Diterpenoids target SARS-CoV-2 RdRp from the roots of Steud.

INTRODUCTION

Currently, the development of new antiviral drugs against COVID-19 remains of significant importance. In traditional Chinese medicine, the herb Steud is often used for antiviral treatment, yet its therapeutic effect against the COVID-19 has been scarcely studied. Therefore, this study focuses on the roots of Steud, exploring its chemical composition, antiviral activity against COVID-19, and the underlying basis of its antiviral activity.

METHODS

Isolation and purification of phytochemicals from Steud. The elucidation of their configurations was achieved through a comprehensive suite of 1D and 2D NMR spectroscopic analyses as well as X-ray diffraction. Performed cytopathic effect assays of SARS-CoV-2 using Vero E6 cells. Used molecular docking to screen for small molecule ligands with binding to SARS-CoV-2 RdRp. Microscale thermophoresis (MST) was used to determine the dissociation constant Kd.

RESULTS

Ultimately, nine new ent-atisane-type diterpenoid compounds were isolated from Steud, named Eupfisenoids A-I (compounds 1-9). The compound of 1 was established as a C-19-degraded ent-atisane-type diterpenoid. During the evaluation of these compounds for their antiviral activity against COVID-19, compound 1 exhibited significant antiviral activity. Furthermore, with the aid of computer virtual screening and microscale thermophoresis (MST) technology, it was found that this compound could directly bind to the RNA-dependent RNA polymerase (RdRp, NSP12) of the COVID-19, a key enzyme in virus replication. This suggests that the compound inhibits virus replication by targeting RdRp.

DISCUSSION

Through this research, not only has our understanding of the antiviral components and material basis of Steud been enriched, but also the potential of atisane-type diterpenoid compounds as antiviral agents against COVID-19 has been discovered. The findings mentioned above will provide valuable insights for the development of drugs against COVID-19.