In Vitro Neurotrophic Properties and Structural Characterization of a New Polysaccharide LTC-1 from Pyrola corbieri Levl (Luticao)

Pyrola corbieri Levl has been used to strengthen bones and nourish the kidney (the kidney governs the bone and is beneficial to the brain) by the local Miao people in China. However, the functional components and neurotrophic activity have not been reported. A new acidic homogeneous heteropolysaccharide named LTC-1 was obtained and characterized by periodate oxidation, Smith degradation, partial acid hydrolysis, GC-MS spectrometry, methylation analysis, and Fourier transform infrared spectroscopy, and its molecular weight was 3239 Da. The content of mannuronic acid (Man A) in LTC-1 was 46%, and the neutral sugar was composed of L-rhamnose (L-Rha), L-arabinose (L-Ara), D-xylose (D-Xyl), D-mannose (D-Man), D-glucose (D-Glc) and D-galactose (D-Gal) with a molar ratio of 1.00:3.63:0.86:1.30:6.97:1.30. The main chain of LTC-1 was composed of Glc, Gal, Man, Man A and the branched chain Ara, Glc, Gal. The terminal residues were composed of Glc and Gal. The main chain and branched chains were linked by (1→5)-linked-Ara, (1→3)-linked-Glc, (1→4)-linked-Glc, (1→6)-linked-Glc, (1→3)-linked-Gal, (1→6)-linked-Gal, (1→3, 6)-linked-Man and ManA. Meanwhile, neurotrophic activity was evaluated through PC12 and primary hippocampal neuronal cell models. LTC-1 exhibited neurotrophic activity in a concentration-dependent manner, which significantly induced the differentiation of PC12 cells, promoted the neurite outgrowth of PC12 cells, enhanced the formation of the web architecture of dendrites, and increased the density of dendritic spines in hippocampal neurons and the expression of PSD-95. These results displayed significant neurotrophic factor-like activity of LTC-1, which suggests that LTC-1 is a potential treatment option for neurodegenerative diseases.