Synthesis and Evaluation of Novel 1,2,3,4-Tetrahydroquinoxaline Derivatives as Potential Fungicidal Agents

Nitrogen-containing heterocyclic compounds play a significant role in the development of novel pesticides. To promote the discovery and development of new fungicides, a series of 1,2,3,4-tetrahydroquinoxaline derivatives were synthesized and assessed for their fungicidal activities. Bioassays demonstrated that compound B1 exhibited significant fungicidal activity against Gaeumannomyces graminis var. tritici, Botrytis cinerea, and Valsa mali, with EC₅₀ values of 0.486, 1.83, and 3.66 mg/L, respectively. In particular, compound B1 showed good fungicidal efficacy against G. graminis compared to the positive control Tebuconazole (EC₅₀ = 0.625 mg/L). In vivo studies revealed that at 200 mg/L, compound B1 exhibited inhibition rates of 39.7% and 78.7% against G. graminis and B. cinerea, respectively. Mechanistic investigations indicated that compound B1 enhanced cell membrane permeability and disrupted membrane integrity, potentially hindering normal mycelial growth. This study provides insights into the potential of 1,2,3,4-tetrahydroquinoxaline derivatives as promising agricultural fungicides.