Geranylated flavonoids displaying SARS-CoV papain-like protease inhibition from the fruits of Paulownia tomentosa

A series of geranylated flavonoids 1-12 demostrated a high inhibition against SARS-CoV pain like protease. The flavonoids 1-5 were identified as new compounds and have very rare functionality, 3,4-dihydro-2H-pyran.