The major aim of this study is to develop the new class of coumarin candidate clubbed with dihydropyridine-3-carbonitrile with an improved potency as an antimicrobial and antioxidant agent. The key intermediate 6-nitro-4-methyl coumarin-yl chloro acetate 5 have been linked to the 6-(4-fluorophenyl)-2-oxo-4-phenyl-1,2-dihydro pyridine-3-carbonitrile IIa-j derivative to afford 4-methyl-6-nitro-2-oxo-2H-chromen-7-yl-2-(3-cyano-6-(4-fluoro phenyl)-4-(substituted-phenyl) pyridin-2-yl-oxy) acetates 7a-j via efficient organic transformations. All the new derivatives have been characterized by spectral studies (IR, ¹H and ¹³C NMR and mass spectroscopy). In vitro antimicrobial activity have been carried out using the broth microdilution method and antioxidant potency using DPPH bioassays. Bioassay results reveal that compound 7e are equipotent against E. coli with MIC value 50 µg/ mL compared to standard drug ciprofoloxacin. A final analogue 7c with 4-chlorophenyl substituent indicated better antifungal potency against C. albicans with MIC value 100 µg/ mL compared to standard drug griseofulvin. In addition, newly synthesized analogues have been found to be significant scavengers of DPPH radical with IC₅₀ values of 32.11 μg/mL. It has been observed that the potent antibacterial candidate has proved to possess significant antioxidant activity. The presence of chlorine and hydroxy group on phenyl ring plays an important role for the potency in above mentioned biological assay.

中文翻译：

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吡啶棒状香豆素类似物：作为抗菌剂和抗氧化剂的合成与生物学研究

这项研究的主要目的是开发一种新型的香豆素候选物，该香豆素候选物与二氢吡啶-3-甲腈成团，具有增强的抗菌和抗氧化剂作用。关键中间体6-硝基-4-甲基香豆素基氯乙酸酯5已与6-（4-氟苯基）-2-氧代-4-苯基-1,2-二氢吡啶-3-腈IIa-j连接衍生物，得到4-甲基-6-硝基-2-氧代-2 H-铬基-7-基-2-（3-氰基-6-（4-氟苯基）-4-（取代的苯基）吡啶-2通过有效的有机转化生成乙酸基酯7a-j 。所有新的衍生物均已通过光谱研究（IR，¹ H和¹³ C NMR和质谱法）进行了表征。体外使用肉汤微稀释法进行了抗微生物活性，使用DPPH生物测定法进行了抗氧化能力的研究。生物测定结果表明，与标准药物环丙沙星相比，化合物7e对大肠杆菌的效价为MIC为50 µg / mL。与标准药物灰黄霉素相比，最终的具有4-氯苯基取代基的类似物7c对MIC为100 µg / mL的白色念珠菌具有更好的抗真菌效力。此外，发现新合成的类似物是具有IC ₅₀的DPPH自由基的重要清除剂。值为32.11μg/ mL。已经观察到，已证明有效的候选抗菌剂具有显着的抗氧化活性。在上述生物测定中，苯环上氯和羟基的存在对于效价起重要作用。