Natural-product-based pesticides: Semisynthesis, structural elucidation, and evaluation of new cholesterol–matrine conjugates as pesticidal agents

Article abstract of DOI:10.1016/j.bmcl.2021.128350

To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new cholesterol–matrine conjugates (I(a–e)–IV(a–e)) were prepared from two lead compounds cholesterol and matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3 and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0 folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads for further structural optimization as the insecticidal and aphicidal agents.

Full text of DOI:10.1016/j.bmcl.2021.128350

Bioorg. Med. Chem. Lett. 50 (2021) 128350
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Natural-product-based pesticides: Semisynthesis, structural elucidation,
and evaluation of new cholesterol–matrine conjugates as pesticidal agents
,
,*
Jianwei Xua, Min Lva *, Meng Haoa, Tianze Lia, Shaoyong Zhangb, Hui Xua
a College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi Province, PR China
b Key Laboratory of Vector Biology and Pathogen Control of Zhejiang Province, College of Life Science, Huzhou University, Huzhou 313000, Zhejiang Province, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords:
To develop new potential pesticide candidates from low value-added natural bioactive products, a series of new
cholesterol–matrine conjugates (I(a–e)–IV(a–e)) were prepared from two lead compounds cholesterol and
matrine. Against Mythimna separata Walker, compound IVa exhibited 3.0 and 2.6 folds promising insecticidal
activity of cholesterol and matrine, respectively; against Aphis citricola Van der Goot, compound IVd showed 4.3
and 2.2 folds potent aphicidal activity of their precursors; notably, it also showed good control effects in the
Synthesis
Matrine
Cholesterol
Pesticidal activity
Control efficiency
greenhouse; against Plutella xylostella Linnaeus at a dose of 20 μg/nymph, compound IIIe exhibited 2.8 and 2.0
folds oral toxicity of cholesterol and matrine, respectively. Compounds IIIe, IVd and IVe can be used as the leads
for further structural optimization as the insecticidal and aphicidal agents.
A steroidal natural product cholesterol (Fig. 1), a derivative of
cyclopentane polyhydrophenanthrene, is an indispensable substance for
human and animal cells. As an important component of mammalian cell
membranes, for instance, cholesterol can efficiently regulate the related
structures and functions of lipid bilayers.1 On the other hand, choles-
terol has recently been used as a lead compound for synthesis of
cholesterol-type analogs which displayed lots of biological properties
including antitumor activity,2 antioxidant activity,3,4 antileishmanial
activity,5,6 and antimicrobial activity.7,8 In our previous paper, to our
delight, we found that some hydrazones derivatives of cholesterol at the
C-7 position showed more potent insecticidal activity than toosendanin;
notably an intermediate, 3-acetyloxy-7-oxocholesterol (Fig. 1), also
exhibited the promising insecticidal activity.9 Matrine (Fig. 1) is isolated
as the main component from Sophora alopecuroides, Sophora subprostrata
and Sophora flavescens which are found in China, Japan and some Eu-
ropean countries.10 Although matrine was registered as a botanical
pesticide in China, its pesticidal activities were much lower in magni-
tude than those of commercially agrochemicals.11 To increase its pes-
ticidal activities, therefore, structural optimization of matrine has been
extensively carried out.12–15 Interestingly, a series of matrinic acids
(Fig. 1) were found to show the potent pesticidal activities.14
Furthermore, structural optimization of natural products as lead com-
pounds for the discovery and development of pesticide candidates has
received much attention in recent years.16–19 Based upon the above-
mentioned interesting results, and to discover natural-product-based
potential pesticide candidates, in this paper a series of new cholester-
ol–matrine conjugates (I(a–e)–IV(a–e), Fig. 1) were designed by com-
bination of 3-acetyloxy-7-oxocholesterol and matrinic acids fragments
together via the oxime group at the C-7 position of cholesterol. Their
agricultural activities were evaluated against three typically crop-
threatening pests, Mythimna separata Walker, Aphis citricola Van der
Goot and Plutella xylostella Linnaeus. Their control efficiency was tested
against A. citricola in the greenhouse.
