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Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Review Article Publication Acceptance Date: 3/22/2015 Publication Date: 3/30/2015 Publication URL: http://dx.doi.org/10.1021/acs.jafc.5b00818 Citation: Friedman, M. 2015. The chemistry and anticarcinogenic mechanisms of glycoalkaloids produced by eggplants, potatoes, and tomatoes. Journal of Agricultural and Food Chemistry. doi: 10.1021/acs.jafc.5b00818. Interpretive Summary: This review is intended to stimulate interest in the use of both pure and food-containing glycoalkaloids at nontoxic levels to help protect against or ameliorate multiorgan carcinogenesis. The described results may make it possible to better relate the structures of the active compounds to their health-promoting function, individually, in combination, and in food, and allow the consumer to select glycoalkaloid-containing food with the optimal content of nontoxic beneficial compounds. With respect to potatoes, unofficial worldwide guidelines recommend a guideline for total glycoalkaloid content of 20 mg/100 g fresh weight. It seems that this level in commercial potatoes might help protect against multiple cancers. Epidemiological studies are, however, needed to demonstrate this possibility. Guidelines for maximum glycoalkaloid content of eggplants and tomatoes have not been established. Because compared to the other glycoalkaloids, the tomato glycoalkalaoid tomatine exhibits low toxicity in animals and humans, future studies should concentrate on two tomato compounds. Plant scientists are challenged to develop high-tomatine red tomatoes by suppressing the genes that partly degrade tomatine during ripening of the fruit on the vine. High-tomatine red tomatoes will contain two anticarcinogenic and cholesterol-lowering compounds – tomatine and the antioxidative red pigment lycopene. The potential payoff will benefit the agricultural economy and human health. Technical Abstract: Inhibition of cancer can occur via apoptosis, a genetically directed process of cell self-destruction that involves numerous biomarkers and signaling pathways. Glycoalkaloids are nitrogen-containing secondary plant metabolites found in numerous Solanaceous plants including eggplants, potatoes, and tomatoes. Exposure of cancer cells to glycoalkaloids produced by eggplants (a-solamargine and a-solasonine), potatoes (a-chaconine and a-solanine), and tomatoes (a-tomatine), their hydrolysis products (mono-, di-, and tri-saccharide derivatives and the aglycones solasodine, solanidine, and tomatidine) inhibits the growth of the cells in culture (in vitro) as well tumor growth in vivo. This review comprehensively surveys and consolidates worldwide efforts to define the following aspects of these natural compounds: (a) prevalence in the three foods; (b) their chemistry and structure–activity relationships; (c) the reported factors (biomarkers, signaling pathways) associated with apoptosis of bone, breast, cervical, colon, gastric, glioblastoma, leukemia, liver, lung, lymphoma, melanoma, pancreas, prostate, and squamous cell carcinoma cell lines in vitro, and the in vivo inhibition of tumor formation and growth in fish and mice and in human skin cancers; and (d) future research needs. The described results may make it possible to better relate the structures of the active compounds to their health-promoting function, individually, in combination, and in food, and allow the consumer to select glycoalkaloid-containing food with the optimal content of nontoxic beneficial compounds. We expect the described findings to be a valuable record and resource for further investigation of the health benefits of food-related natural compounds. |
