M. Tajiri, R. Yamada, M. Hotsumi et al.
European Journal of Medicinal Chemistry 215 (2021) 113289
2,3-Dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]
isoquinolinium (12)
Mp:163e165 ꢀC, 1H NMR (500 MHz, CDCl3):
d
¼ 2.60 (dd, J ¼ 16.0,
3.5 Hz, 1H), 2.64 (d, J ¼ 16.0 Hz, 1H), 2.78 (d, J ¼ 16.0 Hz, 1H), 3.08
(m, 2H), 3.20 (dd, J ¼ 16.0, 4.0 Hz, 1H), 3.51 (d, J ¼ 16.0 Hz, 2H), 3.84
(s, 6H), 4.21 (d, J ¼ 16.0 Hz,1H), 5.91 (s, 2H), 6.59 (s, 1H), 6.73 (s, 1H),
6.77 (d, J ¼ 8.5 Hz, 1H), 6.85 (d, J ¼ 8.5 Hz, 1H) ppm. 13C NMR
9-Methoxy-2,3,10-trihydroxy-5,6-dihydroisoquinolino[3,2-a]
isoquinolinium (13)
Boron tribromide (2 mL) was added dropwise to the solution of
Berberine (500 mg, 1.49 mmol) in dry dichloromethane (7 mL)
at ꢂ80 ꢀC. The mixture was stirred for 30 min. The mixture was
slowly heated to 30 ꢀC and stirred for 18.5 h, water was added and
the solvent removed in vacuo. The residue was purified by silica gel
chromatography (90 : 10 ¼ chloroform: MeOH) to afford 2,3-
dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]iso-
quinolinium (12) (68 mg, 13%) as yellow powder and 9-methoxy-
2,3,10-trihydroxy-5,6-dihydroisoquinolino[3,2-a]isoquinolinium
(13) (4.33 mg, 1%) as red solid. 12: Mp 164e165 ꢀC, 1H NMR
(150 MHz, CDCl3):
d
¼ 29.7, 36.6, 51.5, 54.0, 56.0, 59.8, 60.3, 100.9,
105.6, 108.5, 111.0, 124.0, 127.9, 128.8, 130.9, 145.1, 146.0, 146.2,
150.4 ppm. IR (film) vmax cmꢂ1:2952, 2860, 2777, 1525, 1389, 1334,
1304, 1248,1160,1038,1015, 990, 956, 845, 805 cmꢂ1. ESIHRMS m/z:
calcd. for C20H22NO4 [MþH]þ 340.1549, found: 340.1571.
5,6,13,13a-tetrahydro-9-methoxy-2,3,10-trihydroxy-8H-dibenzo
[a,g]quinolizine (16)
Boron tribromide (600 mL) was added dropwise to a solution of
15 (204 mg, 601
m
mol) in dry dichloromethane (2 mL) at ꢂ80 ꢀC.
(600 MHz, DMSO‑d6):
d
¼ 3.06 (t, J ¼ 6.0 Hz, 2H), 4.02 (s, 3H), 4.04
The mixture was stirred for 10 min. Then the mixture was slowly
heated to 0 ꢀC and stirred for 15 h. After the reaction, water was
added to the mixture and solvent was removed in vacuo. The res-
(s, 3H), 4.84 (t, J ¼ 6.0 Hz, 2H), 6.77 (s, 1H), 7.46 (s, 1H), 8.00 (d,
J ¼ 9.0 Hz, 1H), 8.13 (d, J ¼ 9.0 Hz, 1H), 8.72 (s, 1H), 9.29 (brs, 1H),
