Fig 1.
Chemical structure, initial hit assessment data and metabolic soft spots for compound 1.
Fig 2.
Synthesis of 2-aminobenzimidazoles.
Reagents and conditions: a) alkylamine, K2CO3, KF, DMF, 0°C—r.t.; b) NH3 (7.0 mol.L-1 in MeOH), 80°C, 1h, microwave; c) Aldehyde, NaBH(OAc)3, TFA or DCM, 0°C-r.t, 3h; d) H2 (1 bar), Pd/C, EtOAc/MeOH, r.t.; e) BrCN (1M in DCM), MeOH, 60°C; f) EDC, HOBt, DMF, r.t.. Detailed synthetic schemes are shown in S1 Information.
Fig 3.
Reagents and conditions: a) trifluoroethylamonium chloride, DCM, DIPEA, -78°C-r.t.; b) H2 (1 bar), Pd/C, MeOH, r.t.; c) thio-CDI, THF, 70°C, 14h; d) HBr (48%), bromine, AcOH, 0°C-r.t., 15h; e) NH3 (7 mol.L-1 in MeOH), 120°C, 2h, microwave; e) EDC, HOBt, DMF, r.t.
Fig 4.
In vitro profiling of analogues with modifications in the benzimidazole ring.
SI: selectivity index (CC50 / IC50); a IC50 represented in μM; MLM: mouse liver microsome; b intrinsic clearance represented in μL/min/mg.
Fig 5.
In vitro profiling of analogues with modifications at the N-alkyl chain.
ND: not determined; SI: selectivity index (CC50 / IC50); a IC50 represented in μM; MLM: mouse liver microsome; b intrinsic clearance represented in μL/min/mg; c calculated logD.
Fig 6.
In vitro profiling of analogues with modifications at the amide group.
ND: not determined; SI: selectivity index (CC50 / IC50); a IC50 represented in μM; MLM: mouse liver microsome; b intrinsic clearance represented in μL/min/mg; c calculated logD.
Fig 7.
In vitro profiling of analogues with additional modifications at the benzimidazole core and side chain.
SI: selectivity index (CC50 / IC50); a IC50 represented in μM; MLM: mouse liver microsome; b intrinsic clearance represented in μL/min/mg; c calculated logD.
Fig 8.
Summary of SARs and SPRs for 2-aminobenzimidazole derivatives.
Table 1.
Summary of in vitro ADME and in vivo PK data for selected compounds.
Fig 9.
Proof of concept in vivo activity in a VL acute model.
BALB/c mice were inoculated with L. infantum and a 5-day treatment was initiated 14 days post-infection. The parasite load was evaluated by bioluminescence at the end of treatment (A, C, E, G) and 5 days later (B, D, F, H). Groups of animals: untreated (A, B), treated with the vehicle (C, D), with 40 mg/kg/day miltefosine (E, F) and 25 mg/kg/day compound 29 (G, H). The bars on the right show a pseudo-colour scale representing light intensities. (I) Percentage variation of parasite burden in treated animals shown as the average bioluminescence in each group at the end of the experiment.