Synthesis, Characterization, and Biological Evaluation of Mannich Bases of Coumarin Derivatives

Abstract

Coumarin agents (known as 1, 2-benzopyrone), consist of fused benzene and α-pyrone rings that have carbon and two oxygen atom in the third and fourth positions. Coumarin itself is the simplest member of the Coumarin family, with the molecular formula C₉H₆O₂. According to various reviews in the literature, Coumarin derivatives show several activities such as antimicrobial, antioxidant, anticoagulant anti-inflammatory, anthelmintic, anticancer, etc. The possible improvements in the activity can be further achieved by the few modifications in the substituents on the basic Coumarin nucleus. The coumarin moiety plays an important role in their biological activity. In this investigation, our reaction scheme is based on the formation of the mannich base of coumarin derivatives; coumarin derivatives are synthesized by refluxing 7-hydroxy-4-methyl- coumarin, secondary amine and formaldehyde, and ethanol. Coumarin derivatives were synthesized in the first step and were further heated in a round bottom flask protected from moisture with a calcium chloride dryness tube in pyridine until dissolution was completed the benzoyl chloride was added and heat the solution at 100⁰C which is further evaluated for antibacterial and antioxidant activity. The structures of the newly synthesized compounds have been established based on spectral analytical data such as I.R, 1H-NMR, Mass, and various substitutes of a secondary amine such as diphenylamine, benzimidazole, diethanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine and so on are used in the basic ring for antibacterial and anti-fungal activity. Screening results of synthesized compounds show that the final compounds, containing Diphenylamine, Diethanolamine, and Benzimidazole, possess significant activity against gram-negative Escherichia coli, and diphenylamine and benzimidazole possess significant activity against gram-negative Pseudomonas aureginosa. Diphenylamine and diethanolamine, possess significant activity against Gram-positive Staphylococcus aureus. Benzimidazole, and Dimethylamine, possess significant activity against gram-positive Bacillus subtilis. Dimethylamine. The remaining compounds in the entire series of compounds possess antibacterial activity. The pharmacological evaluation of the antibacterial and Antioxidant activity of the final compounds shows that CU1, CU2, CU3 and CU4, possess significant activity.