9.80 (s, 1H), 10.07 (brs, 1H) ppm. 13C NMR (150 MHz, DMSO‑d6):
idue was purified by silica gel chromatography (90
10 chloroform: MeOH) to afford 5,6,13,13a-Tetrahydro-9-
methoxy-2,3,10-trihydroxy-8H-dibenzo[a,g]quinolizine (16)
(82.3 mg, 44%) as orange crystals. Mp: 175e176 ꢀC, 1H NMR
(600 MHz, MeOH-d4):
:
d
¼ 26.2, 56.1, 57.6, 62.4, 113.2, 115.4, 118.3, 119.6, 121.7, 124.1, 127.2,
¼
127.7, 133.8, 144.0, 145.7, 146.1, 149.7, 150.5 ppm. IR (film) vmax
cmꢂ1: 3421, 1608, 1561, 1531, 1457, 1365, 1333, 1262, 1141, 1107,
1065, 999, 979, 901, 869, 826, 505, 425, 415 cmꢂ1.ESIHRMS m/z:
calcd. for C19H18ClNO4 [M-Cl-]þ 324.1230, found: 324.1206.13: Mp:
d
¼ 2.90 (d, J ¼ 15.0 Hz, 1H), 2.97 (q,
J ¼ 11.4 Hz,1H), 3.18 (td, J ¼ 13.2, 4.2 Hz,1H), 3.50 (t, J ¼ 12.0 Hz,1H),
3.63 (m, 1H), 3.82 (m, 4H), 4.28 (dd, J ¼ 15.0, 5.4 Hz, 1H), 4.63 (td,
J ¼ 12.0, 4.2 Hz, 1H), 4.70 (m, 1H), 6.62 (s, 1H), 6.64 (d, J ¼ 8.4 Hz,
178e179 ꢀC, 1H NMR (500 MHz, MeOH-d4):
d
¼ 3.03 (t, J ¼ 6.0 Hz,
2H), 3.98 (s, 3H), 4.80 (t, J ¼ 6.6 Hz, 2H), 6.75 (s, 1H), 7.44 (s, 1H),
7.69 (d, J ¼ 9.0 Hz, 1H), 8.01 (d, J ¼ 9.0 Hz, 1H), 8.61 (s, 1H), 9.26 (s,
1H), 9.81 (s, 1H), 10.03 (s, 1H), 11.14 (s, 1H) ppm. 13C NMR (150 MHz,
1H), 6.76 (m, 2H) ppm. 13C NMR (150 MHz, DMSO‑d6):
d
¼ 25.3,
32.9, 50.8, 51.6, 56.6, 59.4, 112.2, 112.8, 115.5, 119.4, 119.5, 122.6,
MeOH-d4):
d
¼ 26.7, 55.9, 55.9, 111.8, 114.4, 114.4, 118.0, 118.5, 119.0,
123.0, 124.9, 142.7, 145.1, 145.7, 146.2 ppm. IR (film) vmax cmꢂ1
:
.
127.1, 128.8, 137.4, 142.1, 143.5, 144.1, 145.7, 149.0, 149.1 ppm. IR
3394, 1607, 1497, 1457, 1363, 1278, 1053, 867, 749, 471 cmꢂ1
(film) vmax cmꢂ1: 3178, 1609, 1509, 1458, 1308, 875, 428, 412 cmꢂ1
.
ESIHRMS m/z: calcd. for C18H20NO4 [MþH]þ 314.1392, found:
ESIHRMS m/z: calcd. for C19H16ClNO4 [M-Cl-]þ 310.1074, found:
314.1393.
310.1006.
5,6,13,13a-tetrahydro-2,3,9,10-tetrahydroxy-8H-dibenzo[a,g]
quinolizine (17)
2,3,9,10-Tetrahydroxy-5,6-dihydroisoquinolino[3,2-a]
isoquinolinium (14)
Boron tribromide (1.2 mL) was added dropwise to a solution of
Boron tribromide (3 mL) was added dropwise to a solution of
berberine (1) (400 mg,1.19 mmol) in dry dichloromethane (6 mL) at
15 (100 mg, 295
m
mol) in dry dichloromethane (3 mL) at ꢂ80 ꢀC.
