Cytotoxic effect of pure compounds from Piper rivinoides Kunth against oral squamous cell carcinoma.

The oral squamous cell carcinoma (OSCC) is the eighth more common cancer in men. The development of new and more efficient drugs is needed. Plants of the genus Piper are popularly used in the treatment of many diseases. This study evaluated the antitumor effect of extract, fraction and isolated compounds from leaves of P. rivinoides in oral cancer. The isolated compounds (conocarpan, eupomatenoid-5 and eupomatenoid-6) were effective in inducing cell death in OSCC cell lines (SCC4, SCC9 and SCC25) compared to the standard chemotherapeutic agent carboplatin, and this effect was time-dependent. Conocarpan was more selective and stable than eupomatenoid-5 and eupomatenoid-6, resembling the stability of carboplatin. There was a significant presence of pyknotic nuclei and active caspase-3 expression under conocarpan treatment, suggesting cell death through apoptosis. In conclusion, conocarpan was the most effective compound against OSCC cells and might be considered for future cancer studies.