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Chai JQ, Wang XB, Yue K, Hou ST, Jin F, Liu Y, Tai L, Chen M, Yang CL. Design, Synthesis, Antifungal Activity, and Action Mechanism of Pyrazole-4-carboxamide Derivatives Containing Oxime Ether Active Fragment As Succinate Dehydrogenase Inhibitors. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:11308-11320. [PMID: 38720452 DOI: 10.1021/acs.jafc.3c07880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
The dearomatization at the hydrophobic tail of the boscalid was carried out to construct a series of novel pyrazole-4-carboxamide derivatives containing an oxime ether fragment. By using fungicide-likeness analyses and virtual screening, 24 target compounds with theoretical strong inhibitory effects against fungal succinate dehydrogenase (SDH) were designed and synthesized. Antifungal bioassays showed that the target compound E1 could selectively inhibit the in vitro growth of R. solani, with the EC50 value of 1.1 μg/mL that was superior to that of the agricultural fungicide boscalid (2.2 μg/mL). The observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that E1 could reduce mycelial density and significantly increase the mitochondrial number in mycelia cytoplasm, which was similar to the phenomenon treated with boscalid. Enzyme activity assay showed that the E1 had the significant inhibitory effect against the SDH from R. solani, with the IC50 value of 3.3 μM that was superior to that of boscalid (7.9 μM). The mode of action of the target compound E1 with SDH was further analyzed by molecular docking and molecular dynamics simulation studies. Among them, the number of hydrogen bonds was significantly more in the SDH-E1 complex than that in the SDH-boscalid complex. This research on the dearomatization strategy of the benzene ring for constructing pyrazole-4-carboxamides containing an oxime ether fragment provides a unique thought to design new antifungal drugs targeting SDH.
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Affiliation(s)
- Jian-Qi Chai
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiao-Bin Wang
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
- College of Pharmacy, Jiangsu Ocean University, Lianyungang 222005, China
| | - Kai Yue
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuai-Tao Hou
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Fei Jin
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Yv Liu
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Lang Tai
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Min Chen
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
| | - Chun-Long Yang
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China
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Simplification of Natural β-Carboline Alkaloids to Obtain Indole Derivatives as Potent Fungicides against Rice Sheath Blight. Molecules 2020; 25:molecules25051189. [PMID: 32155800 PMCID: PMC7179428 DOI: 10.3390/molecules25051189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 12/23/2022] Open
Abstract
The increasing resistance of rice sheath blight caused by Rhizoctonia solani highlights the need for highly effective and environmentally benign agents. Natural β-carboline alkaloids were simplified to obtain a series of indole derivatives, and their fungicidal activity and preliminary mode of action against R. solani were also evaluated. The initial hit indole (7) displayed significant fungicidal activity with an EC50 value of 25.56 μg/mL, and was selected for further optimization. Importantly, compound 55, the most active compound, had an EC50 value of 0.62 μg/mL, and approximately 300-fold more potent than validamycin A (EC50 = 183.00 μg/mL). In vivo bioassay also demonstrated that compound 55 showed better fungicidal activities than validamycin A. Moreover, the mechanism studies revealed that compound 55 not only caused remarkable morphological and structural alterations of R. solani hyphae, but also induced the loss of mitochondrial membrane potential and interfered with DNA synthesis. Therefore, compound 55 showed superior fungicidal activity against R. solani, and the elucidated mode of action supported the potential application of compound 55 against rice sheath blight.
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