Synthesis, insecticidal activity and molecular docking study of clothianidin analogues with hydrazide group

Article abstract of DOI:10.1016/j.cclet.2014.03.026

A series of novel neonicotinoid analogues were designed and synthesized by introducing a hydrazide group into clothianidin. Their structures were confirmed by IR, ¹H NMR, and HRMS (ESI). Preliminary bioassay showed that some compounds, 5b and 5g, exhibited good activity against soybean aphids (Aphis glycines) at 100 mg L^-1. In addition, molecular docking with receptor was carried out to explain their different activity from clothianidin.

Full text of DOI:10.1016/j.cclet.2014.03.026

G Model
CCLET-2912; No. of Pages 4
Chinese Chemical Letters xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Original article
Synthesis, insecticidal activity and molecular docking study of
clothianidin analogues with hydrazide group
Shao-Hua Liu a, Wei Peng a, Yan-Yan Qu b, Dan Xu a, Hong-Yue Li a, Dun-Lun Song b,
Hong-Xia Duan a, Xin-Ling Yang a,
*
a Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
b Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University, Beijing 100193, China
A R T I C L E I N F O
A B S T R A C T
Article history:
A series of novel neonicotinoid analogues were designed and synthesized by introducing a hydrazide
group into clothianidin. Their structures were confirmed by IR, 1H NMR, and HRMS (ESI). Preliminary
bioassay showed that some compounds, 5b and 5g, exhibited good activity against soybean aphids (Aphis
glycines) at 100 mg Lꢀ1. In addition, molecular docking with receptor was carried out to explain their
different activity from clothianidin.
Received 18 December 2013
Received in revised form 6 March 2014
Accepted 7 March 2014
Available online xxx
ß 2014 Xin-Ling Yang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights
reserved.
Keywords:
Clothianidin analogues
Hydrazide group
Insecticidal activity
Molecular docking
1. Introduction
and a series of novel neonicotinoid derivatives similar to
diacylhydrazine were designed by introducing a hydrazide group
into clothianidin. Their insecticidal activity against soybean aphids
(Aphis glycines) was evaluated at different concentrations. Fur-
thermore, the interactions between these new compounds and
nAChR were also investigated by molecular docking.
Neonicotinoid insecticides (NNs), exemplified by imidacloprid,
have agonistic effects on the insect nicotinic acetylcholine receptor
(nAChR) [1,2], which makes this kind of insecticide particularly
effective in controlling sap-feeding pests and relatively safe toward
mammals [3–6]. These NNs are widespread and account for one-
fifth of the global insecticide market [7–9]. However, during the
past decade, increases in resistance and cross resistance were
observed in a range of species after their frequent applications in
the field [10–13]. Further, it was reported that NNs have toxicity
towards honey bees, which also limited their applications [14].
Hence, it is necessary to design and screen novel insecticidal lead
compounds with low resistance and high safety.
2. Experimental
Melting points of all compounds were determined on an X-5
binocular microscope (Fukai Instrument Co., Beijing, China), and
were not corrected. 1H NMR spectra were recorded on Bruker AM-
300 (300 MHz) spectrometer with DMSO-d6 as the solvent and
TMS as the internal standard. Chemical shifts are reported in
d
Most structure optimizations of NNs are based on cyclic
neonicotinoid insecticides [15–18], but few studies have been
focused on the structural modification of acyclic NNs, such as
clothianidin. In addition, diacylhydrazine compounds have been
widely used as one of the most important insect growth regulators
[19,20], and the hydrazide group has also been proved to be a
useful section in the scaffold of active insecticides [21,22].
Encouraged by this, we hereby introduced a new structure
developing strategy, using clothianidin as the lead compound,
(parts per million) values. High resolution mass spectrometry
(HRMS) data were obtained on an FTICR-MS Varian 7.0T FTICR-MS
instrument. All the reagents were obtained commercially and used
after further purification. Column chromatography purification
was carried out by using silica gel.
