In vitro anti-Toxoplasma effects and apoptotic induction of queen bee acid (10-hydroxy-2-decenoic acid) alone and in combination with atovaquone

Toxoplasmosis, which is created by the Toxoplasma gondii parasite is a parasitic, infectious disease. 10-hydroxy-2-decenoic acid (10-H2DA, queen bee acid (QBA), is one of the most prevalent fatty acid (>40%) presents in royal jelly. Studies reported various beneficial effects of 10-H2DA antitumor, anti-inflammatory, antiangiogenic, improving the immune system, and antimicrobial effects. This experimental survey aimed to evaluate the in vitro efficacy of QBA against tachyzoites and intracellular parasites of the T. gondii RH strain. Anti-Toxoplasma effects of QBA against tachyzoites were examined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay for 30, 60, 120, and 180 min. In addition, the effect of QBA on infection rate and intracellular parasites was studied. Real-time PCR was also applied to assess the expression level of the Caspase-3 gene. The best efficiency of QBA was reported at 100 and 50 µg/mL whereas all tachyzoites were diminished followed by 120- and 180-min treatment, respectively. We also found that the best repressing efficacy of QBA on the infection rate and the load of parasites into the Vero cells was indicated at 100 µg/mL (p<0.001): but, the combination of QBA (12.5 µg/mL) along with atovaqoune 30 µg/mL displayed the highest effect on the infection rate and the load of parasites into the Vero cells in the infected Vero cells. The expression level of the Caspase-3 gene was dose-dependently increased after exposure of tachyzoites to QBA; mainly at ½ IC50, and IC50 compared to the normal saline. The achieved findings exhibited the high in vitro potency of QBA especially in combination with atovaqoune against T. gondii RH strain tachyzoites. Although apoptosis induction can be suggested as one of the principle mechanisms; more studies are required to elucidate its accurate mechanisms as well as its efficacy and safety in animal models and clinical settings.