A new salt of dyclonine (DYC): Synthesis, crystal structure, luminescent properties, thermal and biological activities

Article abstract of DOI:10.1007/s11164-013-1507-3

A new organic salt of dyclonine (DYC) with p-toluenesulfonic acid (p-TSA) has been synthesized and characterized by elemental analysis, single-crystal X-ray diffraction, IR spectra, UV spectra, and hot stage microscopy. The structure determination shows t

Full text of DOI:10.1007/s11164-013-1507-3

Res Chem Intermed
DOI 10.1007/s11164-013-1507-3
A new salt of dyclonine (DYC): synthesis, crystal
structure, luminescent properties, thermal
and biological activities
Chen-Guang Zhang
Bai-Wang Sun
•
Yuan Li
•
Tian-Wen Wen
•
Received: 1 September 2013 / Accepted: 4 December 2013
Ó Springer Science+Business Media Dordrecht 2013
Abstract A new organic salt of dyclonine (DYC) with p-toluenesulfonic acid
p-TSA) has been synthesized and characterized by elemental analysis, single-crystal
(
X-ray diffraction, IR spectra, UV spectra, and hot stage microscopy. The structure
determination shows that the asymmetric unit of the salt consisting of two entire ions
?
of DYC and p-TSA , and that they are not symmetric. The salt is primarily stabilized
-
?
-
by a strong N–HꢀꢀꢀO hydrogen bonding interaction between DYC and p-TSA . In
addition, the luminescent properties and biological activities are discussed.
Keywords Synthesis ꢀ Crystal structure ꢀ Dyclonine ꢀ p-Toluenesulfonic
acid ꢀ Biological activities
Introduction
Local anaesthetic (LA) drugs of general formula lip–CO–hydr (lip = lipophilic end,
mostly phenyl ring; CO = negatively charged linkage, commonly ester or amide;
hydr = hydrophilic group, tertiary or secondary amine) are well known for the
formation of polymorphs and solvates [1, 2]. LA compounds are commonly
separated into two main groups, the ester type LA with a short duration of
anaesthesia and the amide type LA with a longer duration of action [3], whereas
Electronic supplementary material The online version of this article (doi:10.1007/s11164-013-1507-3)
contains supplementary material, which is available to authorized users.
C.-G. Zhang ꢀ Y. Li ꢀ B.-W. Sun (&)
College of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096,
People’s Republic of China
e-mail: chmsunbw@seu.edu.cn
T.-W. Wen
Nanjing Tefeng Pharmaceutical Co., Ltd, Nanjing, People’s Republic of China
123

C.-G. Zhang et al.
DYC belongs to a different group of local anesthetics classified as ketones [4]. DYC
is exclusively used for topical anesthesia, delivering the effects of analgesia and
anti-infection at the same time, it is effective during bronchoscopy or awake
endotracheal intubation [5]. It is used for oral pain and used to anesthetize mouths
for patients who have sensitivity. It is also useful as a mouthwash or gargle in
suppressing the gag reflex. In addition, DYC also has bactericidal and fungicidal
properties, used topically as the hydrochloride salt. Dyclonine hydrochloride (DYC
0
HCL), chemically denoted as 3-piperidino 4 -butoxypropiophenone hydrochloride,
is a well-known anesthetic/analgesic agent for topical use on the mucous
membranes of the mouth and throat [6]. It is a topical anesthetic which is said to
have a wide margin of safety, good anesthetic properties, and a low sensitizing
potential [4]. The crystal structure of DYC HCL has been reported [7]. In addition to
its anesthetic/analgesic properties, DYC HCL is known to possess antimicrobial
activity [8].
There appears to have been very little attention given in the past to the study of
the antimicrobial properties of agents intended for topical anesthesia. That such
concomitant action would be of definite advantage is apparent, not only from the
standpoint of prevention and control of infection but also for formulation purposes.
In this work, we applied the crystal engineering strategy on the DYC with p-TSA
and obtained a salt. This salt was characterized by single-crystal X-ray diffraction,
IR spectroscopy, elemental analysis, UV, and hot stage microscopy (HSM). Its
luminescence properties and biological activities are discussed.
Experimental
Materials and measurements
All chemicals were of analytical grade and solvents were purified by
conventional methods. Melting points were determined using an X4 digital
microscopic melting point apparatus and are uncorrected. Elemental analyses for
C, H, N and S were performed on a Perkin-Elmer 240 analyzer. UV–Vis spectra
were recorded on a UV-6000PC spectrometer at room temperature in H O
2
solution. Infrared spectra were recorded on a SHIMADZU IR prestige-21 FTIR-
-
1
400S spectrometer in the spectral range 4,000–400 cm , with the samples in
8
the form of potassium bromide pellets. Fluorescence spectroscopy data for salt 1
were recorded on a F-2700 FL spectrophotometer. Hot stage microscopy for salt
1 was performed on a LEICA DM750P microscope using a Mettler-Toledo
FP82HT hot stage (Scheme 1).
Synthesis of DYC
The compound DYC was synthesized by the following reaction: DYC HCL was
added to a solution of NaOH in H O at r.t.. The mixture was stirred for 10 min, the
water phase was extracted three times with EtOAc. The organic phase was dried
2
1
23

