1287
diagnostic peaks to be identified as a flavonoid derivative with hydroxyl group on C-
3, C-5 and C-7, appearing as sharp singlets at į 9.41, 12.33 and 10.81 ppm,
respectively. The H-6 and H-8 occurred as sharp doublet at į 6.25 and 6.41 ppm,
respectively. The B ring signals were easily assigned by consideration of symmetry.
The H-2' and H-6' occurred as sharp doublet at į 8.07 ppm. The H-3' and H-5'
appeared as doublet at į 7.05 ppm, and 4'-OCH
3
occurred as a singlet at į 3.79 ppm.
The
13
C experiments of compound
2
gave fourteen peaks. The most downfield shifted
peak was 176.0 ppm which was assigned as ketone group (C-4) and most upfield
shifted peak was 55.1 ppm which was assigned as ether group (4'-OCH
3
). By direct
comparison of the
1
H-NMR and
13
C-NMR data of conpound
2
(Table 1) with those of
the known compound 3,5,7-trihydroxy-4'-methoxyflavone (kaempferide)(Eunjung
2008) they were closely equivalent indicating that compound
2
is 3,5,7-trihydroxy-
4'-methoxyflavone (kaempferide)(Fig. 1).
Compound
3
was obtained as a bright yellow powder and the IR spectrum
showed strong absorption band at 3650-3200, 2970, 2825, 1639, 1625 and 1200 cm
-1
of
compound
3
suggested that compound
3
is a flavonoid glucoside derivative
compound(Paolo 2001, Xu 2008). The
1
H-NMR and
13
C-NMR spectra of compound
3
(Table 1) showed that all the glucose units had ȕ-linkages to either another glucose
or glycone since the constant coupling between the anomeric protons and 22-H were
always 7-8 Hz and anomeric carbon resonances were in the į 100 ppm
region(Agrawal 1992). The
13
C NMR spectral data suggested that glucose in
compound
3
was attached to the flavonol aglycone at C-3, because of the lack of
downfield shift for C-3 and the presence of a hydrogen bonding with the carbonyl
group in position 4 at į 176.84 ppm. By direct comparison of the
1
H-NMR and
13
C-
NMR data of conpound
3
(Table 1) with those of the known compound kaempferide-
3-
O
-
ȕ
-D-glucoside (Juha-Pekka 2004) they were closely equivalent indicating that
compound
3
is kaempferide-3-
O
-
ȕ
-D-glucoside (Fig. 1).
