (d, 7.7)
3.74 (dd, 9.2, 7.7)
3.55 (m)
3.37 (t, 9.3)
3.33 (m)
100.3
79.6
79.0
71.7
77.1
67.9
5.65 (d, 7.6)
3.62 (dd, 9.4, 7.6)
3.56 (t, 9.0)
100.5
80.1
79.0
72.1
77.3
68.3
3.25 (t, 9.3)
3.35 (ddd, 9.6, 6.4, 1.9)
3.82 (dd, 11.4, 1.7)
3.39 (m)
3.81 (m)
3.42 (m)
3.40 (m)
Glc
2
1
2
3
4
5
6
-O-a-Rha (I)
5.22 (d, 1.8)
4.11 (dd, 3.4, 1.8)
3.88 (dd, 9.7, 3.4)
3.47 (t, 9.5)
4.11 (m)
1.01 (d, 6.2)
102.6
72.2
80.2
73.3
70.2
17.5
5.23 (d, 1.7)
4.10 (m)
3.88 (dd, 9.6, 3.2)
3.46 (m)
4.10 (m)
0.95 (d, 6.2)
102.4
72.3
80.2
73.2
70.1
17.5
5.22 (d, 1.7)
102.7
72.3
80.2
73.3
70.3
17.7
4.10 (dd, 3.4, 1.8)
3.87 (dd, 9.7, 3.3)
3.46 (t, 9.7)
4.09 (dd, 9.7, 6.2)
0.98 (d, 6.2)
RhaI
3
1
2
3
4
5
6
-O-
a
-Rha (II)
5.03 (d, 1.8)
104.1
72.2
72.3
74.2
70.1
18.0
5.02 (d, 1.8)
104.1
72.2
72.3
74.2
70.1
18.0
5.03 (d, 1.8)
104.2
72.3
72.4
74.3
70.2
18.1
3.97 (dd, 3.4, 1.8)
3.77 (dd, 9.6, 3.4)
3.40 (t, 9.5)
3.84 (dd, 9.7, 6.2)
1.30 (d, 6.3)
3.96 (dd, 3.3, 1.8)
3.77 (dd, 9.6, 3.4)
3.40 (t, 9.5)
3.84 (dd, 9.7, 6.2)
1.30 (d, 6.3)
3.97 (dd, 3.4, 1.8)
3.77 (dd, 9.5, 3.4)
3.40 (t, 9.5)
3.83 (dd, 9.5, 6.2)
1.31 (d, 6.3)
Glc
6
1
2
3
4
5
6
-O-a-Rha (III)
4.50 (d, 1.8)
3.55 (dd, 3.4, 1.8)
3.47 (m)
3.22 (t, 9.5)
3.41 (m)
102.2
72.1
72.3
73.9
69.7
17.8
4.52 (d, 1.7)
3.61 (dd, 3.4, 1.7)
3.52 (dd, 9.4, 3.4)
3.20 (t, 9.6)
3.40 (m)
1.06 (d, 6.2)
102.1
72.2
72.1
73.9
69.7
17.8
4.49 (d, 1.7)
3.55 (dd, 3.4, 1.7)
3.46 (dd, 9.5, 3.4)
3.22 (t, 9.5)
3.41 (m)
1.07 (d, 6.2)
102.3
72.2
72.4
74.0
69.8
17.9
1.07 (d, 6.2)
7-O-a-Rha (IV)
1
2
3
4
5
6
5.55 (d, 1.9)
100.0
71.8
72.1
73.7
71.3
18.1
5.55 (d, 1.9)
100.0
71.8
72.1
73.7
71.3
18.1
5.56 (d, 1.8)
100.1
71.8
72.2
73.7
71.3
18.2
4.01 (dd, 3.4, 1.8)
3.82 (dd, 9.5, 3.5)
3.48 (t, 9.5)
3.62 (dd, 9.5, 6.2)
1.26 (d, 6.2)
4.01 (dd, 3.4, 1.8)
3.82 (dd, 9.5, 3.5)
3.48 (t, 9.5)
3.62 (dd, 9.5, 6.2)
1.26 (d, 6.2)
4.01 (dd, 3.5, 1.8)
3.83 (dd, 9.5, 3.4)
3.48 (t, 9.5)
3.61 (dd, 9.6, 6.2)
1.26 (d, 6.2)
a
Rotameric form of 1b.
