Isolation, characterization and SARS-CoV-2 3CL protease inhibitory activity of a new methylsulfinyl-butanyl derivative from Raphani Semen

A new compound named raphanised A (1), along with two known methylsulfinyl -butanyl derivatives (2-3) and seven known indole derivatives (4-10), were isolated from the Raphani Semen. Among the indole derivatives, 5 was identified as a new natural product, and 4, 6, 7, 8, 9, 10 were isolated from the genus of Raphanus for the first time. Their structures were elucidated based on the NMR and HR-EI-MS analysis. Additionally, the inhibitory activity of methylsulfinyl-butanyl derivatives 1-3 on SARS CoV-2 3CL protease was evaluated. The results showed that 1-3 exhibited inhibition of SARS-CoV-2 3CL protease activity at concentrations ranging from 3.3 to 30 µM.