2.1. General procedure for synthesis of compounds 5a–5l
A solution of 3 (10.0 mmol) and hydrazine hydrate (12.0 mmol)
in methanol (20 mL) was refluxed for 0.5 h. Then the mixture was
concentrated and the residue was purified by recrystallization
with ethanol to afford the pure compound 4. Then a solution
of 4 (5.0 mmol), DMAP (0.25 mmol) and TEA (7.5 mmol) in
*
Corresponding author.
E-mail address: yangxl@cau.edu.cn (X.-L. Yang).
http://dx.doi.org/10.1016/j.cclet.2014.03.026
1001-8417/ß 2014 Xin-Ling Yang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Please cite this article in press as: S.-H. Liu, et al., Synthesis, insecticidal activity and molecular docking study of clothianidin analogues
with hydrazide group, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.03.026

G Model
CCLET-2912; No. of Pages 4
2
S.-H. Liu et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
Table 1
dichloromethane (15 mL) was cooled to ꢀ5 to 0 8C, and acyl
chloride (7.5 mmol) was added dropwise. After that, the mixture
was stirred at room temperature for 6 h. After being quenched by
water (5 mL), the mixture was filtered, and the precipitate was
washed with dichloromethane then purified by recrystallization
with ethanol to afford the pure products 5a–5l.
Insecticidal activity of target compounds 5a–5l against soybean aphid (Aphis
glycines).
Compd.
R1
R2
Mortality (%) at different
concentrations (mg Lꢀ1
)
500
41.2
100
20
5a
F-Ph
Me
nta
82.2
nt
nt
2.2. Insecticidal test for soybean aphids (A. glycines)
5b
Cl-Pyr
Cl-Pyr
Cl-Pyr
Cl-Pyr
Cl-Pyr
Cl-Thy
Cl-Thy
Cl-Thy
Cl-Thy
Cl-Thy
Cl-Thy
–
Me
91.5
77.6
66.3
62.7
48.5
94.5
83.0
75.1
65.3
50.4
54.2
100.0
53.4
nt
5c
Et
5d
n-Pr
n-Bu
n-Hep.
Me
nt
nt
The activities of the insecticidal compounds against soybean
aphids were tested by the leaf-dip method. Horsebean plant leaves
with 40–60 apterous adults were dipped in diluted solutions of the
chemicals containing Triton X-100 (0.05 mg Lꢀ1) for 5 s, the excess
dilution was sucked out with filter paper, and the burgeons were
placed in the conditioned room (25 ꢁ 1 8C, 50% RH). Watercontaining
Triton X-100 (0.05 mg Lꢀ1) was used as a control, and clothianidin was
used as positive control at the same time. The mortality rates were
evaluated 48 h after treatment. Each treatment had three repetitions
and the data was subjected to probit analysis [23].
5e
nt
nt
5f
nt
nt
5g
83.9
44.5
nt
51.9
19.8
nt
5h
Et
5i
n-Pr
n-Bu
n-Hep.
4-Cl-Ph
–
5j
nt
nt
5k
nt
nt
5l
nt
nt
clothianidin
100.0
92.6
a
nt= not tested.
100
90
80
70
60
50
40
30
Pyr
Thy
2.3. Experimental protocol of docking study
The highly active compound 5g was chosen for investigation of
the ligand–protein interactions in detail with clothianidin as a
contrast, and a Surflex-Dock was used to carry out the molecular
modelling study. The crystal structure of the Aplysia californica
acetylcholine binding protein (Ac-AChBP) complexed with thia-
cloprid (PDB: 3C84) was used as the template to construct the
models [24,25]. The receptor was prepared for docking by the
addition of hydrogen atoms and the removal of cocrystallized
molecules. The low energy conformation of each neonicotinoid
analogue was optimized by a MMFF94 force field and MMFF94
charges as an initial docking conformation.
methyl
ethyl
Compounds with aliphatic chain length
Fig. 1. Effect of the number of carbon atoms on the insecticidal activity.
n-propyl
n-butyl
n-heptyl
isothiourea
1 was prepared by the literature method [26].