A new salt of dyclonine (DYC)
O
O
NaOH
,
HCl
N
N
O
O
O
O
S
HO
p-toluenesulfonic acid
N
,
O
O
Scheme 1 The synthetic scheme of salt 1
over MgSO , and concentrated. A light yellow liquid was obtained after the solvent
4
were removed under reduced pressure (yield 87 %).
Synthesis of salt 1
The preparation of salt 1 was conducted in solution crystallization experiments. Salt
1
was obtained by the following procedure: a 1:1 stoichiometric amount of DYC
and p-TSA were added to a 20 ml stirring EtOAc solution at a temperature of 40 °C,
the resulted solution stired for 10 min before being left to evaporate at room
temperature. Colorless club-shaped crystals of 1 were obtained within 3 days (yield
8
6 %). m.p. 134–137 °C. Elemental analysis for C H NO S, Anal. Calcd. (%): C,
2
5
35
5
6
5.05; N, 3.03; H, 7.64; S, 6.95. Found: C, 65.18; N, 3.24; H, 7.30; S, 6.87. UV
-
nm): 221, 282. IR (KBr pellet, cm ): 2,955, 2,871, 2,678, 2,546, 1,670, 1,601,
1
(
1
9
,574, 1,457, 1,425, 1,316, 1,261, 1,227, 1,177, 1,148, 1,116, 1,039, 1,028, 1,007,
65, 800, 679. (The IR spectra of salt 1 and DYC HCL are shown in Fig. S1.)
X-ray crystallographic study
The single-crystal X-ray diffraction data of salt 1 was collected at 296 K with
graphite-monochromated MoKa radiation (k = 0.071073 nm), a Rigaku SCXmini
diffractometer with the x-scan technique were used [9]. The lattice parameters were
integrated using vector analysis and refined from the diffraction matrix, and the
absorption correction was carried out by using the Bruker SADABS program with
the multi-scan method. A summary of crystallographic data, data collection, and
refinement parameters for salt 1 are given in Table 1. Their structures were solved
2
by full-matrix least-squares methods on all F data, using the SHELXS-97 and
SHELXL-97 programs [10] for structure solution and structure refinement,
respectively. Reliability factors were defined as R1 = R(|F | - |F |)/R|F | and the
o
4 ‘
c
o
2
o
2 2
function as minimized was R = [R (F - F ) /w(F ) ] , where, in the least-
w
w
c
o
squares calculation, the unit weight was used. All non-hydrogen atoms were refined
anisotropically, and hydrogen atoms were inserted at their calculated positions and
fixed at these positions [11]. The molecular graphics were prepared by using the
DIAMOND program [12] and mercury [13]. CCDC references number 943026
contains the supplementary crystallographic data in CIF format for salt 1 reported in
123

C.-G. Zhang et al.
Table 1 Crystal data and
structure refinement for salt 1
Compound
Salt 1
5
35NO S
Formula
C
25
H
Formula weight
Crystal system
Space group
461.61
Triclinic
P-1
˚
a(A)
7.5053(10)
˚
b(A)
14.1987(19)
23.819(3)
88.029(2)
83.134(2)
78.761(2)
2,471.6(6)
4
˚
c(A)
a(°)
b(°)
c(°)
3
)
˚
V(A
Z
-
3
)
c
D (Mg m
1.240
T(K)
296(2)
-1
l(mm
)
0.166
Cryst dimensions
No. of reflns collected
No. of unique reflns
No. of params
0.40 9 0.20 9 0.20
17,350
8,490
581
2
Goodness-of-fit on F
1.000
R
1
, wR
, wR
2
2
((I [ 2r(I))
0.0983, 0.2153
0.0687, 0.1973
943,026
R
1
(all data)
CCDC No.
this paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Results and discussion
Structure description
Salt 1crystallizesas colorless club-shaped crystals. The structure determination shows
?
that 1 forms a 1:1 (DYC :p-TSA ) salt in the Triclinic P-1 space group with Z = 4
-
?
Fig. 1a). The asymmetric unit (ASU) consisting of two entire ions of DYC and p-
(
TSA , for they are not symmetric. They can be described as two hydrogen-bonded
-
?
˚
dimer units consisting of a DYC ion connected by N–HꢀꢀꢀO [N1–H1ꢀꢀꢀO5 = 1.84 A;
-
˚
N2–H2AꢀꢀꢀO8 = 1.82 A] hydrogen bonds to a p-TSA ion (Fig. 1a). Every two
dimers are buckled together to form a double-hook structure when viewed along the
a axis (Fig. 1b). The double-hook structures are further stacked by many hydrogen
bonds (Table 2) and C–Hꢀꢀꢀp (Fig. 1d) intermolecular interactions in the adjacent
double-hook units, into an interlaced three-dimensional structure (Fig. 1c).
1
23

