Bio-Fe3O4-MNPs Promoted Green Synthesis of Pyrido[2,1-a]isoquinolines and Pyrido[1,2-a]quinolines: Study of Antioxidant and Antimicrobial Activity

Abstract In this work, synthesis of pyrido[2,1-a]isoquinolines and pyrido[1,2-a]quinolines in excellent yield using multicomponent reactions of isoquinoline, methyl malonyl chloride, alkyl bromides, and triphenylphosphine in the presence of catalytic amount of Fe3O4-MNPs in water at 80 °C were investigated. The reduction of ferric chloride solution with Clover Leaf water extract caused to synthesis of magnetic iron oxide nanoparticles (Fe3O4-NPs) as a green method. As well, antioxidant activity was studied for some newly synthesized compounds such as 6a, 6b, 8b, and 8c using the DPPH radical trapping and reducing of ferric ion experiments and comparing results with synthetic antioxidants (TBHQ and BHT). As a result, compounds 6a, 6b, 8b, and 8c show trace DPPH radical trapping and excellent reducing strength of ferric ion. These compounds have biological potential because of isoquinoline or quinoline core. For this reason, the antimicrobial activity of some synthesized compounds was studied employing the disk diffusion test on Gram-positive bacteria and Gram-negative bacteria. The results of disk diffusion test showed that compound 6a, 6c, 6d, 8a, and 8b prevented the bacterial growth. Highlights Organic solvents that are needed for performing some organic reactions are often toxic and expensive. For this reason, elimination of these solvents is a suitable work for nature. The present procedure avoids the use of toxic solvent. Isoquinoline or quinoline derivatives are one of the important heterocyclic compounds that have outstanding moiety in medicinal chemistry and display a broad variety of biological and pharmacological properties. This recoverable catalyst is very easy and performed by external magnet.