As described in Fig. 2, according to our previous reports,9 cholesterol
(1) was esterified with benzoyl chlorides R1COCl to afford 2a–d, which
were then oxidized by CrO3 and t-BuOOH to obtain 3a–d. Next, com-
pounds 3a–d reacted with NH2OH to give 4a–d.13,20 Compounds 6a–e
were obtained by opening the lactam of matrine (5), and subsequently
esterifying and substitution reaction with benzyl chlorides/bromides.14
Further hydrolysis of 6a–e gave matric acids 7a–e.14 Finally, new cho-
lesterol–matrine conjugates (I(a–e)–IV(a–e)) were produced by reaction
of 4a–d with 7a–e in 11%–58% yields (Fig. 3).21 The influence of the
functional groups at the C-7 position on the chemical shift of H-6 of
cholesterol derivatives was obvious. In Fig. 4, there was no obvious
difference in the chemical shifts of H-3 of 3a (δ = 4.956 ppm), 4a (δ =
Meanwhile, a large number of pesticides were extensively sprayed to
control pests, however pests resistance and negative impacts of pestici-
des residues on human health and environment accordingly appeared.
* Corresponding authors.
E-mail addresses: lvmin@nwsuaf.edu.cn (M. Lv), orgxuhui@nwsuaf.edu.cn (H. Xu).
https://doi.org/10.1016/j.bmcl.2021.128350
Received 6 February 2021; Received in revised form 19 August 2021; Accepted 26 August 2021
Available online 31 August 2021
0960-894X/© 2021 Elsevier Ltd. All rights reserved.

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
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Fig. 3. Synthetic route of target compounds I(a-e)–IV(a-e).
Fig. 1. Design of target compounds from cholesterol and matrine.
Fig. 4. Comparison of partial 1H NMR spectra of 3a, 4a, Ia and Ie.
4.925 ppm), Ia (δ = 4.900 ppm) and Ie (δ = 4.907 ppm); in contrast, the
difference in the chemical shifts of H-6 of 3a, 4a, Ia and Ie was signif-
icant, for example, the chemical shift of H-6 of 3a was at 5.748 ppm,
whereas the chemical shifts of H-6 of 4a, Ia and Ie were at 6.621, 6.451
Fig. 2. Synthetic routes of (a) intermediates 4a–d, and (b) intermediates 7a–e.
2

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
and 6.441 ppm. Due to the carbonyl group at the C-7 position of 3a was
substituted by the oxime, the corresponding chemical shifts of H-6 of 4a,
Ia and Ie were all moved to the low field. The chemical shifts of two
hydrogen atoms of H-1′ of Ia and Ie were at 3.08/4.07 and 3.05/4.03
ppm, respectively. Their structures were characterized by optical rota-
tion, IR, 1H NMR or 13C NMR, and mp (see Supplementary data).
Compounds 4a (CCDC: 2013575) and IVe (CCDC: 2024764) were
further determined by X-ray crystallography (Fig. 5).
Table 1
Growth inhibitory activity of compounds 1, 2a–d, 3a–d, 4a–d, 5 and I(a–e)–IV
(a–e) against M. separata at 1 mg/mL.
Compound
Corrected mortality rate (mean ± SE, %)
10 days
20 days
35 days
1
6.7 ± 3.3
16.7 ± 3.3
20.0 ± 0
20.7 ± 3.3
24.1 ± 3.3
44.8 ± 6.7
27.6 ± 5.8
44.8 ± 3.3
51.7 ± 3.3
41.4 ± 3.3
31.0 ± 3.3
41.4 ± 3.3
37.9 ± 0
5
10.0 ± 0
2a
36.7 ± 3.3
13.3 ± 3.3
36.7 ± 3.3
36.7 ± 6.7
30.0 ± 5.8
20.0 ± 0
36.7 ± 3.3
26.7 ± 3.3
43.3 ± 3.3
36.7 ± 6.7
43.3 ± 3.3
30.0 ± 5.8
40.0 ± 5.8
33.3 ± 6.7
26.7 ± 6.7
40.0 ± 5.8
30.0 ± 5.8
40.0 ± 5.8
30.0 ± 5.8
23.3 ± 3.3
33.3 ± 3.3
30.0 ± 5.8
40.0 ± 5.8
36.7 ± 3.3
40.0 ± 5.8
26.7 ± 3.3
