LC-HRMS/MS-based phytochemical profiling of Piper spices: Global association of piperamides with endocannabinoid system modulation

The plant genus Piper comprises extensively consumed spice taxa like black pepper (P. nigrum L.) or long pepper (P. longum L.). The chronic dietary use of different Piper spices has been associated with different health benefits, though the molecular mechanisms remain poorly understood. The aim of this work was to perform the liquid-chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) profiling and LC-DAD quantification of piperamides in several Piper species and varieties and study their ability to modulate the endocannabinoid system (ECS). LC-HRMS/MS analysis revealed a number of 42 piperamides grouped into six structural classes, with 22 of them, notably piperine, retrofractamide B, guineensine, piperchabamide C, being also quantified by LC-DAD. The multivariate analysis showed that P. nigrum and P. longum are very similar with respect to their piperamide profile, while the other Piper spices (P. retrofractum, P. guineense, P. cubeba, P. borbonense) might have significantly different metabolite patterns. The results from the biological assays confirmed that guineensine and total piperamides are strongly correlated with anandamide (AEA) cellular uptake inhibition. While none of the Piper spice extracts showed binding activity at cannabinoid CB₁ receptors, some P. nigrum varieties exhibited moderate binding interactions with CB₂ receptors. Overall, the analytical profiling enabled global annotations of piperamides associated to cannabimimetic effects in Piper spices.