Leveraging SARS-CoV-2 Main Protease (Mpro) for COVID-19 Mitigation with Selenium-Based Inhibitors.

The implementation of innovative approaches is crucial in an ongoing endeavor to mitigate the impact of COVID-19 pandemic. The present study examines the strategic application of the SARS-CoV-2 Main Protease (Mpro) as a prospective instrument in the repertoire to combat the virus. The cloning, expression, and purification of Mpro, which plays a critical role in the viral life cycle, through heterologous expression in Escherichia coli in a completely soluble form produced an active enzyme. The hydrolysis of a specific substrate peptide comprising a six-amino-acid sequence (TSAVLQ) linked to a p-nitroaniline (pNA) fragment together with the use of a fluorogenic substrate allowed us to determine effective inhibitors incorporating selenium moieties, such as benzoselenoates and carbamoselenoates. The new inhibitors revealed their potential to proficiently inhibit Mpro with IC50-s in the low micromolar range. Our study contributes to the development of a new class of protease inhibitors targeting Mpro, ultimately strengthening the antiviral arsenal against COVID-19 and possibly, related coronaviruses.

The Effect of Substituted Benzene-Sulfonamides and Clinically Licensed Drugs on the Catalytic Activity of CynT2, a Carbonic Anhydrase Crucial for Escherichia coli Life Cycle.

Proteins are relevant antimicrobial drug targets, and among them, enzymes represent a significant group, since most of them catalyze reactions essential for supporting the central metabolism, or are necessary for the pathogen vitality. Genomic exploration of pathogenic and non-pathogenic microorganisms has revealed genes encoding for a superfamily of metalloenzymes, known as carbonic anhydrases (CAs, EC 4.2.1.1). CAs catalyze the physiologically crucial reversible reaction of the carbon dioxide hydration to bicarbonate and protons. Herein, we investigated the sulfonamide inhibition profile of the recombinant ß-CA (CynT2) identified in the genome of the Gram-negative bacterium Escherichia coli. This biocatalyst is indispensable for the growth of the microbe at atmospheric pCO2. Surprisingly, this enzyme has not been investigated for its inhibition with any class of CA inhibitors. Here, we show that CynT2 was strongly inhibited by some substituted benzene-sulfonamides and the clinically used inhibitor sulpiride (KIs in the range of 82-97 nM). This study may be relevant for identifying novel CA inhibitors, as well as for another essential part of the drug discovery pipeline, such as the structure-activity relationship for this class of enzyme inhibitors.

A new hexapeptide from the leader peptide of rMnSOD enters cells through the oestrogen receptor to deliver therapeutic molecules.

A 24-amino acid leader peptide of a new human recombinant manganese superoxide dismutase can enter cells and carry molecules. Here, we demonstrated that six of the 24 amino acids penetrate cells through a particular gate represented by a specific amino acid sequence of the oestrogen receptor (ER). We analysed the internalization of the synthetic hexapeptide and the cytotoxic activity of the hexapeptide conjugated to cisplatin on a cell line panel. In most cell lines, the hexapeptide delivered an amount of cisplatin that was 2 to 8 times greater than that released by cisplatin when the drug was used alone. This increased delivery increases the therapeutic index of cisplatin and reduces side effects caused by a high dosage or long-term treatment times. We may consider this hexapeptide a new molecular carrier to deliver molecules with therapeutic activity into ER(+) cells for diagnostic purposes and clinical or immune therapy.

Associations of selenium status with cardiometabolic risk factors: an 8-year follow-up analysis of the Olivetti Heart study.

OBJECTIVE: High selenium status has been associated with adverse cardiometabolic outcomes in selenium-replete populations such as the US. In populations with lower selenium status such as in Italy, there is little epidemiological evidence about the association of selenium with cardiometabolic risk factors. We therefore examined cross-sectional and prospective relationships of serum selenium concentrations with cardiometabolic risk factors including blood pressure, diabetes and blood lipids in the Olivetti Heart Study. METHODS: The study population consisted of 445 adult male individuals for whom baseline serum selenium measurement and cardiometabolic risk factors at baseline (1994-1995) and follow-up examination (2002-2004: average follow-up=8 years) were available. Serum selenium was measured by atomic absorption spectrophotometry. RESULTS: Average serum selenium concentration at baseline was 77.5 ± 18.4 µg/L. In cross-sectional analyses, serum selenium levels were positively associated with serum total cholesterol (p for trend <0.0001) and prevalent diabetes (p for trend <0.05). In prospective analysis, serum selenium at baseline was likewise a strong predictor of serum total cholesterol (p=0.002) and LDL-cholesterol (p=0.001) at follow-up, after adjustment for age, BMI, cigarette smoking, physical activity, and lipid-lowering medication. These associations, however, were no longer significant after additional adjustment for baseline blood lipids. Selenium at baseline did not predict changes in total cholesterol levels between the baseline and follow-up examinations [ß-coefficient (± SE)= 0.09 ± 0.12 (p=0.46)]. CONCLUSION: These findings corroborate previous cross-sectional associations of high selenium status with adverse blood lipid profile and diabetes. However, prospective analyses do not support the causality of these relations. Randomized and experimental evidence is necessary to clarify the mechanisms underlying the observed cross-sectional associations.