Development of new spiro[1,3]dithiine-4,11'-indeno[1,2-b]quinoxaline derivatives as S. aureus Sortase A inhibitors and radiosterilization with molecular modeling simulation.

Multi-drug resistant microbes have become a severe threat to human health and arise a worldwide concern. A total of fifteen spiro-1,3-dithiinoindenoquinoxaline derivatives 2-7 were synthesized and evaluated for their biological activities against five standard and MDRB pathogens. The MIC and MBC/MFC for the most active derivatives were determined in vitro via broth microdilution assay. These derivatives showed significant activity against the tested strains with microbicidal behavior, with compound 4b as the most active compound (MIC range between 0.06 and 0.25 µg/mL for bacteria strains and MIC = 0.25 µg/mL for C. albicans). The most active spiro-1,3-dithiinoindenoquinoxaline derivatives were able to inhibit the activity of SrtA with IC50 values ranging from 22.15 ± 0.4 µM to 37.12 ± 1.4 µM. In addition, the active spiro-1,3-dithiinoindenoquinoxaline attenuated the in vitro virulence-related phenotype of SrtA by weakening the adherence of S. aureus to fibrinogen and reducing the biofilm formation. Surprisingly, compound 4b revealed potent SrtA inhibitory activity with IC50 = 22.15 µM, inhibiting the adhesion of S. aureus with 39.22 ± 0.15 % compared with untreated 9.43 ± 1.52 %, and showed a reduction in the biofilm biomass of S. aureus with 32.27 ± 0.52 %. We further investigated the effect of gamma radiation as a sterilization method on the microbial load and found that a dose of 5 kGy was sufficient to eradicate the microbial load. The quantum chemical studies exhibited that the tested derivatives have a small energy band gap (ΔE = -2.95 to -3.61 eV) and therefore exert potent bioactivity by interacting with receptors more stabilizing.

A new exploration toward adamantane derivatives as potential anti-MDR agents: Design, synthesis, antimicrobial, and radiosterilization activity as potential topoisomerase IV and DNA gyrase inhibitors.

Developing novel antimicrobial agents has become a necessitate due to the increasing rate of microbial resistance to antibiotics. All the newly adamantane derivatives were evaluated for their antimicrobial activities against six MDR clinical pathogenic isolates. The results exhibited that 13 compounds have from potent to good activity. Among those, five derivatives (6, 7, 9, 14a, and 14b) displayed the potent activities against the different isolates tested (MIC < 0.25 µg/ml with bacteria and <8 µg/ml with fungi) compared with Ciprofloxacin (CIP) and Fluconazole (FCA). Additionally, the potent adamantanes showed bactericidal and fungicidal effects based on (MBCs and MFCs) and the time-kill assay. The most active adamantane derivatives 7 and 14b exhibited a synergistic effect of ΣFIC ≤ 0.5 with CIP and FCA against the bacterial and fungal isolates. Moreover, no antagonistic effect appeared for the tested derivatives. Additionally, the interaction of DNA gyrase and topoisomerase IV enzymes with the compounds 6, 7, 9, 14a, and 14b exhibited potent antimicrobial activity using in vitro biochemical assays and gel-based DNA-supercoiling inhibition method. The activity of DNA gyrase and topoisomerase IV enzymes showed inhibitory activity (IC50 ) of 6.20 µM and 9.40 µM with compound 7 and 10.14 µM and 13.28 µM with compound 14b, respectively. Surprisingly, exposing compound 7 to gamma irradiation sterilized and increased its activity. Finally, the in-silico analysis predicted that the most active derivatives had good drug-likeness and safe properties. Besides, molecular docking and quantum chemical studies revealed several important interactions inside the active sites and showed the structural features necessary for activity.

One-pot synthesis of pyrazolo[4,3-d]thiazole derivatives containing α-aminophosphonate as potential Mur A inhibitors against MDR pathogens with radiosterilization and molecular modeling simulation.

