Anti-Parasitic Activity of Cherry Tomato Peel Powders

Abstract

Trichomoniasis in humans, caused by the protozoal parasite Trichomonas vaginalis, is the most common non-viral sexually transmitted disease, while Tritrichomonas foetus causes trichomonosis, an infection of the gastrointestinal tract and diarrhea in farm animals and domesticated cats. As part of an effort to determine the inhibitory effects of plant-based extracts and pure compounds, seven commercially available cherry tomato varieties were hand-peeled, freeze-dried, and pounded into powders. The anti-trichomonad inhibitory activities of these peel powders at 0.02% concentration determined using an in vitro cell assay varied widely from 0.0% to 66.7% against T. vaginalis G3 (human); from 0.9% to 66.8% for T. foetus C1 (feline); and from 0.0% to 81.3% for T. foetus D1 (bovine). The organic Solanum lycopersicum var. cerasiforme (D) peels were the most active against all three trichomonads, inhibiting 52.2% (G3), 66.8% (C1), and 81.3% (D1). Additional assays showed that none of the powders inhibited the growth of foodborne pathogenic bacteria, pathogenic fungi, or non-pathogenic lactobacilli. Tomato peel and pomace powders with high content of described biologically active compounds could serve as functional food and feed additives that might help overcome adverse effects of wide-ranging diseases and complement the treatment of parasites with the anti-trichomonad drug metronidazole.

Keywords: animal health; anti-trichomonad properties; cherry tomato peels; cherry tomato pomace; cherry tomatoes; composition; food and industrial uses; human health; research needs.

Figure 1

Cherry tomato powders and peels inhibit the growth of trichomonad parasites. The graph shows the percentage growth inhibition for T. vaginalis G3, T. foetus C1, and T. foetus D1 at the final concentration of 0.02% w/v for each powder and peel. Percentage growth inhibition was calculated relative to the DMSO:water vehicle control at the same concentration as the test substance in each experiment. There was very little if any toxicity associated with the vehicle control. Differential inhibition of parasites is observed.

Figure 2

Structures of three classes of biologically active tomato compounds: (a) pigments, (b) phenolics, and (c) tomato glycoalkaloids discussed in the text.