Various Bioactivity and Relationship of Structure-Activity of Matrine Analogues

Article abstract of DOI:10.1021/acs.jafc.6b05474

For the first time, the botanic source natural product matrine was reported to have more potent inhibitory activity against tobacco mosaic virus (TMV) than the commercial virucide ribavirin. On the basis of the structural diversity modification strategy, a series of matrine derivatives was synthesized and systematically evaluated for their antiviral activity against TMV, fungicidal activity, and insecticidal activity. As a result, compounds 3 (inhibitory rate 67.3%, 69.5%, 63.7%, 63.0% at 500 μg/mL for in vitro activity, inactivation, curative, and protection activities in vivo, respectively), 16 (66.7%, 60.7%, 63.8%, 68.9% at 500 μg/mL), and 32 (74.6%, 76.9%, 72.3%, 75.7% at 500 μg/mL) were found to have much higher anti-TMV activity than ribavirin (40.8%, 37.5%, 38.2%, 37.7% at 500 μg/mL), even exhibiting as well as NK-007 (70.3%, 66.1%, 68.4%, 67.5% at 500 μg/mL), which was an efficient compound created by our group previously. At the same time, it was found that matrine and its derivatives had a broad spectrum fungicidal activity (14 fungi), especially the inhibition of compound 32 against Phytophthora capsici Leonian reached 96.4% at a concentration of 50 μg/mL. What's more, all compounds exhibited very good insecticidal activity to five kinds of insects (including Mythimna Separate, Helicoverpa Armigera, Ostrinia Nubilalis, Plutella xylostella, and Culex Pipiens Pallens); especially, the inhibition rate of C. Pipiens Pallens of compound 22 could still reach 70% at 1 μg/mL.

Full text of DOI:10.1021/acs.jafc.6b05474

Article
pubs.acs.org/JAFC
Various Bioactivity and Relationship of Structure−Activity of Matrine
Analogues
Wanjun Ni,† Chaojie Li,† Yuxiu Liu,*,† Hongjian Song,† Lizhong Wang,† Haibin Song,†
and Qingmin Wang*,†,‡
†State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Nankai University,
Tianjin 300071, People’s Republic of China
‡Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, People’s Republic of China
S
* Supporting Information
ABSTRACT: For the first time, the botanic source natural product matrine was reported to have more potent inhibitory activity
against tobacco mosaic virus (TMV) than the commercial virucide ribavirin. On the basis of the structural diversity modification
strategy, a series of matrine derivatives was synthesized and systematically evaluated for their antiviral activity against TMV,
fungicidal activity, and insecticidal activity. As a result, compounds 3 (inhibitory rate 67.3%, 69.5%, 63.7%, 63.0% at 500 μg/mL
for in vitro activity, inactivation, curative, and protection activities in vivo, respectively), 16 (66.7%, 60.7%, 63.8%, 68.9% at
500 μg/mL), and 32 (74.6%, 76.9%, 72.3%, 75.7% at 500 μg/mL) were found to have much higher anti-TMV activity than riba-
virin (40.8%, 37.5%, 38.2%, 37.7% at 500 μg/mL), even exhibiting as well as NK-007 (70.3%, 66.1%, 68.4%, 67.5% at 500 μg/mL),
which was an efficient compound created by our group previously. At the same time, it was found that matrine and its derivatives
had a broad spectrum fungicidal activity (14 fungi), especially the inhibition of compound 32 against Phytophthora capsici Leonian
reached 96.4% at a concentration of 50 μg/mL. What’s more, all compounds exhibited very good insecticidal activity to five kinds
of insects (including Mythimna Separate, Helicoverpa Armigera, Ostrinia Nubilalis, Plutella xylostella, and Culex Pipiens Pallens);
especially, the inhibition rate of C. Pipiens Pallens of compound 22 could still reach 70% at 1 μg/mL.
KEYWORDS: natural product of plant sources, matrine, anti-TMV activity, fungicidal activity, insecticidal activity,
structure−activity relationship
Matrine and total matrines (total alkaloids extracted from
certain Sophora species) were reported to have various medicinal
activities, such as antipyretic,5 analgesic,6 and anti-inflammatory
activities,7 and they were used for treatment of lipopolysacchar-
ide-induced liver injury.8 As a botanical pesticide and being
friendly to natural environment, the total matrines have also been
commercialized as a broad spectrum insecticide (that was named
by Kudun); however, their insecticidal activities were two orders
of magnitude lower than the world’s most popular pesticides
discovered by the international pesticide companies in the last
ten years.
