Design, Synthesis, and Insecticidal Activity of Novel Doramectin Derivatives Containing Acylurea and Acylthiourea Based on Hydrogen Bonding

Article abstract of DOI:10.1021/acs.jafc.0c00230

Our recent investigation on the insecticidal activities of several doramectin derivatives preliminarily revealed that the presence of hydrogen bonds at the C4″ position of the molecule with target protein γ-aminobutyric acid (GABA) receptor was crucial for retaining high insecticidal activity. As a continuation of our research work on the development of new insecticides, two series of novel acylurea and acylthiourea doramectin derivatives were designed and synthesized. The bioassay results indicated that the newly synthesized compounds (5o, 5t, and 6t) exhibited higher insecticidal activity against diamondback moth, oriental armyworm, and corn borer than the control compounds doramectin, commercial avermectins, chlorbenzuron, and lead compound 3g in our laboratory. Specifically, compound 5t was identified as the most promising insecticide against diamondback moth, with a final mortality rate of 80.00% at the low concentration of 12.50 mg/L, showing approximately 7.75-fold higher potency than the parent doramectin (LC₅₀ value of 48.1547 mg/L), 6.52-fold higher potency than commercial avermectins (LC₅₀ value of 40.5507 mg/L), and 3.98-fold higher potency than compound 3g (LC₅₀ value of 24.7742 mg/L). Additionally, molecular docking simulations revealed that compound 5t (2.17, 2.20, 2.56, and 2.83 ?) displayed stronger hydrogen-bond action in binding with the GABA receptor, better than that of compound 5o (1.64 and 2.15 ?) and compound 6t (2.20 and 2.31 ?) at the C4″ position. This work demonstrated that these compounds containing hydrogen-bond groups might contribute to the improvement of insecticidal activity and supply certain hints toward structure optimization design for the development of new insecticides.

Full text of DOI:10.1021/acs.jafc.0c00230

Subscriber access provided by BIU Pharmacie | Faculté de Pharmacie, Université Paris V
Agricultural and Environmental Chemistry
Design, Synthesis, and Insecticidal Activity of Novel Doramectin Derivatives
Containing Acylurea and Acylthiourea Based on Hydrogen Bonding
Qi Zhang, Yao Cheng, Cheng Zheng, Ping Bai, Jian Yang, and Xiaoxia Lu
J. Agric. Food Chem., Just Accepted Manuscript • Publication Date (Web): 01 May 2020
Downloaded from pubs.acs.org on May 2, 2020
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Design, Synthesis, and Insecticidal Activity of Novel Doramectin
Derivatives Containing Acylurea and Acylthiourea Based on
Hydrogen Bonding
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Qi Zhanga,b,+, Yao Chenga,c,+, Cheng Zhenga,c, Ping Baia,c, Jian Yanga,c, and Xiaoxia
9
Lua,c*
a
b
c
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22
Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041,
People’s Republic of China.
Department of Chemical and Chemical Engineering, Hefei Normal University,
Hefei, 230601, People’s Republic of China.
University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of
China.
+ These authors contributed equally to this paper.
* Corresponding author：
Xiaoxia Lu
Tel.: +86 28 82890809;
fax: +86 28 85222753.
E-mail address: luxx@cib.ac.cn
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ABSTRACT
Our recent investigation on the insecticidal activities of several doramectin
derivatives preliminarily revealed that the presence of hydrogen bonds at the C4″
position of the molecule with target protein GABA receptor was crucial for retaining
high insecticidal activity. As a continuation of our research work on the development
of new insecticides, two series of novel acylurea and acylthiourea doramectin
derivatives were designed and synthesized. The bioassay results indicated that the
newly synthesized compounds (5o, 5t, and 6t) exhibited higher insecticidal activity
against diamondback moth, oriental armyworm, and corn borer than the controls
compounds doramectin, commercial avermectins, chlorbenzuron, and the lead
compound 3g in our laboratory. Specifically, compound 5t was identified as the most
promising insecticide against diamondback moth with a final mortality rate of 80.00%
at the low concentration of 12.50 mg/L, showing approximately 7.75-fold higher
potency than the parent doramectin (LC50 value of 48.1547 mg/L), 6.52-fold higher
potency than commercial avermectins (LC50 value of 40.5507 mg/L), and 3.98-fold
higher potency than 3g (LC50 value of 24.7742 mg/L). Additionally, molecular
docking simulations revealed that 5t (2.17, 2.20, 2.56, and 2.83 Å) displayed stronger
hydrogen bond action in binding with GABA receptor, better than that of 5o (1.64 and
2.15 Å) and 6t (2.20 and 2.31 Å) at the C4″ position. This work demonstrated that
these compounds containing hydrogen bond groups might contribute to the
improvement of insecticidal activity and supplies certain hints toward structure
optimization design for the development of new insecticides.
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KEYWORDS: Acylurea, acylthiourea, insecticidal activities, molecular docking,
oriental armyworm, diamondback moth, and corn borer.
INTRODUCTION
Currently, Lepidoptera (diamondback moth, oriental armyworm, corn borer, etc.) is
becoming a major threat to the agricultural system.1 To obtain higher food production,
many chemical and biological pesticides have been widely applied for control of
insect pests.2-8 In the quest for new insect control agents, natural products have been
and remain an excellent source of novel chemistry and inspiration for insecticides.
Among natural product-based insecticides, avermectin, a macrocyclic lactone with
high efficiency and without cross-resistance, is an important insecticide that has been
commercialized in crop protection and plays an important role in modern agriculture
by increasing both crop quality and yield while improving living standards due to a
unique mechanism of action.9 To further identify more stable, efficient, low-toxicity
and broad-spectrum chemical compounds, scientists have made a large number of
structural modifications using natural avermectin components as parent compounds,
and obtained many highly active derivatives.10-15 Among the avermectin-based
insecticides, doramectin, a third generation of the avermectins family with a
cyclohexyl group at C25 position in lieu of the sec-butyl or isopropyl of avermectins,
can aid in the identification of new mode of action and might be used as a lead
structure to derive new potent pesticides. Therefore, doramectin might be a promising
template for the discovery of new insecticide candidates.
The gamma-aminobutyric acid (GABA) receptor (GABAR) is a crucial target for
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insecticide action. Studies suggested that the target of avermectin and doramectin was
the GABA-gated chloride channel, and this targeting caused hyperpolarization of
nerve membrane potential and inhibited nerve membrane, thus blocking normal nerve
conduction and paralyzing insects.16 In previous papers from our laboratory, we
reported that with the introduction of carbamate, ester, sulfonate active groups to
replace the hydroxyl group at the C4" position of doramectin, compound 3g (Figure 1)
containing cyclopropyl carbamate exhibited excellent insecticidal activities.17
A
molecular docking study indicated that 3g could form the N−H···O H bond, which
was crucial to the binding of the macrolide and GABAR, and the NH group on the
C4" position of doramectin was necessary to retaining higher insecticidal activity. In
fact, Yamamoto,18 Kagabu,19 Casida,20 and Qian21 demonstrated the importance of
the hydrogen bond between pesticide molecules and target proteins in various modes.
To the best of our knowledge, use of acylureas and acylthioureas has reported for
many years in insecticidal, herbicidal, fungicidal applications for crop protection.22-24
Acylureas and acylthioureas contain two NH groups, which are also highly
susceptible to additional hydrogen bonds with the target protein.25, 26 With this
characteristic in mind, we speculated whether the insecticidal activity could be
enhanced by forming additional hydrogen bonds through the introduction of acylurea
and acylthiourea moieties.
