Structural changes, and anti-inflammatory, anti-cancer potential of polysaccharides from multiple processing of Rehmannia glutinosa

Polysaccharides play important roles in the bioactivities of Rehmannia glutinosa. This study examined the physiochemical structure and biological activity of the polysaccharides of R. glutinosa during nine steps of processing. Characteristic study showed galactose, glucose, and fructose were the major sugars in the polysaccharides. The percentage of the high-molecular weight polysaccharide increased after processing. In addition, polysaccharides from repeated steam and dry processing of R. glutinosa can effectively increase the anti-inflammatory activity. Secretions of tumor necrosis factor (TNF-α), interleukin (IL)-6, and transforming growth factor (TGF)β after lipopolysaccharide (LPS) stimulation were detected in RAW264.7 macrophages because of its anti-inflammatory activity. RG-B9, a polysaccharide of the ninth steam and dry processing, showed the strongest inhibitory activity on bacterial LPS-induced macrophage IL-6 and TGFβ production. Mechanically, RG-B9 down-regulated the phosphorylation of AKT/ERK. The anti-inflammation of RG-B9 involved AKT/ERK/JNK signaling. In addition, RG-B9 inhibited the viability of lung cancer cells via EGFR/AKT signaling.