The present study involves the synthesis of a new series of α-aminophosphonate derivatives in good yields with a simple workup via the Kabachnik-Fields reaction using lithium perchlorate (LiClO4) as a catalyst to facilitate the reaction. All the newly synthesized compounds were confirmed using various physical, spectroscopic, and analytical data, and the obtained results correlated with the proposed molecular structure. The in vitro antimicrobial activities of each compound were evaluated against different clinical isolates. The results indicated that among these derivatives, two compounds (5a and 5b) were the most active and displayed potent activity with MICs in the range from 0.06 to 0.25 µg mL-1 compared with fosfomycin and fluconazole as standard antibiotics. Moreover, the synthesized phosphonates displayed a broad spectrum of bactericidal and fungicidal activities depending on MICs, MBCs/MFCs, and the time-kill kinetics. In addition, the checkerboard assay showed synergistic and partial synergistic activities between the active compounds combined with fosfomycin and fluconazole. Furthermore, the SEM images showed distinct ruptures of the OM integrity of the FOS-R E. coli at their MICs, which was further indicated by the increased EtBr accumulation within the bacterial cells. Moreover, active derivatives revealed MurA inhibitory activity with IC50 values of 3.8 ± 0.39 and 4.5 ± 0.23 µM compared with fosfomycin (IC50 = 12.7 ± 0.27 µM). To our surprise, exposing 5a and 5b compounds to different gamma radiation doses revealed that 7.0 kGy eradicated the microbial load completely. Finally, the results of quantum chemical study supported the binding mode obtained from the docking study performed inside the active site of MurA (PDB: 1UAE), suggesting that these phosphonates may be promising safe candidates for MDR infection therapy clinical trials with no toxic effects on the normal human cells.

Antibiofilm and Anti-Quorum-Sensing Activities of Novel Pyrazole and Pyrazolo[1,5-a]pyrimidine Derivatives as Carbonic Anhydrase I and II Inhibitors: Design, Synthesis, Radiosterilization, and Molecular Docking Studies.

Nowadays, searching for new anti-infective agents with diverse mechanisms of action has become necessary. In this study, 16 pyrazole and pyrazolo[1,5-a]pyrimidine derivatives were synthesized and assessed for their preliminary antibacterial and antibiofilm activities. All these derivatives were initially screened for their antibacterial activity against six clinically isolated multidrug resistance by agar well-diffusion and broth microdilution methods. The initial screening presented significant antibacterial activity with a bactericidal effect for five compounds, namely 3a, 5a, 6, 9a, and 10a, compared with Erythromycin and Amikacin. These five derivatives were further evaluated for their antibiofilm activity against both S. aureus and P. aeruginosa, which showed strong biofilm-forming activity at their MICs by >60%. The SEM analysis confirmed the biofilm disruption in the presence of these derivatives. Furthermore, anti-QS activity was observed for the five hybrids at their sub-MICs, as indicated by the visible halo zone. In addition, the presence of the most active derivatives reduces the violacein production by CV026, confirming that these compounds yielded anti-QS activity. Furthermore, these compounds showed strong inhibitory action against human carbonic anhydrase (hCA-I and hCA-II) isoforms with IC50 values ranging between 92.34 and 168.84 nM and between 73.2 and 161.22 nM, respectively. Finally, radiosterilization, ADMET, and a docking simulation were performed.

Development and radiosterilization of new hydrazono-quinoline hybrids as DNA gyrase and topoisomerase IV inhibitors: Antimicrobial and hemolytic activities against uropathogenic isolates with molecular docking study.

