Anti-cancer Activity of Natural and Synthetic Capsaicin Analogs

The nutritional compound capsaicin is the major spicy ingredient of chili peppers. Although traditionally associated analgesic activity, recent studies have shown that capsaicin has profound anti-neoplastic effects in several types of human cancers. However, the applications of capsaicin as a clinically viable drug are limited by its unpleasant side effects like gastric irritation, stomach cramps and burning sensation. This has led to extensive research focused on the identification and rational design of a second generation of non-pungent capsaicin-analogs which will retain the biological activity of capsaicin. A majority of these natural capsainoids and synthetic capsaicin mimetics have been studied for their pain-relieving activity. Only a few of these capsaicin-analogs have been investigated for their anti-cancer activity in cell culture and animal models. The present review summarizes the current knowledge on the growth-inhibitory activity of natural capsaicinoids and synthetic capsaicin analogs. Future studies that examine the anti-cancer activity of a greater number of capsaicin-mimetics represent novel strategies in the treatment of human cancers.