drug-resistant strains of influenzavirus. Our earlier studies have identified that certain pentacyclic triterpene derivatives are effective inhibitors of influenzavirus infection. In the present study, a series of C-28 modified pentacyclic triterpene derivatives via conjugation with a series of polyphenols were synthesized, and their antiviral activities againstinfluenza A/WSN/33 (H1N1) virus in MDCK (Madin-Darby