4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) is an important target site for discovering new bleaching herbicides. To explore novel HPPD inhibitors with excellent herbicidal activity, a series of novel N-aroyl diketone/ triketone derivatives were rationally designed by splicing active groups and bioisosterism. Bioassays revealed that most of these derivatives displayed preferable herbicidal activity against Echinochloa crus-galli (EC) at 0.045 mmol/m 2 and Abutilon juncea (AJ) at 0.090 mmol/m 2 . In particular, compound I-f was more potent compared to the commercialized compound mesotrione. Molecular docking indicated that the corresponding active molecules of target compounds and mesotrione shared similar interplay with surrounding residues, which led to a perfect interaction with the active site of Arabidopsis thaliana HPPD.
Tribenuron-methyl
(TM), as one of the sulfonylurea (SU) herbicides, has been widely
and effectively applied for many kinds of plants. SUs inhibit plant
growth by restraining the biosynthetic pathway of branched-chain amino
acids (BCAAs) catalyzed by acetolactate synthase (ALS). Safeners are
agrochemicals that protect crops from herbicide injuries. To improve
the crop tolerance under TM toxicity stress, this paper evaluated
the protective effect of N-tosyloxazolidine-3-carboxamide.
It turned out that most of the tested compounds showed significant
protection against TM via enhancing the glutathione (GSH) content
and glutathione S-transferase (GST) activity. Among
all of the tested compounds, compound 16 exhibited more
excellent protection than the contrast safener R-28725 and other target
compounds. A positive correlation between the growth level, endogenous
GSH content, and GST activity was observed in this research. The GST
kinetic parameter V
max of the maize was
increased by 29.6% after treatment with compound 16,
while K
m was decreased by 51.9% compared
to the untreated control. The molecular docking model indicated that
compound 16 could compete with TM in the active site
of ALS, which could interpret the protective effects of safeners.
The present work demonstrated that N-tosyloxazolidine-3-carboxamide
derivatives could be considered as potential candidates for developing
new safeners in the future.
Herbicide
safeners selectively protect crops from herbicide damage without reducing
the herbicidal efficiency on target weed species. The title compounds
were designed by the intermediate derivatization approach and fragment
splicing to exploit novel potential safeners. A total of 31 novel
diazabicyclo derivatives were synthesized by the microwave-assistant
method using isoxazole-4-carbonyl chloride and diazabicyclo derivatives.
All synthetic compounds were confirmed by infrared, 1H
and 13C nuclear magnetic resonance, and high-resolution
mass spectrometry. The bioassay results demonstrated that most of
the title compounds could reduce the nicosulfuron phytotoxicity on
maize. The glutathione S-transferase (GST) activity in vivo was assayed, and compound 4(S15) revealed an inspiring safener activity comparable to commercialized
safeners isoxadifen-ethyl and BAS-145138. The molecular docking model
exhibited that the competition at the active sites of target enzymes
between compound 4(S15) and nicosulfuron
was investigated with respect to herbicide detoxification. The current
work not only provided a powerful supplement to the intermediate derivatization
approach and fragment splicing in design pesticide bioactive molecules
but also assisted safener development and optimization.
To seek new protoporphyrinogen oxidase (PPO) inhibitors with better
biological activity, a series of novel diphenyl ether derivatives
containing tetrahydrophthalimide were designed based on the principle
of substructure splicing and bioisomerization. PPO inhibition experiments
exhibited that 6c is the most potential compound, with
the half-maximal inhibitory concentration (IC50) value
of 0.00667 mg/L, showing 7 times higher activity than Oxyfluorfen
(IC50 = 0.0426 mg/L) against maize PPO and similar herbicidal
activities to Oxyfluorfen in weeding experiments in greenhouses and
field weeding experiments. In view of the inspected bioactivities,
the structure–activity relationship (SAR) of this series of
compounds was also discussed. Crop selection experiments demonstrate
that compound 6c is safe for soybeans, maize, rice, peanuts,
and cotton at a dose of 300 g ai/ha. Accumulation analysis experiments
showed that the accumulation of 6c in some crops (soybeans,
peanuts, and cotton) was significantly lower than Oxyfluorfen. Current
work suggests that compound 6c may be developed as a
new herbicide candidate in fields.
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