INTRODUCTION
■
Matrine alkaloids, including matrine, oxymatrine, sophocarpine,
and oxysophocarpine,1,2 etc. (Figure 1), are the main effective com-
ponents of Chinese herbal medicine such as Sophora flavescens,
Sophora alopecuroides, and Sophora subprostrara.3 Matrine was
isolated from the root of Kushen in 1889 first by Japanese scholars,
and its structure was confirmed by Kondo in 1936.4
Recently, the synthesis and bioactivity study on matrine
analogues had been investigated extensively in China. However,
most researches mainly focused on the antitumor activity,9−15
antiangiogenesis,16 antioxidant activity,17 and antiviral activ-
ity;18−20 comparably, the study on the agricultural use such as
antiplant virus activity, fungicidal activity, and insecticidal activity21
was not as much.
As one of our everlasting projects on the application of natural
products, the botanical source product matrine was evaluated its
inhibitory activity against tobacco mosaic virus (TMV) for the
first time, and matrine was found to exhibit higher anti-TMV
Received: December 6, 2016
Revised: February 16, 2017
Accepted: February 18, 2017
Figure 1. Matrine alkaloids.
© XXXX American Chemical Society
A
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a
Table 1. In Vitro and in Vivo Antiviral Activities of Ribavirin, NK-007, Matrine Analogues, and Compounds 1−30 against TMV
a
The data are presented in means SD.
water (30 mL). After evaporation of THF, the aqueous layer was
extracted with ethyl acetate (80 mL × 3). The combined organic phase
was washed with brine, dried over MgSO4, filtered, and concentrated
under reduced pressure. The resulting residue was purified by column
chromatography on alkaline alumina to give compound 1 (1.23 g, 88%)
as a white solid, mp 60−61 °C. 1H NMR (400 MHz, CDCl3) δ 2.86−
2.70 (m, 4H), 2.38−2.32 (m, 2H), 2.21−2.14 (m, 1H), 2.04 (t, J =
4.0 Hz, 1H), 1.99−1.85 (m, 5H), 1.80−1.71 (m, 2H), 1.69−1.50 (m,
5H), 1.48−1.24 (m, 5H), 1.03−0.93 (m, 1H). 13C NMR (100 MHz,
CDCl3) δ 64.4, 58.3, 57.7, 57.4, 56.5, 56.2, 41.8, 35.3, 29.5, 28.3, 26.3,
25.8, 24.8, 21.7, 21.3; HRMS (ESI) calcd. for [C15H26N2+H]+ 235.2169,
found 235.2173.
activity than commercialized ribavirin in four modes (in vitro,
inactivation effect, curative effect, and protection effect in vivo)
(Table 1). Thus, in this report, a series of matrine derivatives
(Figure 2), especially the esters of 14-hydroxymethyl-15-deoxy-
matrine, was synthesized to seek more potent anti-TMV com-
pounds. Fungicidal and insecticidal activities of matrine and its
derivatives were also evaluated systematically.
MATERIALS AND METHODS
■
Instruments and Chemicals. Matrine was from Baoji Biological
Development Co. Ltd. Reagents were purchased from commercial
sources and were used as received. All anhydrous solvents were dried
and purified by standard techniques just before use. Reaction progress
was monitored by thin-layer chromatography on silica gel GF254 with
detection by UV. Melting points were determined using an X-4
binocular microscope melting point apparatus, and the thermom-
eter was uncorrected. 1H NMR spectra were obtained by using Bruker
AV 400 with CDCl3 or DMSO-d6 as solvent. Chemical shifts (δ) were
given in parts per million (ppm) and were measured downfield from
internal tetramethylsilane. 13C NMR spectra were recorded by using
a Bruker AV 400 (100 MHz) with CDCl3 or DMSO-d6 as solvent.
Chemical shifts (δ) were reported in parts per million using the solvent
peak as standard. High-resolution mass spectra were obtained with an
FT-ICR MS spectrometer (Ionspec, 7.0 T).