Herein, as a continuation of our work and to verify our hypothesis, a series of
novel acylurea and acylthiourea derivatives were rationally designed and synthesized
by replacing the hydroxyl group at the C4" position with acylurea and acylthiourea
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active groups (Figure 1). The insecticidal activities of these target compounds were
tested against diamondback moth, oriental armyworm, and corn borer. Furthermore,
structure-activity relationship (SAR) studies and docking analysis were also
discussed.
MATERIALS AND METHODS
Chemicals.
Doramectin
was
purchased
from
Chongqing
Qiantai
Biopharmaceutical Co., Ltd. (Chongqing, China). Imidazole, triphosgene,
tert-butyldimethylsiyl chloride (TBDMS-Cl), and N, N-dimethypyridin-4-amine
(DMAP) were purchased from Energy Chemical Ltd. (Beijing, China). All chemical
materials amides and acid chlorides, phenyl dichlorophosphate, sodium
cyanoborohydride, ammonium thiocyanate, oxalyl chloride, and dry dichloromethane
(DCM) were purchased from J&K Chemical Ltd. (Beijing, China). Triethylamine,
p-toluenesulfonic acid (TsOH), sodium carbonate, magnesium sulfate, methanol,
dichloromethane (DCM), and dimethyl sulfoxide (DMSO) were purchased from
Kelong Chemical Reagent Co., Ltd. (Chengdu, China). All reagents and solvents were
reagent grade without further purification.
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Instruments. The melting points were determined on an X-6 precision
micro-melting point apparatus (Beijing Fukui Technology Development Co., Ltd). 1H
13
NMR (400 MHZ) and C NMR (100 MHZ) spectra were obtained using a Bruker
400 spectrometer in CDCl3 solution with tetramethylsilane as the internal standard.
Reaction progress was monitored according to thin-layer chromatography (TLC) on
silica gel GF254 with ultraviolet (UV) detection. High resolution mass spectra
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(HRMS) data were recorded on a Micro Q-TOF II mass spectrometer (HR-ESI-MS,
Bruker, Germany) in the negative ion detection mode.
General Synthesis. The silica gel chromatography was performed with a column
of 254 mm × 26 mm i.d. (Synthware glass Co. Ltd., Beijing, China) using 100-140
mesh silica gel (Sinopharm Chemical reagent Co. Ltd., Shanghai, China). The general
synthetic methods for doramectin derivatives containing acylurea (5a-5v) and
acylthiourea (6a-6v) groups are shown in Schemes 1 and Schemes 2, and their
structures are listed in S-1 (Supporting Information). Acyl isocyanate and acyl
isothiocyanate were prepared according to the methods in the literature.27, 28
General Procedure for Synthesis of Acylurea Derivatives of Doramectin
(5a-5v) (Scheme 1).
Synthesis of [5-O-(tert-butyldimethylsilyl)doramectin](2).29 To a solution of
doramectin (20.00 g, 22.24 mmol) in dry dichloromethane (200.00 mL), imidazole
(15.10 g, 222.00 mmol), N, N-dimethypyridin-4-amine (DMAP, 271.00 mg, 2.22
mmol), and tert-butyldimethylsiyl chloride (TBDMS-Cl, 11.72 g, 77.77 mmol) were
added. The mixture was stirred for 15 h at room temperature. When the reaction was
completed according to TLC analysis, water (200.00 mL) and dichloromethane
(200.00 mL) were added to the mixture. The aqueous phase was extracted with
dichloromethane (3 × 100.00 mL), and the combined organic phases were washed
with saturated brine (3 × 100.00 mL), dried over anhydrous magnesium sulfate,
filtered, and concentrated by evaporation under vacuum to yield a white solid. The
residue was purified by column chromatography on silica gel eluted with petroleum
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ether/ethyl acetate (2: 1, v/v) to produce 19.48 g (86 %) of compound 2 as a white
foamy solid. 1H NMR (400 MHz, CDCl3) δ 5.88-5.80 (m, 1H, H9), 5.79-5.66 (m, 3H,
H10, H11, H23), 5.53 (dd, J = 9.9, 2.6 Hz, 1H, H22), 5.41-5.32 (m, 3H, H3, H19,
H1"), 5.04-4.97 (m, 1H, H15), 4.78 (dd, J = 4.0, 1.3 Hz, 1H, H1'), 4.68 (dd, J = 14.5,
2.4 Hz, 1H, H8a-a), 4.58 (dd, J = 14.5, 2.3 Hz, 1H, H8a-b), 4.46-4.39 (m, 1H, H4"),
4.12 (d, J = 13.1 Hz, 1H, H13), 3.93 (s, 1H, H7-OH), 3.90-3.72 (m, 4H, H17, H5',
H5", H5), 3.61 (ddd, J = 11.0, 8.4, 4.6 Hz, 1H, H3'), 3.51-3.44 (m, 1H, H3"), 3.41 (d,
J = 2.9 Hz, 6H, H3'-OMe, H3"-OMe), 3.39 (d, J = 2.4 Hz, 1H, H6), 3.33-3.11 (m, 3H,
H2, H25, H4'), 2,58 (s, 1H, H4"-OH), 2.55-2.47 (m, 1H, H12), 2.37-2.19 (m, 5H,
H16, H18a, H2'a, H2"a), 2.04-1.96 (m, 1H, H20a), 1.83-1.75 (m, 6H, H4a-CH3, H27a,
H30a, H31a), 1.73-1.55 (m, 5H, H24, H28a, H26, H29), 1.52-1.44 (m, 4H,
H14a-CH3, H20b), 1.32-1.10 (m, 15H, H2"b, H27b, H28b, H30b, H31b, H2'b,
H5'-Me, H5"-Me, H12a-CH3), 0.98-0.79 (m, 13H, H24a-CH3, H18b, H-C(CH3)3),
0.13 (s, 6H, H-Si(CH3)2). 13C NMR (100 MHz, CDCl3) δ 173.9, 140.1, 137.6, 137.5,
136.1, 135.1, 127.7, 124.7, 119.4, 118.2, 117.2, 98.4, 95.7, 94.8, 81.8, 80.4, 80.2,
80.1, 79.3, 78.2, 77.2, 76.1, 69.5, 68.3, 68.2, 68.1, 67.9, 67.2, 56.5, 56.4, 45.7, 40.3,
39.6, 38.7, 36.6, 34.6, 34.4, 34.1, 31.4, 30.0, 27.0, 26.9, 26.6, 26.5, 25.8(3-C), 25.5,
20.3, 20.0, 18.4, 17.6, 16.6, 15.2, -4.5, -4.8.
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Synthesis
of
[4"-O-5-O-(tert-butyldimethylsilyl)doramectin].30
Dimethyl
sulfoxide (DMSO, 25.00 mL) and triethylamine (TEA, 60.00 mL) were added to a
solution of compound 2 (15.00 g, 14.80 mmol) in 100.00 mL of dry
dichloromethane. A solution of PhOPOCl2 (22.00 mL) in CH2Cl2 (100.00 mL) was
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added dropwise over 60 minutes to the mixture at -15 °C, which was stirred at -15 °C
overnight until TLC indicated that the reaction was completed. The reaction solution
was poured into 1% H3PO4, the aqueous phase was extracted with dichloromethane
(3 × 100.00 mL), and the combined organic layers were washed with saturated brine
(3 × 100.00 mL), dried over anhydrous magnesium sulfate, filtered, and evaporated
to yield a yellow solid (14.21 g), and the product was not purified for use in the next
step.
