Discovery of novel rost‐4‐ene derivatives as potential plant activators for preventing phytopathogenic bacterial infection: Design, synthesis and biological studies

Abstract

BACKGROUND Gradually aggravated disease caused by phytopathogenic bacteria severely restricts food security and crop yield, and few pesticides can relieve this severe situation. Thus, development and excavation of new agrochemicals with high bioactivity and novel action mechanism may be a feasible strategy to control intractable bacterial diseases. As a privileged molecular framework, steroid molecules exhibit diversiform bioactivities. Herein, a series of novel androst‐4‐ene derivatives were designed, synthesised and investigated for their antibacterial behaviour to excavate novel agrochemicals on the base of steroid molecules. RESULTS Bioassay results indicated that target compounds displayed high bioactivities toward three destructive phytopathogenic bacteria, including Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac) and Pseudomonas syringae pv. actinidiae (Psa). Compound III19 displayed excellent in vitro antibacterial profiling (EC50 = 2.37 mg L−1 towards Xoo, EC50 = 2.10 mg L−1 towards Xac, EC50 = 9.50 mg L−1 towards Psa). Furthermore, compound III19 showed outstanding in vivo protective activities, with values of 81.81% and 58.75% towards kiwifruit bacterial canker and rice bacterial leaf blight, respectively. Analysis of the antibacterial mechanism disclosed that compound III19 enhanced host defence enzyme activities superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and catalase (CAT) and increased the salicylate synthase content to induce host resistance. In addition, compound III19 increased the membrane permeability, destroyed the cell membrane and killed the bacteria. CONCLUSION Given these profiles of target compounds, we highlight a new strategy for controlling intractable plant bacterial diseases by inducing plant resistance and targeting the bacterial cell membrane. © 2022 Society of Chemical Industry.

Novel Benzothiazole Derivatives as Potential Anti-Quorum Sensing Agents for Managing Plant Bacterial Diseases: Synthesis, Antibacterial Activity Assessment, and SAR Study

“…In order to determine the structure–activity relationships (SARs) of the title compounds, the title compounds were further modified according to the following four schemes: (a) rigid and saturated aliphatic amines were replaced with variably flexible benzylamines groups; (b) the p -dioxybenzene group was substituted with a m -dioxybenzene, o -dioxybenzene, or piperazinyl group; (c) the antibacterial efficiency of optimized molecules was examined after removal of hydroxyl or isopropanolamine groups; and (d) substituent groups (−Cl, −F, or −OCH 3 ) were introduced into the 4- or 6-position of the benzothiazole pharmacophore. Finally, the antibacterial activity of the 53 newly synthesized compounds was screened against three plant pathogen strains ( Xoo , Xac , and Psa ) using the turbidimetric method …”

“…are particularly intractable, as exemplified by Xanthomonas oryzae pv oryzae ( Xoo ), which is ranked fourth among the top 10 most important plant pathogenic bacteria. Xoo causes rice bacterial leaf-blight disease, which can diminish rice production by 20–80%. , Although several commercial pesticides are currently used to control rice bacterial leaf-blight disease, including bismerthiazol (BT), streptomycin, and amobam, emerging pesticide resistance has reduced their control efficiency. − Therefore, the need for new agrochemicals exhibiting novel antibacterial modes of action has sparked considerable research interest.…”

Design, Synthesis and Bioactivity Evaluation of Novel 2-(pyrazol-4-yl)-1,3,4-oxadiazoles Containing an Imidazole Fragment as Antibacterial Agents

“…Based on the in vitro bioassays, the active compound 9a (afforded with the lowest EC 50 value of 12.85 μg/mL toward Psa ) was chosen to assess the in vivo anti- Psa activity via the pot experiment [ 47 , 48 , 49 ]. The results ( Table 4 ) showed that compound 9a presented commendable protective and curative activities against kiwifruit bacterial canker at 200 μg/mL with control efficiencies of 46.05% and 32.89%, respectively, which were much better than those of the commercial bactericide TC (31.58% and 17.11%, respectively).…”

Evaluation of the Abilities of Three Kinds of Copper-Based Nanoparticles to Control Kiwifruit Bacterial Canker

“…The minimum bactericidal concentration (MBC) of the three kinds of nanoparticles was 1.56 μg/mL, which was much lower than that of thiodiazole copper (MBC > 100 μg/mL, Figure S4 ). Compared with the antibiotics [ 51 ], natural compounds [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], and synthetic compounds [ 18 , 19 , 20 , 21 , 22 , 23 ] reported in the literature, copper-based nanoparticles also have advantages in bactericidal performance. The antibacterial mechanism of copper-based nanoparticles may be related to their compositions, morphologies, and sizes [ 52 ].…”

“…Recently, many novel compounds or methods have been developed to control kiwifruit bacterial canker, including natural products [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], synthetic organic compounds [ 3 , 18 , 19 , 20 , 21 , 22 , 23 ], copper complexes [ 24 , 25 ], sulfur [ 26 ], bacteriophages [ 27 , 28 , 29 ], and other biological control agents [ 30 , 31 ]. These methods exhibited excellent control efficacies for kiwifruit bacterial canker.…”