The mixture was slowly heated to room temperature and stirred for
0
ꢀC. The mixture was slowly warmed to room temperature and
11 h; water was added, and solvent was removed in vacuo. The
stirred. After 14.5 h, water was added to the mixture and the sol-
vent removed in vacuo. The residue was purified with column
chromatography (90 : 10 ¼ chloroform: MeOH) to afford 2,3,9,10-
Tetrahydroxy-5,6-dihydroisoquinolino[3,2-a]isoquinolinium (14)
(130 mg, 37%) as brown crystal. Mp: 186e187 ꢀC, 1H NMR
residue was purified by silica gel chromatography (90 :
10 ¼ chloroform: MeOH) to afford 5,6,13,13a-Tetrahydro-2,3,9,10-
tetrahydroxy-8H-dibenzo[a,g]quinolizine (17) (24.7 mg, 28%) as
light yellow crystals. Mp 201e203 ꢀC, 1H NMR (600 MHz, MeOH-
d4):
d
¼ 2.91 (dd, J ¼ 16.2, 2.4 Hz, 1H), 2.98 (m, 1H), 3.17 (td, J ¼ 12.6,
(600 MHz, DMSO‑d6):
d
¼ 3.03 (t, J ¼ 6.0 Hz, 2H), 4.78 (t, J ¼ 6.0 Hz,
4.8 Hz, 1H), 3.50 (td, J ¼ 12.6, 4.2 Hz, 1H), 3.65 (d, J ¼ 17.4, 4.2 Hz,
1H), 3.86 (dd, J ¼ 11.4, 4.8 Hz, 1H), 4.30 (d, J ¼ 15.0 Hz, 1H), 4.65 (dd,
J ¼ 12.0, 4.2 Hz, 1H), 4.72 (d, J ¼ 16.2 Hz, 1H), 6.64 (s, 1H), 6.66 (d,
J ¼ 7.2 Hz, 1H), 6.77 (d, J ¼ 7.2 Hz, 1H), 6.80 (s, 1H) ppm. 13C NMR
2H), 6.75 (s, 1H), 7.44 (s, 1H), 7.58 (d, J ¼ 9.0 Hz, 1H), 7.72 (d,
J ¼ 9.0 Hz, 1H), 8.56 (s, 1H), 9.23 (s, 1H), 9.71 (s, 1H), 9.99 (s, 1H)
10.64 (s, 1H), 10.72 (s, 1H) ppm. 13C NMR (150 MHz, DMSO‑d6):
d
¼ 26.4, 55.7, 113.0, 115.4, 118.6, 118.6, 118.7, 119.3, 127.4, 129.5,
(150 MHz, DMSO‑d6):
d
¼ 25.4, 33.0, 49.1, 50.9, 59.5, 112.8, 115.5,
132.8, 137.2, 141.7, 143.8, 145.0, 145.9, 149.2 ppm. IR (film) vmax
cmꢂ1: 3606, 2860, 1656, 1576, 1409, 1340, 1253, 1137, 1044, 1025,
951, 845, 762 cmꢂ1. ESIHRMS m/z: calcd. for C17H14ClNO4 [M-Cl-]þ
296.0917, found: 296.0933.
115.6, 116.8, 119.5, 122.5, 123.0, 123.1, 141.9, 143.7, 145.2, 145.7 ppm.
IR (film) vmax cmꢂ1: 3652, 3550, 3268, 1656, 1554, 1522, 1335,
1304, 1132, 1011, 909, 826, 762, 678 cmꢂ1. ESIHRMS m/z: calcd. for
C
17H18NO4 [MþH]þ 300.1236, found: 300.1227.
5,6,13,13a-tetrahydro-9,10-dimethoxy-2,3-(methylenedioxy)-8H-
dibenzo[a,g] quinolizine (15)
Assay of ab aggregation inhibitory activity
NaBH4 (200 mg, 5.29 mmol) was added to a solution of
Berberine (1) (500 mg, 1.50 mmol) in MeOH (30 mL) at 0 ꢀC. The
reaction mixture was stirred for 17 h at room temperature. Then,
the MeOH was removed in vacuo. The mixture was added to water
and extracted with chloroform/MeOH (95 : 5). The obtained organic
layer was washed with brine, dried over MgSO4, and concentrated
The aggregation of A
Briefly, 25 M A 42 (Peptide Institute, Inc.; Ibaraki, Japan) was
combined with 0 M (control) or 10 M BBR intermediates or an-
alogues in the presence of 50 mM sodium phosphate buffer, pH 7.5,
100 mM NaCl, 1% (v/v) DMSO. The total fluid volume was 25 L.
Reactions were incubated at 37 ꢀC. To monitor amount of A
aggregate, aliquots were diluted fourfold into 5 M ThT and
b was assessed with the ThT method.
m
b
m
m
m
b
in
vacuo.
5,6,13,13a-Tetrahydro-9,10-dimethoxy-2,3-(methyl-
m
enedioxy)-8H-dibenzo[a,g]quinolizine (15) (377 mg, 83%) was ob-
tained as light yellow crystals without further purification.
immediately evaluated for fluorescence (excitation ¼ 445 nm,
emission ¼ 490 nm).
9