Synthesis, Characterization, Computational and Antibacterial Studies of Novel Dopamine-Based Derivatives

Two novel dopamine hydrochloride Schiff bases (E)-4-(2-((4-hydroxy-2H-chromen-2-ylidene)amino)ethyl)benzene-1,2-diol (1) and (E)-3-((3,4-dihydroxyphenethyl)imino)indolin-2-one (2) have been synthesized using isatin and 4-hydroxycoumarin. The prepared compounds have been characterized by solubility in different solvents, melting point determination, elemental analysis, FT-IR, 1H-NMR, 13C-NMR and powder X-ray diffraction spectroscopic techniques, with the structures of the Schiff bases proposed. The proposed structures of the compounds have been optimized using the Spartan program so as to get the most stable conformers. The synthesized Schiff bases have been tested for their biological activity against two Gram positive bacteria; Staphylococcus aureus, Bacillus subtilis, and two Gram negative bacteria; Klebsiella pneumoniae and Escherichia coli with their minimum inhibition concentration (MIC) values determined. The Schiff base 1 was found to inhibit E. coli and K. pneumonia with MIC values of 3.12 and 6.25 μg/mL, followed by K. pneumonia compared to the reference standards with MIC values of 3.12 μg/ml indicating that 1 could be a potential lead compound.