Phytoalexins in cancer prevention.
Plant phytoalexins are a class of low molecular weight compounds that accumulate in response to biotic and abiotic elicitors such as pathogens, wounding, freezing, UV light, and exposure to agricultural chemicals.  Phytoalexins have been identified in at least 75 plants including cruciferous vegetables, soybean, garlic, tomato, rice, beans, and potatoes suggesting plants may be a rich source of cancer-fighting compounds. Preclinical evidence suggests these compounds possess anticancer properties including an inhibition of microbial activity, cell proliferation, invasion and metastasis, hormonal stimulation, and stimulatory effects on expression of metabolizing enzymes. This review highlights the plausible molecular mechanisms through which phytoalexins regulate biological processes that can impinge cancer development.  Targets of phytoalexins include signal transduction pathways, transcription factors, cell cycle checkpoints, intrinsic and extrinsic apoptotic pathways, cell invasion and matrix metalloproteinase, nuclear receptors, and the phase II detoxification pathway.  Additional research should address physiological relevant dietary concentrations, combinations of phytoalexins and interactions with other dietary compounds, duration of exposure, and tissue specificity as variables that influence the effectiveness of phytoalexins on normal and cancerous processes.
Department of Nutritional Sciences and Arizona Cancer Center, The University of Arizona, Tucson, AZ 85721-0038, USA. donato@u.arizona.edu
Donato F
DF
Romagnolo
Cindy D
CD
Davis
John A
JA
Milner
D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D016588:Anticarcinogenic Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001682:Biological Availability; D049109:Cell Proliferation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D006801:Humans; D009361:Neoplasm Invasiveness / Q000517:prevention & control; D009362:Neoplasm Metastasis / Q000517:prevention & control; D009369:Neoplasms / Q000517:prevention & control*; D009376:Neoplasms, Hormone-Dependent / Q000517:prevention & control; D012717:Sesquiterpenes / Q000493:pharmacokinetics / Q000494:pharmacology*; D000094162:Phytoalexins
D000890:Anti-Infective Agents; D016588:Anticarcinogenic Agents; D004791:Enzyme Inhibitors; D006727:Hormone Antagonists; D012717:Sesquiterpenes; D000094162:Phytoalexins