May function as a flavin mononucleotide (FMN)-dependent alkene reductase on substrates carrying alpha,beta-unsaturated carbonyl groups (ketones, aldehydes, carboxylic acids, esters, lactones or cyclic imides). The catalysis depends on NAD(P)H, which acts as hydride donor for the reduction. Seems to be involved in metabolic pathways required for efficient replication of amastigotes within macrophages. Acts as a FMN-dependent nitroreductase that activates anti-leishmanial bicyclic nitroaromatic prodrugs including delamanid, DNDI-VL-2098 and (R)-PA-824, forming toxic products that kill the parasites. Monomer. Detected in all developmental stages: log phase promastigotes, metacyclic promastigotes and axenic amastigotes. Knockout parasites show reduced replication within macrophages, but are resistant to bicyclic nitro-drugs including delamanid and DNDI-VL-2098. Sensitivity to bicyclic nitro-drugs is fully restored on expression of this reductase. Belongs to the NADH:flavin oxidoreductase/NADH oxidase family.