AcOH) to give MOM-protected cholic acid (633 mg, 96%,
2 step) as a white sold. To a suspension of SN-38 (104 mg,
0.266 mmol) in CH2Cl2 (13 mL, 0.02 M) was added MOM-
protected cholic acid (155 mg, 0.286 mmol), EDC¢HCl (74 mg,
0.388 mmol), and DMAP (6.3 mg, 0.0516 mmol). After stirring
for 24 h at room temperature, the reaction mixture was diluted
with CH2Cl2 and washed with saturated aqueous solution of
NH4Cl, water, and brine. The organic layer was then dried
(MgSO4), filtered, and concentrated under reduced pressure.
The residue was purified by silica gel column chromatography
(CHCl3/MeOH = 100:1) to give MOM-protected SN-38-
cholate (201 mg, 86%) as a pale yellow solid. To a solution
of MOM-protected SN-38-cholate (25 mg, 0.0450 mmol) in
MeCN/H2O (25:1 = 2.6 mL, 0.01 M) was added LiBF4 (26.4
mg, 0.282 mmol) and heated at 80 °C. After stirring for 24 h at
80 °C, the reaction mixture was cooled to room temperature and
diluted with CH2Cl2 and washed with water, and brine. The
organic layer was then dried (MgSO4), filtered, and concen-
trated under reduced pressure. The residue was purified by
silica gel column chromatography (CHCl3/MeOH = 100:1 ¼
25:1) to give SN-38-cholate (8) (19 mg, 87%) as a pale yellow
for 20 h at room temperature, the reaction mixture was diluted
with CH2Cl2 and washed with saturated aqueous solution of
NH4Cl, water, and brine. The organic layer was then dried
(MgSO4), filtered, and concentrated under reduced pressure.
The residue was purified by silica gel column chromatography
(CHCl3/MeOH = 100:1) to give SN-38-menthol (10) (86 mg,
68%) as a pale yellow solid. 1H NMR (400 MHz, CDCl3)
¤ = 0.75 (3H, d, J = 6.8 Hz), 0.87-1.10 (12H, m), 1.37-1.50
(5H, m), 1.66-1.69 (2H, m), 1.87-1.91 (5H, m), 1.99-2.02 (4H,
m), 2.76-2.80 (2H, m), 2.96-2.99 (2H, m), 3.13 (2H, q,
J = 3.6 Hz), 4.00 (1H, s), 4.75 (1H, ddd, 6.8, 6.8, 4.4 Hz), 5.24
(1H, s), 5.29 (1H, d, J = 16.4 Hz), 5.73 (1H, d, J = 16.4 Hz),
7.54 (1H, dd, J = 9.2, 2.4 Hz), 7.65 (1H, s), 7.81 (1H, d, J =
2.4 Hz), 8.21 (1H, d, J = 9.2 Hz) ppm. 13C NMR (100 MHz,
CDCl3) δ = 8.0, 14.1, 16.5, 20.9, 22.1, 23.3, 23.6, 26.4, 29.5,
29.6, 31.5, 31.7, 34.3, 41.0, 47.2, 49.5, 66.4, 72.9, 75.1, 98.2,
114.6, 118.7, 125.5, 127.4, 127.5, 132.2, 145.4, 147.0, 147.5,
149.7, 150.3, 152.0, 157.7, 171.0, 171.8, 174.0 ppm. HR-MS
(ESI-TOF): m/z calcd for C36H43N2O8 ([M + H]+) 631.3014,
found 631.3018.
SN-38-Cholesterol (11). To a suspension of SN-38 (100
mg, 0.255 mmol) in CH2Cl2 (13 mL, 0.02 M) was added cho-
lesterol hydrogen succinate (126 mg, 0.259 mmol), EDC¢HCl
(104 mg, 0.544 mmol), and DMAP (3.1 mg, 0.0255 mmol).
After stirring for 18 h at room temperature, the reaction mixture
was diluted with CH2Cl2 and washed with saturated aqueous
solution of NH4Cl, water, and brine. The organic layer was then
dried (MgSO4), filtered, and concentrated under reduced pres-
sure. The residue was purified by silica gel column chroma-
tography (CHCl3/MeOH = 100:1) to give SN-38-cholesterol
(11) (171 mg, 78%) as a pale yellow solid. 1H NMR (400 MHz,
CDCl3) ¤ = 0.67 (3H, s), 0.85-2.02 (48H, m), 2.35 (2H, d,
J = 8.0 Hz), 2.77-2.80 (2H, m), 2.95-2.99 (2H, m), 3.14 (1H,
q, J = 3.6 Hz), 3.87 (1H, brs), 4.61-4.72 (1H, m), 5.25 (1H, s),
5.30 (1H, d, J = 16.4 Hz), 5.37 (1H, d, J = 4.0 Hz), 5.74 (1H,
d, J = 16.4 Hz), 7.56 (1H, dd, J = 9.2, 2.4 Hz), 7.66 (1H, s),
7.82 (1H, brs), 8.23 (1H, d, J = 9.2 Hz) ppm. 13C NMR (100
MHz, CDCl3) δ = 8.0, 12.0, 14.1, 18.9, 19.5, 21.2, 22.7, 23.0,
23.3, 24.0, 24.4, 27.9, 28.2, 28.4, 29.5, 29.6, 31.8, 31.98,
32.04, 35.9, 36.3, 36.7, 37.1, 38.2, 39.7, 39.9, 42.5, 49.5, 50.2,
56.3, 56.8, 66.5, 72.9, 74.9, 98.3, 114.7, 118.8, 123.0, 125.6,
127.4, 127.6, 132.1, 139.6, 146.9, 147.4, 149.8, 150.3, 151.9,
157.8, 171.1, 171.6, 174.0 ppm. HR-MS (ESI-TOF): m/z calcd
for C53H69N2O8 ([M + H]+) 861.5048, found 861.5048.