23.3 ± 6.7
33.3 ± 3.3
33.3 ± 3.3
36.7 ± 3.3
40.0 ± 5.8
33.3 ± 6.7
26.7 ± 3.3
43.3 ± 3.3
26.7 ± 3.3
26.7 ± 3.3
30.0 ± 5.8
36.7 ± 3.3
30.0 ± 5.8
In Table 1, at 1 mg/mL against M. separata,22 the results revealed
that the insecticidal activity of all derivatives was improved when
compared with their precursors matrine and cholesterol. The final
mortality rates (FMRs) of 2d, IIb, IId, IVa, IVd and IVe were 51.7%,
55.1%, 48.2%, 62.0%, 51.7% and 48.2%, respectively, which exhibited
more potent insecticidal activity than toosendanin. The FMRs of 2d, IIb,
IVa and IVd were greater than 50%. Among them, compound IVa
showed the best insecticidal activity. There was no significant difference
in the insecticidal activity between 2a–c and 3a–c, and it generally
demonstrated that introduction of a carbonyl group at the C-7 position
of 2a-c has no perceptible effect on the insecticidal activity. To conju-
gates IIa–e, compounds IIb (R1 = p-methylphenyl, R2 = p-methylbenzyl;
FMR: 55.1%) and IId (R1 = p-methylphenyl, R2 = p-chlorobenzyl; FMR:
48.2%) displayed more promising insecticidal activity than their pre-
cursors and toosendanin. To conjugates IVa–e, compounds IVa (R1 = p-
methoxyphenyl, R2 = benzyl), IVd (R1 = p-methoxyphenyl, R2 = p-
chlorobenzyl), and IVe (R1 = p-methoxyphenyl, R2 = p-fluorobenzyl)
showed the pronounced insecticidal activity with the FMRs of 62.0%,
51.7% and 48.2%, respectively.
2b
2c
2d
3a
3b
3c
30.0 ± 5.8
16.7 ± 6.7
26.7 ± 6.7
36.7 ± 6.7
23.3 ± 3.3
33.3 ± 8.8
23.3 ± 6.7
23.3 ± 3.3
30.0 ± 5.8
20.0 ± 0
3d
4a
31.0 ± 6.7
44.8 ± 3.3
31.0 ± 3.3
44.8 ± 3.3
31.0 ± 3.3
31.0 ± 6.7
34.5 ± 6.7
37.9 ± 5.8
44.8 ± 3.3
37.9 ± 0
4b
4c
4d
Ia
Ib
Ic
Id
Ie
36.7 ± 6.7
30.0 ± 5.8
20.0 ± 5.8
13.3 ± 3.3
23.3 ± 6.7
33.3 ± 3.3
23.3 ± 3.3
30.0 ± 5.8
36.7 ± 3.3
33.3 ± 6.7
23.3 ± 3.3
43.3 ± 3.3
23.3 ± 6.7
16.7 ± 3.3
20.0 ± 5.8
33.3 ± 3.3
26.7 ± 3.3
IIa
IIb
IIc
55.1 ± 3.3
31.0 ± 6.7
48.2 ± 0
IId
IIe
IIIa
IIIb
IIIc
IIId
IIIe
IVa
IVb
IVc
IVd
IVe
toosendanin
37.9 ± 5.8
37.9 ± 5.8
44.8 ± 6.7
37.9 ± 5.8
37.9 ± 0
In Fig. 6, the largest part of the percentages of FMRs at three growth
37.9 ± 5.8
62.0 ± 3.3
27.6 ± 0
31.0 ± 3.3
51.7 ± 3.3
48.2 ± 5.8
44.8 ± 3.3
Fig. 6. The percentages of final mortality rates (FMRs) at three growth stages of
M. separata treated with 2d, IIb, IId, IVa, IVd and toosendanin.
stages of M. separata treated with 2d, IIb, IId, IVa and IVd was at the
larval stage, and it was in accordance with that of toosendanin. Com-
pounds 2d, IIb, IId, IVa and IVd may have the similar mechanism of
action with toosendanin against M. separata. At the larval stage, some
poisoned larvae were dehydrated and curled up eventually to die
(Fig. 7). At the pupal stage, some deformed pupae appeared (Fig. 8). At
the adult stage, malformed moths emerged with vestigial wings (Fig. 9).
In Table 2, at 0.04
μ
g/nymph against A. citricola,23 the 48 h MRs of
2a–d, 3a–d and 4a–d was higher than that of cholesterol. Among them,
the 48 h MR of 2d was 34.1%, which was twice as high as that of
cholesterol (17.0%). To compounds 2a–d and 4a–d, the aphicidal ac-
tivity of compounds containing p-methoxyphenyl group was slightly
higher than those containing p-methylphenyl, p-chlorophenyl and
Fig. 5. X-ray crystal structures of 4a (top) and IVe (bottom).