Synthesis of [4"-epi-NH2-5-O-(tert-butyldimethylsilyl)doramectin].30 A mixture of
compound 3 (14.00 g, 13.8 mmol), methanol (200.00 mL), and ammonium acetate
(5.32 g, 69.00 mmol) was stirred 1 h at room temperature, and sodium
cyanoborohydride (4.33 g, 69.00 mmol) was added. The mixture was stirred for 4 h at
room temperature until the reaction was completed according to TLC analysis. Water
(100.00 mL), saturated sodium carbonate (100.00 mL), and ethyl acetate (200.00 mL)
were added, the aqueous phase was extracted with ethyl acetate (3 × 100.00 mL), and
the combined organic phases were washed with saturated sodium chloride solution (3
× 100.00 mL), dried over anhydrous magnesium sulfate, filtered, and evaporated to
yield a yellow solid. The residue was purified by column chromatography on silica
gel eluted with dichloromethane/methanol (20: 1, v/v) to produce 5.38 g (38 %) of
intermediate compound 4 as a yellow solid.
Synthesis of (4"-N- benzoylurea doramectin) (5a).27, 29 A mixture of benzoylamide
(1.21 g, 10.00 mmol), 1,2-dichloroethane (1.75 mL, 20.00 mmol), and oxalyl chloride
(1.75 mL, 20.00 mmol) was stirred overnight at 84 °C under an N2 atmosphere. The
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residue was concentrated in vacuo to benzoyl isocyanate (1.12 g) as a colorless liquid
and was not purified for use in the next step.
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Benzoyl isocyanate (218.00 mg, 1.48 mmol) was added to a solution of compound
4 (300.00 mg, 0.29 mmol) and N, N-dimethypyridin-4-amine (DMAP, 3.60 mg) in dry
dichloromethane (20.00 mL). The mixture was stirred for 2 h at room temperature
until the reaction was completed according to TLC analysis. Saturated sodium
bicarbonate (20.00 mL) was added, the aqueous phase was extracted with
dichloromethane (3 × 20.00 mL), and the combined organic phases were washed with
saturated sodium chloride solution (3 × 20.00 mL), dried over anhydrous magnesium
sulfate, filtered, and concentrated in vacuo. The residue was purified by column
chromatography on silica gel eluted with petroleum ether/ethyl acetate (4: 1, v/v) to
produce 280.00 mg as a yellow solid. A deprotection reagent solution of 7.50 mL of
p-toluenesulfonic acid-methanol complex (0.02 g/mL) was added dropwise to a
solution of yellow solid (280.00 mg) in methanol (15.00 mL). The mixture was stirred
1 h at room temperature until the reaction was completed according to TLC analysis.
Saturated sodium bicarbonate (30.00 mL) and dichloromethane (30.00 mL) were
added, the aqueous phase was extracted with dichloromethane (3 × 10.00 mL), and
the combined organic phases were washed with saturated brine (3 × 10.00 mL), dried
over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. The crude
product was purified by column chromatography on silica gel eluted with petroleum
ether/ethyl acetate (4: 1, v/v) to produce 195.21 mg (78 %) of compound 5a. 1H NMR
(400 MHz, CDCl3) δ 8.95 (d, J = 9.8 Hz, 1H, CONHCO), 8.45 (s, 1H, CONH), 7.86
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(d, J = 7.1 Hz, 2H, Ph), 7.63-7.56 (m, 1H, Ph), 7.49 (dd, J = 8.4, 7.0 Hz, 2H, Ph), 5.90
(d, J = 10.1 Hz, 1H, H9), 5.83-5.68 (m, 3H, H10, H11, H23), 5.54 (dd, J = 9.9, 2.5 Hz,
1H, H22), 5.50-5.32 (m, 3H, H3, H19, H1"), 5.01 (d, J = 10.6 Hz, 1H, H15), 4.79 (d,
J = 3.8 Hz, 1H, H1'), 4.69 (t, J = 2.9 Hz, 2H, H8a ), 4.42-4.35 (m, 1H, H4"), 4.30 (t, J
= 7.3 Hz, 1H, H5), 4.16-4.09 (m, 1H, H5"), 4.07 (s, 1H, H7-OH), 3.97 (d, J = 6.2 Hz,
1H, H6), 3.94 (s, 1H, H13), 3.92-3.81 (m, 2H, H17, H5'), 3.74 (dt, J = 12.2, 4.4 Hz,
1H, H3"), 3.66-3.57 (m, 1H, H3'), 3.44 (s, 3H, H3'-OMe), 3.43 (s, 3H, H3"-OMe),
3.35-3.20 (m, 3H, H2, H25, H4'), 2.59-2.46 (m, 1H, H12), 2.37 (d, J = 8.2 Hz, 1H,
H5-OH), 2.33-2.19 (m, 4H, H16, H24, H2"a), 2.09-1.97 (m, 2H, H2'a, H20a), 1.88 (d,
J = 2.1 Hz, 3H, H4a-CH3), 1.83-1.72 (m, 3H, H27a, H30a, H31a), 1.74-1.64 (m, 2H,
H18a, H28a), 1.56 (d, J = 11.1 Hz, 3H, H26, H29), 1.49 (d, J = 8.1 Hz, 4H, H14a-CH3,
H20b), 1.31-1.14 (m, 15H, H2"b, H27b, H28b, H30b, H31b, H2'b, H5'-Me, H5"-Me,
H12a-CH3), 0.93 (d, J = 7.1 Hz, 3H, H24a-CH3), 0.88 (d, J = 12.4 Hz, 1H, H18b). 13C
NMR (100 MHz, CDCl3) δ 173.5, 168.1, 154.8, 139.5, 138.0, 137.8, 136.2, 135.0,
132.9, 132.5, 128.7(2-C), 127.8(2-C), 124.7, 120.5, 118.2, 118.1, 98.7, 95.7, 94.9,
81.8, 81.0, 80.4, 79.2, 73.9, 68.4, 68.3, 68.2, 67.7, 67.1, 65.4, 56.7, 56.0, 52.5, 49.8,
45.7, 41.1, 40.4, 39.7, 38.6, 36.6, 34.6, 34.3, 31.8, 31.4, 30.0, 29.7, 26.9, 26.6, 26.5,
25.5, 20.2, 19.9, 18.3, 17.3, 16.6, 15.1. HRMS (ESI) m/z calcd. for C58H80O15N2Na:
(M+Na)+, 1067.5451; found 1067.5416.
The target compounds (5b-5v) were synthesized according to a procedure similar to
1
that used for compound 5a. Their HRMS, H NMR, and 13C NMR data can be found
in Supporting Information.
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General Procedure for Synthesis of Acylthiourea Derivatives of Doramectin
(6a-6v) (Scheme 2).
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Synthesis of benzoyl isothiocyanate.28 A mixture of benzoyl chloride (703.00 mg,
5.00 mmol), acetone (15.00 mL), and ammonium thiocyanate (381.00 mg, 5.00
mmol) was stirred 1 h at room temperature under an N2 atmosphere. The mixture was
filtered, and concentrated in vacuo to yield 600.00 mg of light yellow liquid, which
was not purified for use in the next step.
Synthesis of (4"-N- benzoylthiourea doramectin) (6a).28, 29 Benzoyl isothiocyanate
(322.32 mg, 1.98 mmol) was added to a solution of compound 4 (400.00 mg, 0.39
mmol) and N, N-dimethypyridin-4-amine (DMAP, 4.80 mg, 0.04 mmol) in dry
dichloromethane (20.00 mL). The mixture was stirred for 1 h at room temperature
until the reaction was completed according to TLC analysis. Saturated brine (20.00
mL) was added, the aqueous phase was extracted with dichloromethane (3 × 20.00
mL), and the combined organic phases were washed with saturated brine (3 × 20.00
mL), dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo.