Calculation of clogP Value. clogP value was calculated
by ChemDraw Professional 16.0 using the function “Chemical
Properties”.
1
solid. H NMR (400 MHz, DMSO-d6) ¤ = 0.63 (3H, s), 0.82-
2.27 (36H, m), 2.55-2.62 (1H, m), 2.69-2.75 (1H, m), 3.16-
3.19 (1H, m), 3.62 (1H, brs), 3.82 (1H, brs), 4.04 (1H, d,
J = 3.6 Hz), 4.19 (1H, d, J = 3.6 Hz), 4.34 (1H, d, J = 4.4 Hz),
5.33 (1H, s), 5.44 (1H, s), 6.54 (1H, s), 7.32 (1H, s), 7.65 (1H,
dd, J = 9.2, 2.4 Hz), 7.99 (1H, d, J = 2.4 Hz), 8.20 (1H, d,
J = 9.2 Hz) ppm. 13C NMR (100 MHz, DMSO-d6) δ = 7.8,
12.4, 13.9, 17.1, 22.3, 22.7, 22.8, 26.3, 27.4, 28.6, 30.3,
30.5, 30.7, 34.4, 34.9, 35.1, 41.5, 45.8, 46.0, 49.6, 65.3, 66.3,
70.5, 71.0, 72.4, 79.2, 96.7, 115.3, 119.0, 125.7, 127.1, 128.6,
131.3, 145.3, 145.9, 146.5, 149.3, 150.1, 152.0, 156.8, 172.4,
172.5 ppm. HR-MS (ESI-TOF): m/z calcd for C46H59N2O9
([M + H]+) 783.4215, found 783.4210.
SN-38-Benzoate (9). To a suspension of SN-38 (100 mg,
0.255 mmol) in CH2Cl2 (13 mL, 0.02 M) was added benzoic
acid (31.1 mg, 0.255 mmol), EDC¢HCl (122 mg, 0.638 mmol),
and DMAP (3.1 mg, 0.0255 mmol). After stirring overnight at
room temperature, the reaction mixture was diluted with
CH2Cl2 and washed with saturated aqueous solution of NH4Cl,
water, and brine. The organic layer was then dried (MgSO4),
filtered, and concentrated under reduced pressure. The residue
was purified by silica gel column chromatography (CHCl3/
MeOH = 100:1) to give SN-38-benzoate (9) (46 mg, 36%) as a
pale yellow solid. 1H NMR (400 MHz, CDCl3) ¤ = 1.05 (3H, t,
J = 7.6 Hz), 1.42 (3H, t, J = 7.6 Hz), 1.85-1.97 (2H, m), 3.19
(2H, dd, J = 15.2, 7.6 Hz), 3.71 (1H, s), 5.29 (2H, s), 5.32 (1H,
d, J = 16.0 Hz), 5.77 (1H, d, J = 16.4 Hz), 7.55-7.66 (2H, m),
7.67-7.72 (2H, m), 7.98 (1H, d, J = 2.4 Hz), 8.27-8.32 (3H, m)
ppm. 13C NMR (100 MHz, CDCl3) δ = 8.0, 14.1, 23.3, 31.8,
49.6, 66.4, 72.9, 98.2, 114.9, 118.7, 125.7, 127.4, 127.6, 128.9
(2C), 129.1, 130.4 (2C), 132.3, 134.2, 145.5, 146.9, 147.5,
150.0, 150.4, 152.0, 157.8, 165.2, 174.0 ppm. HR-MS (ESI-
TOF): m/z calcd for C29H25N2O6 ([M + H]+) 497.1707, found
497.1709.
Fabrication and Characterization of Nano-Prodrugs.
The nano-prodrugs (NPs) were fabricated by the reprecipitation
method. Water was purified to 18.2 M³ cm using an Arium
611UV (Sartorius Mechtronics Japan K.K.). 100 ¯L of the THF
solution (10 mM) of SN-38 prodrug was rapidly injected into
vigorously stirred pure water (10 mL) using a microsyringe.
The size and shape of the fabricated NPs was observed by
SEM. In addition, average particle size, size distributions were
measured using dynamic light scattering (DLS) method. 0.75
mL of SN-38 NPs (0.1 mM) was added to the capillary cell. For
the measurement He-Ne laser (3.0 mW, 633 nm) was used and
the temperature was set at 25 °C.
SN-38-Menthol (10). To a suspension of SN-38 (74.8
mg, 0.191 mmol) in CH2Cl2 (10 mL, 0.02 M) was added (¹)-
menthyl succinate (52.2 mg, 0.204 mmol), EDC¢HCl (82 mg,
0.425 mmol), and DMAP (9.1 mg, 0.0745 mmol). After stirring
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