The prodigiosins: a new family of anticancer drugs.

Apoptosis is involved in the action of several (and perhaps all) cancer-chemotherapeutic agents. Prodigiosins, a family of natural red pigments characterized by a common pyrrolylpyrromethene skeleton, are produced by various bacteria. Three members of the prodigiosin family, viz. prodigiosin (PG), undecylprodigiosin (UP) and cycloprodigiosin hydrochloride (cPrG.HCl), have immunosuppressive properties and apoptotic effects on cancer cells in vitro and in vivo. Their cytotoxic effect is attributed to the presence of the C-6 methoxy substituent. The A-pyrrole ring plays a key role in both the copper nuclease activity and the cytotoxicity of prodigiosins. Here, we have reviewed the pharmacological activity of PG and related compounds, including novel synthetic PG-derivatives with lower toxicity. The mechanism of action for these molecules is a current topic in biomedicine. The molecular targets of prodigiosins are also discussed.