0
0
tion property of C-glycosylated flavonoids,13 it has not been re-
ported previously for O-linked flavonoid glycosides.
Compounds 3 and 4 were identified from spectroscopic data
and literature comparisons as the known saponins, 3-O-b-xylopyr-
for B-ring carbons (C-1 –C-6 ), C-2, and C-3. Correlations between
the duplicated resonances of B-ring protons were observed in
selective 1D NOE experiments; thus excitation of d
.88 (H-5 ), and 7.64 (H-6 ) of 1b elicited responses at d
H-2 ), 6.69 (H-5 ), and 7.52 (H-6 ), respectively, of 1bà, and vice
versa (Table 1). These exchange phenomena were consistent with
the presence of conformational isomers (rotamers). However, no
evidence for conformational isomerism was detected for the
kaempferol analog 2b. Rotamer formation in 1b appears to origi-
nate from restricted rotation about the C-2 to C-1 bond of the agly-
cone due to steric hindrance between the bulky O-linked branched
0
H
7.61 (H-2 ),
0
0
6
(
H
7.44
0
0
0
anosyl(1?2)[
28-O-b-glucopyranosyl-oleanolic acid, and 3-O-
syl(1?3)-b-glucuronopyranosyl-28-O-b-glucopyranosyl-oleanolic
a
-rhamnopyranosyl(1?3)]-b-glucuronopyranosyl-
a-rhamnopyrano-
1
4
acid (putranoside C), respectively (Fig. 1). Neither compound has
been reported previously as a constituent of B. madagascariensis
(including work published using the synonym, Swartzia madaga-
scariensis), although saponins with similar structures occur in the
0
0
0
6
tetrasaccharide at C-3, and the disubstituted flavonol B-ring (3 ,4 -
diOH). Although conformational isomerism is a well-known solu-
pods. Other sources of both 3 and 4 in the Leguminosae include
1
5
the aerial parts of Sesbania sesban (L.) Merr. , and the leaves of

4
730
P. C. Stevenson et al. / Tetrahedron Letters 51 (2010) 4727–4730
Swartzia simplex (Sw.) Spreng.,14 while 4 was also reported from
the fruits of Swartzia langsdorffii Raddi.16
ICART project and the ACP Science and Technology Program. The
authors thank Dr. Gwil Lewis (Royal Botanic Gardens Kew) for
the herbarium material and advice, Drs. Tam Bui and Alex Drake
(Pharmaceutical Optical and Chiroptical Spectroscopy Facility,
King’s College London) for optical rotation measurements, and
the Medical Research Council Biomedical NMR Centre (National
Institute for Medical Research, Mill Hill, London, UK) for access to
higher-field NMR facilities.
Pentaglycosides represent fewer than 1% of the known flavonol
17
glycosides, which number more than 1500. There are no previous
reports of the O-linked branched tetrasaccharide that characterizes
1
b and 2b, although the corresponding b-D-galactopyranosyl iso-
mer has been found as a component of mildbraedin, a kaempferol
tetraglycoside from the leaves of Mildbraediodendron excelsum
Harms (Leguminosae), and four species of Cordyla (Legumino-
1
1,18
sae).
It was also present in cordylasins A (1a) and B (2a), flavo-
References and notes
nol pentaglycosides that accumulate in the leaves of three species
of Cordyla. The occurrence of flavonol pentaglycosides in MeOH
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1
1
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Hutchinson, J.; Dalziel, J. M. In Flora of West Tropical Africa; Keay, R. W. J., Ed.;
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(
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been assigned to the tribe Swartzieae of the Leguminosae. How-
ever, DNA sequence analyses indicate that the tribe is polyphyletic,
and in need of reclassification.19 Although Bobgunnia has been
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1
0. Ito, A.; Chai, H.-B.; Kardono, L. B. S.; Setowati, F. M.; Afriastini, J. J.; Riswan, S.;
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group of seven genera, both Cordyla and Mildbraediodendron fall
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The distinctive flavonoid chemistry shared by Bobgunnia, Cordyla,
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2
16. Magalhães, A. F.; Tozzi, A. M. G. A.; Santos, C. C.; Serrano, D. R.; Zanotti-
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D
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Acknowledgments
The financial support for this work was provided by the Euro-
pean Union via the Southern African Development Community