Protozoocidal activity of Stemona collinsiae against Giardia duodenalis

Giardia duodenalis is a major pathogen of the gastrointestinal tract, and infections impact both human health and the economy. The ongoing issues with drug resistance and the side effects of current anti- Giardia treatments highlight the urgent need for new therapeutic options. This study focused on investigating the in vitro efficacy of crude extracts of Stemona collinsiae from Thailand against G. duodenalis . S. collinsiae was initially extracted with hexane, followed sequentially by dichloromethane, ethanol, and water. The extracts were tested for growth inhibition against G. duodenalis . Dichloromethane and hexane extracts were highly active against the parasite after 48 h of exposure, with half-maximal inhibitory concentration (IC50) values of 60.77 μg/mL and 66.66 μg/mL, respectively. Both extracts reduced G. duodenalis trophozoite motility and adherence, altered trophozoite architecture, and induced apoptosis. Our findings demonstrate the anti- Giardia activity of S. collinsiae root extracts, especially those of dichloromethane and hexane. Our results will support the potential development of new and effective medications for the treatment of giardiasis.