3. Results and discussion
Compound 2 was obtained in high yield by reaction of 1 with
phthaloyl dichloride at 0 8C to room temperature. Then it was
reacted with benzylamine and purified by alcohol to afford 3.
The synthetic route of the target compounds (5a–5l) was
summarized in Scheme 1. The starting material S-methyl-N-nitro-
Scheme 1. Synthetic route for neonicotinoids containing hydrazide group. Reagents and conditions: (a) phthaloyl dichloride (1.5 equiv.), pyridine, 0 8C for 1 h; (b)
benzylamine (1.2 equiv.), CH2Cl2, 0 8C for 1 h, r.t. for 3 h; (c) hydrazine hydrate (1.2 equiv.), CH3OH, reflux for 0.5–1 h; (d) acyl chloride (1.5 equiv.), Na2CO3 (1.5 equiv.), DMAP
(0.5 equiv.), CH2Cl2, 0 8C for 0.5 h, r.t. for 6–8 h.
Please cite this article in press as: S.-H. Liu, et al., Synthesis, insecticidal activity and molecular docking study of clothianidin analogues
with hydrazide group, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.03.026

G Model
CCLET-2912; No. of Pages 4
S.-H. Liu et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
3
Fig. 2. The interactional model between ligands and Ac-AChBP. (a) The binding interactions between clothianidin and the active site residues. (b) The binding interactions
between 5g and the active site residues. Key H-bonds and cation- are indicated by black dotted lines.
p
Compound 4 was produced by hydrazinolysis of 3 with hydrazine
hydrate. The target compounds 5a–5l were obtained by reaction of
4 with acyl chloride in moderate yields.
cation-p interaction might lead to weaker insecticidal activity of
the analogues than clothianidin.
The structures of the target compounds 5a–5l were fully
confirmed by their melting points, 1H NMR, IR, and HRMS (ESI).
Analytical data of compounds 5a–5l can be found in Supporting
information. In the 1H NMR spectra, methylene connected to an
4. Conclusion
In summary, a series of novel clothianidin analogues were
designed and synthesized by introducing a hydrazide group with
different alkyl and phenyl substituents. The bioassay results
indicated that some target compounds, 5b and 5g, had good
insecticidal activity at 100 mg Lꢀ1, but still lower than clothianidin.
Molecular docking with receptor Ac-AChBP revealed the reason of
different activity between the title analogues and clothianidin.
These results were worthy for further study in new pesticide
discovery.
aromatic ring was observed at
NH protons were clearly detected at
d
4.34–4.45. Furthermore, three
8.30–8.36, 9.91–10.10
d
and 10.20–10.25 respectively. In the IR spectra, strong
absorptions at 3200–3400 cmꢀ1 were detected, due to the
secondary amino groups.
A strong absorption at about
1700 cmꢀ1 was detected because of carbonyl group. The HRMS
(ESI) spectral data of all compounds were in good agreement
with theoretical data.
The results of insecticidal activity against soybean aphids (A.
glycines) of all target compounds were listed in Table 1, in which
some compounds, 5b and 5g, showed similar insecticidal activity
of 91.5%, 94.5% respectively to that of the positive control
clothianidin at 500 mg Lꢀ1. In addition, 5b and 5g exhibited good
Acknowledgment
This work was financially supported by the National Basic
Research Program of China (No. 2010CB126104).
insecticidal activity of 82.2% and 83.9% respectively at 100 mg Lꢀ1
.
Appendix A. Supplementary data
However, 5b and 5g showed less activity than clothianidin at
20 mg Lꢀ1. The results indicated that a heterocycle substituent,
such as pyridyl or thiazolyl, was more beneficial to insecticidal
activity than a phenyl substituent. Besides, substituent R2 also
played an important role in insecticidal activity. Increasing the
number of carbon atoms or the introduction of a phenyl group led
to a decline in bioactivity (Fig. 1). A small sized group is conducive
to bioactivity, e.g., 5b and 5g have better activity than 5f, 5k and 5l.
To further understand the activity differences between the
analogues and clothianidin, binding site interactions of 5g and
clothianidin were simulated with Ac-AChBP based on the structure
cocrystallized with bound thiacloprid (3C84). Fig. 2a showed, in
compliance with neonicotinoids’ binding mode, the hydrogen
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.cclet.2014.03.026.
