Structural elucidation of a polysaccharide from Lonicera japonica flowers, and its neuroprotective effect on cerebral ischemia-reperfusion injury in rat

•LJPB2 was a neutral hetero-polysaccharide isolated from Lonicera japonica flowers.•LJPB2 exhibited a strong DPPH scavenging activity.•LJPB2 improved the neurological deficit scores and infract volume.•LJPB2 remarkably reduced the MDA level and NO production.•LJPB2 elevated the SOD and GSH-Px enzyme activities.

A water-soluble polysaccharide, LJPB2, was purified from Lonicera japonica flowers. The present study was aimed to illustrate its structural features and its neuroprotective effect via anti-oxidant activity on focal ischemia/reperfusion (I/R) injury in rat brain. Via chemical and spectral methods, LJPB2, a polysaccharide with molecular weight of 8.9 × 103 Da, was composed of arabinose, mannose, glucose, and galactose, in a molar ratio of 1.8: 1.0: 3.6: 3.7. In addition, the linkage analysis revealed that it mainly contained 1, 4, 6-linked mannose, 1, 4-linked glucose and 1, 4-linked galactose, with a highly branched structure of araban and terminal glucose. LJPB2 exhibited a strong capacity of scavenging DPPH free radical in vitro. Moreover, in vivo assay using a commonly used cerebral I/R model demonstrated that LJPB2 could significantly improve the neurological deficit scores and infract volume. In addition, LJPB2 remarkably reduced the MDA level and NO production, and elevated the SOD and GSH-Px enzyme activities in the rat brain tissues. These results certainly indicated that LJPB2 had a distinct neuroprotective effect related to its strong antioxidant capacity in the cerebral ischemia/reperfusion injury.