Construction and application of H1R ligand screening materials based on SMA stabilization and his-tag covalent immobilization of membrane proteins.

The histamine H1 receptor (H1R) plays a pivotal role in allergy initiation and undergoes the necessity of devising a high-throughput screening approach centered on H1R to screen novel ligands effectively. This study suggests a method employing styrene maleic acid (SMA) extraction and His-tag covalent bonding to immobilize H1R membrane proteins, minimizing the interference of nonspecific proteins interference while preserving native protein structure and maximizing target exposure. This approach was utilized to develop a novel material for high-throughput ligand screening and implemented in cell membrane chromatography (CMC). An H1R-His-SMALPs/CMC model was established and its chromatographic performance (selectivity, specificity and lifespan) validated, demonstrating a significant enhancement in lifespan compared to previous CMC models. Subsequently, this model facilitated high-throughput screening of H1R ligands in the compound library and preliminary activity verification of potential H1R antagonists. Identification of a novel H1R antagonist laid the foundation for further development in this area.

Synthesis and anti-SARS-CoV-2 activity of amino acid modified cephalotaxine derivatives.

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) pandemic has triggered a significant impact on global public health security, it is urgent to develop effective antiviral drugs. Previous studies have found that binding to ACE2 is a key step in the invasion of SARS-CoV-2 into host cells, so virus invasion can be inhibited by blocking ACE2, but there are few reports on this kind of specific inhibitor. Our previous study found that Harringtonine (HT) can inhibit the entry of SARS-CoV-2 spike pseudovirus into ACE2h cells, but its relatively high cytotoxicity limits its further development. Amino acid modification of the active components can increase their solubility and reduce their cytotoxicity. Therefore, in this study, seven new derivatives were synthesized by amino acid modification of its core structure Cephalotaxine. The target compounds were evaluated by cell viability assay and the SARS-CoV-2 spike pseudovirus entry assay. Compound CET-1 significantly inhibited the entry of pseudovirus into ACE2h cells and showed less cytotoxicity than HT. Molecular docking results showed that CET-1 could bind TYR83, an important residue of ACE2, just like HT. In conclusion, our study provided a novel compound with more potential activity and lower toxicity than HT on inhibiting the SARS-CoV-2 spike pseudovirus infection, which makes it possible to be a lead compound as an antiviral drug in the future.

A Temporin Derived Peptide Showing Antibacterial and Antibiofilm Activities against Staphylococcus aureus.

BACKGROUND: Temporin is one family of the shortest antimicrobial peptides found in Ranidae frogs. Staphylococcus aureus is one of the main pathogens of suppurative diseases and food contamination, causing severe local or systemic infections in humans. Temporin-GHa (GHa) was previously obtained from Hylarana guentheri, showing weak antibacterial activity against S. aureus. Most temporin peptides are positively charged by arginine and lysine; however, GHa contains histidine. OBJECTIVE: In order to investigate the impact of positively charged amino acid on its antibacterial and antibiofilm activity, GHa4R was designed and synthesized by replacing histidine with arginine in GHa. METHODS: The antibacterial activity and efficacy against S. aureus were detected by minimum inhibitory concentration, minimum bactericidal concentration, and time-killing kinetics assays. The action mechanism was determined by propidium iodide uptake and scanning electron microscopy assays. The antibiofilm activity was measured by the MTT method. Eradication of biofilm was observed by fluorescence microscope. RESULTS: Compared to GHa, GHa4R had stronger antibacterial activity and bactericidal efficacy against S. aureus. Impressively, GHa4R presented antibacterial activity against methicillin-resistant S. aureus (MRSA). It was barely affected by temperature, pH, and storage period, showing high stability. Furthermore, it increased the permeability of the cell membrane and damaged the membrane integrity, leading to cell death. In addition, GHa4R did not induce antibiotic resistance in S. aureus in 30 days, but the MIC of vancomycin was doubled. It not only inhibited S. aureus biofilm formation but also eradicated 24 h-biofilms. CONCLUSION: The above-mentioned characteristics make GHa4R a promising candidate for the treatment of S. aureus infections.