Piperlongumine (PL) is a natural product constituent of the fruit of the Long pepper (Piper longum), a pepper plant found in southern India and southeast Asia.

Piperlongumine may have anti-cancer properties. In in vitro experiments, it selectively kills some types cancer cells over normal cells. One study in a xenograft mouse model of cancer showed that piperlongumine inhibits the growth of malignant breast tumors and their associated metastases.