Paper
New class of 2-aryl-6-chloro-3,4-dihydroisoquinolinium salts as potential antifungal agents for plant protection: synthesis, bioactivity and structure-activity relationships.
Published Feb 13, 2015 · Rui Yang, Zhaohua Gao, Jie-Yu Zhao
Journal of agricultural and food chemistry
46
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Abstract
Thirty-four new 2-aryl-6-chloro-3,4-dihydroisoquinolin-2-ium bromides were synthesized, and their structures were elucidated by spectroscopic analysis. Antifungal activities against Alternaria alternate, Curvularia lunata and Valsa mali were evaluated by the mycelium linear growth rate method. SAR was discussed also. All compounds showed some activity against each of the fungi at 25 μg/mL. Compared to azoxystrobin, a commercial fungicide, 31 out of 34 test compounds showed higher inhibition rates against C. lunata and 10 were more effective against A. alternate and V. mali. Compounds 5-4, 5-2 and 5-34 showed the highest activity against A. alternate (EC50 = 10.3 μg/mL), C. lunata (EC50 = 4.6 μg/mL) and V. mali (EC50 = 3.9 μg/mL), respectively, superior to azoxystrobin (EC50 = 12.8, 71.9, 37.2 μg/mL). Compound 5-4 displayed good activities against each of the fungi with EC50 of 10.3, 4.7, and 18.0 μg/mL while 5-34 displayed excellent activities against V. mali (EC50 = 3.9 μg/mL) and C. lunata (EC50 = 5.8 μg/mL). The SAR showed that the type and position of substituents on the C-ring had significant effects on the activity. Generally, the presence of 2'-F, 4'-F or 2'-CH3 could significantly improve the activities, whereas OH, OMe, NO2 or CF3 groups decreased the activities. Thus, it was concluded that the present research provided a new series of 2-aryl-6-chloro-3,4-dihydroisoquinolin-2-iums with excellent antifungal potency, and the results were of importance for the structure optimization design, synthesis and development of more potent isoquinoline antifungal agents.
A new series of 2-aryl-6-chloro-3,4-dihydroisoquinolin-2-ium bromides with excellent antifungal potency has been synthesized, providing valuable insights for the development of more potent isoquinoline antifungal agents.
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