Phytochemicals and amino acids: Inducers or inhibitors of cell death?

Abstract

Phytochemicals and amino acids have long been considered as important inducers of cell death. However, many of these natural compounds have been demonstrating dual action effects on cell death through inhibition as well as induction. Clinical applications may require dosage adjustment and determination of selectively vulnerable cells, either normal or cancer cells. Indeed, the opposing actions and controversial uses as cytoprotective and/or cytotoxic agents, in different tissues and diseases, need further scrutiny. The potential usefulness of these natural compounds as combined chemoprotectants for cancer chemotherapy should also be taken into consideration. Special emphasis will be placed on curcumin and Astragalus constituents as potential phytochemicals. Relevant amino acids include the excitatory and branched-chain ones, as well as glycine and cysteine.