Synthesis, anti-ferroptosis, anti-quorum sensing, antibacterial and DNA interaction studies of chromene-hydrazone derivatives.

Nineteen chromene-hydrazone derivatives containing a variety of structural modifications on the hydrazone moiety were synthesized. Structure-activity correlations were investigated to determine the influence of structural variations on anti-ferroptosis, anti-quorum sensing, antibacterial, DNA cleavage and DNA binding properties. Ferroptosis inhibitory activity was determined by measuring the ability of the derivatives to reverse erastin-induced ferroptosis. Several of the derivatives were more effective than fisetin at inhibiting ferroptosis, with the thiosemicarbazone derivative being the most effective. Quorum sensing inhibition was evaluated using Vibrio harveyi, and both V. harveyi and Staphylococcus aureus were used to determine antibacterial activity. The semicarbazone and benzensulfonyl hydrazone derivatives showed moderate quorum sensing inhibition with IC50 values of 27 µM and 22 µM, respectively, while a few aryl hydrazone and pyridyl hydrazone derivatives showed bacterial growth inhibition, with MIC values ranging from 3.9 to 125 µM. In addition, the interaction of the hydrazone derivatives with DNA was investigated by gel electrophoresis, UV-Vis spectroscopy and molecular docking. All of the derivatives cleaved plasmid DNA and showed favorable interaction with B-DNA through minor groove binding. Overall, this work highlights a broad range of pharmacological applications for chromene-hydrazone derivatives.

A Substituted Diphenyl Amide Based Novel Scaffold Inhibits Staphylococcus aureus Virulence in a Galleria mellonella Infection Model.

Antimicrobial compounds can combat microbes through modulating host immune defense, inhibiting bacteria survival and growth, or through impeding or inhibiting virulence factors. In the present study, a panel of substituted diphenyl amide compounds previously found to disrupt bacterial quorum sensing were investigated and several were found to promote survival in the Galleria mellonella model when provided therapeutically to treat a Gram-positive bacterial infection from methicillin-resistant Staphylococcus aureus strain MW2. Out of 21 tested compounds, N-4-Methoxyphenyl-3-(4-methoxyphenyl)-propanamide (AMI 82B) was the most potent at disrupting S. aureus virulence and promoted 50% larvae survival at 120 and 96 h when delivered at 0.5 and 5 mg/Kg, respectively, compared to untreated controls (p < 0.0001). AMI 82B did not exhibit G. mellonella toxicity (LC 50 > 144 h) at a delivery concentration up to 5 mg/Kg. Further assessment with mammalian cells suggest AMI 82B hemolytic effects against erythrocytes has an HL 50 greater than the highest tested concentration of 64 µg/mL. Against HepG2 hepatic cells, AMI 82B demonstrated an LD 50 greater than 64 µg/mL. AMI 82B lacked direct bacteria inhibition with a minimal inhibitory concentration that exceeds 64 µg/mL and no significant reduction in S. aureus growth curve at the same concentration. Assessment via qPCR revealed that AMI 82B significantly depressed quorum sensing genes agr, spa, and icaA (p < 0.05). Thus, AMI 82B therapeutic effect against S. aureus in the G. mellonella infection model is likely an influence on bacterial quorum sensing driven virulence factors and provides an interesting hit compound for this medically important pathogen.