Antiprotozoal Effects of the Tomato Tetrasaccharide Glycoalkaloid Tomatine and the Aglycone Tomatidine on Mucosal Trichomonads

Abstract

The present study investigated the inhibitory effects of the commercial tetrasaccharide tomato glycoalkaloid tomatine and the aglycone tomatidine on three mucosal pathogenic protozoa that are reported to infect humans, cattle, and cats, respectively: Trichomonas vaginalis strain G3, Tritrichomonas foetus strain D1, and Tritrichomonas foetus strain C1. A preliminary screen showed that tomatine at 100 μM concentration completely inhibited the growth of all three trichomonads. In contrast, the inhibition of all three pathogens by tomatidine was much lower, suggesting the involvement of the lycotetraose carbohydrate side chain in the mechanism of inhibition. Midpoints of concentration-response sigmoid plots of tomatine on the three strains correspond to IC values, the concentration that inhibits 50% of growth of the pathogenic protozoa. The concentration data were used to calculate the IC values for G3, D1, and C1 of 7.9, 1.9, and 2.2 μM, respectively. The results show an approximately 4-fold variation from the lowest to the highest value (lowest activity). Although the inhibition by tomatine was not as effective as that of the medicinal drug metronidazole, the relatively low IC values for both T. vaginalis and T. foetus indicated tomatine as a possible natural alternative therapeutic for trichomoniasis in humans and food-producing (cattle and pigs) and domestic (cats) animals. Because tomatine has the potential to serve as a new antiprotozoan functional (medical) food, the distribution of this glycoalkaloid in tomatoes and suggestions for further research are discussed.

The Inhibitory Activity of Anthraquinones against Pathogenic Protozoa, Bacteria, and Fungi and the Relationship to Structure

“…We previously reported on the anti-oxidative and anti-inflammatory activities of four anthraquinones in chemical and cell assays [13] and on the anti-obesity properties of purpurin in mice on a high-fat diet [14]. In several publications related to the present study, we reported that the tomato glycoalkaloid tomatine [33], theaflavin-rich black tea extracts [34], potato-peel-containing glycoalkaloids and phenolic compounds [35] inhibited the growth of T. vaginalis human strain G3, T. foetus bovine strain D1, and T. foetus feline strain C1. We also reported that the potato peels and glycoalkaloids exhibited strong anti-obesity properties in mice on a high-fat diet [36].…”

Comparative Therapeutic Effects of Natural Compounds Against Saprolegnia spp. (Oomycota) and Amyloodinium ocellatum (Dinophyceae)

“…Tomatine administrated in vivo at a dose of 2,000 ppm showed anticarcinogenic effects against dibenzo[a,l]pyrene (DBP)-induced liver and stomach tumors in rainbow trout (O. mykiss) without adverse effects on animals (62). More recently, Liu et al (63) documented inhibitory effects of Tomatine on human and animal pathogenic protozoa. In particular, the reported doses of the compound, which inhibited the growth of the three surveyed trichomonads, are in line with the concentrations tested in the present trial against A. ocellatum, in which Tomatine displayed inhibitory effects for the whole duration of the experiment (24 h) in the dose ranges 6.25-50 µg/ml (0.006-0.05 mM).…”

Food Glycoalkaloids: Distribution, Structure, Cytotoxicity, Extraction, and Biological Activity

“…However, in contrast, Simons et al found that the aglycone tomatidine has far more antifungal activity toward yeast and a more distinct mode of action than α-tomatine [120]. The membrane lytic effect of α-tomatine is pH dependent, and it has also mentioned that some fungi are able to colonize α-tomatine-containing tomato tissue by lowering the pH of the infection site [121].…”