Inhibitory effect of thymoquinone and capsaicin on Blastocystis grown in vitro

Blastocystis is enteric parasites that live in both humans and animals gastrointestinal tracts. Metronidazole (MTZ) is generally preferred in the treatment of Blastocystis infection. However, it has been shown to have teratogenic and carcinogenic potential, causing various side effects. In this study, we have made an attempt to find an alternative drug with less toxic side effects in the treatment of Blastocystis. For this purpose, the anti-Blastocystis activities of thymoquinone (TQ) and capsaicin (CAP) were evaluated in vitro. Blastocystis isolate was inoculated in Jones medium in 1.5 mL eppendorf tubes supplemented with fetal calf serum (FCS) and incubated at 37°C. The anti-Blastocystis effect of TQ and CAP was evaluated by light microscopy (LM) and scanning electron microscopy (SEM). Both TQ and CAP had anti Blastocystis effects. It was observed that 500 ug/mL of TQ and 1000 ug/mL of CAP inhibited 100% of Blastocystis growth. In the LM and SEM images, it was observed that Blastocystis treated with TQ decreased in size and CAP had an effect on the cell surface when compared to the control group. It was concluded that TQ could be a more reliable anti-Blastocystis drug compared to MTZ and CAP, but more comprehensive studies should be performed.