Design, synthesis and drug resistance reversal potential of novel curcumin mimics Van D: Synergy potential of curcumin mimics

Synergistic Antibacterial Activity of Gallic Acid Based Chalcone Indl 2 by Inhibiting Efflux Pump Transporters

As a part of novel discovery of drugs from natural resources, present study was undertaken to explore the antibacterial potential of chalcone Indl-2 in combination with different group of antibiotics. MIC of antibiotics was reduced up to eight folds against the different cultures of E. coli by both chalcones. Among the two compounds, the i. e. 1-(3', 4,'5'-trimethoxyphenyl)-3-(3-Indyl)-prop-2-enone (6, Indl-2), a chalcone derivative of gallic acid (Indl-2) was better along with tetracycline (TET) worked synergistically and was found to inhibit efflux transporters as obvious by ethidium bromide efflux confirmed by ATPase assays and docking studies. In combination, Indl-2 kills the MDREC-KG4 cells, post-antibiotic effect (PAE) of TET was prolonged and mutant prevention concentration (MPC) of TET was also decreased. In-vivo studies revealed that Indl-2 reduces the concentration of TNF-α. In acute oral toxicity study, Indl-2 was non-toxic and well tolerated up-to dose of 2000 mg/kg. Perhaps, the study is going to report gallic acid derived chalcone as synergistic agent acting via inhibiting the primary efflux pumps.

Nisin Mutant Prevention Concentration and the Role of Subinhibitory Concentrations on Resistance Development by Diabetic Foot Staphylococci

The most prevalent microorganism in diabetic foot infections (DFI) is Staphylococcus aureus, an important multidrug-resistant pathogen. The antimicrobial peptide nisin is a promising compound for DFI treatment, being effective against S. aureus. However, to avoid the selection of resistant mutants, correct drug therapeutic doses must be established, being also important to understand if nisin subinhibitory concentrations (subMIC) can potentiate resistant genes transfer between clinical isolates or mutations in genes associated with nisin resistance. The mutant selection window (MSW) of nisin was determined for 23 DFI S. aureus isolates; a protocol aiming to prompt vanA horizontal transfer between enterococci to clinical S. aureus was performed; and nisin subMIC effect on resistance evolution was assessed through whole-genome sequencing (WGS) applied to isolates subjected to a MEGA-plate assay. MSW ranged from 5–360 μg/mL for two isolates, from 5–540 μg/mL for three isolates, and from 5–720 μg/mL for one isolate. In the presence of nisin subMIC values, no transconjugants were obtained, indicating that nisin does not seem to promote vanA transfer. Finally, WGS analysis showed that incubation in the presence of nisin subMIC did not promote the occurrence of significant mutations in genes related to nisin resistance, supporting nisin application to DFI treatment.

Drug resistance reversal potential of multifunctional thieno[3,2-c]pyran via potentiation of antibiotics in MDR P. aeruginosa

We explored the antibacterial potential (alone and combination) against multidrug resistant (MDR) Pseudomonas aeruginosa isolates KG-P2 using synthesized thieno[3,2-c]pyran-2-ones in combination with different antibiotics. Out of 14 compounds, two compounds (3g and 3l) abridged the MIC of tetracycline (TET) by 16 folds. Compounds was killing the KG-P2 cells, in time dependent manner, lengthened post-antibiotic effect (PAE) of TET and found decreased the mutant prevention concentration (MPC) of TET. In ethidium bromide efflux experiment, two compounds repressed the drug transporter (efflux pumps) which is further supported by molecular docking of these compounds with efflux complex MexAB-OprM. In another study, these compounds inhibited the synthesis of biofilm.