Synthetic Procedure for 1,16-Dioxy-15-deoxymatrine hydrate (2).
To a solution of compound 1 (0.78 g, 3.30 mmol) in hydrogen peroxide
(30%, 40 mL) was added solid sodium hydroxide slowly at 50 °C. After
30 min, a small amount of manganese dioxide was added to decompose
the residual hydrogen peroxide. When cooled and filtered, the filtrate
was concentrated, and the resulting residue was purified by column
chromatography on silica gel (DCM: MeOH = 5:1) followed by
recrystallization from petroleum ether/acetone to give compound
2 (0.65 g, 68%) as a white solid, mp 196−197 °C (gradually
1
becoming red). H NMR (400 MHz, CDCl3) δ 5.10−4.98 (m, 2H),
4.10 (s, 2H), 3.23−3.00 (m, 8H), 2.79 (dd, J = 8.0, 4.0 Hz, 1H), 2.73−
2.42 (m, 4H), 1.93−1.40 (m, 11H). 13C NMR (100 MHz, CDCl3) δ
69.6, 69.2, 68.7, 68.5, 67.1, 66.3, 34.2, 28.8, 25.1, 24.0, 23.4, 23.0, 20.0,
17.3, 17.2. HRMS (ESI) calcd. for [C15H26N2O2+H]+ 267.2067, found
267.2070.
The synthetic routes are given in Figure 3.
Synthetic Procedure for 15-Deoxymatrine (1). To a suspension of
LiAlH4 (0.46 mg, 12.00 mmol) in THF (40 mL) was added matrine
(1.50 g, 6.00 mmol) in one portion at ice bath. The reaction was stirred
at 0 °C for 10 min, refluxed for another 10 h, and then quenched with
Synthetic Procedure for 14-R-14-Hydroxymethyl-15-deoxyma-
trine (3) and 14-S-14-Hydroxy methyl-15-deoxymatrine (4). To a
solution of i-Pr2NH (11.3 mL, 80.5 mmol) in THF (10 mL) was added
B
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Figure 2. Structures of synthesized matrine derivatives 1−32.
n-BuLi (37.6 mL, 2.4 M in THF, 90.2 mL) dropwise at −78 °C under
an atmosphere of argon. After 10 min, a solution of dimethyl carbonate
(3.5 mL, 41.9 mmol) in THF (10 mL) was added via a syringe slowly.
The reaction mixture was stirred at this temperature for 30 min and then
warmed to room temperature naturally. Two hours later, saturated
aqueous NH4Cl (20 mL) was added to quench the reaction. After evapo-
ration of THF, the aqueous layer was extracted with CH2Cl2 (80 mL × 3).
The combined organic phase was washed with brine, dried over MgSO4,
filtered, and concentrated under reduced pressure to give mixture A
(yield 98%) as yellow oil.
C
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Figure 3. Synthetic routes for 1−32.
To a solution of mixture A obtained above in dry methanol (500 mL)
was added calcium chloride (10.6 g, 96.6 mmol), then it was added
sodium borohydride (7.30 g, 193.2 mmol) in batches at ice bath. When
refluxed for 5 h, the mixture was quenched with 20 mL of water. After
evaporation of methanol, the aqueous layer was extracted with EA
(60 mL × 3). The combined organic phase was washed with brine, dried
over MgSO4, filtered, and concentrated under reduced pressure to give
white solid B (yield 85%).
2.53 (m, 1H), 2.49−2.43 (m, 1H), 2.38 (dd, J = 8.0, 4.0 Hz, 1H), 2.02
(t, J = 4.0 Hz, 1H), 1.97−1.61 (m, 13H), 1.56−1.34 (m, 5H). 13C NMR
(100 MHz, CDCl3) δ 68.9, 64.1, 59.6, 58.0, 57.6, 57.3, 55.9, 41.9, 35.3,
33.6, 28.9, 28.1, 27.1, 26.1, 21.6, 21.3. HRMS (ESI) calcd. for
[C16H28N2O+H]+ 265.2274, found 265.2276.