References
[1] J.E.C. Jepson, L.A. Brown, D.B. Sattelle, The actions of the neonicotinoid imidaclo-
prid on cholinergic neurons of Drosophila melanogaster, Invert. Neurosci. 6 (2006)
33–40.
[2] S. Kagabu, R. Ishihara, Y. Hieda, K. Nishimura, Y. Naruse, Insecticidal and neuro-
blocking potencies of variants of the imidazolidine moiety of imidacloprid-related
neonicotinoids and the relationship topartition coefficient and charge density on
the pharmacophore, J. Agric. Food Chem. 55 (2007) 812–818.
[3] K. Kiriyama, K. Nishimura, Structural effects of dinotefuran and analogues in
insecticidal and neural activities, Pest Manage. Sci. 58 (2002) 669–676.
[4] M. Tomizawa, D.L. Lee, J.E. Casida, Neonicotinoid insecticides: molecular features
conferring selectivity for insect versus mammalian nicotinic receptors, J. Agric.
Food Chem. 48 (2000) 6016–6024.
[5] S.J. Lee, M. Tomizawa, J.E. Casida, Nereistoxin and cartap neurotoxicity attribut-
able to direct block of the insect nicotinic receptor/channel, J. Agric. Food Chem.
51 (2003) 2646–2652.
bond force and the cation-p interaction were found between
clothianidin and AChBP. Compound 5g showed a similar binding
mode with clothianidin (Fig. 2b). However, the introduction of
hydrazide into 5g extended the centroid distance between the
benzene ring in Tyr188 and N atom of imino group in ligand to
˚
˚
[6] M. Tomizawa, J.E. Casida, Selective toxicity of neonicotinoids attributable to
specificity of insect and mammalian nicotinic receptors, Annu. Rev. Entomol.
48 (2003) 339–364.
[7] A. Elbert, M. Schindler, R. Nauen, P. Jeschke, Overview of the status and global
strategy for neonicotinoids, J. Agric. Food Chem. 59 (2011) 2897–2908.
3.18 A, which is longer than the 2.84 A of clothianidin. The longer
distance decreased the cation- interaction with AChBP. Since
cation- interaction was confirmed to play an important role in
neonicotinoids’ insecticidal activities [27], this decreasing of the
p
p
Please cite this article in press as: S.-H. Liu, et al., Synthesis, insecticidal activity and molecular docking study of clothianidin analogues
with hydrazide group, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.03.026

G Model
CCLET-2912; No. of Pages 4
4
S.-H. Liu et al. / Chinese Chemical Letters xxx (2014) xxx–xxx
[8] S. Kagabu, Discovery of imidacloprid and further developments from strategic
molecular designs, J. Agric. Food Chem. 59 (2011) 2887–2896.
[9] M. Tomizawa, J.E. Casida, Molecular recognition of neonicotinoid insecticides: the
determinants of life or death, Acc. Chem. Res. 42 (2009) 260–269.
[10] A. Elbert, R. Nauen, Resistance of bemisia tabaci (Homoptera: Aleyrodidae) to
insecticides in southern Spain with special referenceto neonicotinoids, Pest
Manage. Sci. 56 (2000) 60–64.
[11] K.D. Ninsin, Acetamiprid resistance and cross-resistance in the diamondback
moth, plutella xylostella, Pest Manage. Sci. 60 (2004) 839–841.
[12] D.M. Sanchez, R.M. Hollingworth, E.J. Grafius, D.D. Moyer, Resistance and cross-
resistance to neonicotinoid insecticides and spinosad in the Colorado potato
beetle, leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), Pest Man-
age. Sci. 62 (2006) 30–37.
[13] K.G. Gorman, G. Devine, J. Bennison, et al., Report of resistance to the neonico-
tinoid insecticide imidacloprid in trialeurodes vaporariorum (Hemiptera: Aleyr-
odidae), Pest Manage. Sci. 63 (2007) 555–558.
