Design, Synthesis, and Fungicidal Activity against Rice Sheath Blight of Novel N-Acyl-1,2,3,4-tetrahydroquinoline Derivatives

Abstract

To discover fungicides with novel targets, a series of N-acyl-1,2,3,4-tetrahydroquinoline (NATHQ) derivatives were designed and synthesized by linking the active substructure NATHQ moiety in aspernigerin with the O-benzyl oxime-ether scaffold in commercial agrochemicals. Target compound structures were identified using proton and carbon-13 nuclear magnetic resonance spectroscopies and high-resolution mass spectrometry. Preliminary bioassays indicated that at 40 mg/L, some target compounds exhibited moderate to considerable in vitro fungicidal activities against Rhizoctonia solani and Botrytis cinerea. In particular, compound 3j exhibited higher fungicidal activities both in vitro (EC 50 = 0.733 mg/L) and in vivo (EC 50 = 15.2 mg/L) against R. solani than the commercial fungicide prochloraz; therefore, it should be a promising fungicide candidate against rice sheath blight. Additionally, compound 3j exhibited good laccase inhibitory activity (73.2% at 200 mg/L). Molecular docking revealed that the biscyano-oxime-ether moiety of compound 3j exhibited an excellent binding mode with the laccase target protein and could be used as a lead compound for developing laccase inhibitors. The structural features of these NATHQ derivatives will provide inspiration for developing laccase inhibitors and discovering more effective fungicides to control agricultural diseases.

Identification of Novel Quinolone and Quinazoline Alkaloids as Phosphodiesterase 10A Inhibitors for Parkinson’s Disease through a Computational Approach

“… 39 It has shown cytotoxic effects on tumor cell lines and has potential as a pharmaceutical or lead compound. In studies, aspernigerin demonstrated certain fungicidal, insecticidal, and herbicidal properties 40 …”

Environmental Evaluation on Toxicity, Toxic Mechanism, and Hydrolysis Behavior of Potential Acethydrazide Fungicide Candidates

“…Plant pathogens seriously affect food security and yield, and the use of fungicides is the most direct and effective way to control crop diseases. , According to FRAC, more than 230 small-molecule fungicides are currently commercialized, providing a guarantee for a global food supply and social security and stability. However, with the long-term use of traditional chemical fungicides, pathogen resistance is becoming more and more serious, and the ecological environment is also under threat. − Therefore, the development of new, green, safe, and efficient fungicides is indispensable and also in line with the concept of green sustainable development.…”

Antifungal Activity and Mechanism of Camphor Derivatives against Rhizoctonia solani: A Promising Alternative Antifungal Agent for Rice Sheath Blight

“…Rhizoctonia solani (R. solani), a major fungal pathogen causing rice sheath blight, poses a significant threat to global agriculture. , It infects various parts of rice plants, leading to substantial yield losses of 10–50%. , In recent years, a variety of unfavorable factors have promoted the occurrence of rice sheath blight, increasing the difficulty of prevention and control, such as unreasonable fertilization, climate change, large-scale cultivation of a single high-yield rice variety, etc. , Additionally, the demand and quality of rice are constantly increasing, whereas the availability of arable land is on the decrease. ,, Therefore, the long-term effective control of R. solani is crucial for the profitability of rice production.…”