Compound 4: yellow solid (3.0 g, 35%), mp 146−147 °C. 1H NMR
(400 MHz, CDCl3) δ 3.48−3.39 (m, 2H), 3.38 (s, 1H), 2.95 (d, J =
12.0 Hz, 1H), 2.97−2.71 (m, 3H), 2.40−2.32 (m, 2H), 2.04 (s, 1H),
1.97−1.63 (m, 10H), 1.54−1.29 (m, 6H), 1.10−0.93 (m, 2H). 13C
NMR (100 MHz, CDCl3) δ 66.1, 64.2, 59.5, 58.3, 57.6, 57.4, 56.1, 41.4,
39.1, 35.1, 28.9, 28.2, 27.8, 26.5, 21.7, 21.3. HRMS (ESI) calcd. for
[C16H28N2O+H]+ 265.2274, found 265.2278.
To a solution of B in dry THF (150 mL) was added lithium aluminum
hydride (3.60 g, 64.40 mmol) at ice bath, and the mixture was refluxed
for 5 h before quenched with water. After evaporation of THF, the
aqueous layer was extracted with ethyl acetate (100 mL × 3). The
combined organic phase was washed with brine, dried over MgSO4,
filtered, and concentrated under reduced pressure. The resulting residue
was purified by column chromatography on alkaline aluminum (meth-
ylene chloride with 1% aqueous ammonia/petroleum ether =1:1) to give
compounds 3 and 4.
Synthetic Procedure for 14-R-14-Chloromethyl-15-deoxymatrine
(5). To a solution of compound 3 (0.52 g, 2.0 mmol) and in CH2Cl2
(40 mL) was added thionyl chloride (0.21 g, 3.0 mmol) dropwise at
room temperature. After the reaction mixture was refluxed 2 h, it
was washed with diluted aqueous Na2CO3, water, and brine. After the
solution was dried over Na2SO4, it was evaporated under reduced
pressure, and the resulting residue was purified by column chroma-
tography on alkaline alumina to give compound 5 (0.48 g, 86%) as a
Compound 3: light yellow solid (3.1 g, 37%), mp 146−147 °C. 1H
NMR (400 MHz, CDCl3) δ 4.02−3.98 (m, 1H), 3.81−3.78 (m, 1H),
2.93−2.90 (m, 1H), 2.85−2.76 (m, 2H), 2.66 (t, J = 12.0 Hz, 1H), 2.57−
D
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white solid, mp 108−109 °C. 1H NMR (400 MHz, CDCl3) δ 3.84−3.67
(m, 2H), 2.86−2.76 (m, 3H), 2.66 (t, J = 12.0 Hz, 1H), 2.37−2.31 (m,
2H), 2.25 (dd, J = 8.0, 4.1 Hz, 1H), 2.01−1.86 (m, 7H), 1.81−1.48 (m,
6H), 1.44−1.25 (m, 4H), 1.11−1.00 (m, 1H). 13C NMR (100 MHz,
CDCl3) δ 64.4, 58.5, 57.8, 57.6, 57.4, 56.1, 47.2, 41.5, 36.8, 35.1, 28.3,
26.5, 26.2, 24.8, 21.8, 21.4. HRMS (ESI) calcd. for [C16H27ClN2+H]+
283.1936, found 283.1940.
Synthetic Procedure for 14-S-14-Chloromethyl-15-deoxymatrine
(6). Compound 6 was obtained using a synthetic procedure similar to
that of compound 5 as a white solid (0.58 g, 71%), mp 57−58 °C. 1H
NMR (400 MHz, CDCl3) δ 3.43−3.31 (m, 2H), 3.00 (d, J = 8.0 Hz,
1H), 3.01−2.76 (m, 3H), 2.42−2.34 (m, 2H), 2.05−1.89 (m, 9H),
1.78−1.60 (m, 2H), 1.55 (s, 2H), 1.46−1.31 (m, 4H), 1.11−0.96 (m,
2H). 13C NMR (100 MHz, CDCl3) δ 64.2, 59.8, 57.9, 57.6, 57.3, 56.0,
48.2, 41.6, 38.7, 35.6, 29.1, 29.0, 28.1, 26.5, 21.7, 21.3. HRMS (ESI)
calcd. for [C16H27ClN2+H]+ 283.1936, found 283.1940.
