Natural Product Research
2253
177.6 due to the characteristic carbonyl carbon signal of C-1, which shows thatZNHCH CH
OH is linked to C-1. With the aid of HMBC and HSQC spectra, the carbon and proton signals
2
2-
0
0
were attributable. Thus, the structure was established to be 2-(4 -hydroxyl-3 -methoxybenzyl)-3-
00
00
(
3 ,4 -dimethoxy benzyl)-4-hydroxy-N-hydroxyethylbutanamide, and the NMR spectral data
are shown in supplementary material (Tables S1, S2).
2
0
Compound 2, ½aꢀ ¼ 239:3, was obtained as white crystalline columnar. HR-ESI-MS gave
D
þ
its quasi molecular ion peak at m/z 431.2298 [M] (calcd 431.2308), exhibiting that the
molecular formula of 2 was confirmed as C H NO . The structure of 2 contains an additional
2
4
33
6
ZNHCH CH CH group by comparing with the molecular weight of (2)-arctigenin. The
2
2
3
1
proton signals at d 3.00 (2H, m) in the H NMR spectrum due to methylene in ZNHCH CH CH
3
2
2
showed long-range correlation with d 177.1 due to the characteristic carbonyl carbon signal of
C-1, indicating that ZNHCH CH CH is linked to C-1. By comparing the spectral data with
2
2
3
1
13
those of 1, the complete molecule of 2 was established by H and C NMR, HSQC and HMBC
experiments, whose structure was almost identical to that of 1, besides those of the side chain.
0
0
00 00
Therefore, the structure of 2 was determined to be 2-(4 -hydroxyl-3 -methoxybenzyl)-3-(3 ,4 -
dimethoxy benzyl)-4-hydroxy-N-propylbutanamide, and the NMR spectral data are shown in the
supplementary material (Tables S1, S2).
Compound 3 was obtained as colourless oil. Two methoxyls were observed by the signal at d
1
.78 (6H, s) in the H NMR spectrum and their corresponding carbon signals were attributed at d
3
5
1
6.5 and 56.6, respectively, in the C NMR spectrum according to the HSQC spectrum of 3. Six
3
1
aromatic protons emerged in the H NMR spectrum at d 6.64 (1H, d, J ¼ 1.8 Hz), 6.68 (1H, d,
J ¼ 8.0 Hz), 6.48 (1H, dd, J ¼ 8.0 and 1.8 Hz), 6.60 (1H, d, J ¼ 1.9 Hz), 6.82 (1H, d,
J ¼ 8.2 Hz) and 6.61 (1H, dd, J ¼ 8.2 and 1.9 Hz), suggesting two ABX coupling systems in two
1
3
phenyl groups. They coupled with the C NMR signals of 3 at the low field, and the structure of
3
was deduced to contain two 1,2,4-trisubstituted phenyl fragments. The carbon signal at d 181.5
1
3
belonged to the carboxyl group. The carbon signals at d 35.3, 47.6, 38.8 and 42.7 in the C NMR
spectrum and the proton signals at d 2.77 (1H, dd, J ¼ 5.0 and 13.3 Hz), 2.87 (1H, dd, J ¼ 5.5
and 13.4 Hz), 2.49 (1H, dd, J ¼ 8.5 and 13.8 Hz), 2.59 (1H, dd, J ¼ 5.8 and 13.1 Hz), 2.62 (1H,
1
m) and 2.47 (1H, m) in the H NMR spectrum belonged to two ZCH Z and two ZCHZ
2
1
13
fragments. The complete molecule of 3 was confirmed by H and C NMR, HSQC and HMBC
experiments, whose structure was almost identical to that of (2)-arctigenin, expect for the lost
of methyl at 3 -OCH . Therefore, the structure of 3 was determined to be 3-(3 ,4 -
3
0
0
0
00
00
dihydroxylbenzyl)-4-(3 ,4 -dimethoxy benzyl)dihydrofuran-2(3H)-one, and the NMR spectral
data are shown in the supplementary material (Tables S1, S2).
Compound 4 was afforded as white powder. In the NMR spectra of 4, methoxyl signals were
1
not observed in the H NMR spectrum and their corresponding carbon signals were absent in the
3
C NMR spectrum. Comparing the spectral data with that of 3, the complete molecule of 4 was
1
1
determined by H and C NMR, HSQC and HMBC experiments, and the structure of 4 was
13
0
0
00 00
determined to be 3-(3 ,4 -dihydroxylbenzyl)-4-(3 ,4 -dihydroxylbenzyl)dihydrofuran-2(3H)-
one, whose NMR spectral data are shown in the supplementary material (Tables S1, S2).
Compound 5, [a ] ¼ þ15.5, was obtained as white needle crystal. The molecular formula of
compound 5 was confirmed as C H O S Na by HR-ESI-MS spectroscopic data. Compared
2
1
22 12
2
2
with the molecular weight of (2)-arctigenin, the structure of 5 contains two additional ZSO Na
3
1
groups. In the NMR spectra of 5, four aromatic protons emerged in the H NMR spectrum at d
1
.27 (1H, s), 6.35 (1H, s), 7.35 (1H, s) and 6.33 (1H, s). They coupled with the C NMR signals
3
7
of 5 at low field and the structure of 5 was deduced to posses two 1,2,4,5-four-substituted phenyl
fragments by comparing with that of (2)-arctigenin. Three methoxyls were observed by the
1
signals at d 3.89 (3H, s) and 3.62 (6H, overlapped) in the H NMR spectrum and their
1
3
corresponding carbon signals at d 55.9, 56.1 and 56.3, respectively, in the C NMR spectrum
according to the HSQC spectrum of 5. The carbon signal at d 184.2 belonged to carboxyl