Eugenol, a potential schistosomicidal agent with anti-inflammatory and antifibrotic effects against Schistosoma mansoni, induced liver pathology.

Schistosomiasis is one of the most prevalent parasitic infections in developing countries. Although chemotherapy is one of the main strategies in controlling the disease, it is less effective in reversal of schistosome-induced pathology especially in the chronic and advanced stages of schistosomiasis. New strategies and prospective therapeutic agents with antifibrotic effects are needed. Eugenol has a wide anti-inflammatory effect. In the present study, we investigated the possible antischistosomal effect of eugenol on Schistosoma mansoni.

The murine model of S. mansoni was established in three groups of adult male Balb-c mice; group I (infected non-treated group) and groups II and III (infected groups) treated orally with eugenol and praziquantel (PZQ), respectively. The expression of the sensitive immunohistochemical marker α-smooth muscle actin (α-SMA) in schistosome-infected tissues was determined. In addition, parasitological, biochemical, and histological parameters that reflect disease severity and morbidity were examined.

Eugenol treatment showed significant reduction in total worm burden by 19.2%; however, the oogram pattern showed no marked difference compared to that of the PZQ group. Yet, eugenol significantly reduced the serum levels of hepatic enzymes: aspartate aminotransferase and alanine aminotransferase. Histopathological examination revealed a significant reduction in both numbers and diameters of hepatic granulomata, which was consistent with reduction in collagen fiber deposition. Additionally, the antifibrotic effect of eugenol was validated by its considerable reduction in the expression of the sensitive marker α-SMA in both eugenol- and PZQ-treated groups.

Although eugenol could not totally eradicate adults of S. mansoni, the significant amelioration of liver enzymes and hepatic fibrosis potentiate eugenol's role as a promising antifibrotic and a complementary antischistosomal agent.