Synthetic Procedure for 14-R-14-Methylsulfonyloxymethyl-15-
deoxymatrine (7). To a solution of compound 3 (0.69 g, 2.6 mmol)
and in CH2Cl2 (40 mL) was added methylsulfonyl chloride (0.59 g,
5.2 mmol) dropwise at room temperature. After the reaction mixture
was stirred at room temperature for about 2.5 h, it was washed with
diluted aqueous NaHCO3, water, and brine. After the solution was dried
over anhydrous Na2SO4, it was evaporated under reduced pressure, and
the resulting residue was purified by column chromatography on
alkaline alumina to give compound 7 as a white solid (0.94 g, 80%), mp
106−107 °C. 1H NMR (400 MHz, CDCl3) δ 4.48−4.35 (m, 2H), 3.02
(s, 3H), 2.84−2.65 (m, 4H), 2.39−2.34 (m, 2H), 2.20 (dd, J = 8.0,
4.0 Hz, 1H), 2.10−2.08 (m, 1H), 2.01 (t, J = 4.0 Hz, 1H), 1.93−1.70 (m,
7H), 1.60−1.49 (m, 3H), 1.45−1.26 (m, 5H), 1.13−1.02 (m, 1H). 13C
NMR (100 MHz, CDCl3) δ 71.6, 64.2, 58.3, 57.6, 57.4, 56.5, 56.0, 41.5,
36.9, 35.1, 33.4, 28.2, 26.2, 25.1, 24.9, 21.7, 21.3. HRMS (ESI) calcd. for
[C17H30N2O3S+H]+ 343.2050, found 343.2058.
Synthetic Procedure for 14-S-14-Methylsulfonyloxymethyl-15-
deoxymatrine (8). Compound 8 was obtained by using compound 4
as substrate and adopting a synthetic procedure similar to that of
compound 7 as a white solid (0.92 g, 90%), mp 110−112 °C. 1H NMR
(400 MHz, CDCl3) δ 4.11−3.98 (m, 2H), 3.01 (s, 3H), 2.94−2.91 (m,
1H), 2.84−2.74 (m, 3H), 2.40−2.34 (m, 2H), 2.05−2.04 (m, 2H),
1.99−1.84 (m, 7H), 1.77−1.62 (m, 2H), 1.56−1.47 (m, 2H), 1.47−1.31
(m, 4H), 1.12−1.04 (m, 2H). 13C NMR (100 MHz, CDCl3) δ 72.4,
64.0, 58.5, 57.8, 57.4, 57.2, 55.9, 41.4, 37.2, 36.0, 35.1, 28.6, 28.1, 27.2,
26.3, 21.5, 21.2. HRMS (ESI) calcd. for [C17H30N2O3S+H]+ 343.2050,
found 343.2054.
ammonia and petroleum ether (volume ratio 1:1) as eluent. The
crude yield could reach 82% (separation yield of 3 was 37%, that
of 4 was 35%), which ensured further diversity derivation. With
optically pure substrates 3 and 4 in hand, a series of sulfate, car-
boxylate, and heterocycle carboxylate was synthesized (Figure 2)
by reacting 3 or 4 with corresponding sulfonyl chloride or
acyl chlorides (Figure 3); chlorinated matrines 5 and 6 were
synthesized by refluxing 3 and 4, respectively, with thionyl
chloride.
Configuration of 3 and 4. The absolute configurations of
1
14-C of 3 and 4 were difficult to assign through the H NMR
spectra analysis, so we decided to analyze the configurations of
intermediate B1 and B2 to deduce the configurations of 3 and 4.
Though B1 and B2 could not be separated by column chroma-
tography as we previously described, by repeated recrystalliza-
tion (ethyl acetate, petroleum ether), they can be obtained as
mixtures with ratios about 3:1 (mixture I) and 1:1 (mixture II).
By comparing the NOE difference spectrum of mixture II
1
(Figure S1) and H NMR spectra of mixture I and mixture II
(Figures S2 and S3), we successfully figured out that 11-H (peak b)
and 14-H (peak c) of B1 were at the same side of the pyridinone
ring, which indicated a 14-R configuration. Hence, by reducing
mixture I and comparing the obtained quantities of the two
products, we could assign compound 3 in higher separation yield
to be the one reduced from B1, therefore also bearing a 14-R
configuration.
