Diphyllin is primarily known for its application as a precursor in the synthesis of antiviral agents. It exhibits inhibitory activity against certain enveloped viruses by interfering with viral entry and fusion processes, particularly through the inhibition of vacuolar ATPase (V-ATPase), a key enzyme involved in endosomal acidification required for viral replication. This mechanism makes diphyllin a subject of interest in developing treatments for viruses such as dengue, influenza, and Ebola.

It also shows potential in anticancer research due to its ability to induce apoptosis and inhibit tumor cell proliferation, especially in studies involving leukemia and other cancer cell lines. Additionally, diphyllin derivatives are explored for their immunomodulatory and anti-inflammatory properties, offering avenues for therapeutic development in chronic inflammatory conditions.