3

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
Fig. 7. The representative abnormal larvae pictures of M. separata treated with 2d (XJW-53), 4d (XJW-61), Ie (XJW-66), IIa (XJW-67), IIIb (XJW-73), IIIc (XJW-
74) and IVa (XJW-77) during the larval period (CK: blank control group).
Fig. 8. The representative malformed pupae pictures of M. separata treated with 2d (XJW-53), 4d (XJW-61), IIe (XJW-71), IIIa (XJW-72), IIId (XJW-75), IVa
(XJW-77) and IVe (XJW-81) during the pupation period (CK: blank control group).
4

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
Fig. 9. The representative malformed moths pictures of M. separata treated with 4b (XJW-59), 4d (XJW-61), IIb (XJW-68), IIIa (XJW-72), IVa (XJW-77), IVc
(XJW-79) and IVe (XJW-81) during the adult period (CK: blank control group).
IIIa. So introduction of a fluorine atom on the N-benzyl group of
Table 2
matrinic acid (IIIa) was necessary for the aphicidal activity. The 48 h
Aphicidal activity of compounds 1, 2a–d, 3a–d, 4a–d, 5 and I(a–e)–IV(a–e)
MRs of IVa–IVe were 22.0%, 20.9%, 30.2%, 51.2%, and 43.0%,
against A. citricola at 0.04 µg/nymph.
respectively. Obviously, introduction of a halogen atom on the N-benzyl
Compound
Corrected mortality rate (mean ± SE, %)
fragment of Iva was vital for the aphicidal activity.
24 h
48 h
In Table 3, the 48 h LD50 values of IIIe, IVd and IVe against
A. citricola were 0.045, 0.042, and 0.052 μg/nymph, respectively, so
1
7.9 ± 1.1
17.0 ± 1.1
29.5 ± 2.9
20.5 ± 2.2
27.3 ± 4.4
25.0 ± 3.8
34.1 ± 2.2
27.3 ± 2.9
23.9 ± 4.0
33.0 ± 2.9
23.9 ± 4.0
32.2 ± 2.9
27.6 ± 1.9
29.9 ± 2.9
35.6 ± 2.2
26.4 ± 2.9
31.0 ± 3.8
25.6 ± 2.2
23.3 ± 1.9
33.7 ± 1.9
36.1 ± 1.1
34.9 ± 1.1
39.5 ± 1.1
38.4 ± 1.1
32.6 ± 4.0
24.4 ± 4.0
31.4 ± 1.1
19.8 ± 1.9
33.7 ± 1.9
48.8 ± 4.0
22.0 ± 1.1
20.9 ± 2.9
30.2 ± 1.9
51.2 ± 1.9
43.0 ± 1.1
their aphicidal activity was 3.4–4.3 folds of that of cholesterol (LD50
:
5
14.6 ± 2.2
11.2 ± 1.1
16.9 ± 2.9
12.4 ± 1.9
15.7 ± 3.3
11.2 ± 1.1
14.6 ± 1.1
9.0 ± 1.9
2a
2b
2c
0.179 g/nymph), and 1.7–2.2 folds of that of matrine (LD50: 0.091 g/
μ
μ
nymph). Especially compound IVd showed 4.3 and 2.2 folds potent
aphicidal activity of cholesterol and matrine, respectively. Moreover,
compound IVd showed good control effects in the greenhouse against
A. citricola (Table 4). The control effect of IVd after 7 days was 65.8%,
however, the control effects of 1 and 5 after 7 days were only 17.4% and
32.1%, respectively.
2d
3a
3b
3c
3d
4a
4b
4c
13.4 ± 2.2
17.8 ± 2.9
14.4 ± 2.9
13.3 ± 1.9
12.2 ± 4.8
11.1 ± 1.1
15.6 ± 2.9
7.9 ± 1.1
In Table 5, at 20
μ
g/nymph against P. xylostella,22,24 when R1 was p-
chlorophenyl or p-methoxyphenyl, and R2 was p-fluorobenzyl, the 48 h
MRs of corresponding compounds IIIe and IVe were 51.2% and 46.5%,
respectively, which were better or equivalent to that of toosendanin
(46.5%). The 48 h MRs of Ia–Ie (R1 = phenyl) against P. xyllostella were
25.0%, 35.7%, 40.5%, 35.7%, and 38.1%, respectively. The oral toxicity
of Ib–Ie was higher than that of Ia, which indicated that introduction of
electron-withdrawing or electron-donating groups on the N-benzyl
fragment of Ia could lead to increasing the activity.