Though we did not obtain the crystal of 3 or 4 or any one of
their derivatives at the beginning of our project, we fortunately
obtained the single-crystal of compound 2 in its dihydrate form.
In fact, X-ray diffraction of compound 2 not only well explained
the extra peaks around 4.10 ppm in 1H NMR spectrum, but also
clarified the spatial configuration of 1,16-dioxy-15-deoxymatrine
(Figure 3 and Figure S4), which could be used to deduce the
configuration of compounds 3 and 4. Since we could know from
Figure S4 that the oxygen atom at N1 was at the trans position to
the hydrogen at C5 (numbering in the X-ray drawing of 2), we
could deduce that in compounds 3 and 4 the lone pair electrons
at N1 are also trans to the hydrogen at C11 (C5 in the X-ray
drawing of 2). Therefore, in compound 3, the hydroxymethyl
group is at the same direction with the lone pair electrons, and
they should form intramolecular hydrogen bond (Figure S5);
thus, 3 should have less polarity and occur in the upper position
on TLC plate. That is truly the case. Fortunately, we finally
obtained the single crystal of compound 17 (Figure S6), a deriv-
ative of compound 3, which proved the correctness of con-
figuration assignment of compounds 3 and 4.
Compounds 9−32 were prepared similarly by reacting 3 or 4 with
corresponding sulfonyl chloride or acyl chloride. The physical data were
provided in the Supporting Information.
Biological Assay. Detailed bioassay procedures for the anti-TMV,22
fungicidal,23 and insecticidal24 activities were described in our published
literature and can also be found in the Supporting Information. Accord-
ing to statistical requirements, each bioassay was repeated at least three
times. The error of the experiments was 5%.
Antiviral Activity. A series of matrine analogues was
synthesized and assessed the antivirus activity against tobacco
mosaic virus (TMV) in four modes (in vitro, inactivation effect,
curative effect, and protection effect in vivo), with commercial
ribavirin and NK-007, an efficient antivirus compound created by
our group previously, as standards (Table 1). Compared with
matrine, compound 1 had increased anti-TMV activity more or
less after reducing the amide in matrine to tertiary amine, and
when both nitrogen atoms were oxidized, 2 had decreased
activity (1 > matrine > 2), which indicated that the lone pair
electrons of the two nitrogen atoms was beneficial to the activity.
The 14-hydroxymethyl-15-deoxymatrine was a pair of diaster-
eoisomers, of which the one in 14-R configuration was 3, and
the one in 14-S was 4. The two compounds had remarkable
differences: the activity of 3 (67.3%, 69.2%, 63.7%, 63.0% at
500 μg/mL for in vitro activity, inactivation, curative and protec-
tion activities in vivo, respectively) was approximately equal to
RESULTS AND DISCUSSION
■
Synthesis. Compound 1 was synthesized by reducing
matrine with LiAlH4, and compound 2 was made by oxidation
of 1 with hydrogen peroxide (Figure 3). The optically pure
substrates 3 and 4 needed a three-step reaction. The first step was
to synthesize compound A by reacting matrine with dimethyl
carbonate in the presence of LDA at −78 °C. Compound A was a
mixture of two diastereomers, but the two isomers could not be
separated by column chromatography because they had almost
the same polarity and occurred at the same place on the TLC
plate. In the second step, compound A reacted with sodium boro-
hydride to afford compound B. Similarly, the two diastereomers of
B could not be separated due to a situation just like compound A.
At last, compound B was treated with LiAlH4 to give the iso-
mers 3 and 4, which were successfully separated on an alkaline
alumina column using methylene chloride with 1% aqueous
E
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Figure 4. Representative pictures of compounds in anti-TMV assay (curative effect, in vivo, at 500 μg/mL) after 3 days.
that of NK-007 (70.3%, 66.1%, 68.4%, 67.5% at 500 μg/mL)
(Figure 4), whereas compound 4 was less than matrine (NK-007
> 3 > matrine > 4 ≈ ribavirin). We noticed that 3 could form an
intramolecular hydrogen bonding between the hydroxyl hydro-
gen and tertiary nitrogen, but 4 could not, so we presumed that
the hydroxyl of 14−OH in free style may be detrimental to the
activity. Therefore, we further synthesized the chlorides and
several pairs of esters from 3 and 4, respectively, to study how this
difference could affect their activities.