The residue was purified by column chromatography on silica gel eluted with
petroleum ether/ethyl acetate (7:1, v/v) to produce 401.00 mg as a yellow solid. A
deprotection reagent solution of 15.00 mL of p-toluenesulfonic acid-methanol
complex (0.02 g/mL) was added dropwise to a solution of yellow solid (401.00 mg) in
methanol (15.00 mL). The mixture was stirred for 1 h at room temperature until the
reaction was completed according to TLC analysis. Saturated sodium bicarbonate
(50.00 mL) and dichloromethane (50.00 mL) were added, the aqueous phase was
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extracted with dichloromethane (3 × 10.00 mL), and the combined organic phases
were washed with saturated brine (3 × 10.00 mL), dried over anhydrous magnesium
sulfate, filtered, and concentrated in vacuo. The crude product was purified by column
chromatography on silica gel eluted with petroleum ether/ethyl acetate (2.5: 1, v/v) to
produce 254.00 mg (70 %) of compound 6a. 1H NMR (400 MHz, CDCl3) δ 11.11 (d,
J = 9.8 Hz, 1H, CONHCS), 9.07 (s, 1H, CSNH), 7.88-7.82 (m, 2H, Ph), 7.64-7.59 (m,
1H, Ph), 7.51 (t, J = 7.6 Hz, 2H, Ph), 5.92-5.85 (m, 1H, H9), 5.83-5.67 (m, 3H, H10,
H11, H23), 5.57-5.50 (m, 2H, H22, H1"), 5.47-5.36 (m, 2H, H3, H19), 5.09 (dd, J =
10.0, 3.6 Hz, 1H, H4"), 5.03-4.98 (m, 1H, H15), 4.79 (d, J = 3.8 Hz, 1H, H1'),
4.73-4.62 (m, 2H, H8a), 4.33-4.24 (m, 1H, H5), 4.22-4.13 (m, 1H, H5"), 4.06 (s, 1H,
H7-OH), 3.97 (d, J = 6.2 Hz, 1H, H6), 3.94 (s, 1H, H13), 3.92-3.78 (m, 3H, H17, H5',
H3"), 3.62 (ddd, J = 11.2, 8.5, 4.8 Hz, 1H, H3'), 3.52 (s, 3H, H3"-OMe), 3.43 (s, 3H,
H3'-OMe), 3.34-3.21 (m, 3H, H2, H25, H4'), 2.57-2.49 (m, 1H, H12), 2.41 (s, 1H,
H5-OH), 2.27 (dddd, J = 18.9, 11.4, 5.8, 2.2 Hz, 4H, H16, H24, H2"a), 2.14 (dd, J =
13.7, 5.0 Hz, 1H, H2'a), 2.03-1.97 (m, 1H, H20a), 1.87 (t, J = 2.0 Hz, 3H, H4a-CH3),
1.84-1.74 (m, 3H, H27a, H30a, H31a), 1.71-1.63 (m, 2H, H18a, H28a), 1.56 (d, J =
8.2 Hz, 3H, H26, H29), 1.49 (d, J = 7.9 Hz, 4H, H14a-CH3, H20b), 1.30-1.14 (m,
15H, H2"b, H27b, H28b, H30b, H31b, H2'b, H5'-Me, H5"-Me, H12a-CH3), 0.92 (d,
J = 7.2 Hz, 3H, H24a-CH3), 0.87-0.82 (m, 1H, H18b). 13C NMR (100 MHz, CDCl3) δ
181.2, 173.5, 166.9, 139.5, 138.0, 137.8, 136.2, 135.0, 133.4, 131.8, 129.0(2-C),
127.7, 127.5(2-C), 124.7, 120.5, 118.2, 118.1, 98.6, 95.7, 94.8, 81.8, 81.0, 80.4, 79.2,
79.2, 73.8, 68.4, 68.2, 68.2, 67.7, 67.0, 65.7, 57.1, 56.6, 55.7, 45.7, 40.3, 39.7, 38.6,
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36.7, 34.6, 34.3, 32.3, 31.4, 30.0, 29.6, 26.9, 26.6, 26.5, 25.5, 20.2, 19.9, 18.3, 17.2,
16.6, 15.1. HRMS (ESI) m/z calcd. for C58H80O14SN2Na: (M+Na)+, 1083.5222; found
1083.5187.
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The target compounds (6b-6v) were prepared by following the same procedure as
for 6a. Their HRMS, 1H NMR, and 13C NMR data are list in Supporting Information.
Biological Assay and Insecticidal Test. Diamondback moth, oriental armyworm,
and corn borer were used to examine the insecticidal activities of the target
compounds (5a-5v and 6a-6v) according to the previously reported methods.31-33 For
each compound, 30 larvae (10 larvae per group) were used. The percentage of
mortalities was evaluated 2 days after treatment. Each bioassay was repeated in
triplicate at 25 ± 1 °C. For comparative purposes, doramectin, commercial
avermectins, chlorbenzuron, diafenthiuron, and our previous work 3g were tested
under the same condition. Assessments were made on a dead/alive basis, and
mortality rates were corrected using Abbott’s formula.34 Percentage mortalities were
based on a percentage scale of 0-100, where 0 was no activity, 100 was total kill.
Homology Modeling and Molecular Docking.17 In our previously reported study,
the crystal structure of human glycine receptor alpha-3 (PDB ID 5TIN) was chosen as
the template to build the 3D structure of Plutella xylostella GABA receptor.
Schrodinger-Glide was used to investigate the binding mode between compounds and
the target protein. The best-scoring pose judged by the Glide docking score was
chosen and analyzed using Schrodinger software.
RESULTS AND DISCUSSION
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Chemical Synthesis. As shown in Scheme 1 and Scheme 2, two series of novel
acylurea and acylthiourea derivatives of doramectin (5a–5v and 6a–6v) modified at
position C4"-OH were prepared. As an initial material, doramectin 1 was reacted with
tert-butylchlorodimethylsilane (TBDMS-Cl) for selective protection of the hydroxyl
group at the 5-position of doramectin to prepare 5-O-TBDMS doramectin 2, as
described previously.29 In an attempt to introduce the C4" acyl isocyanate and acyl
isothiocyanate side chain, the protected intermediate 2 was first oxidized using
diphenyl phosphate dichloride (PhOPOCl2) in DMSO at low temperature to produce
4"-oxo-5-O- TBDMS doramectin (3). Subsequently, C4"=O was reductively aminated
to C4"-NH2 with ammonium acetate and sodium cyanoborohydride (NaCNBH3) to
produce the key intermediate 4"-epi-NH2-5-O-TBDMS doramectin (4) at 38 % yield.
The amine intermediate 4 was first reacted with different newly prepared acyl
isocyanate (RCONCO) or acyl isothiocyanate (RCONCS) using N,
N-dimethypyridin-4-amine (DMAP) as a catalyst in a solution of dichloromethane,
which was further deprotected using p-toluenesulfonic acid-methanol complex,
according to published procedures.30 All target compounds were purified by column
1
13
chromatography, and their structures were characterized by H NMR, C NMR, and
HRMS.
Insecticidal Activities. Forty-four newly synthesized acylurea and acylthiourea
doramectin derivatives ( 5a-5v and 6a-6v) were evaluated for insecticidal activities
against diamondback moth and oriental armyworm, and a few representative
compounds 5l, 5o, 5t, 6l, 6o, 6n, 6p, and 6t were further evaluated for insecticidal
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efficacy against corn borer, and the results are listed in Tables 1, 2 and 3. The LC50
values were calculated using five different concentrations (200.00 mg/L, 100.00
mg/L, 50.00 mg/L, 25.00 mg/L, and 12.50 mg/L) and are listed in Table 4.