4d
Ia
Ib
Ic
Id
9.0 ± 1.9
Ie
15.7 ± 1.9
7.9 ± 2.2
IIa
IIb
IIc
IId
IIe
IIIa
IIIb
IIIc
IIId
IIIe
IVa
IVb
IVc
IVd
IVe
12.4 ± 1.9
6.7 ± 1.1
In summary, to discover new natural-product-based potential
14.6 ± 2.2
9.0 ± 3.3
7.9 ± 2.2
10.1 ± 2.9
17.9 ± 4.0
12.4 ± 1.9
25.8 ± 1.9
6.8 ± 2.9
Table 3
LD50 values of some compounds at 48 h against A. citricola.a.
Compound
Linear regression
equation
LD50
(
μ
g/
Confidence interval
95% ( g/nymph)
r
nymph)
0.179
μ
11.4 ± 3.3
10.2 ± 2.2
19.3 ± 1.1
14.8 ± 3.3
1
Y = 1.714 +
2.292X
0.158–0.21
0.074–0.13
0.040–0.052
0.038–0.048
0.046–0.064
0.939
0.966
0.983
0.978
0.956
5
Y = 1.605 +
1.545X
0.091
0.045
0.042
0.052
IIIe
IVd
IVe
Y = 3.399 +
2.521X
phenyl ones. Compared to that of 4b (FMR: 27.6%), the aphicidal ac-
tivity of all its corresponding target compounds IIa–IIe (R1 = p-meth-
ylphenyl; FMRs: greater than 39.5%) was increased. The 48 h MRs of
IIIa–IIIe (R1 = p-chlorophenyl) were 24.4%, 31.4%, 19.8%, 33.7% and
48.8%, respectively. IIIe showed two folds potent aphidicidal activity of
Y = 3.626 +
2.632X
Y = 2.990 +
2.331X
a
Regression analysis by IBM SPSS Statistics 20.0, P < 0.05.
5

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
the work reported in this paper.
Table 4
Control efficiency of compounds 1, 5 and IVd against A. citricola in the green-
house tests at a concentration of 1 mg/mL.
Compound
Acknowledgement
Control efficiency (mean ± SE, %)
The work was supported by National Natural Science Foundation of
China (No. 21877090, 31672071).
1st day
3rd day
5th day
7th day
1
4.3 ± 1.0
8.6 ± 1.0
11.0 ± 1.7
11.5 ± 1.4
27.5 ± 1.3
54.0 ± 1.3
15.3 ± 1.3
30.6 ± 1.3
61.2 ± 1.3
17.4 ± 2.7
32.1 ± 0.5
65.8 ± 1.4
5
Appendix A. Supplementary data
IVd
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.bmcl.2021.128350.
Table 5
Oral toxicity of compounds 1, 2a–d, 3a–d, 4a–d, 5 and I(a–e)–IV(a–e) against
References
P. xylostella at 20
Compound
μ
g/nymph.
Corrected mortality rate (mean ± SE, %)
1 Johnson BB, Anguita J, Heuck AP. Biophys J. 2013;104:86a.
2 Cui J, Lin Q, Gan C, et al. Steroids. 2014;79:14–18.
24 h
48 h
3 Choteau F, Durand G, Ranchon-Cole I, et al. Bioorg Med Chem Lett. 2010;20:
7405–7409.