Table 2. In Vitro and in Vivo Antiviral Activities of 31, 32, and
related compounds against TMV
a
The result showed that when compounds 3 and 4 were
separately converted to chlorides 5 and 6, the anti-TMV activity
of 6 was better than 5. Similarly, after 3 was converted into
esters, the activities of the derivatives decreased obviously, but
some of them still had higher anti-TMV activities than matrine
such as 14-R-methylsulfonate (7), 14-R-acetate (11), 14-R-(3-
nitro)benzolate (21), 14-R-(2-iodo)benzolate (23), and 14-R-β-
(3,4-dimethoxyphenyl)acrylate (29). Comparably, the activ-
ities of derivatives from compound 4 increased remarkably;
14-S-methylsulfonate (8), 14-S-acetate (12), 14-S-pivalate (14),
14-S-benzolate (16), 14-S-(3-nitro)benzolate (22), 14-S-(2-
iodo)benzolate (24), 14-S-naphthoate (26), and 14-S-β-(3,4-
dimethoxyphenyl)acrylate (30) all exhibited higher activity than
matrine, especially the activity of 14-S-benzolate (16) (66.7%,
60.7%, 63.8%, 68.9% at 500 μg/mL) was close to that of NK-007.
It turned out that although the activity of substrate 4 was lower
than 3, the corresponding esters of 4 had similar activities to
esters of 3 with the same acid or even higher than that of 3.
However, the substituent effect of these compounds was
unobvious.
Since benzo-1,2,3-thiadiazole-containing carboxylic acid was
also reported to have considerable anti-TMV activity,25 we
prepared esters 31 and 32 by reacting 3 and 4 separately with
benzo-1,2,3-thiadiazole-7-carboxylic acid (C) (Table 2) to
investigate if the two parts have a synergistic effect. Table 2
showed that the activity of 32 (74.6%, 76.9%, 72.3%, 75.7% at
500 μg/mL) was much higher than 4 (43.5%, 41.2%, 35.9%,
37.3%, 43.5% at 500 μg/mL) and C (61.0%, 63.5%, 59.8%, 62.4%
at 500 μg/mL), which showed that the existence of the ester
group in 32 is beneficial to the activity, and this also meant that
the fragments of 4 and C in 32 may have a synergistic effect. On
the other hand, the activity of 31 was lower than 3 and C, which
showed the fragments of 3 and C in 31 have a negative synergistic
effect, and this further demonstrated that the esterification of 3
was detrimental to the anti-TMV activity. We also noticed that
31 (57.9%, 60.0%, 53.0%, 55.8% at 500 μg/mL) had lower
activity than 3+C (68.4%, 71.8%, 70.0%, 71.2% at 500 μg/mL),
and 32 had higher activity than 4+C (43.4%, 54.1%, 51.9%,
61.2% at 500 μg/mL); this phenomenon suggested that 31 and
32 would not discompose quickly to 3, 4, and C in plant to
exhibit their own activities.
a
The molar ratio of the tow components in the mixture is 1:1. The
data are presented in means SD.
plant pathogens (Fusarium oxysporum sp. cucumeris; Cercospora
arachidicola Hori; Physalospora piricola; Rhizoctonia cerealis;
Bipolaris maydis; Colletotrichum orbiculare; Fusarium moniliforme;
Alternaria solani; Fusarium graminearum; Phytophthora infestans;
Phytophthora capsici; Sclerotinia sclerotiorum; Botrytis cinerea;
Rhizoctonia solani) by mycelial growth method (Table 3). The
inhibitory rate of many derivatives exceeded 60% at 50 μg/mL.
