Active components of Bupleurum chinense and Angelica biserrata showed analgesic effects in formalin induced pain by acting on Nav1.7

Ethnopharmacology relevance: Pain is an unpleasant sensory and emotional experience, often accompanied by the occurrence of a variety of diseases. More than 800 kinds of traditional Chinese medicines (TCM) has now been reported for pain relief and several monomers have been developed into novel analgesic drugs. Bupleurum chinense and Angelica biserrata were representatives of the TCM that are currently available for the treatment of pain. Aim of the study: The study aims to detect the potential analgesic activity of each monomer of Bupleurum chinense and Angelica biserrata and to explore whether Nav1.7 is one of the targets for its analgesic activity. Materials and methods: In this study, five monomers from Bupleurum chinense (Saikosaponin A, Saikosaponin B1, Saikosaponin B2, Saikosaponin C, Saikosaponin D) and five monomers from the Angelica biserrata (Osthole, Xanthotoxin, Imperatorin, Isoimperatorin, Psoralen) were examined by whole-cell patch-clamp on Nav1.7, which was closely associated with pain. Classical mouse pain models were also used to further verify the analgesic activity in vivo. Results: The results showed that monomers of Saikosaponins and Angelica biserrata all inhibited the peak currents of Nav1.7, indicating that Nav1.7 might be involved in the analgesic mechanism of Saikosaponins and Angelica biserrata. Among them, Saikosaponin A and Imperatorin showed the strongest inhibitory effect on Nav1.7. Furthermore, both Saikosaponin A and Imperatorin showed inhibitory effects on thermal pain and formalin-induced pain in phase II in vivo. Conclusion: The results provide valuable information for future studies on the potential of TCM in alleviating pain.