1
6.8 ± 2.2
11.4 ± 0
18.6 ± 4.4
25.6 ± 2.2
30.2 ± 0
4 Kumar M, Padmini T, Ponnuvel K. J Saudi Chem Soc. 2017;21:S322–S328.
5 Bazin MA, Loiseau PM, Bories C, et al. Eur J Med Chem. 2006;41:1109–1116.
6 Ghosh P, Ghosh A, Mandal A, et al. Steroids. 2016;107:65–73.
5
2a
11.4 ± 3.8
15.6 ± 2.2
8.9 ± 2.2
13.3 ± 0
2b
27.3 ± 2.2
29.6 ± 2.2
34.1 ± 5.8
29.6 ± 5.8
34.1 ± 2.2
27.3 ± 5.8
34.1 ± 5.8
27.3 ± 2.2
29.6 ± 2.2
34.1 ± 5.8
38.6 ± 0
7 Sribalan R, Padmini V, Lavanya A, Ponnuvel K. Saudi Pharm J. 2016;24:658–668.
8 Banday MR, Farshori NN, Ahmad A, et al. Eur J Med Chem. 2010;45:1459–1464.
9 Yang C, Shao Y, Zhi X, et al. Bioorg Med Chem Lett. 2013;23:4806–4812.
10 Huang JL, Xu H. Curr Top Med Chem. 2016;16:3365–3378.
2c
2d
3a
13.3 ± 3.8
11.1 ± 4.4
13.3 ± 3.8
13.3 ± 6.6
9.1 ± 2.2
13.6 ± 2.2
18.2 ± 3.8
20.5 ± 4.4
13.6 ± 5.8
11.6 ± 4.4
7.0 ± 2.2
9.3 ± 0
3b
11 Zhong B, Lu C, Sun X, et al. Agrochemicals. 2010;49:924–926.
12 Ni W, Li C, Liu Y, et al. J Agric Food Chem. 2017;65:2039–2047.
13 Li S, Sun Z, Zhang B, et al. Ind Crop Prod. 2019;131:134–141.
14 Zhang B, Sun Z, Lv M, Xu H. J Agric Food Chem. 2018;66:12898–12910.
15 Xu H, Xu M, Sun Z, Li S. J Agric Food Chem. 2019;67:12182–12190.
16 Ji X, Guo J, Liu Y, et al. J Agric Food Chem. 2018;66:4062–4072.
17 Lin L, Mulholland N, Wu QY, et al. J Agric Food Chem. 2012;60:4480–4491.
18 Yang R, Guo Y, Zhang Y, Xu H. Chin Chem Lett. 2018;29:995–997.
19 Lv M, Sun ZQ, Li SC, et al. Bioorg Med Chem Lett. 2020;30, 127346.
20 Cui JG, Fan L, Huang LL, et al. Steroids. 2009;74:62–72.
3c
3d
4a
4b
4c
4d
Ia
25.0 ± 0
Ib
35.7 ± 3.8
40.5 ± 4.4
35.7 ± 3.8
38.1 ± 5.8
31.0 ± 2.2
26.2 ± 4.4
33.3 ± 4.4
35.7 ± 3.8
38.1 ± 5.8
40.5 ± 2.2
42.9 ± 3.8
31.0 ± 2.2
28.6 ± 3.8
51.2 ± 3.8
34.9 ± 4.4
41.9 ± 2.2
39.5 ± 5.8
30.2 ± 0
Ic
21 General procedure for synthesis of target compounds I(aꢀ e)ꢀ IV(aꢀ e): A mixture of
4aꢀ d (0.30 mmol), 7aꢀ e (0.36 mmol), DCC (0.36 mmol) and DMAP (0.06 mmol) in
dry CH2Cl2 (5 mL) was stirred at room temperature. After 72ꢀ 96 h, the mixture was
diluted with 20 mL of CH2Cl2, washed with 10 mL of H2O, 10 mL of 0.1 N aq. HCl,
10 mL of 5% aq. Na2CO3 and 10 mL of brine, and dried by anhydrous Na2SO4.
