Structural characterization and anti-neuroinflammatory activity of polysaccharides isolated from the leaves of Perilla frutescens.

In this study, the effect of crude polysaccharide (PF50) from the leaves of Perilla frutescens on the levels of inflammatory mediator proteins was evaluated through Western blotting and immunofluorescence analysis. The results showed that PF50 exerted potent anti-neuroinflammatory effects by significantly suppressing the NO release and expression of the proinflammatory cytokine mediators. Importantly, the PF50 concentration is independently protected against lipopolysaccharide (LPS)-triggered microglial activation-mediated neurotoxicity via inhibiting ROS production and improving mitochondrial function. To further investigate the active ingredients of PF50, a novel polysaccharide (PFP50-1) was purified and its anti-inflammatory activity was studied. PFP50-1 is composed of → 6) - β - D-Galp - (1 →, → 3,6) - α - D-Man p - (1 →, α - L-Araf - (1 →, → 4,6) - α-D-Glcp - (1 →, → 2,3,4) - α - L-Rhap - (1→ and β - D-Glcp - (1 →, which significantly reduced the abnormal elevation of proinflammatory cytokines in LPS-induced BV2 cells. Further experiments revealed that PFP50-1 inhibited the expression of proinflammatory mediator proteins including iNOS and COX-2. In summary, PFP50-1 has exhibited markedly anti-neuroinflammatory effects and may be one of the biologically active ingredients in PF50 for its anti-neuroinflammation and neuroprotection.