Doramectin, commercial avermectins, chlorbenzuron, diafenthiuron, and 3g were
used as positive controls. Leaves treated with acetone were used as a blank control
group.
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Insecticidal Activity against Diamondback Moth. As shown in Table 1, acylurea
and acylthiourea derivatives of doramectin except for 5r, 5u, 6b, 6e, 6h, 6i, 6p, 6q,
and 6u, exhibited insecticidal activities against diamondback moth at the
concentration of 100.00 mg/L. Moreover, the acylurea derivatives (5a-5e, 5g-5j,
5m-5q, and 5t-5v) had higher insecticidal activities than the corresponding
acylthiourea series (6a-6e, 6g-6j, 6m-6q, and 6t-6v). Furthermore, among all
derivatives, compounds 5j, 5o, 5t, 6l, and 6o exhibited insecticidal activities equal to
or higher than that of the positive control, doramectin, commercial avermectins, and
chlorbenzuron. Particularly, 5j, 5o, 5t, and 6l displayed high insecticidal activities (≥
80%) against diamondback moth at a concentration of 100.00 mg/L. When the
concentration was reduced to 12.50 mg/L, 5o and 5t exhibited desirable insecticidal
activities, and compound 5t still had 80.00% mortality. The insecticidal activity of 5t
against diamondback moth was much higher than that of the control compounds,
including doramectin, commercial avermectins, chlorbenzuron, and 3g (the most
active compound in our group), which was parallel to that of diafenthiuron at the same
concentration of 12.50 mg/L. The LC50 value of 5t (LC50= 6.2123 mg/L) was
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6.52-fold that of avermectins (LC50= 40.5507 mg/L), 7.75-fold that of doramectin
(LC50= 48.1547 mg/L), and 3.98-fold that of 3g (LC50= 24.7742 mg/L).
Insecticidal Activity against Oriental Armyworm. The insecticidal activities of all
compounds against oriental armyworm were evaluated, and the results are shown in
Table 2. Acylurea and acylthiourea doramectin derivatives, except for 5a, 5d, 5e, 5f,
5h, 5k, 5r, 5s and 5v, exhibited insecticidal activities against oriental armyworm at
concentrations of 200.00-50.00 mg/L. Unlike the insecticidal efficacy against
diamondback moth, the acylthiourea series were more active than the corresponding
acylurea series at the same concentration. Most acylthiourea derivatives displayed
good to excellent insecticidal activities at high concentration (≥ 50.00 mg/L) and
certain insecticidal activities at low concentration (12.50 mg/L), whereas a few
acylurea derivatives (5e, 5f, 5k, and 5v) displayed no insecticidal activities against
oriental armyworm at 200.00 mg/L, and only three compounds (5l, 5o, and 5t) had
insecticidal activities at the concentration of 12.50 mg/L. In addition, compounds 5l,
5o, 5t, 6l, 6n, and 6p exhibited good insecticidal activities against oriental armyworm
with mortality rates of 56.67%, 50.00%, 60.00%, 56.67%, 53.67%, and 50.00%,
respectively, at 12.50 mg/L, which were superior to those of doramectin (20.00%),
avermectins (23.33%), and chlorbenzuron (40.00%) under the same concentration.
Interestingly, compounds 6o and 6t with mortality rates of 66.67% and 73.33%
showed a much more potent inhibitory effect against oriental armyworm than the
most effective 3g (60.00%), as reported in our previous paper. The insecticidal
activity of compound 6t against oriental armyworm was the highest, and the LC50
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value of 6t (LC50= 6.2816 mg/L) was 5.08-fold that of avermectins (LC50= 31.9488
mg/L), 6.21-fold that of doramectin (LC50= 39.0069 mg/L), and 1.29-fold that of 3g
(LC50= 8.1391 mg/L).
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Insecticidal Activity against Corn Borer. From Table 1 and Table 2, several
compounds (5l, 5o, 5t, 6l, 6o, 6n, 6p, and 6t) exhibited excellent insecticidal activities
against diamondback moth or oriental armyworm among all synthesized compounds.
For further evaluation of the insecticidal efficacy of these compounds, the results of
insecticidal activities against corn borer are shown in Table 3. From Table 3, we
found that all compounds had insecticidal efficacy at concentrations from 200.00 to
25.00 mg/L, and only compound 6p lost insecticidal activity at a concentration of
12.50 mg/L. Additionally, compounds 5o, 5t and 6t exhibited insecticidal activities
higher than those of doramectin, avermectins, chlorbenzuron and diafenthiuron.
Specifically, compound 5o showed the highest insecticidal activity with a mortality
rate of 60.00% at a concentration of 12.50 mg/L, which was superior to those of 5t
(43.33%), 6t (40.00%), and the contrast 3g (36.67%) at the same concentration. The
LC50 values of compounds 5o, 5t, 6t and 3g against corn borer were 10.0931,
22.7966, 26.7018 and 23.0991 mg/L, respectively. Compound 5o exhibited better
insecticidal activity than 3g.
Structure-Activity Relationship (SAR). A comparison of the insecticidal
activities of different types of doramectin acylurea and acylthiourea derivatives is
shown in Table 1, Table 2, and Table 3. The overall contrasting trends are given as
follows: (1) insecticidal activities against diamondback moth: acylurea > acylthiourea
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groups, such as, 5t >> 6t, 5o > 6o; 4-aromatic-substituted compounds (5g, 5j) are
superior to 2-aromatic-substituted compounds (5b-5d) and 3-aromatic-substituted
compounds (5e, 5f); cyclopropyl-substituted compound (5o) is better than other
alkyl-substituted compounds (5l-5n, 5p, 5q); (2) insecticidal activities against oriental
armyworm: acylthiourea > acylurea groups, such as, 6t > 5t, 6o > 5o, 6p >> 5p;
alkyl-substituted acylthiourea compounds (6l, 6n-6p) are superior to monosubstituted
aromatic compounds (6a-6k); compound 6t has the highest activity; (3) insecticidal
activities against corn borer: 5o > 5t > 6t.
Docking Analysis. To better elucidate the effect of the acylurea and acylthiourea
moieties on insecticidal activity against diamondback moth, we selected the sequence
of Plutella xylostella Rdl-1 for homology modeling to investigate the binding mode
between three compounds (5o, 5t, and 6t) and the target protein using
Schrodinger-Glide. Compounds 5o, 5t, and 6t were docked into human glycine
receptor alpha-3, and the detailed interactions of the compounds and receptor are
shown in Figure 2. Due to the different substituents at C4" position, different types of
hydrogen bonds were formed. The acylureas and acylthioureas contained two NH
groups and were highly susceptible to more hydrogen bonds with the target protein.
As shown in Figure 2, two N−H···O H-bonds (1.64 and 2.15 Å for 5o; 2.20 and 2.30
Å for 6t) were formed between two NH groups on acylurea and the oxygen atom of
Asp165. Impressively, four hydrogen bonds were formed between the acylurea of
compound 5t and the target protein. Two NH groups on acylurea of compound 5t
formed N−H···O H-bonds (2.17 and 2.56 Å) with the oxygen atom of Asp165, and
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two CO groups on acylurea also formed O···H H-bonds (2.20 and 2.83 Å) with the
hydrogen atom of Asn164. Among the three compounds, the hydrogen bonds between
compound 5t and the receptor protein in the docking simulation were the most
numerous and strongest. Accordingly, compound 5t, with the strongest H-bonding
strengths, exhibited the highest insecticidal activity against diamondback moth
compared with 5o and 6t.