Finally, it was purified by PTLC eluting with CH2Cl2/MeOH (15:1, v/v) to afford I
(aꢀ e)ꢀ IV(aꢀ e) in 11%–58% yields. Representative data for compounds Ia–IVa are as
Id
Ie
7.0 ± 4.4
11.6 ± 4.4
14.0 ± 2.2
14.0 ± 5.8
9.1 ± 4.4
11.4 ± 3.8
11.4 ± 0
IIa
IIb
IIc
IId
IIe
IIIa
IIIb
IIIc
IIId
IIIe
IVa
IVb
IVc
IVd
IVe
toosendanin
follows: Compound Ia: Yield: 29%, white solid; mp 151ꢀ 152 ◦C; [
α]20D = -19 (c 1.8
mg/mL, CHCl3); IR cm-1 (KBr): 2933, 2860, 1762, 1717, 1631, 1539, 1454, 1272,
1118, 707. 1H NMR (500 MHz, CDCl3) δ: 8.05 (d, J = 7.5 Hz, 2H, Ar-H), 7.55ꢀ 7.58
(m, 1H, Ar-H), 7.43ꢀ 7.46 (m, 2H, Ar-H), 7.31ꢀ 7.33 (m, 2H, Ar-H), 7.26ꢀ 7.28 (m,
2H, Ar-H), 7.16ꢀ 7.19 (m, 1H, Ar-H), 6.45 (s, 1H, -CH=C), 4.90ꢀ 4.96 (m, 1H, -OCH),
4.10 (d, J = 14.0 Hz, 1H), 3.11 (d, J = 13.5 Hz, 1H), 2.74-2.88 (m, 3H), 2.49ꢀ 2.69
(m, 4H), 2.31ꢀ 2.45 (m, 4H), 2.03ꢀ 2.09 (m, 3H), 1.88ꢀ 1.99 (m, 4H), 1.73ꢀ 1.86 (m,
6H), 1.64ꢀ 1.70 (m, 2H), 1.50ꢀ 1.57 (m, 7H), 1.30ꢀ 1.41 (m, 9H), 1.25 (s, 2H),
1.01ꢀ 1.18 (m, 9H), 0.93 (d, J = 6.5 Hz, 3H), 0.87 (d, J = 2.5 Hz, 3H), 0.86 (d, J =
2.5 Hz, 3H), 0.70 (s, 3H). Compound IIa: Yield: 16%, white solid; mp 121ꢀ 122 ◦C;
15.9 ± 5.8
13.6 ± 4.4
20.5 ± 5.8
26.7 ± 3.8
17.8 ± 4.4
20.0 ± 3.8
17.8 ± 2.2
11.1 ± 4.4
15.6 ± 5.8
13.6 ± 2.2
[α]20D = -16 (c 2.9 mg/mL, CHCl3); IR cm-1 (KBr): 2933, 2857, 1761, 1717, 1627,
46.5 ± 2.2
46.5 ± 2.2
1575, 1453, 1273, 1111, 845. 1H NMR (500 MHz, CDCl3) δ: 8.05 (d, J = 7.0 Hz, 2H,
Ar-H), 7.55ꢀ 7.58 (m, 1H, Ar-H), 7.43ꢀ 7.46 (m, 2H, Ar-H), 7.21 (d, J = 7.5 Hz, 2H,
Ar-H), 7.08 (d, J = 7.5 Hz, 2H, Ar-H), 6.45 (s, 1H, -CH=C), 4.91ꢀ 4.95 (m, 1H,
-OCH), 4.06 (d, J = 13.5 Hz, 1H), 3.06 (d, J = 13.0 Hz, 1H), 2.81ꢀ 2.85 (m, 2H),
2.67ꢀ 2.76 (m, 2H), 2.49ꢀ 2.63 (m, 4H), 2.36ꢀ 2.46 (m, 3H), 2.30 (s, 3H), 2.02ꢀ 2.13
(m, 3H), 1.92ꢀ 1.99 (m, 4H), 1.77ꢀ 1.85 (m, 5H), 1.63ꢀ 1.74 (m, 4H), 1.50ꢀ 1.56 (m,
7H), 1.29ꢀ 1.41 (m, 8H), 1.25 (s, 3H), 1.18 (s, 3H), 1.11ꢀ 1.15 (m, 4H), 1.01ꢀ 1.05
(m, 1H), 0.93 (d, J = 6.5 Hz, 3H), 0.87 (d, J = 2.0 Hz, 3H), 0.86 (d, J = 2.0 Hz, 3H),
pesticide candidates, a series of new cholesterol–matrine conjugates
were synthesized. Against M. separata, compounds 2d, IIb, IId, IVa, IVd
and IVe showed better insecticidal activity than toosendanin; especially
compound IVa exhibited 3.0 and 2.6 folds promising insecticidal ac-
tivity of cholesterol and matrine, respectively. Against A. citricola,
compounds IIIe, IVd and IVe displayed good aphicidal activity with
0.70 (s, 3H). Compound IIIa: Yield: 11%, white solid; mp 188ꢀ 190 ◦C; [
