The applications of mesoionic compounds and their analogues as
agents against plant viruses remain unexplored. This was the first
evaluation of the antiviral activities of mesoionic compounds on this
issue. Our study involved the design and synthesis of a series of
novel imidazo[1,2-a]pyridine mesoionic compounds
containing a sulfonamide moiety and the assessment of their antiviral
activities against potato virus Y (PVY). Compound A33 was assessed on the basis of three-dimensional quantitative
structure–activity relationship (3D-QSAR) model analysis and
displayed good curative, protective, and inactivating activity effects
against PVY at 500 mg/L, up to 51.0, 62.0, and 82.1%, respectively,
which were higher than those of commercial ningnanmycin (NNM, at 47.2,
50.1, and 81.4%). Significantly, defensive enzyme activities and proteomics
results showed that compound A33 could enhance the defense
response by activating the activity of defense enzymes, inducing the
glycolysis/gluconeogenesis pathway of tobacco to resist PVY infection.
Therefore, our study indicates that compound A33 could
be applied as a potential viral inhibitor.
A series of novel mesoionic pyrido[1,2-a]pyrimidinone
compounds incorporating a dithioacetal skeleton were designed and
synthesized for use as insecticidal agents. The biological activity
of the title compounds indicated good to excellent insecticidal activities
against bean aphids (Aphis craccivora) and white-backed planthoppers (Sogatella furcifera). Compound 34 showed excellent insecticidal activity
against bean aphids (A. craccivora)
with an LC50 value of 2.80 μg/mL, exceeding the insecticidal
activity of trifluoropyrimidine (LC50 = 4.20 μg/mL).
Proteomics and molecular docking results indicated that compound 34 could act on nicotinic acetylcholine receptors. This study
provides support for the application of mesoionic pyrido[1,2-a]pyrimidinone compounds containing dithioacetal as novel
insecticidal agents.
The development of effective antibacterial agents equipped
with
novel action modes and unique skeletons starting from natural compounds
serves as an important strategy in the modern pesticide industry.
Disclosed here are a series of novel indole derivatives containing
pyridinium moieties and their antibacterial activity evaluation against
two prevalent phytopathogenic bacteria, Xanthomonas
oryzae pv. oryzicola (Xoc) and X. oryzae pv. oryzae (Xoo). A three-dimensional (3D)-QSAR model was
adopted to discover higher activity like title compounds based on
the Xoc antibacterial activity of the tested compounds.
Compound 43 was consequently designed, and it displayed
higher antibacterial activity as expected with the half-maximal effective
concentration EC50 values of 1.0 and 1.9 μg/mL for Xoo and Xoc, respectively, which were better
than those of the commercial drug thiodiazole copper (TC) (72.9 and
87.5 μg/mL). Under greenhouse conditions, the results of a rice in vivo pot experiment indicated that the protective and
curative activities of compound 43 against rice bacterial
leaf streak (BLS) and rice bacterial blight (BLB) were 45.0 and 44.0%
and 42.0 and 39.3%, respectively, which were better than those of
the commercial agent thiodiazole copper (38.0 and 37.9%, 38.6 and
37.0%) as well. Scanning electron microscopy images, defense enzyme
activity tests, and proteomic techniques were utilized in a preliminary
mechanism study, suggesting that compound 43 shall modulate
and interfere with the physiological processes and functions of pathogenic
bacteria.
In
this study, a series of novel mesoionic pyrido[1,2-a]pyrimidinone compounds containing a natural skeleton indole were
designed and synthesized, and the insecticidal activities of the target
compounds were tested. The results showed that the target compounds
had good to excellent insecticidal activities against white-backed
planthoppers (Sogatella furcifera)
and bean aphids (Aphis craccivora).
Among them, compound 7 showed outstanding insecticidal
activities against both S. furcifera and A. craccivora, with LC50 values of 0.86 and 0.85 μg/mL, respectively. The insecticidal
activity against bean aphids (A. craccivora) was superior to that of triflumezopyrim (LC50 = 3.67
μg/mL). Proteomics and quantitative real-time polymerase chain
reaction (qRT-PCR) results revealed that compound 7 may
interact with α1 and α7 nAChR subunits of S. furcifera. The results of enzyme activities indicated
that compound 7 was an inhibitor of AChE in S. furcifera. This study provides new ideas for the
discovery of new mesoionic pyrido[1,2-a]pyrimidinone
insecticides.
Cucumber mosaic virus (CMV) is currently a known plant virus with the most hosts, broadest distribution, and economic hazard. To develop new antiviral drugs against this serious virus, a new range of coumarin derivatives containing sulfonamide and dithioacetal structures were designed and synthesized, and their anti-CMV activities were detected by the half-leaf dead spot method. The results of the biological activity assay showed that most of the compounds exhibited outstanding anti-CMV activity. Especially, compound C23 displayed the optimal in vivo anti-CMV activity, with an EC 50 value of 128 μg/mL, which was remarkably better than that of COS (781 μg/mL) and ningnanmycin (436 μg/mL). Excitingly, we found that compound C23 could be a promising plant activator that significantly increased defense-related enzyme activities and the tobacco chlorophyll content. Furthermore, compound C23 enhanced defense responses against viral infection by inducing the abscisic acid (ABA) pathway in tobacco. This work established a basis for multifunction pesticide discovery involving mechanism of action study and structure optimization.
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