"Identification of alkaloid compounds as potent inhibitors of Mycobacterium tuberculosis NadD using computational strategies"

Isoliquiritigenin: a potential drug candidate for the management of erectile dysfunction

OBJECTIVE

This study aimed to assess the erectogenic properties of isoliquiritigenin taking sildenafil (SDF) as the standard.

METHODS

The binding affinity of isoliquiritigenin (ISL) with the erectile marker proteins (endothelial nitric oxide synthase [eNOS] and enzyme phosphodiesterase type 5 [PDE5]) was investigated using Autodock Vina, which was validated using molecular dynamics simulation. Furthermore, the effect of ISL on the eNOS and PDE5 messenger ribonucleic acid (mRNA) expression and the sexual behavior of mice was investigated, along with the assessment of the pharmacokinetics of ISL.

KEY FINDINGS

The results revealed that the binding affinity of ISL-eNOS/PDE5 and SDF-eNOS/PDE5 was in the range of -7.5 to -8.6 kcal/mol. The ISL-eNOS/PDE5 complexes remained stable throughout the 100 ns simulation period. Root mean square deviation, Rg, SASA, hydrogen, and hydrophobic interactions were similar between ISL-eNOS/PDE5 and SDF-eNOS/PDE5. Analysis of mRNA expressions in paroxetine (PRX)-induced ED mice showed that the co-administration of PRX with ISL reduced PDE5 and increased eNOS mRNA expression, similar to the co-administered group (PRX+SDF). The sexual behavior study revealed that the results of PRX+ISL were better than those of the PRX+SDF group. Pharmacokinetic evaluation further demonstrated that ISL possesses drug-like properties.

CONCLUSIONS

The results showed that ISL is equally potent as SDF in terms of binding affinity, specific pharmacological properties, and modulating sexual behavior.

In silico and structural investigation of sulfonamides targeting VraSR two component system in methicillin-resistant Staphylococcus aureus

Drug-resistant Staphylococcus aureus strains are global health concerns. Several studies have shown that these strains can develop defences against cell wall antibiotics such as β-lactams, glycopeptides and daptomycin which target cell wall biosynthesis. The coordination of these responses have been associated with two component system (TCS) regulated by histidine kinase protein (VraS) and its cognate regulator VraR which influences the target DNA upon signal recognition. Computer-based screening methods, predictions and simulations have emerged as more efficient and quick ways to identify promising new compound leads from large databases against emerging drug targets thus allowing prediction of small select set of molecules for further validations. These combined approaches conserve valuable time and resources. Due to methicillin resistance, sulfonamide-derivative medications have been found to be effective treatment strategy to treat S. aureus infections. The current study used ligand-based virtual screening (LBVS) to identify powerful sulfonamide derivative inhibitors from an antibacterial compound library against VraSR signaling components, VraS and VraR. We identified promising sulfonamide derivative [compound 5: (4-[(1-{[(3,5-Dimethoxyphenyl)Carbamoyl]Methyl}-2,4-Dioxo-1,2,3,4-Tetrahydroquinazolin-3-Yl)Methyl]-N-[(Furan-2-Yl)Methyl]Benzamide)] with reasonable binding parameters of -31.38 kJ/mol and ΔGbind score of -294.32 kJ/mol against ATP binding domain of sensor kinase VraS. We further identified four compounds N1 (PCID83276726), N3 (PCID83276757), N9 (PCID3672584), and N10 (PCID20900589) against VraR DNA binding domain (VraRC) with ΔGbind energies of -190.27, -237.54, -165.21, and -190.88 kJ/mol, respectively. Structural and simulation analyses further suggest their stable interactions with DNA interacting residues and potential to disrupt DNA binding domain dimerization; therefore, it is prudent to further investigate and characterize them as VraR dimer disruptors and inhibit other promoter binding site. Interestingly, the discovery of drugs that target VraS and VraR may open new therapeutic avenues for drug-resistant S. aureus. These predictions based on screening, simulations and binding affinities against VraSR components hold promise for opening novel therapeutic avenues against drug-resistant S. aureus and present opportunities for repositioning efforts. These efforts aim to create analogs with enhanced potency and selectivity against two-component signaling systems that significantly contribute to virulence in MRSA or VRSA. These analyses contribute valuable insights into potential avenues for combating antibiotic-resistant S. aureus through computationally driven drug discovery strategies.Communicated by Ramaswamy H. Sarma.