Y.-Q. Wu et al. / Dyes and Pigments 88 (2011) 326e332
327
2.22 (s, 1H, -OH). HR-MS: Calcd. for C13H21O6S: 305.1059, [M þ H]þ.
Found: 305.1055.
2.2.2. 2-[2-(2-hydroxyethoxy)ethoxy]ethoxyl niclosamide (2a)
2a was synthesized according to the literature procedure
[17,18]. Niclosamide (2.0 g, 6 mmol) was dissolved in 1, 4-dioxane
(10 mL) at 85 ꢂC in a 50 mL three-neck flask. K2CO3 (0.85 g,
6 mmol) and Bu4NBr (0.20 g, 6 mmol) were added with stirring. 4
(1.55 g, 5 mmo1) dissolved in l, 4-dioxane (8 mL) was added
dropwise and the ensuing mixture was heated under reflux for
6 h, and allowed to cool. Water (20 mL) was then added and the
mixture was shaken in a separating funnel. The organic phase
was separated, and the water phase extracted with CH2Cl2
(20 mL ꢀ 3). The combined organic layer was dried over anhy-
drous Na2SO4. After removing the solvent under reduced pressure,
the crude product was purified by column chromatography, and
a slightly yellow solid 2a was obtained. Yield 78%. mp 84e86 ꢂC.
IR (KBr) cmꢁ1: 3458, 3385, 3272, 3104, 2952, 2905, 2854, 1674,
1589, 1561, 1503, 1471, 1207, 1113, 818, 744, 648. 1H NMR
Scheme 1. Structures of niclosamide 1, novel niclosamide derivatives 2 (2a and 2b)
and fluorescent compound 3, n ¼ 4.14 is the average degree of polymerization of PEG.
N-hexanoic acid-4-morpholin-1, 8-naphthalimide (compound 6,
Supplement Materials, Scheme S1) to niclosamide derivative 2a.
The interaction of 3 with S. japonicum cercariae was further
investigated by confocal fluorescence microscopy.
(400 MHz, CDCl3):
d 10.58 (s, 1H, eNHeCOe), 8.83 (d, 1H,
J ¼ 7.2 Hz, niclosamide-H), 8.31e8.32 (d, 1H, J ¼ 2.4 Hz, niclosa-
mide-H), 8.21e8.22 (d, 1H, J ¼ 2.4 Hz, niclosamide-H), 8.17e8.20
(dd, 2H, J ¼ 2.4 Hz, niclosamide-H), 7.45e7.48 (dd, 1H, J ¼ 2.4 Hz,
niclosamide-H), 7.07e7.09 (d, 1H, J ¼ 8.8 Hz, niclosamide-H),
2. Experimental section
4.45e4.47 (t, 2H,
J
¼
4.8 Hz, eCH2Oe), 3.92e3.95 (t, 2H,
J ¼ 4.8 Hz, eCH2Oe), 3.63e3.65 (t, 4H, J ¼ 4.8 Hz, eOCH2CH2Oe),
2.1. Materials and instrumentations
3.56e3.58 (t, 2H, 4.8 Hz, eOCH2e), 3.49e3.51 (t, 2H,
J
¼
J ¼ 4.8 Hz, eOCH2e), 2.11 (s, 1H, eOH). HR-MS: Calcd. for
All starting materials (reagents and solvents) were obtained
from commercial supplies and used as received. Niclosamide was
purchased from Huainan 3rd Pharmaceutical Factory (China). The
KB cell lines were provided by Institute of Biochemistry and Cell
Biology (China). Infected Oncomelania hupensis snails were
supplied by Hunan Institute of Parasitic Diseases (WHO collabo-
rating center for Schistosomiasis control in lakes).
C19H21Cl2N2O7: 459.0726, [M þ H]þ. Found: 459.0712.
2.2.3. Polyethylene glycol 200-ethoxyl niclosamide (2b)
The snthesis and separation methods for 2b were similar to
those adopted for 2a, and a slight yellow liquid was obtained. Yield
60%; 1H NMR (400 MHz, CDCl3):
d 10.58 (s, 1H, eNHeCOe),
1H NMR and 13C NMR spectra were recorded on a Mercuryplus
spectrometer at 400 MHz and 100 MHz, respectively. Electrospray
ionization mass spectra (ESI-MS) were measured on a Bruker APEX
II FT-ICRMS 4.7T system. UVevisible spectra were recorded on
a Shimadzu UV-2550 spectrometer. Fluorescence spectra were
measured on an Edinburgh LFS920 fluorescence spectrophotom-
eter. Fourier transform infrared (FT-IR) spectra were measured
using a Nicolet Nexus 470 spectrometer with KBr pellet or film.
