We have successfully completed the project. By using structure-based design approach, first we synthesized pyrimidine derivative (first year report). These dihydropyrimidine derivatives emerged as potent antileishmanial agents. Furthermore, we also evaluated these derivatives against human and L. major dihydrofolate reductase. Dihydropyrimidine derivative showed good selectivity for parasite enzyme (LmDHFR) over human enzyme. The findings of this research were published in high impact Journal named European Journal of Medicinal Chemistry (Impact Factor 5.572).

In the next step we have synthesized synthetically feasible DHPMs-pteridine hybrids through a rigid or flexible spacer to achieve the Methotrexate mimics. Three-dimensional structures of target receptors were used for the Structure-Based Drug Design (SBDD) of the new antileishmanial drugs. MOE (molecular operating environment) software was used to carry out docking studies. Synthesized compounds were assessed for their potential against promastigotes of L. major and L. donovani. All compounds showed high affinity and have IC₅₀ values in the range of submicromolar range against both tested promastigotes. Enzyme inhibition potential of all the synthesized DHPMs-pteridine hybrids was also evaluated against dihydrofolate reductase (DHFR) from L. major and human. The synthesized compounds were evaluated against DHFR. Compound 8 indicated excellent inhibition activity against LmDHFR and hDHFR with values of 0.008 + 0.001 μM and 0.071 + 0.001 μM, respectively. Docking studies showed the interaction of ligands (synthesized compounds) with target LmDHFR and hDHFR and L. major pteridine reductase enzymes  To explore the potential drugs for the treatment of leishmaniasis, we will pursue a strategy to synthesize novel scaffolds by using 3D crystal structures of the target enzymes PTR and DHFR. Based on the insights gained from the 3D structural information of Pteridine reductase 1 (PTR1) and DHFR, we will pursue the strategy to synthesize a synthetically feasible DHPMs linked to pteridine motif through a rigid or flexible spacer to achieve specific interactions with the hydrophobic and hydrophilic regions of the active site of PTR1 and DHFR. With rounds of SBDD, synthesis and bioassays, we will develop potent inhibitors of PTR1 and DHFR. Another paper is ready for submission.