Multidisciplinary Preclinical Investigations on Three Oxamniquine Analogues as New Drug Candidates for Schistosomiasis

Schistosomiasis is a disease of poverty affecting millions of people. Praziquantel (PZQ), with its strengths and weaknesses, is the only treatment available. We previously reported findings on three lead compounds derived from oxamniquine (OXA), an old antischistosomal drug: ferrocene-containing (Fc-CH2-OXA), ruthenocene-containing (Rc-CH2-OXA) and benzene-containing (Ph-CH2-OXA) OXA derivatives. These derivatives showed excellent in vitro activity against bothSchistosoma mansonilarvae and adult worms andS. haematobiumadult worms, and were also active in vivo against adultS. mansoni. Encouraged by these promising results, we conducted additional in-depth preclinical studies and report in this investigation on metabolic stability studies, in vivo studies onS. haematobiumand juvenileS. mansoni, computational simulations, and formulation development. Molecular dynamics simulations supported the in vitro results on the target protein. Though all three compounds were poorly stable within an acidic environment, they were only slightly cleared in the in vitro liver model. This is likely the reason why the promising in vitro activity did not translate into in vivo activity onS. haematobium. This limitation could not be overcome by the formulation of lipid nanocapsules as a way to improve the in vivo activity. Further studies should focus on increasing the compound's bioavailability, to reach an active concentration in the microenvironment of the parasite.