Fig. 3. Determination of CC₅₀ and IC₅₀ of hydrazide (Hyd), hydrazone (HQ) and pyrrolone (15A) in Vero E6 cells against SARS-CoV-2, MERS-CoV, and HCoV-229E. Values of CC₅₀ and IC₅₀ were calculated using non-linear regression analysis with Graph Pad Prism software (version 5.01).