Phytochemical Profile, Biological Activities and Potential Involvement of Opioid Receptors in Antinociceptive Effects of a Canarium Schweinfurthii Engl. Stem Bark Aqueous Extract

The decoction of barks of Canarium schweinfurthii (DCS) is used by the Gabonese population against roundworms, colic, stomach and intestinal pain. However, compounds and biological mechanisms involved in its effect on pain are not known. The aim of the present study is to investigate the safety, the phytochemical profile and the analgesic activities of DCS, as well as the involvement of opioid receptors in its antinociceptive effects. The phytochemical composition was determined by spectrophotometry, gas chromatography-electron impact mass spectrometry (GC-MS) and by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-ESI-MS/MS). Phenolic compounds were revealed by spectrophotometry and many secondary metabolites were identified by UHPLC-ESI-MS/MS, including quinic acid and its derivatives. DCS did not exhibit any cytotoxicity in vitro on two human cell lines. Antinociceptive activity were investigated using the tests of acetic acid-induced torsion and of formaldehyde-induced leg licking. This decoction was demonstrated to exhibit a dose-dependent antinociceptive property in the two tests, while quinic acid has a central effect only in the formaldehyde test. Moreover, these effects were inhibited by naloxone. Together, these results show that DCS exhibits antinociceptive opioid-like activities which attenuate effects of pro-inflammatory and neurogenic mediators. This supports its potential medicinal for the treatment of pain in the traditional medicine of Gabon.