Alpha-carotene is a provitamin A carotenoid present in fruits and vegetables. Higher serum concentrations of α-carotene have been associated with lower risk of cancer and all-cause mortality. It was suggested that genetic variants influence serum concentrations of provitamin A. Recently was found, that α-carotene effectively inhibits Lewis lung carcinoma (LLC) metastasis and suppresses lung metastasis in combination with taxol in LLC-bearing mice, suggesting that Alpha-carotene could be used as an anti-metastatic agent or as an adjuvant for anti-cancer drugs.

ETRYPTAMINE (MONASE®), similar to the hallucinogenic tryptamines, is an inhibitor of monoamine oxidase, introduced for use as an antidepressant. It was withdrawn from the market due to problems with agranulocytosis and other side effects. However, it's activity is still under scientific investigation.