Alkamides from Piper nigrum and their potential inhibitory effect on NLRP3 inflammatory activation

Four previously undescribed alkamides (1-4) were isolated from the fruits of Piper nigrum. Their chemical structures were elucidated using HRESIMS, NMR, and optical rotation analyses. A classical NLRP3 inflammasome activation model was established by priming macrophages with LPS followed by nigericin stimulation. Compounds 1-4 exhibited markedly stronger inhibition than the reference compound piperine. Molecular docking further revealed their binding modes within the NACHT domain of NLRP3. All four derivatives displayed higher docking scores than piperine, with compound 2 showing the strongest predicted binding affinity. Molecular dynamics simulations have verified that the molecule had good binding free energy with NLRP3 and indicated the key amino acids involved in the binding. These findings enrich the structural diversity of piperine derivatives and expand the molecular scaffold available for further structure-activity relationship studies, thereby providing a solid molecular basis for the rational design and synthesis of new piperine-derived NLRP3 inhibitors.