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To better explain the structure-activity relationship, we also calculated the binding
free energy, as shown in Table 5, and compared the binding conformations of 5o and
5t with those of the lead compound 3g (described in our previous study) and 6t,
respectively. The results (Table 5) showed that the binding free energy of 5o (-3.637
kcal mol-1) was comparable to that of 3g (-3.964 kcal mol-1), and the binding free
energy of 5t (-1.758 kcal mol-1) was much lower than that of 6t (-0.821 kcal mol-1).
Additionally, the H-bonding strengths of 5o (1.64 and 2.15 Å) were comparable to
those of 3g (2.12 and 2.31 Å), whereas the H-bonding strengths of 5t (2.17, 2.20, 2.56
and 2.83 Å) were much better than those of 6t (2.20 and 2.30 Å) at the C4" position.
The docking results of compounds 5o, 5t, 6t and 3g were in good agreement with our
insecticidal assays; the activity of 5o with acylurea was comparable to that of 3g with
carbamate and the activity of 5t with acylurea was better than that of 6t. From the
results above, it can be preliminarily concluded that the insecticidal activity of our
synthesized compounds had a positive correlation with the H-bonds at the C4"
position.
In conclusion, forty-four novel doramectin derivatives containing acylurea and
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acylthiourea groups were designed and synthesized based on hydrogen bonds. The
results from bioassays of the insecticidal activities were evaluated. Compounds 5t, 6t,
and 5o exhibited excellent insecticidal activities against diamondback moth, oriental
armyworm and corn borer, respectively. Molecular docking also showed that
compound 5t formed stronger hydrogen bonds with the target protein, and the docking
result was consistent with the corresponding insecticidal activity test result. Therefore,
the rationality of the designed novel doramectin derivatives based on hydrogen
bonding was fully supported in our study. A future detailed study on the structural
optimization and mechanism of action are in progress at our laboratory.
Acknowledgements
This work is partly supported by the National Science Foundation of China (No.
21861142007) and the Biological Resources Programme, Chinese Academy of
Sciences (No. KFJ-BRP-008).
Supporting Information
Supplementary data associated with this article can be found in Supporting
1
Information. H NMR and 13C NMR data and spectrums of compounds 5a-5v, 6a-6v
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were available free of charge via the Supporting Information.
REFERENCES
(1) Oben, E. O.; Ntonifor, N. N.; Kekeunou, S.; and Abbeytakor, M. N. Farmers
438
439
440
knowledge and perception on maize stem borers and their indigenous control
methods in south western region of Cameroon. J. Ethnobiol. Ethnomed. 2015,
11(77), 1-13.
20
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Page 21 of 33
Journal of Agricultural and Food Chemistry
441
(2) Ren, Z. L.; Zhang, J.; Li, H. D.; Chu, M. J.; Zhang, L. S.; Yao, X. K.; Xia, Y.; Lv,
X. H.;, and Cao H. Q. Design, Synthesis and Biological Evaluation of
α-Aminophosphonate Derivatives Containing a Pyrazole Moiety. Chem. Pharm.
Bull. 2016, 64, 1755-1762.
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
(3) Nguyen, B. C. Q.; Chompoo, J.; and Tawata, S. Insecticidal and Nematicidal
Activities of Novel Mimosine Derivatives. Molecules. 2015, 20, 16741-16756.
(4) Zhao, Q. Q.; Li, Y. Q.; Xiong, L. X.; Wang, Q. M. Design, synthesis and
insecticidal
activity
of
novel
phenylpyrazoles
containing
a
2,2,2-trichloro-1-alkoxyethyl moiety. J. Agric. Food. Chem. 2010, 58, 4992-4998.
(5) Chen, L.; Huang, Z. Q.; Wang, Q. M.; Shang, J.; Huang, R. Q.; and Bi, F. C.
Insecticidal Benzoylphenylurea-S-Carbamate: A New Propesticide with Two
Effects of Both Benzoylphenylureas and Carbamates. J. Agric. Food. Chem. 2007,
55, 2659-2663.
(6) Ma, H. J.; Xie, R. L.; Zhao, Q. F.; Mei, X. D.; and Ning, J. Synthesis and
Insecticidal Activity of Novel Carbamate Derivatives as Potential Dual-Binding
Site Acetylcholinesterase Inhibitors. J. Agric. Food. Chem. 2010, 58,
12817-12821.
(7) Chang, F.; Dutta, S.; Becnel, J. J.; Estep, A. S.; and Mascal, Mark. Synthesis of
the Insecticide Prothrin and Its Analogues from Biomass-Derived 5 ‑
(Chloromethyl) furfural. J. Agric. Food. Chem. 2014, 62, 476-480.
(8) Nishii, Y.; Maruyama, N.; Wakasugi, K.; and Tanabe, Y. Synthesis and
Stereostructure–Activity Relationship of Three Asymmetric Center Pyrethroids:
21
ACS Paragon Plus Environment

Journal of Agricultural and Food Chemistry
Page 22 of 33
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
2-Methyl-3-phenylcyclopropylmethyl 3-Phenoxybenzyl Ether and Cyanohydrin
Ester. Bioorg. Med. Chem. 2001, 9, 33-39.
(9) Bird, L. J.; Downes, S. J. Toxicity and Cross-Resistance of Insecticides to
Cry2Ab-Resistant and Cry2Ab-Susceptible Helicoverpa armigera and Helicoverpa
punctigera(Lepidoptera: Noctuidae). J. Econ. Entomol. 2014, 107(5), 1923-1930.
(10)Mrozik, H.; Eskola, P.; Fisher, M. H.; Egerton, J. R.; Cifelli, S.; Ostlind, D. A.
Avermectin acyl derivatives with anthelmintic activity. J. Med. Chem. 1982. 25:
658-663.
(11)Mrozik, H.; Linn, B. O.; Eekola, P.; Lusi, A.; Matzuk, A.; Preiser, F. A.; Ostlind,
D. A.; Schaeffer, J. M.; Fisher, M. H. Syntheses and biological activities of
13-substituted avermectin aglycons. J. Med. Chem. 1989, 32, 375-381.
(12)Blizzard, T.; Margiatto, G.; Linn, B.; Mrozik, H.; Fisher, M. Avermectin analogs
with a spacer betweenthe aglycone and the disaccharide. Bioorg. Med. Chem. Lett.
1991, 1, 369-372.
(13)Campbell, W. C. Fisher, M. H.; Stapley, E. O.; Albers-Schönberg, G.; Jacob, T.
A. Ivermectin: a potent new antiparasitic agent. Science, 1983, 221, 823-828.
(14)Shang, Q.; Shi, Y. L.; Zhang, Y. H.; Zheng, T.; Shi, H. Y. Pesticide-conjugated
polyacrylate nanoparticles；novel opportunities for improving the photostability
of emamectin benzoate. Polym. Adv. Technol. 2013, 24, 137-143.
(15)Shoop, W. L.; Egerton J. R.; Eary, C. H.; Haines, H. W.; Turner, M. J.
Eprionomectin: a novel avermectin for use as a topical endectocide for cattle. Int.
J. Parasitol. 1996, 26, 1237-1242.
22
ACS Paragon Plus Environment

Page 23 of 33
Journal of Agricultural and Food Chemistry
485
(16)Pang, S.; Qi, S. Z.; Ran, Z. J.; Song, X. Y.; Li, X. F.; Wang, C. J.; Duan, L. S.
