Trypanosoma brucei is a parasite responsible for human African trypanosomiasis, also known as sleeping sickness, a disease endemic in sub-Saharan Africa, with 70 million people at risk of infection. Current treatments are limited by their toxicity, administration in endemic countries and treatment resistance. Therapies against infectious diseases typically rely on targeting components of the parasite that are not present in humans. Here, to identify novel inhibitors, we aimed at targeting the Trypanosoma brucei trypanothione reductase (TR), an enzyme that synthetizes a key molecule for preserving the parasite redox balance. This enzyme does not exist in humans. Through use of a recent, higher quality, TR activity assay to test a collection of compounds previously reported to have antiparasitic activity, we identified and validated a new chemotype with a unique mode of TR inhibition. The chemotype’s central spiro scaffold is suitable for brain active compounds in humans, providing a drug-like starting point for treatment of the CNS stage of T. brucei infections.