This study aimed to synthesize new potent quinoline derivatives based on hydrazone moieties and evaluate their antimicrobial activity. The newly synthesized hydrazono-quinoline derivatives 2, 5a, 9, and 10b showed the highest antimicrobial activity with MIC values ≤1.0 µg/ml against bacteria and ≤8.0 µg/ml against the fungi. Further, these derivatives exhibited bactericidal and fungicidal effects with MBC/MIC and MFC/MIC ratio ≤4. Surprisingly, the most active compounds displayed good inhibition to biofilm formation with MBEC values ranging between (40.0 ± 10.0 - 230.0 ± 31.0) and (67.0 ± 24.0 - 347.0 ± 15.0) µg/ml against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. The hemolytic assays confirmed that the hydrazono-quinoline derivatives are non-toxic with low % lysis values ranging from 4.62% to 14.4% at a 1.0 mg/ml concentration. Besides, compound 5a exhibited the lowest hemolytic activity value of ~4.62%. Furthermore, the study suggests that the hydrazono-quinoline analogs exert their antibacterial activity as dual inhibitors for DNA gyrase and DNA topoisomerase IV enzymes with IC50 values ranging between (4.56 ± 0.3 - 21.67 ± 0.45) and (6.77 ± 0.4 - 20.41 ± 0.32) µM, respectively. Additionally, the recent work advocated that compound 5a showed the reference SAL at the É£-radiation dose of 10.0 kGy in the sterilization process without affecting its chemical structure. Finally, the in silico drug-likeness, toxicity properties, and molecular docking simulation were performed. Besides, the result exhibited good oral-bioavailability, lower toxicity prediction, and lower binding energy with good binding mode rather than the positive control.

Development of gamma irradiated SSD-embedded hydrogel dyed with prodigiosin as a smart wound dressing: Evaluation in a MDR infected burn rat model.

Burn wounds are prone to infections and cause a large amount of death worldwide. Although burn wound is sterile at the beginning but due to the risk factors such as prolonged hospital stay, immune suppression and burn affecting large surface area, it turns to infected burn. This study aims to examine the possible protective properties of silver sulfadiazine embedded in alginate macromolecule to prepare hydrogel. The prepared hydrogel dyed with prodigiosin was used as a smart wound dressing to treat burn wounds that were infected with S. aureus and E. coli. Rats were divided into four groups: (1) control group, (2) burn-infected with S. aureus and E. coli group, (3) burn-infected treated with silver nitrate cream group and (4) burn-infected gamma irradiated silver sulfadiazine-embedded hydrogel dyed with prodigiosin. The biochemical results verified the histopathological results and our findings showed that silver sulfadiazine-embedded hydrogel dyed with prodigiosin is an effective product in compared with silver nitrate cream.

The increasing threat of silver-resistance in clinical isolates from wounds and burns.

PURPOSE: The widespread use of silver-containing compounds has led to emergence of silver-resistant bacteria. Few studies are available on the detectability of plasmid-mediated silver-resistance in developing countries. Therefore, we aimed to detect silver-resistance in isolates from wounds and burns, and to genetically characterize plasmid-mediated silver-resistance genes (sil genes). METHODS: One hundred and fifty clinical isolates were obtained from burns and wounds. They were identified using the suitable Analytical Profile Index and MicroScan identification systems. Their antimicrobial susceptibility was tested by the disk diffusion and broth microdilution methods. Their silver nitrate (AgNO3) minimum inhibitory concentration (MIC) was determined using the broth macrodilution method. The presence of different sil genes on plasmids extracted from silver-resistant isolates and the replicon types of the extracted plasmids were investigated using polymerase chain reaction (PCR). The ability of these plasmids to impart silver-resistance was tested by transformation. RESULTS: All except two isolates were multidrug-resistant. Nineteen silver-resistant bacterial isolates (12.6%) were detected; with AgNO3 MIC ≥512 µg/mL. They were identified as Klebsiella pneumoniae (n=7), Staphylococcus aureus (n=4), Escherichia coli (n=2), Enterobacter cloacae (n=2), Pseudomonas aeruginosa (n=2) and Acinetobacter baumannii (n=2). PCR revealed the presence of different sil genes on the extracted plasmids. Plasmid transformation resulted in the transfer of silver-resistance to the resulting transformants. The extracted plasmids had different replicon types. CONCLUSION: Plasmid-mediated silver-resistance was detected for the first time, in clinical P. aeruginosa, A. baumannii and S. aureus isolates; in addition to its detection in K. pneumoniae, E. coli and Enterobacter cloacae. Therefore, strict monitoring on the use of silver compounds in medical settings is required; with implementation of an approved standardized method for silver-resistance detection.