A new salt of dyclonine (DYC)
UV–Vis spectrum
In the UV–Vis spectrum of salt 1 (or DYC HCL) in H O solution, two intense bands
2
at 221.0 (or 220.5) and 282.0 (or 282.5) nm are attributed to the DYC p-p* and n-
p* transitions, for the acids in the two salts are not the same (Fig. S1).
Luminescence properties
Although there is a similarity between the UV–Vis spectrum of salt 1 and DYC
HCL, their solid-state emission spectra have a great difference. The emission
spectrum for salt 1 showed a broad emission maximum at 432 nm but there is no
obvious peaks in excitation spectrum in the range of 250–400 nm, while for DYC
HCL, no obvious peaks were observed in its solid-state emission and excitation
spectra. The emission peak (432 nm) of salt 1 is probably due to p-p* transitions of
p-TSA because no similar peak appears for DYC HCL (Fig. S2).
Evaluation of antifungal activities
The synthesized salt 1 were tested for antifungal activity against Candida albicanes
(
[
ATCC 10231) and Aspergillus niger (ATCC 16404) by the disc diffusion method
14] at different concentrations using DMSO (dimethylsulphooxide) as solvent
control, while nutrient agar was employed as culture medium. After 72 h of
incubation at 28 °C, the zone of inhibition was measured in mm. A standard
antibiotic Nystatin was used as control to compare antifungal activities of salt 1 and
the results are represented in Table 3.
Fig. 1 a Molecular structure of
salt 1. b The crystal packing of
salt 1 viewed along the a axis
showing hydrogen bonding.
c 3D Pack structure of salt 1
along the b axis showing
hydrogen bonding. d View of
six edge-to-face C–Hꢀꢀꢀp
stacking interactions in salt 1.
Some hydrogens have been
omitted for clarity. (Color figure
online)
123

C.-G. Zhang et al.
Fig. 1 continued
The antifungal activities of different concentrations of salt 1 were tested. From
the data obtained in Table 2, it is clear that antifungal activities of salt 1 were
increased gradually with the enhanced concentrations, but it was found to be
-
1
inactive against Aspergillus niger up to 200 lg disk . We conclude that salt 1
showed highly biological activity against Candida albicans and moderately activity
1
23

A new salt of dyclonine (DYC)
Table 2 The hydrogen bonding geometry and p-stacking interaction for salt 1
D–HꢀꢀꢀA
D–H
HꢀꢀꢀA
DꢀꢀꢀA
\DHA
a
N1–H1ꢀꢀꢀO5
0.91
0.91
0.97
0.97
0.97
0.93
0.96
0.97
0.97
0.97
0.93
0.93
0.93
0.93
0.93
0.93
1.84
1.82
2.58
2.39
2.59
2.54
2.55
2.48
2.46
2.51
3.06
2.91
3.18
3.04
3.09
2.99
2.750(3)
2.735(3)
3.402(4)
3.332(4)
3.535(4)
3.380(4)
3.428(5)
3.446(4)
3.362(4)
3.466(4)
3.532(3)
3.558(6)
3.829(8)
3.724(4)
3.579(6)
3.578(6)
177
178
143
164
165
150
151
176
154
168
113
128
129
132
115
122
b
N2–H2AꢀꢀꢀO8
C12–H12BꢀꢀꢀO3
C17–H17AꢀꢀꢀO6
C17–H17BꢀꢀꢀO3
c
C22–H22ꢀꢀꢀO10
C25–H25AꢀꢀꢀO3
C43–H43BꢀꢀꢀO10
C45–H45AꢀꢀꢀO10
C45–H45BꢀꢀꢀO2
C5–H5ꢀꢀꢀp
C20–H20ꢀꢀꢀp
C23–H23ꢀꢀꢀp
C27–H27ꢀꢀꢀp
C30–H30ꢀꢀꢀp
C37–H37ꢀꢀꢀp
d
For the intermolecular C–Hꢀꢀꢀp interactions, the meaning of ‘‘A’’ indicate the centroid of the phenyl ring
a
-
1 ? x, y, z
b
c
d
1
? x, y, z
x, 1 ? y, z
x,-1 ? y, z
Table 3 Antifungal activities
of salt 1 in terms of diameter of
inhibition zone in mm
Compounds
Concentrations
lg/disk)
Inhibition zones (mm)
(
Candida
albicans
Aspergillus
niger
Salt 1
12.5
7.5
8.1
–
2
5
1
2
4
8
1
5
–
0
10.8
13.7
14.4
15.3
18.1
18.5
8.4
–
00
00
00
00
,000
–
10
15.1
18.3
11
Nystatin
1.25
–
2
5
1
2
4
.5
9.1
–
14.4
20.5
20.9
21.6
12.8
21.8
23.9
25.6
0
0
0
123

