Erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin inhibit cytopathic effect, papain-like protease, and MPRO enzymes of SARS-CoV-2.

Background: Although tremendous success has been achieved in the development and deployment of effective COVID-19 vaccines, developing effective therapeutics for the treatment of those who do come down with the disease has been with limited success. To repurpose existing drugs for COVID-19, we previously showed, qualitatively, that erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin inhibit SARS-COV-2-induced cytopathic effect (CPE) in Vero cells. Aim: This study aimed to quantitatively explore the inhibition of SARS-CoV-2-induced CPE by erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin and to determine the effect of these drugs on SARS-CoV-2 papain-like protease and 3CL protease (MPRO) enzymes. Methods: Neutral red (3-amino-7-dimethylamino-2-methyl-phenazine hydrochloride) cell viability assay was used to quantify CPE after infecting pre-treated Vero cells with clinical SARS-Cov-2 isolates. Furthermore, SensoLyte® 520 SARS-CoV-2 papain-like protease and SensoLyte® 520 SARS-CoV-2 MPRO activity assay kits were used to evaluate the inhibitory activity of the drugs on the respective enzymes. Results: Erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin dose-dependently inhibit SARS-CoV-2-induced CPE in Vero cells, with inhibitory concentration-50 (IC50) values of 3.27 µM, 4.23 µM, 9.29 µM, 3.19 µM, and 84.31 µM, respectively. Furthermore, erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin dose-dependently inhibited SARS-CoV-2 papain-like protease with IC50 values of 0.94 µM, 0.88 µM, 1.14 µM, 1.07 µM, and 1.51 µM, respectively, and inhibited the main protease (MPRO) with IC50 values of 1.35 µM, 1.25 µM, 7.36 µM, 1.15 µM, and 2.44 µM, respectively. Conclusion: The IC50 for all the drugs, except ivermectin, was at the clinically achievable plasma concentration in humans, which supports a possible role for the drugs in the management of COVID-19. The lack of inhibition of CPE by ivermectin at clinical concentrations could be part of the explanation for its lack of effectiveness in clinical trials.

Innovative, rapid, high-throughput method for drug repurposing in a pandemic-A case study of SARS-CoV-2 and COVID-19.

Several efforts to repurpose drugs for COVID-19 treatment have largely either failed to identify a suitable agent or agents identified did not translate to clinical use. Reasons that have been suggested to explain the failures include use of inappropriate doses, that are not clinically achievable, in the screening experiments, and the use of inappropriate pre-clinical laboratory surrogates to predict efficacy. In this study, we used an innovative algorithm, that incorporates dissemination and implementation considerations, to identify potential drugs for COVID-19 using iterative computational and wet laboratory methods. The drugs were screened at doses that are known to be achievable in humans. Furthermore, inhibition of viral induced cytopathic effect (CPE) was used as the laboratory surrogate to predict efficacy. Erythromycin, pyridoxine, folic acid and retapamulin were found to inhibit SARS-CoV-2 induced CPE in Vero cells at concentrations that are clinically achievable. Additional studies may be required to further characterize the inhibitions of CPE and the possible mechanisms.

Carotenoid-Enriched Fractions From Spondias mombin Demonstrate HER2 ATP Kinase Domain Inhibition: Computational and In Vivo Animal Model of Breast Carcinoma Studies.

Human epidermal growth factor 2 (HER2) is overexpressed in about 20% of breast cancer and is associated with a poor prognosis. We report in this study that carotenoid-enriched fractions from Spondias mombin demonstrate HER2 ATP kinase domain inhibition. HER2 breast carcinoma was modeled in female Wistar rats and authenticated via immunohistochemical studies. Inhibition of HER2 ATP kinase domain by the carotenoid-enriched fractions was investigated by molecular docking, atomistic simulation, and the expression of HER2 mRNA in HER2-positive breast carcinoma model in female Wistar rats. The therapeutic efficacy of the treatments (carotenoid-rich fractions) was determined by biochemical, tumor volume, and histopathological analysis. Immunohistochemical analysis revealed 7,12-dimethylbenz[a]anthracene (DMBA)-induced HER2-positive breast carcinoma. Phytoconstituents of the carotenoid-enriched fractions astaxanthin, 7,7',8,8'-tetrahydro-ß,ß-carotene, beta-carotene-15,15'-epoxide, and lapatinib (standard drug) demonstrate inhibition of HER2 with docking scores of -3.0, -8.5, -11.5, and -10.6 kcal/mol, respectively; and during atomistic simulation, the compounds ruptured the canonical active-state K753/E770 salt-bridge interaction. The treatment similarly downregulated HER2 mRNA expression significantly at p < 0.05. It also upregulated the expression of p53 and p27 mRNAs significantly at p < 0.05 and reduced creatinine and urea concentrations in the serum at p < 0.05. The tumor volume was also significantly reduced when compared with that of the untreated group. Carotenoid-enriched fractions from S. mombin demonstrate anti-HER2 positive breast carcinoma potentials via HER2 ATP kinase domain inhibition.