Among these compounds, three compounds, 14-R-14-(4-meth-
ylsulfonyl)oxymethyl-15-deoxymatrine (5), 14-R-14-[2-E-3-
(3,4-dimethoxyphenyl)acryloyl]oxymethyl-15-deoxymatrine
(29), and 14-S-14-(benzo[d][1,2,3]thiadiazole-4-carbonyl)-
oxymethyl-15-deoxymatrine (32), had more than 70% inhibition
rate for R.C., and other three compounds, 14-R-14-hydrox-
ymethyl-15-deoxymatrine (3), 14-R-14-(4-methyl) benzene-
sulfonyloxymethyl-15-deoxymatrine (9), and 14-S-14-chloro-
methyl-15-deoxymatrine (6), had more than 70% inhibition rate
for B.C. Moreover, compound 32 showed higher fungicidal
activity against P.C. (96.4%, at 50 μg/mL). It showed that these
15-deoxymatrine derivatives had a broad spectrum of fungicidal
activity. However, compared with commercial fungicides car-
bendazim and chlorothalonil, these derivatives were less potent.
Insecticidal Activities. Matrine and its derivatives all
exhibited insecticidal activities against five kinds of insect larvae
(including Mythimna Separate, Helicoverpa Armigera, Ostrinia
Nubilalis, Plutella xylostella, and Culex Pipiens Pallens), and they
showed high selectivity. Many compounds exhibited higher
activities than matrine, and most of the derivatives showed very
good larvacidal activities against C. Pipiens Pallens, especially
compounds 4, 5, and 22 exhibited obviously higher activities
(60%, 60%, 70% at 1 μg/mL). Furthermore, most of matrine
derivatives had very good insecticidal activity against P. xylostella
(half of them had 100% fatality at 600 μg/mL), especially the
activities of compounds 13 and 14, which were 40% and 30%
Fungicidal Activity. Generally, matrine and its derivatives all
exhibited fungicidal activities to some extent against 14 kinds of
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a
Table 3. Fungicidal Activity of Compounds 1−32 against 14 Kinds of Phytopathogens
a
F.C., Fusarium oxysporum sp. cucumeris; C.H., Cercospora arachidicola Hori; P.P., Physalospora piricola; R.C., Rhizoctonia cerealis; B.M., Bipolaris
maydis; C.O., Colletotrichum orbiculare; F.M., Fusarium moniliforme; A.S., Alternaria solani; F.G., Fusarium graminearum; P.I., Phytophthora infestans;
P.C., Phytophthora capsici; S.S., Sclerotinia sclerotiorum; B.C., Botrytis cinerea; R.S., Rhizoctonia solani.
at 100 μg/mL, but matrine itself had no activity at the same
concentration (Table 4). However, though some compounds
exhibited high selectivity and good insecticidal activity on some
species, the potency of these compounds as insecticide was not
comparable with that of commercial insecticides. More modi-
fication on the structure should be conducted.
derivatives had significantly increased anti-TMV activity; it
can be further illustrated that 15-carbonyl was adverse to the
anti-TMV activity. Chirality of 14-carbon could also influence
the activities; for most compounds, compounds with 14-S
configuration had equivalent to or much better anti-TMV
activity than corresponding compounds with 14-R configura-
tion. Among them, compounds 3, 16, and 32 exhibited the
most potent anti-TMV activity, which could be further
In summary, compared with natural compound matrine,
when the amido of matrine was reduced to tertiary amine, most
G
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Table 4. Larvacidal Activities against Oriental Armyworm
(Mythimna Separate), Cotton Bollworm (Helicoverpa
Armigera), Corn Borer (Ostrinia Nubilalis), Diamond Back
Moth (Plutella xylostella), and Mosquito (Culex Pipiens
Pallens) of Compounds 1−32
ACKNOWLEDGMENTS
■
We are grateful to the Tianjin Natural Science Foundation
(16JCZDJC32400) and the National Natural Science Founda-
tion of China (21421062, 21372131 and 21672117) for generous
financial support for our programs.
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jafc.6b05474.
■
S
Figures for determination of configuration of 3 and 4;
1
physical−chemical data for compounds 9−32; H NMR
and 13C NMR spectra for compounds 1−32; detailed
bioassay methods for anti-TMV, fungicidal, and insectici-
dal activities (PDF)
AUTHOR INFORMATION
Corresponding Authors
*E-mail: wangqm@nankai.edu.cn. Phone: +86-(0)22-23503952.
Fax: +86-(0)22-23503952.
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*E-mail: liuyuxiu@nankai.edu.cn.
ORCID
Qingmin Wang: 0000-0002-6062-3766
Notes
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