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.
3-Hydroxy-2-oxindole motif constitutes a core structure in numerous natural products and imparts notable biological activities. Here, we describe the design and synthesis of four series of novel 3-substituted-3-hydroxy-2-oxindole derivatives containing sulfonamide moiety along with their antiviral activities against potato virus Y (PVY). Compound 10b displayed optimal antiviral activity and superior anti-PVY activity compared with the lead compound and commercial Ningnanmycin in terms of curative and protective effects. Additionally, 10b considerably inhibited PVY systemic infection in Nicotiana benthamiana. Physiological and biochemical analyses revealed that the activities of the four crucial defense-related enzymes increased in the tobacco plant following treatment with 10b. RNA-sequencing analysis revealed that 10b substantially induced the upregulation of 38 differentially expressed genes, which were enriched in the photosynthesis pathway. These findings suggest that 10b is a promising antiviral agrochemical that can effectively control PVY infection and trigger plant host immunity to develop virus resistance. This study provides novel molecular entities and ideas for developing new pesticides.
The specific conation of our research is to invent a
series of
indole derivatives containing a 4,5-dihydro-1H-pyrazoline
motif with effective antiviral activity. The anti-potato virus Y (PVY)
activities of target compounds were systematically investigated. Most
target compounds exhibited good PVY activities. Compound D40, which exhibited outstanding anti-PVY activities, was sieved using
a three-dimensional quantitative structure–activity relationship.
Based on the anti-PVY activity assessments, the curative and protective
activities of D40 were found to be 64.9 and 60.8%, respectively,
which were superior to those of the commercial drug Ningnanmycin (50.2
and 50.7%, respectively). In addition, defensive enzyme activities
and proteomics results indicate that D40 can increase
the three crucial defense-related enzyme activities and regulate the
carbon fixation pathway in photosynthetic organisms to intensify the
resistance of plants to PVY. Therefore, our study suggests that compound D40 might be used as a suitable crop protection pesticide.
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