In this study, we have modified 4-hydroxypyran-2-ones, especially introduced heteroatoms (S or O) into the substituents, and detected their interactions with the binding pockets of HIV-1 protease (PR). The results indicated that the ethoxyl groups at C-20 and C-50 of the phenyl ring could enhance the affinities to the S1 0 and S2 0 pockets and improve the inhibitory activities. The most potent compound 10f with an IC50 of 3.5 nM in enzymatic assay also exhibited good antiviral activity at the cellular level; it exhibited an EC50 value of 2.9 lM in Simian immunodeficiency virus-infected CEM cells and suppressed the PR activity in 293T cells using western blot analysis.