Investigating cannabinoids as P2X purinoreceptor 4 ligands by using surface plasmon resonance and computational docking

P2X purinoceptor 4 (P2X4) is an ATP-gated ion channel receptor with diverse neurophysiological functions, and P2X4 modulators hold promise as potential therapeutics for neuropathic pain, neuroinflammation, and neurodegenerative diseases. While several cannabinoids have been reported as modulators of purinoreceptors, their specific purinoreceptor-binding characteristics remain elusive. In this study, we established a comprehensive workflow that included a binding screening platform and a novel surface plasmon resonance (SPR) competitive assay, complemented by computational docking, to identify potential P2X4 binders among a panel of twenty-eight cannabinoids. Through SPR, we determined the binding affinities of cannabinoids (KD values ranging from 3.4 x 10-4 M to 1 x 10-6 M), along with two known P2X4 antagonists, BX430 (KD = 4.5 x 10-6 M) and 5BDBD (KD = 7.8 x 10-6 M). The competitive SPR assay validated that BX430 and 5-BDBD acted as non-competitive binders with P2X4. In the following competitive assays, two cannabinoids including cannabidiol (CBD) and cannabivarin (CBV) were identified as competitive P2X4-binders with 5-BDBD, while the remaining cannabinoids exhibited non-competitive binding with either BX430 or 5-BDBD. Our molecular docking experiments further supported these findings, demonstrating that both CBD and CBV shared identical binding sites with residues in the 5-BDBD binding pocket on P2X4. In conclusion, this study provides valuable insights into the P2X4-binding affinity of cannabinoids through SPR and sheds light on the interactions between cannabinoids (CBD and CBV) and P2X4.