Determining the potential targets of silybin by molecular docking and its antibacterial functions on efflux pumps and porins in uropathogenic E. coli.

BACKGROUND: One of the causes of antibiotic resistance is the reduced accumulation of antibiotics in bacterial cells through pumping out the drugs. Silybin, a key component of the Silybum marianum plant, exhibits various beneficial properties, including anti-bacterial, anti-inflammatory, antioxidant, and hepatoprotective effects. METHODS AND RESULTS: Clinical isolates of E. coli were procured from 17 Shahrivar Children's Hospital in Rasht, Guilan, located in northern Iran. Their susceptibility to six antibiotics was assessed using disc diffusion and broth dilution (MIC) methods. The antibacterial effects of silybin-loaded polymersome nanoparticles (SPNs) were investigated with broth dilution (MIC) and biofilm assays. Molecular docking was utilized to evaluate silybin's (the antibacterial component) binding affinity to efflux pumps, porins, and their regulatory elements. Additionally, qRT-PCR analysis explored the expression patterns of acrA, acrB, tolC, ompC, and ompF genes in both SPNs (sub-MIC) and ciprofloxacin (sub-MIC)-treated and untreated E. coli isolates. The combined use of SPNs and ciprofloxacin exhibited a notable reduction in bacterial growth and biofilm formation, in ciprofloxacin-resistant isolates. The study identified eight overlapping binding sites of the AcrABZ-TolC efflux pump in association with silybin, demonstrating a binding affinity ranging from -7.688 to -10.33 Kcal/mol. Furthermore, the qRT-PCR analysis showed that silybin upregulated AcrAB-TolC efflux pump genes and downregulated ompC and ompF porin genes in combination with ciprofloxacin in transcriptional level in uropathogenic E. coli. CONCLUSIONS: Silybin, a safe herbal compound, exhibits potential in inhibiting antibiotic resistance within bacterial isolates, potentially through the regulation of gene expression and plausible binding to target proteins.

Antibacterial potential and cytotoxic activity of iron oxide nanoparticles conjugated with thymol (Fe3O4@Glu-Thymol) on breast cancer cells and investigating the expression of BAX, CASP8, and BCL-2 genes.

The use of metal nanoparticles (NPs) conjugated with natural herbal molecules in biomedical applications has been growing. In this work, we synthesized Iron oxide NPs conjugated with thymol (Fe3O4@Glu-Thymol) and investigated their antibacterial and anticancer potentials. Physicochemical features of the NPs were studied by FT-IR, EDS-mapping, XRD, DLS, zeta potential, and electron microscopy. The antibacterial activity of the NPs against Pseudomonas aeruginosa and anticancer activity for breast cancer cells was investigated by broth microdilution and MTT and flow cytometry assays, respectively. The expression of apoptosis signaling genes in breast cancer cells that were treated with the NPs was studied by qPCR assay. The NPs were spherical, in a size range of 40-66 nm, without impurities, and with zeta potential and hydrodynamic size of - 23 mV and 185 nm, respectively. Moreover, the FT-IR and XRD assays confirmed the proper synthesis of Fe3O4 and conjugation with thymol. The minimum inhibitory concentration of the NPs for P. aeruginosa strains was 64-128 µg/mL. Our results showed that Fe3O4@Glu-Thymol was considerably more toxic for breast cancer cells than normal human cells and the 50% inhibitory concentration were 90.4 and 322 µg/mL, respectively. Upon treating breast cancer cells with the NPs the frequency of cell apoptosis increased by 18.9%. Also, the expression of the BAX and CASP8 genes in NPs treated cells significantly increased by 1.75 and 2.25 folds, respectively while the BCL-2 gene remained almost constant. This study reveals that Fe3O4@Glu-Thymol has considerable potential to be used in biomedical fields.