In 2012, Park et al. 202  reported a tanshinone derivative 173 as a SARS‐CoV‐1 PLpro inhibitor with an IC50 value of 0.8 µM. The same research group also described diarylheptanoids blocking SARS‐CoV‐1 PLpro. In particular compound 174 performed as the best inhibitor of SARS‐CoV PLpro with an IC50 value of 4.1 µM. An α,β‐unsaturated carbonyl functionality was crucial for effective inhibition. The geranylated flavonoid 175 was another plant‐derived natural product, which displayed SARS‐CoV‐1 PLpro inhibition with an IC50 value of 5.0 µM. 203