Identification of Racemic and Chiral Carbazole Derivatives Containing an Isopropanolamine Linker as Prospective Surrogates against Plant Pathogenic Bacteria: In Vitro and In Vivo Assays and Quantitative Proteomics

Abstract

Recent observations on the emergence of drug-resistant plant pathogenic bacteria have highlighted and elicited an acute campaign to develop novel, highly efficient antibiotic surrogates for managing bacterial diseases in agriculture. Thus, a type of racemic and chiral carbazole derivative containing an isopropanolamine pattern was systematically synthesized to discover low-cost and efficient antibacterial candidates. Screening results showed that compounds 2f, 6c, and 2j could significantly suppress the growth of tested plant pathogens, namely Xanthomonas oryzae pv oryzae, X. axonopodis pv citri, and Pseudomonas syringae pv actinidiae, and provided the corresponding EC 50 values of 1.27, 0.993, and 0.603 μg/mL, which were significantly better than those of existing commercial drugs. In vivo studies confirmed their prospective applications for controlling plant bacterial diseases. Label-free quantitative proteomics analysis indicated that compound 2f could dramatically induce the up-and down-regulation of a total of 247 differentially expressed proteins, which was further validated by the parallel reaction monitoring technique. Moreover, fluorescence spectra and SEM images were obtained to further explore the antibacterial mechanism.

Transcriptome Analysis on the Mechanism of Ethylicin Inhibiting Pseudomonas syringae pv. actinidiae on Kiwifruit

“…The antibacterial activity of ethylicin against Psa in vitro was investigated via a turbidimeter test, which followed our reported methods [24]. As shown in Table 1, ethylicin performed excellently in all of the initial concentrations, with overwhelming suppression of Psa.…”

“…In vitro antibacterial activities of ethylicin against Psa followed the reported methods [24]. Sterile water containing dimethyl sulfoxide (DMSO) was used as a negative check; Kocide 3000 and copper rosinate were used as positive controls.…”

Antibiotic activities of propanolamine containing 1,4-benzoxazin-3-ones against phytopathogenic bacteria

“…Intermediates 1 and 3 were prepared using a method described previously. 9 Treatment of intermediate 1 (or 3) with different substituted phenylamine nucleophiles resulted in ring-opening reactions to afford the desired 1,4-benzoxazin-3-one derivatives 2a-2d (or 4a-4n). All the new compounds were conrmed by 1 H NMR, 13 C NMR, 19 F NMR and HRMS spectroscopy (ESI).…”

“…[3][4][5][6] Currently, only a few established commercial bactericides, namely, bismerthiazol (BT), etridiazole, benthiazole and thiodiazole copper (TC), are used for the treatment of these plant bacterial diseases. Unfortunately, longterm use of these antimicrobial agents has resulted in the emergence of antimicrobial resistance in many of these pathogenic bacteria, [7][8][9] so the discovery of new antibiotics that elicit their antimicrobial activity through novel modes of action is very important. 10,11 Recently, 1,4-benzoxazin-3-one derivatives have gained increasing attention because of their broad pharmacological activities, including examples that display antibacterial, 12,13 antifungal, 14,15 herbicidal, 16,17 anticancer, 18,19 neurodegenerative diseases 20 and platelet aggregation inhibitor activities.…”

Quantitative proteomics reveals the antifungal effect of canthin-6-one isolated from Ailanthus altissima against Fusarium oxysporum f. sp. cucumerinum in vitro

“…To further understand the functions and associations of these differentially expressed proteins, protein-protein interaction networks were established using the STRING database [28]. In this section, the 20 highest-scoring differentially expressed proteins with strong interactions were screened for interaction network analysis.…”