Investigating the effect of L-arginine on Blastocystis ST3 In vitro

Blastocystis is an extracellular and noninvasive unicellular enteric parasite with zoonotic potential. Intestinal epithelial cells produce nitric oxide (NO), primarily on the apical side, in order to target luminal pathogens. L-arginine can act as a substrate for inducible nitric oxide synthesis (iNOS), which leads to the synthesis of nitric oxide. The current study was designed to assess the effect of L-arginine on Blastocystis ST3 in vitro conditions.

The parasite was cultivated in DMEM F-12`s medium and was then identified by polymerase chain reaction (PCR) and the subtype of the parasite was determined which was subtype 3. Then, the methyl thiazolyl tetrazolium (MTT) and flow cytometry methods were used to evaluate the cytotoxicity and probable apoptosis of the prepared druges /substances on Caco2 cells. This study investigated the concentrations of L-arginine ( 1/02/04/08/0 and 1/6 mM ) and Metronidazole (1 2 4 8 and 16 µg/mL ), and their effect on 24 and 48 hour time points after exposure to the parasite. Then, the final number of parasites was counted after staining with trypan blue by a Neubauer slide and the values of IC50 were calculated for each substance.

It was found that after 48 hours the number of live Blastocystis trophozoites decreases with the increase in L-arginine concentration and At the concentration of 1.6 mM the number of live trophozoites was 33.83 (P≤0.05).

L-arginine, especially in high concentrations‚ is capable of inhibiting Blastocystis trophozoites In vitro.