α]20D = -22
(c 2.1 mg/mL, CHCl3); IR cm-1 (KBr): 2937, 2861, 1761, 1719, 1632, 1589, 1454,
1273, 1112, 849. 1H NMR (500 MHz, CDCl3) δ: 7.98 (d, J = 8.5 Hz, 2H, Ar-H), 7.43
(d, J = 8.5 Hz, 2H, Ar-H), 7.32ꢀ 7.33 (m, 2H, Ar-H), 7.27ꢀ 7.28 (m, 2H, Ar-H),
7.18ꢀ 7.19 (m, 1H, Ar-H), 6.44 (s, 1H, -CH=C), 4.89ꢀ 4.94 (m, 1H, -OCH), 4.10 (d, J
= 13.5 Hz, 1H), 3.11 (d, J = 13.0 Hz, 1H), 2.75ꢀ 2.88 (m, 2H), 2.50ꢀ 2.67 (m, 4H),
2.32ꢀ 2.42 (m, 3H), 2.03ꢀ 2.08 (m, 3H), 1.89ꢀ 1.99 (m, 5H), 1.74ꢀ 1.86 (m, 6H),
1.55ꢀ 1.70 (m, 8H), 1.47ꢀ 1.54 (m, 3H), 1.31ꢀ 1.41 (m, 8H), 1.22ꢀ 1.25 (m, 3H),
1.18 (s, 3H), 1.11ꢀ 1.15 (m, 4H), 1.01ꢀ 1.05 (m, 1H), 0.93 (d, J = 6.5 Hz, 3H), 0.87
(d, J = 2.0 Hz, 3H), 0.86 (d, J = 2.5 Hz, 3H), 0.69 (s, 3H). Compound IVa: Yield:
LD50 values of 0.042–0.052
μg/nymph; particularly, compound IVd
showed 4.3 and 2.2 folds potent aphicidal activity of cholesterol and
matrine, respectively, and it also displayed good control effects in the
greenhouse (3.8 and 2.0 folds of cholesterol and matrine at 7th day).
Against P. xylostella, compound IIIe exhibited 2.8 and 2.0 folds good oral
toxicity of cholesterol and matrine, respectively. These results will
provide a foundation for future structural modifications and applica-
tions of matrine and cholesterol analogs as pesticides in agriculture.
14%, white solid; mp 191ꢀ 193 ◦C; [
α]20D = -15 (c 2.2 mg/mL, CHCl3); IR cm-1
(KBr): 2934, 2856, 1757, 1709, 1624, 1511, 1456, 1257, 1113, 848. 1H NMR (500
MHz, CDCl3) δ: 8.00 (d, J = 8.5 Hz, 2H, Ar-H), 7.31ꢀ 7.33 (m, 2H, Ar-H), 7.26ꢀ 7.28
(m, 2H, Ar-H), 7.16ꢀ 7.19 (m, 1H, Ar-H), 6.93 (d, J = 9.0 Hz, 2H, Ar-H), 6.44 (s, 1H,
-CH=C), 4.86ꢀ 4.92 (m, 1H, -OCH), 4.10 (d, J = 13.5 Hz, 1H), 3.86 (s, 3H), 3.11 (d, J
= 13.0 Hz, 1H), 2.74ꢀ 2.88 (m, 2H), 2.49ꢀ 2.67 (m, 4H), 2.32ꢀ 2.45 (m, 4H),
2.03ꢀ 2.08 (m, 3H), 1.88ꢀ 1.98 (m, 4H), 1.73ꢀ 1.86 (m, 5H), 1.57ꢀ 1.71 (m, 8H),
1.48ꢀ 1.54 (m, 3H), 1.31ꢀ 1.41 (m, 8H), 1.25 (s, 3H), 1.17 (s, 3H), 1.08ꢀ 1.15 (m,
5H), 1.01ꢀ 1.05 (m, 1H), 0.93 (d, J = 6.5 Hz, 3H), 0.87 (d, J = 1.5 Hz, 3H), 0.86 (d, J
= 2.0 Hz, 3H), 0.70 (s, 3H).
Declaration of Competing Interest
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
6

J. Xu et al.
Bioorganic & Medicinal Chemistry Letters 50 (2021) 128350
24 Yang R, Lv M, Xu H. J Agric Food Chem. 2018;66:11254–11264.
22 Li Q, Huang X, Li S, et al. J Agric Food Chem. 2016;64:5472–5478.
23 Hao M, Sun Z, Xu J, et al. J Agric Food Chem. 2020;68:4131–4143.
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