O P Ummukulsoom, P A Ahammed Shareef
The digenean trematodes Fasciola hepatica and F. gigantica are the major causative agents of human and animal fasciolosis worldwide. Control of fasciolosis relies mainly on chemotherapeutic drugs, particularly triclabendazole (TCBZ). However, the emergence of drug resistant flukes necessitates the need for alternative control strategies. Plant derived compounds and their nanoparticle formulations have recently attracted attention as potential anthelminthic agents due to their bioactivity, biocompatibility and lower risk of development of resistance. The present study evaluated the in vitro anthelmintic efficacy of ethanolic leaf extract of Azadirachta indica and its green synthesized silver nanoparticles (AI-AgNPs) against adult F. gigantica. The A. indica leaf extract and AI-AgNPs were prepared and characterized using standard protocols. The adult flukes of F. gigantica were incubated in RPMI-1640 medium containing 100, 200 and 400 μg/ml of A. indica leaf extract, AI-AgNPs or 15 μg/ml TCBZ (serving as positive control), at 37 ± 1 °C. Parasite motility was assessed hourly for up to 6 hours of incubation, whereas tegumental morphological alterations were evaluated by scanning electron microscopy (SEM) following incubation for 6 and 12 hours. AI-AgNPs induced a faster and more pronounced reduction in worm motility compared with the crude extract of A. indica. SEM revealed concentration and time dependent tegumental alterations, including swelling, blebbing, furrowing, erosion, desquamation and spine loss. Among these three compounds tested, AI-AgNPs produced more severe damage than the crude extract and TCBZ. Damage was more pronounced on the ventral surface and posterior region of the fluke. The present study highlights the potential of AI-AgNPs as a promising alternative for the control of fasciolosis.