Apoptosis and Plant-Derived Pharmaceuticals

Abstract

The medicinal potential of the plant kingdom is widely exploited for its antitumoral properties. Many plant-derived antitumoral compounds such as paclitaxel, the vinca alkaloids, and catechin derivatives exhibit an extraordinary diversity of chemical structures that might exert their effects either by impairing cell division (mitosis) or by stimulating cells to undergo a cell-death program known as apoptosis. This review focuses on the effects of some plantderived antitumoral substances on programmed cell death in animals. Several studies have shown a correlation between plant-derived drug-induced cell death and expression of apoptotic regulators or altered signaling pathways. Among the regulators of programmed cell death that have a modified expression is the protein p53 (a protein that effects either arrest of the cell cycle or activation of cell death) and proteins belonging to the Bcl-2 family, including members that activate or inhibit cell death. In several studies, it was shown that interactions with those regulators involved changes in signal transduction, especially with specialized protein kinases. Although some antitumoral substances are used extensively in the clinical setting, their precise mechanism of action on cell death remains to be elucidated. On the other hand, since apoptosis could be initiated through diverse mechanisms, it appears that the molecular targets of various plant molecules that exhibit a wide diversity of chemical structures could also be diverse and may depend on the cellular context.