Frog Skin Peptides as Potential Therapeutics for Covid-19 Treatment

Since the emergence of Covid-19, more than 99 million people in the United States have been infected, resulting in more than 1 million deaths. SARS‑CoV‑2 is a severe acute respiratory disease related to Covid-19. SARS‑CoV‑2 has been the leading cause of mortality in relation to Covid-19. Treatment for SARS‑CoV‑2 in severe cases includes antiviral medications and anti-viral therapies. Antimicrobial peptides offer a promising alternative therapy for Covid-19 treatment. Among all viral proteins, main protease also known as Chymotrypsin-like protease (3CLpro) regulate both the life cycle and replication of SARS-CoV-2. 3CLpro is a functional homodimer with two active sites of Cys145 and His41 that lead to the cleavage of polyproteins. Main protease emerged as an important target for antiviral drug design for Covid-19 treatment. Although various small molecules showed promising results, peptide-based therapeutics are not explored. In this study, 44 antimicrobial peptides are collected from Lithobates Frog skin and modelled their 3D structures by PEP-FOLD 3.5. To measure the binding affinity and interaction between peptide and 3CLpro protease, molecular docking simulation was performed using HDOCK tool. The peptides that displayed significant interaction with the active sites of the protease are RS26, RS35, RS3, RS20, and RS4. The binding affinity scores for each peptide goes as follows -201.72, -194.71, -189.9, -185.45, -184.46, and -184.01. Using Liberty Blue microwave peptide synthesizer (CEM), the best peptide was synthesized, and subsequent characterization was conducted by mass spectrometry. In future, biochemical assay will be performed by FREQ based protease inhibition protocol