In silico discovery of SARS-CoV-2 main protease inhibitors from the carboline and quinoline database.

Aim: SARS-CoV-2 caused more than 3.8 million deaths according to the WHO. In this urgent circumstance, we aimed at screening out potential inhibitors targeting the main protease of SARS-CoV-2. Materials & methods: An in-house carboline and quinoline database including carboline, quinoline and their derivatives was established. A virtual screening in carboline and quinoline database, 50 ns molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area calculations were carried out. Results: The top 12 molecules were screened out preliminarily. The molecular mechanics Poisson-Boltzmann surface area ranking showed that p59_7m, p12_7e, p59_7k stood out with the lowest binding energies of -24.20, -17.98, -17.67 kcal/mol, respectively. Conclusion: The study provides powerful in silico results that indicate the selected molecules are valuable for further evaluation as SARS-CoV-2 main protease inhibitors.

Nanoparticles of a New Small-Molecule P-Selectin Inhibitor Attenuate Thrombosis, Inflammation, and Tumor Growth in Two Animal Models.

PURPOSE: To assess whether the newly designed small-molecule oral P-selectin inhibitor 3S-1,2,3,4-tetrahydro-ß-carboline-3-methyl aspartyl ester (THCMA) as a nanomedicine enhances antithrombosis, anti-inflammation, and antitumor activity more than the clinical trial drug PSI-697. METHODS: THCMA was designed as an amphiphile containing pharmacophores of PSI-697. Its nanofeatures were explored with TEM, SEM, Tyndall effect, ζ-potential, FT-ICR-MS, and NOESY 2D 1H NMR. The P-selectin inhibitory effect of THCMA was demonstrated with molecular docking, ultraviolet (UV) spectra, and competitive ELISA. In vivo and in vitro assays - anti-arterial thrombosis, anti-venous thrombosis, anti-inflammation, antitumor growth, anti-platelet aggregation, rat-tail bleeding time, anticoagulation index, soluble P-selectin (sP-selectin) expression, and serum TNFα expression - were performed to explore bioactivity and potential mechanisms. Water solubility of THCMA was measured using UV-absorption spectra. RESULTS: THCMA self-assembled into nanorings of approximately 100 nm in diameter. Its water solubility was about 1,030-fold that of PSI-697. THCMA exhibited more potent P-selectin inhibitory effect than PSI-697. The oral efficacy of THCMA was 100-fold that of PSI-697 in inhibiting arterial and venous thrombosis and tenfold in inhibiting inflammation. THCMA inhibited thrombosis at a dose that produces no coagulation disorders and no bleeding risk. THCMA exhibited enhanced antitumor activity over PSI-697 without systemic chemotherapy toxicity. THCMA significantly inhibited platelet aggregation in vitro and downregulated the expression levels of serum sP-selectin and TNFα in vivo. CONCLUSION: A new small-molecule P-selectin inhibitor, THCMA, has been successfully designed as a nanomedicine with largely enhanced oral efficacy compared to the clinical trial drug PSI-697, and thus might be developed for the oral treatment of arterial thrombosis, venous thrombosis, inflammation, and cancer-associated thrombosis.