In vitro efficacy of Cymbopogon citratus (lemon grass) essential oil on Schistosoma mansoni adult worms

Background: Praziquantel (PZQ) remains the primary treatment for schistosomiasis. However, relying on a single drug poses significant risks such as emergence of drug resistance which highlights the urgent need for the development of novel drugs. Objective: To assess the in vitro effect of Cymbopogon citratus (C. citratus) (Lemon grass) crude essential oil on S. mansoni adult worms. Material and methods: Hundred and fifty S. mansoni adult worms were divided into five equal groups, categorized as normal control group (GI), PZQ (1µg/ml) exposed group (GII), and C. citratus oil extract-exposed groups at concentrations of 10 µg/ml, 50 µg/ml and 100 µg/ml were GIII, GIV, and GV, respectively. All groups were incubated and observed after 24h and 48h to evaluate worm motility, tegumental morphological changes, the activity of oxidative stress biomarkers glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA); as well as gene expression of ubiquitin protein ligase Hul5 (SmHul5) and deubiquitinating enzyme Ubp6 (SmUbp6). Results: Lemon grass was found effective against S. mansoni adult worms in vitro in a concentration-dependent manner. It significantly reduced worm motility and induced obvious changes in tegumental ultrastructure. Also, there was a notable decrease in GPx activity, accompanied by an increase in SOD activity at 10 µg/ml and 50 µg/ml concentrations while the higher concentration (100 µg/ml) led to significant SOD inhibition. Activity of MDA showed marked increases. Additionally, the gene expression of SmHul5 and SmUbp6 displayed up-regulations as a result of the oxidative stress and accumulation of damaged proteins. Conclusion: It is concluded that C. citratus crude oil extract was effective against S. mansoni adult worms in vitro by inducing oxidative stress killing. Therefore, C. citratus oil could be considered as a promising schistosomicidal agent.