Antinociceptive activity of a polysaccharide from the roots of Sophora flavescens

A polysaccharide (SFWP), with a molecular weight of 51kDa, was successfully purified from the roots of Sophora flavescens and the antinociceptive actions of SFWP were evaluated using acetic acid induced writhing, tail flick, and formalin tests in mice. GC-MS results showed that SFWP had a backbone composed of (1→2)-linked Glc, (1→2,6)-inkedGal and (1→3,6)-inked Man residues, which were terminated with (1→)-inked Xyl and (1→)-inked Ara at O-6 of (1→2,6)-inkedGal and (1→3,6)-inked Man along the main chain, in the ratio of 2.0: 1.02: 1.09: 1.10: 0.98. Data showed that SFWP (100, 200 and 400mg/kg) significantly reduced the number of writhings induced by acetic acid in a dose-dependent manner. However, SFWP did not produce analgesia in tail-flick test. Moreover SFWP strongly attenuated the formalin-induced flinching behaviour in the second phases but not in the first phase in a dose-dependent manner. These results revealed that SFWP could be used safely to attenuate both inflammatory and peripheral neuropathic pain.