Structure-based design of a 1H-Tetrazole-containing scaffold for Caspase-1 inhibition: Synthesis, biological...

Targeting caspase-1 with small-molecule inhibitors represents a promising strategy for the treatment of inflammatory diseases. Herein, we report the structure-based design, synthesis, and biological evaluation of a new 1H-tetrazole-containing scaffold for caspase-1 inhibitors. This scaffold incorporates a 1H-tetrazole as a carboxylic acid bioisostere and lacks electrophilic functionalities commonly employed to promote covalent modification of the catalytic cysteine. The resulting molecules inhibited caspase-1 with IC₅₀ values ranging from the mid-nanomolar to low-micromolar range, with compounds 6e and 6f emerging as the most potent inhibitors (IC₅₀ = 380 and 360 nM, respectively). Compared with our previously reported 1,5-disubstituted α-aminotetrazole series, compounds 6e and 6f showed an approximately 30-fold improvement in enzymatic potency. Preliminary in vivo evaluation of compound 6e in a dystrophic mouse model suggested a trend toward improved muscle coordination and strength, while no toxicity was observed in murine muscle cells under the tested conditions. Molecular dynamics simulations suggested different binding behaviors, conformational preferences, and interaction patterns for the two enantiomers of compound 6e within the caspase-1 binding pocket. Overall, this work broadens the structural diversity of tetrazole-based caspase-1 inhibitors by introducing a distinct 1H-tetrazole-containing scaffold with enhanced caspase-1 inhibitory activity and provides a promising starting point for further optimization.