C.-G. Zhang et al.
Fig. 2 Hot stage microscopy for salt 1
against Aspergillus niger but lower than the reference Nystatin; these activities may
attributed to piperidine rings in DYC.
Hot stage microscopy (HSM)
The hot stage microscopy for salt 1 is shown in Fig. 2. During the heating
procedure, the big club-shaped crystals of salt 1 begin to be crushed into small
crystals and then melt in a temperature range of 134–137 °C.
Conclusions
We have investigated the detailed crystal formation of DYC with p-TSA through a
solution reaction. A thorough structural investigation of the resulting salt reveals
?
-
that the N–HꢀꢀꢀO hydrogen bonding interactions between DYC and p-TSA play a
key role in forming the elementary structure of the salt. The emission spectrum for
salt 1 showed a broad emission maximum at 432 nm but there is no obvious peak in
the excitation spectrum. From the data obtained in evaluation of antifungal
activities, it is clear that salt 1 showed high biological activity against Candida
1
23

A new salt of dyclonine (DYC)
albicans and moderate activity against Aspergillus niger, and that these activities
may be attributed to piperidine rings in DYC.
Supplementary material
Crystallographic data for the structures reported in this article have been deposited
with the Cambridge Crystallographic Data Center as supplementary publication No.
CCDC 943026. Copies of the data can be obtained free of charge via www.ccdc.
cam.ac.uk (or from the Cambridge Crystallographic Centre, 12 Union Road,
Cambridge CB21EZ, UK; Fax: t44 1223 336033; Email: deposit@ccdc.cam.ac.uk).
Acknowledgments This work has been supported by the prospective joint research project of Jiangsu
province (BY2012193), Fundamental Research Funds for the Central Universities (CXZZ12_0119),
Natural Science Foundation of China (21371031) and Funds for the Ministry of Science and Technology
(212401025).
References
1
2
3
4
5
6
7
8
9
. D. Giron, M. Draghi, C. Goldbronn, S. Pfeffer, P. Piechon, J. Therm. Anal. 49, 913 (1997)
. L. Borka, J. Haleblian, Acta Pharm. Jugosl. 40, 71 (1990)
. A.C. Schmidt, Eur. J. Pharm. Sci. 25, 407 (2005)
. L.C. Harris, J.C. Parry, F.E. Greifenstein, Anesthesiology 17, 648 (1956)
. A.F. Kopman, S.B. Wollman, K. Ross, S.N. Surks, Anesth. Analg. 54, 232 (1975)
. Federal Register, Proposed Rules 47(101), 22810 (1982)
. B.K. Sinha, V. Pattabhi, M. Nethaji, Acta Cryst. C 43, 360 (1987)
. H.J. Florestano, M.E. Bahler, J. Am. Pharm. Assoc. 45, 321 (1956)
. Rigaku CrystalClear, Version 14.0, Rigaku Corporation (Tokyo, Japan, 2005)
1
0. G.M. Sheldrick, SHELXS97, Programs for Crystal Structure Analysis (University of G o¨ ttingen,
Germany, 1997)
1
1. Y.H. Luo, X.M. Qian, G. Gao, J.F. Li, S.L. Mao, Acta Cryst. E 67, m172 (2011)
2. K. Brandenburg, DIAMOND, Crystal and Molecular Structure Visualization, version 3.1b (Crystal
Impact GbR, Bonn, 2006)
1
1
1
3. Mercury 2.3 Supplied with Cambridge Structural Database, CCDC (Cambridge, U.K., 2003–2004)
4. A.Z.A. Abou-Zeid, Y. Shehata, Indian J. Pharm. 31, 72 (1969)
123