[14] G. Arnold, J. Pistorius, T. Steeger, H. Thompson, Statement on the findings in recent
studies investigating sub-lethal effects in bees of some neonicotinoids in consid-
eration of the uses currently authorised in Europe, EFSA J. 10 (2012) 2752–
2779.
[18] C. Sun, J. Zhu, H. Wang, et al., Chiral 1,5-disubstituted 1,3,5-hexahydrotriazine-2-
N-nitroimine analogues as novel potent neonicotinoids: synthesis, insecticidal
evaluation and molecular docking studies, Eur. J. Med. Chem. 46 (2011) 11–20.
[19] Y. Nakagawa, K. Takahashi, H. Kishikawa, et al., Classical and three-dimensional
QSAR for the inhibition of [3H] ponasterone A binding by diacylhydrazine-type
ecdysone agonists to insect Sf-9 cells, Bioorg. Med. Chem. 13 (2005) 1333–1340.
[20] C. Minakuchi, Mode of action of nonsteroidal ecdysone agonists, diacylhydrazine
analogs, J. Pestic. Sci. 30 (2005) 228–238.
[21] X. Liu, L. Zhang, J.G. Tan, H.H. Xu, Design and synthesis of N-alkyl-N0-substituted
2,4-dioxo-3,4-dihydropyrimidin-1-diacylhydrazine derivatives as ecdysone re-
ceptor agonist, Bioorg. Med. Chem. 21 (2013) 4687–4697.
[22] Z. Huang, Y. Liu, Y. Li, et al., Synthesis, crystal structures, insecticidal activities, and
structure-activity relationships of novel N0-tert-Butyl-N0-substituted-benzoyl-N-
[di(octa) hydro] benzofuran{(2,3-dihydro) benzo[1,3] ([1,4]) dioxine} carbohy-
drazide derivatives, J. Agric. Food Chem. 59 (2011) 635–644.
[23] W.S. Abbott, A method of computing the effectiveness of an insecticide, J. Econ.
Entomol. 18 (1995) 265–267.
[24] T.T. Talley, M. Harel, R.E. Hibbs, et al., Atomic interactions of neonicotinoid
agonists with AChBP: molecular recognition of the distinctive electronegative
pharmacophore, Proc. Natl. Acad. Sci. U. S. A. 105 (2008) 7606–7611.
[25] H.X. Duan, W.W. Zhang, J. Zhao, et al., A novel halogen bond and a better-known
hydrogen bond cooperation of neonicotinoid and insect nicotinic acetylcholine
receptor recognition, J. Mol. Model. 18 (2012) 3867–3875.
[15] Z. Ye, S. Xia, X. Shao, et al., Design, synthesis, crystal structure analysis, and
insecticidal evaluation of phenylazoneonicotinoids, J. Agric. Food Chem. 59
(2011) 10615–10623.
[16] W. Zhang, X. Yang, W. Chen, et al., Design, multicomponent synthesis, and
bioactivities of novel neonicotinoid analogues with 1,4-dihydropyridine scaffold,
J. Agric. Food Chem. 58 (2010) 2741–2745.
[26] L. Sun, Y. Ling, C. Wang, et al., Synthesis and biological activities of E-b-Farnesene
analogues containing substituent nitroguanidine, Chin. J. Org. Chem. 31 (2011)
2061–2066.
[17] N.Y. Chen, L.P. Ren, M.M. Zou, et al., Design, synthesis and insecticidal activity of
spiro heterocycle containing neonicotinoid analogs, Chin. Chem. Lett. 25 (2014)
197–200.
[27] J.D. Schmitt, C.G.V. Sharples, W.S. Caldwell, Molecular recognition in nicotinic
acetylcholine receptors: the importance of p-cation interactions, J. Med. Chem.
42 (1999) 3066–3074.
Please cite this article in press as: S.-H. Liu, et al., Synthesis, insecticidal activity and molecular docking study of clothianidin analogues
with hydrazide group, Chin. Chem. Lett. (2014), http://dx.doi.org/10.1016/j.cclet.2014.03.026