2-(Substituted phenyl)-3,4-dihydroisoquinolin-2-iums as Novel Antifungal Lead Compounds: Biological Evaluation and Structure-Activity Relationships
作者:Zhe Hou、Rui Yang、Cen Zhang、Li-Fei Zhu、Fang Miao、Xin-Juan Yang、Le Zhou
DOI:10.3390/molecules180910413
日期:——
The title compounds are a class of structurally simple analogues of quaternary benzo[c]phenanthridine alkaloids (QBAs). In order to develop novel QBA-like antifungal drugs, in this study, 24 of the title compounds with various substituents on the N-phenyl ring were evaluated for bioactivity against seven phytopathogenic fungi using the mycelial growth rate method and their SAR discussed. Almost all the compounds showed definite activities in vitro against each of the test fungi at 50 μg/mL and a broad antifungal spectrum. In most cases, the mono-halogenated compounds 2–12 exhibited excellent activities superior to the QBAs sanguinarine and chelerythrine. Compound 8 possessed the strongest activities on each of the fungi with EC50 values of 8.88–19.88 µg/mL and a significant concentration-dependent relationship. The SAR is as follows: the N-phenyl group is a high sensitive structural moiety for the activity and the characteristics and position of substituents intensively influence the activity. Generally, electron-withdrawing substituents remarkably enhance the activity while electron-donating substituents cause a decrease of the activity. In most cases, ortha- and para-halogenated isomers were more active than the corresponding m-halogenated isomers. Thus, the title compounds emerged as promising lead compounds for the development of novel biomimetic antifungal agrochemicals. Compounds 8 and 2 should have great potential as new broad spectrum antifungal agents for plant protection.
标题化合物是一类四价苯并[c]菲啶生物碱(QBAs)的结构简单的类似物。为了开发新型的类似QBA的抗真菌药物,本研究评估了24种在N-苯基环上具有不同取代基的标题化合物,对七种植物病原真菌的生物活性进行测试,采用菌丝生长速率法,并讨论了其结构活性关系(SAR)。几乎所有化合物在50 μg/mL的浓度下,对每种测试真菌均显示出明显的体外活性,并且具有广泛的抗真菌谱。在大多数情况下,单卤化化合物2–12的活性优于QBAs中的血根碱和美根草碱。化合物8对每种真菌的活性最强,EC50值为8.88–19.88 µg/mL,且显示出显著的浓度依赖性关系。SAR如下:N-苯基基团是影响活性的高度敏感结构部分,取代基的特性和位置对活性有显著影响。通常,电子吸引取代基显著增强活性,而电子供给取代基则导致活性降低。在大多数情况下,邻位和对位卤化异构体的活性高于相应的间位卤化异构体。因此,标题化合物被认为是开发新型仿生抗真菌农药的有希望的先导化合物。化合物8和2在植物保护作为新的广谱抗真菌剂方面具有很大的潜力。