Melting points were determined on a hot-plate melting point
apparatus XT4-100A without correction. Fluorescence imaging
experiments were performed on an OLYMPUS FV1000 IX81
8.84e8.86 (d, 1H, J ¼ 7.2 Hz, niclosamide-H), 8.32e8.34 (d, 1H,
J ¼ 2.4 Hz, niclosamide-H), 8.21e8.23 (d, 1H, J ¼ 2.4 Hz, niclosa-
mide-H), 8.19 (d, 2H, J ¼ 2.4 Hz, niclosamide-H), 7.46e7.49 (dd, 1H,
J ¼ 2.4 Hz, niclosamide-H), 7.10e7.12 (d, 1H, J ¼ 8.8 Hz, niclosamide-
H), 4.46e4.48 (t, 2H, J ¼ 4.8 Hz, eOCH2e), 3.92e3.93 (t, 2H,
J ¼ 4.8 Hz, eCH2Oe), 3.49e3.65 (m, eOCH2CH2Oe). HR-MS: Calcd.
for C23H29Cl2N2O9: 547.1250, [M þ H]þ, n ¼ 5, 2b was further
purified by column chromatography. Found: 547.1243.
2.2.4. [Toluene-4-sulfonic acid-2-(2-ethoxy)ethoxy
ethyl ester] niclosamide (5)
An anhydrous CH2Cl2 solution (10 mL) of compound 4 (0.46 g,
1 mmol) and Et3N (2 mL), was stirred at 0e5 ꢂC to which was added
tosyl chloride (0.38 g, 2 mmol) dropwise. The ensuing mixture was
stirred for 10 h at room temperature, the solvent was removed
under reduced pressure and the residue was subjected to column
chromatography on silica gel. The product was separated with pure
CH2Cl2, yielding a slightly yellow solid. mp 99 ꢂC. Yield 51%. IR (KBr)
cmꢁ1: 3288, 3079, 2908, 2874, 1676, 1546, 1509, 1475, 1342, 1174,
confocal fluorescence microscope equipped with
a
40ꢀ oil-
immersion objective lens, excitation at 405 nm was carried out
with a semiconductor laser and emission was collected at 480 to
580 nm. Observations of anti-Schistosoma cercariae experiments
were performed on a XSZ-CTV biological microscope with Color TV
Screen. BAM imaging experiments were performed with a JB04-
Brewster angle microscope, equipped with a 30 mW laser emitting
light at a wavelength of 532 nm, was used to visualise the structure
of drug layers.
1119, 1096, 819, 744, 659. 1H NMR (400 MHz, CDCl3):
eNHeCOe), 8.83e8.85 (d, 1H, 9.2 Hz, niclosamide-H),
d 10.61 (s, 1H,
J
¼
8.32e3.33 (d, 1H, J ¼ 2.4 Hz, niclosamide-H), 8.23e8.24 (d, 1H,
J ¼ 2.8 Hz, niclosamide-H), 8.20e8.21 (m, 1H, J ¼ 2.8 Hz, niclosa-
mide-H), 7.76e7.77 (d, 2H, J ¼ 8.4 Hz, tosyl-H), 7.47e7.50 (m, 1H,
J ¼ 2.8 Hz, niclosamide-H), 7.33 (d, 2H, J ¼ 8.4 Hz, tosyl-H), 7.10 (d,
1H, J ¼ 8.8 Hz, niclosamide-H), 4.45e4.47 (t, 2H, J ¼ 4.8 Hz,
eCH2Oe), 4.07e4.09 (t, 2H, J ¼ 4.8 Hz, eCH2Oe), 3.93e3.95 (t, 2H,
J ¼ 4.8 Hz, eCH2Oe), 3.59e3.61 (t, 4H, J ¼ 4.8 Hz, eOCH2e),
3.52e3.54(t, 2H, J ¼ 4.8 Hz, eOCH2e), 2.44 (s, 3H, tosyl-CH3). HR-
MS: Calcd. for C26H27Cl2N2O9S: 613.0814, [M þ H]þ. Found:
613.0804.
2.2. Synthesis
2.2.1. Toluene-4-sulfonic acid-2-[2-(2-hydroxy ethoxy)
ethoxy]ethyl ester (4)
4 was synthesized as described previously [16]. IR (KBr) cmꢁ1
:
3404, 3062, 2920, 2870, 1598, 1454, 1355, 1177, 1122, 1100, 817, 664.
1H NMR (400 MHz, CDCl3):
d
7.80 (d, 2H, J ¼ 8.4 Hz, AreH), 7.34 (d,
2H, J ¼ 8.0 Hz, AreH), 4.17 (t, 2H, J ¼ 4.8 Hz, eOCH2), 3.69e3.73 (m,
4H, eOCH2CH2Oe), 3.57e3.61 (m, 6H, eCH2Oe), 2.45 (s, 3H, eCH3),