Discovery of Hybrid Thiouracil-Coumarin Conjugates as Potential Novel Anti-SARS-CoV-2 Agents Targeting the Virus's Polymerase "RdRp" as a Confirmed Interacting Biomolecule

Divakar Vishwanath; Anita Shete-Aich; Manjunath B Honnegowda; Mahesh Padukudru Anand; Saravana Babu Chidambaram; Gajanan Sapkal; Basappa Basappa; Pragya D Yadav

doi:10.1021/acsomega.3c02079

Discovery of Hybrid Thiouracil-Coumarin Conjugates as Potential Novel Anti-SARS-CoV-2 Agents Targeting the Virus's Polymerase "RdRp" as a Confirmed Interacting Biomolecule

ACS Omega. 2023 Jul 14;8(30):27056-27066. doi: 10.1021/acsomega.3c02079. eCollection 2023 Aug 1.

Authors

Divakar Vishwanath¹, Anita Shete-Aich², Manjunath B Honnegowda³, Mahesh Padukudru Anand⁴, Saravana Babu Chidambaram⁵, Gajanan Sapkal², Basappa Basappa¹, Pragya D Yadav²

Affiliations

¹ Laboratory of Chemical Biology, Department of Studies in Organic Chemistry, University of Mysore, Manasagangotri, Mysore 570006, India.
² Indian Council of Medical Research- National Institute of Virology (ICMR-NIV), Pune, Maharashtra411021, India.
³ DRM innovations PVT.LTD, Mysore570029, India.
⁴ Department of Respiratory Medicine, JSS Medical College, and Hospital, JSS Academy of Higher Education & Research, Mysore 570015, Karnataka, India.
⁵ Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research, Mysore 570015, Karnataka, India.

Abstract

The coronavirus (COVID-19) pandemic, along with its various strains, has emerged as a global health crisis that has severely affected humankind and posed a great challenge to the public health system of affected countries. The replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mainly depends on RNA-dependent RNA polymerase (RdRp), a key enzyme that is involved in RNA synthesis. In this regard, we designed, synthesized, and characterized hybrid thiouracil and coumarin conjugates (HTCAs) by ether linkage, which were found to have anti-SARS-CoV-2 properties. Our in vitro real-time quantitative reverse transcription PCR (RT-qPCR) results confirmed that compounds such as 5d, 5e, 5f, and 5i inhibited the replication of SARS-CoV-2 with EC₅₀ values of 14.3 ± 0.14, 6.59 ± 0.28, 86.3 ± 1.45, and 124 ± 2.38 μM, respectively. Also, compound 5d displayed significant antiviral activity against human coronavirus 229E (HCoV-229E). In addition, some of the HTCAs reduced the replication of SARS-CoV-2 variants such as D614G and B.617.2. In parallel, HTCAs in uninfected Vero CCL-81 cells indicated that no cytotoxicity was noticed. Furthermore, we compared the in silico interaction of lead compounds 5d and 5e toward the cocrystal structure of Suramin and RdRp polymerase with Remdesvir triphosphate, which showed that compounds 5d, 5e, and Remdesvir triphosphate (RTP) share a common catalytical site of RdRp but not Suramin. Additionally, the in silico ADMET properties predicted for the lead HTCAs and RTP showed that the maximum therapeutic doses recommended for compounds 5d and 5e were comparable to those of RTP. Concurrently, the pharmacokinetics of 5d was characterized in male Wistar Albino rats by administering a single oral gavage at a dose of 10 mg/kg, which gave a Cmax value of 0.22 μg/mL and a terminal elimination half-life period of 73.30 h. In conclusion, we established a new chemical entity that acts as a SARS-CoV-2 viral inhibitor with minimal or no toxicity to host cells in the rodent model, encouraging us to proceed with preclinical studies.