Phytochemical-rich foods inhibit the growth of pathogenic trichomonads

Authors: NORITAKE, SABRINA - University Of The Pacific; LIU, JENNY - University Of The Pacific; KANETAKE, SIERRA - University Of The Pacific; Levin, Carol; Tam, Christina; Cheng, Luisa; LAND, KIRKWOOD - University Of The Pacific; Friedman, Mendel

Submitted to: BMC Complementary and Alternative Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2017
Publication Date: 9/13/2017
Citation: Noritake, S.M., Liu, J., Kanetake, S., Levin, C.E., Tam, C.C., Cheng, L.W., Land, K.M., Friedman, M. 2017. Phytochemical-rich foods inhibit the growth of pathogenic trichomonads. BMC Complementary and Alternative Medicine. 17(1):461. https://doi.org/10.1186/s12906-017-1967-x.
DOI: https://doi.org/10.1186/s12906-017-1967-x

Interpretive Summary: Trichomoniasis, caused by the pathogenic trichomonad Trichomonas vaginalis, is one of the most common nonviral sexually transmitted infections in the world, contributes to reproductive morbidity, and facilitates transmission of the human immunodeficiency virus (HIV). Because some T. vaginalis strains have become resistant to the FDA-approved synthetic drug metronidazole, a need exists to develop alternative treatments, preferably based on safe natural products. We previously reported that the tomato glycoalkaloid tomatine strongly inhibited the growth of the following three mucosal pathogenic protozoa strains that are reported to infect humans, cattle, and cats: Trichomonas vaginalis strain G3, Tritrichomonas foetus strain D1, and Tritrichomonas foetus strain C1, respectively. The objective of the present study was to determine using cell-based assays the potential of ten food-compatible plant extracts to inactivate multiple strains of antibiotic-susceptible and antibiotic-resistant disease-causing pathogenic protozoa. The results show that theaflavin-rich black tea extracts and, to a lesser extent, catechin-rich green tea and ellagic acid-containing pomegranate extracts are effective under the described in vitro test conditions in inhibiting the growth of drug sensitive and drug resistant strains of T. vaginalis. On the basis of these results and our previous study on tomatine, there is a need for further clinical studies designed to evaluate both tomatine and the active plant extracts to treat animal and human trichomoniasis using these food-compatible and safe formulations that would be expected to receive rapid approval for commercial sale by the Food and Drug Administration (FDA).

Technical Abstract: Plants produce bioactive organic compounds known as secondary metabolites that possess numerous health benefits, including antimicrobial properties. One mechanism of action of these plant bioactive compounds targets the disruption of cell membranes. The main of objective of the present study was to determine the potential of the following plant formulations, known to inhibit pathogenic foodborne bacteria and viruses, to inhibit the growth of nonresistant and antibiotic-resistant Trichomonas vaginalis strains responsible for venereal diseases in animals (cattle, pigs, cats) and humans: black tea extracts with a low and high theaflavin content; grape fruit and grape seed extracts; green tea extracts; jujube fruit and seed extracts; and pomegranate fruit and seed extracts. The results show that (a) the black theaflavin-rich (80%) extract strongly inhibited the growth of both nonresistant strains and a clinical strain that is resistant to metronidazole, a drug widely used to treat human infections; (b) the theaflavin-poor (20%) black tea extract was less effective; (c) the green tea and pomegranate extracts showed intermediate activity; and (d) the other formulations exhibited low or no activity under the test conditions. Given that these protozoal pathogens are mucosal and reside within a complex microbiome, we also screened these plant formulations on a number of common normal flora bacteria and observed no effect on their growth. The results suggest that the black tea, green tea, and pomegranate extracts 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.