Synergistic effect of gamma-aminobutyric acid with avermectin on Bombyx mori.
J. Food. Agric. Environ. 2013, 11(1), 1022-1024.
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
(17)Zhang, Q.; Bai, P.; Zheng, C.; Cheng, Y.; Wang, T.; Lu, X. X. Design, synthesis,
insecticidal activity and molecular docking of doramectin derivatives. Bioorg.
Med. Chem. 2019, 27, 2387-2396.
(18)Tomizawa, M.; Yamamoto, I. Structure activity relationships of nicotinoids and
imidacloprid analogs. J. Pesticide Sci. 1993, 18, 91–98.
(19)Kagabu, S.; Matsuno, H. Chloronicotinyl insecticides. 8. Crystal and molecular
structures of imidacloprid and analogous compounds. J. Agric. Food Chem. 1997,
45, 276–281.
(20)Tomizawa, M.; Zhang, N. J.; Durkin, K. A.; Olmstead, M. M.; Casida, J. E. The
neonicotinoid electronegative pharmacophore plays the crucial role in the high
affinity and selectivity for the Drosophila nicotinic receptor: an anomaly for the
nicotinoid cation-π interaction model. Biochemistry. 2003, 42, 7819–7827.
(21)Wang, Y.; Cheng, J.; Qian, X.; Li, Z. Actions between neonicotinoids and key
residues of insect nAChR based on an ab initio quantum chemistry study:
Hydrogen bonding and cooperative π−π interaction. Bioorg. Med. Chem. 2007, 15,
2624−2630.
(22)Sun, R. F,; Lv, M. Y.; Chen, L.; Li, Q. S.; Song, H. B.; Bi, F. C.; Huang, R. Q.;
and Wang, Q. M. Design, Synthesis, Bioactivity, and Structure-Activity
Relationship (SAR) Studies of Novel Benzoylphenylureas Containing Oxime
23
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Journal of Agricultural and Food Chemistry
Page 24 of 33
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
Ether Group. J. Agric. Food. Chem. 2008, 56, 11376−11391.
(23)Saeed, A.; Batool, M. Synthesis and bioactivity of some new 1-tolyl-3-aryl-4-
methylimidazole-2-thiones. Med. Chem. Res. 2007, 16, 143–154.
(24)Han, J. T.; Dong, H. B.; Xu, Z. H.; Wang, J. M.; and Wang, M. G. Synthesis and
Activity of Novel Acylthiourea with Hydantoin. Int. J. Mol. Sci. 2013, 14,
19526-19539.
(25)Antonio, S.; Helene, F.; Hermine, R.; Elisabeth, T.; Angele, S.; André, M.;
Fabrizio, M.; Maurizio, T.; and Martial, R. Acylthiourea, acylurea, and
acylguanidine derivatives with potent hedgehog inhibiting activity. J. Med. Chem.
2012, 55, 1559−1571.
(26)Venables, B. L.; Sin. N.; Wang, X. D., et al. P3-P4 ureas and reverse carbamates
as potent HCV NS3 protease inhibitors: Effective transposition of the P4 hydrogen
bond donor. Bioorg. Med. Chem. Lett. 2018, 28, 1853–1859.
(27)Wang, S.; Allan, R. D.; Skerritt, J. H.; and Kennedy, I. R. Development of a
Class-Specific Competitive ELISA for the Benzoylphenylurea Insecticides. J.
Agric. Food. Chem. 1998, 46, 3330−3338.
(28)Tan, S. S.; Yanagisawa, S.; Inagaki, K.; Morikawa, Y. and KassimTai, M. B.
Augmented pH-sensitivity absorbance of a ruthenium(II) bis(bipyridine) complex
with elongation of the conjugated ligands: an experimental and theoretical
investigation. Phys.Chem.Chem.Phys. 2017, 19, 25734—25745.
(29)Zhao, J. H.; Xu, X. J.; Ji, M. H.; Cheng, J. L.; Zhu, G. N. Design, synthesis, and
biological activities of milbemycin analogues. J. Agric. Food. Chem. 2011, 59,
24
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529
4836-4850.
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
(30)Zhang, J.; Nan, X.; Yu, H. T.; Cheng, P. L.; Zhang, Y.; Liu, Y. Q.; Zhang, S. Y.;
Hu, G. F.; Liu, H. X.; Chen, A. L. Synthesis, biological activities and
structureactivity relationships for new avermectin analogues. Eur. J. Med. Chem.
2016, 121, 422−432.
(31)Huang, Z. Q.; Cui, Q. M.; Xiong, L. X.; Wang, Z. W.; Wang, K. Y.; Zhao, Q. Q.;
Bi, F. C.; Wang, Q. M. Synthesis and insecticidal activities and SAR studies of
novel benzoheterocyclic diacylhydrazine derivatives. J. Agric. Food. Chem. 2009,
57, 2447-2456.
(32)Luo, Y. P.; Yang, G. F. Discovery of a new insecticide lead by optimizing a
target-diverse scaffold: tetrazolinone derivatives. Bioorg. Med. Chem. 2007, 15,
1716-1724.
(33)Busvine, J. R. FAO Plant production and protection paper; Food and Agriculture
Organization (FAO): Rome, Italy, 1980; no. 21, pp 3-13, 119-122.
(34)Abbott, W. S. A method of computing the effectiveness of an insecticide. J. Econ.
Entomol. 1925, 18, 265-267.
545
546
547
548
549
550
551
552
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Page 26 of 33
553
554
555
556
Figure captions
557
558
559
560
561
562
Figure 1. Design of target compounds.
Figure 2. Molecular docking of compounds 5o, 5t, and 6t.
Scheme 1. General Procedure for Synthesis of Acylurea Derivatives of Doramectin
(5a-5v).
Scheme 2. General Procedure for Synthesis of Acylthiourea Derivatives of
Doramectin (6a-6v).
O
H
H
O
O
O
O
O
N
O
4"
O
25
O
O
O
O
OH
H-donor
O
C4"
H
OH
Compound 3g
H-bonding
H-bonding
Oriental armyworm LC50(5.8859 mg/L)
Corn borer LC50(22.0205 mg/L)
Diamondback moth LC50(22.3214 mg/L)
Our previous work, BMC, 2019, 27, 2387
O
H
H
H
N
O
O
O
O
O
R
N
F
F
F
Cl
4"
O
O
25
O
C
O
O
C
S
O
O
More
H-donor
O
NH C NH
Cl
NH C NH
O
Cl
O
OH
F
Cl
O
Acylthiourea insecticide
Benzoylurea insecticide
H
OH
Excellent
insecticidal
activity
More
H-donor
Combination
principles
O
O
H
H
O
O
O
O
O
H2N
O
O
O
O
O
HO
4"
O
O
25
4"
O
O
25
O
H
H
O
H
O
O
N
O
O
O
O
R
N
O
4"
O
O
OH
25
OH
O
S
O
O
O
O
O
OH
H
H
4"-NH2-DorameOcHtin
OH
Doramectin
O
H
OH
Our present work
563
564
Figure 1. Design of target compounds.
565
566
567
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Journal of Agricultural and Food Chemistry
568
569
570
571
572
5o
573
574
5t
575
576
6t
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Journal of Agricultural and Food Chemistry
Page 28 of 33
577
578
579
Figure 2. Molecular docking of compounds 5o, 5t, and 6t. The H-bonding distance
of 5o (1.64, 2.15 Å), 5t (2.17, 2.20, 2.56, 2.83 Å), and 6t (2.20, 2.30 Å) at
the C4″ position.
