Synthesis and evaluation of the antibacterial activity of benzo [۵,۶] chromeno[۳,۲-c] quinoline derivatives

The emergence and spread of antibiotic resistance in pathogenic bacteria have become a major challenge for human health, necessitating the need to synthesize new compounds against these bacteria. Chromens are among the compounds that are candidates for the production of antimicrobials due to their therapeutic properties. Ten novel ۴-H pyran derivatives (۴a-j) were synthesized via One-Pot, the three-components reaction of various arylglyoxal monohydrates, ۲-naphthole, and quinoline-۲, ۴ dione in H۲O:EtOH (۲:۱), as a green solvent, in the presence of p-Toluene sulfunic acid, as a mild catalyst, under reflux conditions with considerable yields. The structure of new compounds was elucidated using ۱H-NMR, ۱۳ C-NMR, FT-IR, mass spectral data and HRMS. The newly synthesized compounds were evaluated for them in-vitro antibacterial activity against some pathogenic bacteria, using the agar well diffusion method. Minimum inhibitory concentration (MIC) values were determined using the microplate method. Compounds g, h, i and j show more efficiency than Ampicillin (as a reference antibiotic) while a, b, c, d, e, and f show slight activity against tested bacteria. Increasing concentration leads to more antimicrobial activity. The studied compounds had a higher antibacterial effect against gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram-negative bacteria. Some of the synthesized compounds in this study showed good antibacterial potential against the studied microorganisms, which can be used against these bacteria if confirmed in In-vivo experiments.