Potato peels and their bioactive glycoalkaloids and phenolic compounds inhibit the growth of pathogenic trichomonads

Authors: Friedman, Mendel; HUANG, VINCENT - University Of The Pacific; QUIAMBAO, QUINCEL - University Of The Pacific; NORITAKE, SABRINA - University Of The Pacific; LIU, JENNY - University Of The Pacific; KWON, OHKUN - University Of The Pacific; CHINTALAPATI, SIRISHA - University Of The Pacific; Levin, Carol; Tam, Christina; Cheng, Luisa; LAND, KIRKWOOD - University Of The Pacific

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2018
Publication Date: 7/24/2018
Citation: Friedman, M., Huang, V., Quiambao, Q., Noritake, S.S., Liu, J., Kwon, O., Chintalapati, S., Levin, C.E., Tam, C.C., Cheng, L.W., Land, K.M. 2018. Potato peels and their bioactive glycoalkaloids and phenolic compounds inhibit the growth of pathogenic trichomonads. Journal of Agricultural and Food Chemistry. 66(30):7942-7947. https://doi.org/10.1021/acs.jafc.8b01726.
DOI: https://doi.org/10.1021/acs.jafc.8b01726

Interpretive Summary: Trichomoniasis, caused by the pathogenic trichomonad Trichomonas vaginalis is one of the most common nonviral sexually transmitted infections in the world that contributes to reproductive morbidity and facilitates transmission of the human immunodeficiency virus (HIV). Strains of the related protozoan Tritrichomonas foetus are reported to cause pathogenesis of trichomonosis in food (cattle, bulls, and pigs) and domestic animals (cats). In cattle, the disease causes failed pregnancies and is asymptomatic in bulls, leading to reinfection even after the cows are treated. The most cost-effective method to control the disease is often culling the infected animals. In domesticated cats, the disease infects the GI tract causing persisetent diarrhea. Because some. strains have become resistant to the FDA-approved synthetic drug metronidazole, a need exists to develop alternative treatments, preferably based on safe natural food-compatible formulations. We previously reported that the tomato glycoalkaloid tomatine and several food-compatible plant extracts inhibited the growth of the three mucosal pathogenic protozoa strains that are reported to infect humans, cattle, and felines. In the present study we have shown that potato peels prepared from commercial nonorganic and organic potatoes also inhibited the growth of the parasitic pathogens. The peels derived from both nonorganic and organic Russet potatoes showed the highest inhibitory activity against the parasitic protozoa, suggesting that they could serve as anti-trichomonad food and feed additives.

Technical Abstract: Potato peel, a waste product of the potato processing industry, is high in bioactive compounds. We investigated the anti-trichomonad activity of seven potato peel powders prepared from commercial Russet, red, purple, and fingerling nonorganic and organic varieties as well as several known components of potatoes in vitro against three pathogenic strains of Trichomonas vaginalis and Tritrichomonas foetus that cause trichomonosis, a sexually transmitted disease in humans and cattle, and an orally transmitted disease in domesticated cats. The glycoalkaloids a-chaconine and a-solanine were highly active against all cell lines, while their common aglycone solanidine was only mildly inhibitory. a-Solanine was several times more active than a-chaconine. The phenolic compounds caffeic and chlorogenic acids were mildly active against the cells. The activities of the peels against the cells were wide-ranging, and did not correspond to their glycoalkaloid and phenolic content determined by HPLC. The two Russet samples were the most active against all three parasites. Most of the potato samples were at least somewhat active against all three trichomonad species, The purple potato peel sample was highly active against bovine and mostly inactive against feline trichomonad cell lines. All test substances had no effect on common normal flora bacteria, suggesting that possible therapeutic treatments might not be influenced by changes in the microbiota. The results suggest that the potato peels derived from Russet potatoes, the glycoalkaloids, and to a lesser extend the phenolic compounds might present possible natural alternative therapeutic agents to treat Trichomonas vaginalis infections in humans and the related Tritrichomonas foetus in food-producing animals and cats.