580
581
582
Scheme 1. General Procedure for Synthesis of Acylurea Derivatives of
Doramectin (5a-5v).
23
O ''
23
22
O ''
H
14
13
16
24
3
'
'
22
''
''
H
5 O 1 O
O
14
13
16
HO
24
27
3
'
'
2
1
''
''
''
''
5 O 1 O
O
HO
27
21
2
1
4
5
17
18
15
''
28
29
'
25
O
21
4
17
18
'
26
15
4
'
28
29
'
25
''
O
2
3
19 20
'
26
4
'
2
5
11
12
10
19 20
O
O
3
31
11
12
10
O
O
31
30
O
O
TBDMSCl, DMAP
O
30
O
O
O
1
9
OH
1
9
OH
CH2Cl2, imidazole, rt
2
3
4
8
7
6
2
3
4
8
8a
7
6
8a
5
O
5
O
H
H
OTBS
OH
2
(5-O-TBDMS Doramectin)
1
(Doramectin)
23
O ''
23
22
H
14
13
16
O ''
24
3
'
'
22
''
''
5 O 1 O
O
H2N
27
H
14
16
2
1
24
3
'
'
''
''
''
''
5 O 1 O
O
21
O
4
5
17
18
27
15
2
1
28
29
'
25
''
''
O
'
26
21
4
'
4
5
13
17
18
15
28
29
2
19 20
'
25
3
O
'
26
11
4
'
12
10
O
O
31
2
19 20
3
11
12
10
O
O
31
30
O
O
O
30
O
O
1
O
NH4OAc, NaCNBH3
MeOH, rt
9
OH
1
9
PhOPOCl2,TEA,DMSO
DCM, -15 o
OH
2
3
4
8
7
6
2
2
3
4
8a
8
7
6
5
C
8a
O
5
O
H
OTBS
H
OTBS
4
3
583
23
23
O ''
O ''
22
H
H
22
H
14
16
24
'
'
H
3
14
16
24
'
'
''
3
5 O 1 O
O
R
N
N
''
''
27
5 O 1 O
O
2
1
H2N
27
''
''
2
1
''
''
21
4
5
13
17
18
''
15
21
28
29
4
5
13
17
15
'
25
O
28
29
'
25
'
26
O
4
'
2
'
26
O
O
4
'
19 20
3
18
2
19 20
3
11
12
10
O
O
11
31
12
10
O
O
31
1) RCONCO, DMAP, DCM
30
O
O
30
O
O
O
O
1
9
1
OH
9
OH
2) TsOH/CH3OH
2
3
4
8
2
3
4
7
6
8
7
6
8a
8a
5
5
O
O
H
H
OH
OTBS
5
4
5a
5b
5g
5h
5i
5j
5m
5n
5o
5p
5q
5s
5t
5u
: Ph;
: 2-F-Ph;
: 2-Cl-Ph;
: 4-F-Ph;
: CH3CH2;
: CH3CH2CH2;
: C3H5;
: 2,5-difluorophenyl;
: 2,6-difluorophenyl;
: 3,5-dimethoxyphenyl;
: 4-Cl-Ph;
: 4-Br-Ph;
: 4-OCH3-Ph;
5c
5d
5e
5v
: 3,4,5-trimethoxyphenyl
: 2-CF3-Ph;
: 3-CH3-Ph;
: 3-CF3-Ph;
: C6H11
;
5k
5l
: 4-CF3-Ph;
: CH3;
: CH3CH2CH2CH2CH2;
: 2,4-difluorophenyl;
5f
5r
584
585
586
587
588
Scheme 2. General Procedure for Synthesis of Acylthiourea Derivatives of
Doramectin (6a-6v).
23
O ''
23
22
H
H
H
O ''
14
13
16
24
3
'
'
22
''
''
5 O 1 O
O
R
N
N
H
27
14
13
16
24
2
1
3
'
'
''
''
''
''
5 O 1 O
O
H2N
21
27
4
5
17
18
2
1
15
28
29
''
''
'
25
O
'
26
21
4
5
17
18
4
3
'
15
O
S
28
2
19 20
'
25
O
'
26
4
'
11
12
10
O
O
2
19 20
31
3
29 1) RCONCS, DMAP, DCM
11
12
10
O
O
31
30
O
O
O
30
O
O
O
1
9
OH
1
9
OH
2
3
4
2) TsOH/CH3OH
8
7
6
2
3
4
8a
8
7
6
5
8a
O
5
O
H
OH
H
4
OTBS
6
6a
6b
6c
6d
6e
6g
6h
6i
6j
6m
6s
: Ph;
: 2-F-Ph;
: 2-Cl-Ph;
: 2-CF3-Ph;
: 3-CH3-Ph;
: 3-CF3-Ph;
: 4-F-Ph;
: CH3CH2;
: 2,5-difluorophenyl;
6n
6o
6p
6q
6t
6u
: 4-Cl-Ph;
: 4-Br-Ph;
: 4-OCH3-Ph;
: CH3CH2CH2;
: C3H5;
: C6H11
: CH3CH2CH2CH2CH2;
: 2,4-difluorophenyl;
: 2,6-difluorophenyl;
: 3,5-dimethoxyphenyl;
6v
;
: 3,4,5-trimethoxyphenyl;
6k
6l
: 4-CF3-Ph;
: CH3;
6f
6r
589
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591
592
593
Table 1. Insecticidal Activities of Doramectin Derivatives Against Diamondback Moth.
Compd.
200.00 (mg/L)
100.00 (mg/L)
50.00 (mg/L)
25.00 (mg/L) 12.50 (mg/L)
5a
5b
5c
5d
5e
5f
50.00%
56.67%
70.00%
100.00%
40.00%
43.33%
80.00%
46.67%
76.67%
100.00%
30.00%
33.33%
90.00%
70.00%
90.00%
63.33%
40.00%
0
36.67%
33.33%
60.00%
60.00%
10.00%
20.00%
60.00%
20.00%
60.00%
83.33%
10.00%
20.00%
80.00%
50.00%
80.00%
43.33%
20.00%
0
30.00%
0
10.00%
0
0
0
30.00%
30.00%
0
23.33%
0
0
0
0
0
13.33%
50.00%
10.00%
33.33%
70.00%
0
0
0
5g
5h
5i
36.66%
30.00%
0
0
20.00%
10.00%
5j
40.00%
30.00%
5k
5l
0
0
0
0
0
5m
5n
5o
5p
5q
5r
5s
63.33%
36.67%
63.33%
40.00%
10.00%
0
30.00%
0
23.33%
10.00%
50.00%
40.00%
23.33%
10.00%
0
0
0
0
36.67%
100.00%
0
20.00%
100.00%
0
0
0
0
5t
100.00%
0
90.00%
80.00%
5u
5v
6a
6b
6c
6d
6e
6f
0
0
50.00%
30.00%
0
20.00%
26.67%
0
0
0
0
20.00%
0
0
0
0
0
30.00%
50.00%
0
13.67%
30.00%
0
0
0
0
0
0
0
0
0
0
70.00%
73.33%
0
53.33%
40.00%
0
40.00%
30.00%
0
33.33%
0
6g
6h
6i
10.00%
0
0
0
0
0
0
0
0
6j
40.00%
63.33%
90.00%
50.00%
56.67%
76.67%
0
33.33%
46.67%
80.00%
36.33%
50.00%
50.00%
0
0
0
0
6k
6l
20.00%
53.33%
30.00%
10.00%
40.00%
0
10.00%
0
30.00%
20.00%
6m
6n
6o
6p
0
0
0
36.33%
0
0
20.00%
0
29
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