Synthesis and evaluation of analogs of 5′-(((Z)-4-amino-2-butenyl)methylamino)-5′-deoxyadenosine (MDL 73811, or AbeAdo) – An inhibitor of S-adenosylmethionine decarboxylase with antitrypanosomal activity

We describe our efforts to improve the pharmacokinetic properties of a mechanism-based suicide inhibitor of the polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (AdoMetDC), essential for the survival of the eukaryotic parasite Trypanosoma brucei responsible for Human African Trypanosomiasis (HAT). The lead compound, 5′-(((Z)-4-amino-2-butenyl)methylamino)-5′-deoxyadenosine (1, also known as MDL 73811, or AbeAdo), has curative efficacy at a low dosage in a hemolymphatic model of HAT but displayed no demonstrable effect in a mouse model of the CNS stage of HAT due to poor blood–brain barrier permeation. Therefore, we prepared and evaluated an extensive set of analogs with modifications in the aminobutenyl side chain, the 5′-amine, the ribose, and the purine fragments. Although we gained valuable structure–activity insights from this comprehensive dataset, we did not gain traction on improving the prospects for CNS penetration while retaining the potent antiparasitic activity and metabolic stability of the lead compound 1.