Promising antiparasitic effects of Diallyl disulfide against Echinococcus granulosus; targeting disruption of antioxidant defense systems

Abstract

Cystic echinococcosis, also known as hydatid disease, is a chronic parasitic infection of global concern caused by the larval stage of Echinococcus granulosus. The present study aimed to assess the antiparasitic effects and cellular mechanisms of action of Diallyl disulfide (DADS) against larval stage of E. granulosus. The antiparasitic effects of DADS on protoscoleces (PS) were assessed using the eosin exclusion test. The impact of DADS on the expression levels of antioxidant genes, including glutathione S-transferase (GST), thioredoxin (Trx), and thioredoxin peroxidase (TPx) in PTS, was analyzed through Real-time PCR. For cytotoxicity testing, two human cell lines, namely normal liver cells (THLE-2) and liver cancer cells (HepG2), were utilized in the MTT assay. All experiments were conducted in triplicate (n = 3). The results indicated that both the lethality and subsequent mortality of E. granulosus PTS significantly increased with higher concentrations of DADS and extended exposure times (p < 0.001). Among the tested concentrations, DADS indicated the strongest antiparasitic effect against PS at 5 and 10 μg/mL, achieving complete protoscolicidal activity after 30 and 20 min, respectively. Additionally, the calculated CC50 values were 64.4 μg/mL for THLE-2 cells and 28.9 μg/mL for HepG2 cells. Treatment of PTS with DADS led to a dose-dependent decrease in the relative expression levels of the GST, TRx, and TPx genes (P < 0.001), while also significantly increasing the levels of reactive oxygen species in the PTS. In conclusion, DADS exhibited potent protoscolicidal activity in a concentration- and time-dependent manner, achieving complete parasite inactivation at 10 μg/mL within 20 min. These effects were associated with increased ROS production and significant downregulation of GST, Trx, and TPx gene expression. Additionally, DADS indicated a beneficial selective effect on HepG2 cancer cells, with significantly lower toxicity compared to normal THLE-2 cells, underscoring its high selectivity index. These findings suggest that DADS may represent a promising candidate for further antiparasitic development. More research could concentrate on creating the accurate mechanisms of action, and efficacy and safety in vivo and clinical setting.