First-in-class pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones against leishmaniasis and tuberculosis: Rationale, in vitro, ex vivo studies and mechanistic insights

Challenging the Biginelli scaffold to surpass the first line antitubercular drugs: Mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt) inhibition activity and molecular modelling studies

New Biginelli adducts were rationalised, via the introduction of selected anti-tubercular (TB) pharmacophores into the dihydropyrimidine (DHPM) ring of deoxythymidine monophosphate (dTMP), the natural substrate of Mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt). Repurposing was one of the design rationale strategies for some selected mimics of the designed compounds. The anti-TB activity was screened against the Mtb H37Rv strain where 11a was superior to ethambutol (EMB), and was 9-fold more potent than pyrazinamide (PZA). Additionally, compounds 11b, 4a, 4b, 13a, 13b and 14a elicited higher anti-TB activity than PZA, showing better safety profiles than EMB against RAW 264.7 cells' growth. The in vitro TMPKmt inhibition assay released compounds 11a, 11b and 13b as the most potent inhibitors. Docking studies presumed the binding modes and molecular dynamics (MD) simulation revealed the dynamic stability of 11a-TMPKmt complex over 100 ns. In silico prediction of the chemo-informatics properties of the most active compounds was conducted.

Synthesis, antitubercular evaluation, and molecular docking studies of hybrid pyridinium salts derived from isoniazid

In the quest to develop potent inhibitors for Mycobacterium tuberculosis, novel isoniazid-based pyridinium salts were designed, synthesized, and tested for their antimycobacterial activities against the H₃₇ Rv strain of Mycobacterium tuberculosis using rifampicin as a standard. The pyridinium salts 4k, 4l, and 7d showed exceptional antimycobacterial activities with MIC₉₀ at 1 µg/mL. The in vitro cytotoxicity and pharmacokinetics profiles of these compounds were established for the identification of a lead molecule using in vivo efficacy proof-of-concept studies and found that the lead compound 4k possesses LC₅₀ value at 25 µg/mL. The in vitro antimycobacterial activity results were further supported by in silico studies with good binding affinities ranging from -9.8 to -11.6 kcal/mol for 4k, 4l, and 7d with the target oxidoreductase DprE1 enzyme. These results demonstrate that pyridinium salts derived from isoniazid can be a potentially promising pharmacophore for the development of novel antitubercular candidates.

New tetrahydropyrimidine-1,2,3-triazole clubbed compounds: Antitubercular activity and Thymidine Monophosphate Kinase (TMPKmt) inhibition

Two series of new tetrahydropyrimidine (THPM)-1,2,3-triazole clubbed compounds were designed, synthesized and screened for their antitubercular (anti-TB) activity against M. tuberculosis H₃₇Rv strain using microplate alamar blue assay (MABA). The most active compounds 5c, 5d, 5e and 5f were further examined for their cytotoxicity against the growth of RAW 264.7 mouse macrophage cells using MTT assay. The four compounds showed safety profiles better than or comparable to that of ethambutol (EMB). These compounds were evaluated for their inhibition activity against mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt). Compounds 5c and 5e were the most potent exhibiting comparable inhibition activity to that of the natural substrate deoxythymidine monophosphate (dTMP). An in silico study was performed including docking of the most active compounds 5c and 5e into the TMPKmt (PDB: ID 1G3U) binding pocket in addition to prediction of their physicochemical and pharmacokinetic properties to explore the overall activity of these anti-TB candidates. Compounds 5c and 5e are promising anti-TB agents and TMPKmt inhibitors with acceptable oral bioavailability, physicochemical and pharmacokinetic properties.