A stereoselective biosynthesis of a new 3'-azido-3'-deoxythyrnidine 5'-O-beta-D-ribopyranoside (AZT-1) has been achieved from zidovudine (AZT) in PDSM medium, catalyzed by filamentous fungi Cunninghamela echinulata ATCC 9244 (16.6 mg/g, dry weigh/AZT) at 29 degrees C, 250 rpm and yield of 64.6%. Antileishmanial activity of AZT-1 was evaluated on Leishmania (L.) amazonensis and increased for IC50 25 mu M, 2.0 x 10(5) cells/mL(-1) at 24 h with the glycosylation, and according to the results of the in silico prediction, without compromising bioavailability and metabolic stability. An MTT assay determined the cytotoxicity to human macrophages with IC50 20 mu M that was lower than of AZT. Therefore, for design new antileishmanial drug AZT-1 can be used.