Evaluation of some adamantane-based synthetic trioxanes against Plasmodium knowlesi in rhesus monkeys

In our search for synthetic substitutes for artemisinin and its derivatives we had earlier prepared a series of adamantane-based 1, 2, 4-trioxanes 5a–c which had shown promising activity against P. berghei in Swiss mice. We have further evaluated these and two new compounds (5d–e) against Plasmodium knowlesi W1, a virulent malaria parasite in rhesus monkeys, in the dose range of 40–80 mg/kg × 5 days by intramuscular route. Trioxanes 5b and 5c showed 100% protection and cure at 80 mg/kg × 5 days, while trioxane 5a showed 71% cure at this dose. Detailed studies again showed 50% curative effect of 5a at 40 mg/kg × 5 days treatment.