Oral Administration of Fermented Papaya (FPP®) Controls the Growth of a Murine Melanoma through the In Vivo Induction of a Natural Antioxidant Response

Prolonged oxidative stress may play a key role in tumor development. Antioxidant molecules are contained in many foods and seem to have a potential role in future anti-tumor strategies. Among the natural antioxidants the beneficial effect of Fermented Papaya (FPP®) is well known. The aim of this study was to investigate the effects of orally administered FPP® in either the prevention or treatment of a murine model of melanoma. The tumor growth was analyzed together with the blood levels of both oxidants (ROS) and anti-oxidants (SOD-1 and GSH). The results showed that FPP® controlled tumor growth, reducing the tumor mass of about three to seven times vs. untreated mice. The most significant effect was obtained with sublingual administration of FPP® close to the inoculation of melanoma. At the time of the sacrifice none of mice treated with FPP® had metastases and the subcutaneous tumors were significantly smaller and amelanotic, compared to untreated mice. Moreover, the FPP® anti-tumor effect was consistent with the decrease of total ROS levels and the increase in the blood levels of GSH and SOD-1. This study shows that a potent anti-oxidant treatment through FPP® may contribute to both preventing and inhibiting tumors growth.