Rehmannia glutinosa polysaccharides

Rehmannia glutinosa (Gaertn.) DC., a perennial herb, has a rich cultivation history of over a thousand years across numerous Asian countries. This highly valued crop finds utility in both industrial and medicinal applications, providing promising clinical outcomes in enhancing immunity and mitigating inflammation in the body.

To investigate the protective effects of RGP against liver injury in mice and identify the underlying mechanisms.

A mouse model of liver injury was established by treating mice with administered varying concentrations of RGP (50-200 mg/kg) for 14 days before the intraperitoneal administration of 5 mg/kg LPS. Additionally, a RAW264.7 macrophage cell injury model was established using LPS treatment. Comprehensive methodologies, including flow cytometry, Western blot, ELISA, and RT-PCR, were employed in combination with molecular docking and dynamic simulation techniques to simulate and examine the binding interactions between RGP and cell membrane proteins. The goal of this multifaceted approach was to gain deeper insights into the anti-inflammatory mechanisms of RGP against liver injury.

In cell-based experiments, RGP demonstrated the ability to reduce intracellular ROS levels, inhibit cell apoptosis, and decrease intracellular NO levels as well as iNOS mRNA expression. Furthermore, by modulating the TLR4/NF-κB signaling pathway, RGP could decrease the mRNA expression and serum levels of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. Animal experiments further revealed that RGP could reduce MDA and CAT contents, improve the redox balance, and regulate the TLR4/MyD88/NF-κB signaling axis in mice. After RGP treatment, the gene and protein expression levels of pro-inflammatory factors such as TNF-α, IL-1β, IL-6, and caspase-1 were reduced in vivo, while the gene expression levels of the anti-inflammatory factor IL-10 were upregulated. Molecular docking and dynamic simulation analyses indicated that RGP could tightly bind to the TLR4 membrane protein and exert anti-inflammatory effects by directly regulating the TLR4/MyD88/NF-κB signaling axis.

These findings provide a theoretical foundation for the development of effective clinical agents that attenuate acute liver injury and enable its treatment.

To study immuno-antitumor action mechanism of RGP-b. RGP-b (Rehmannia glutinosa polysaccaride b) is a new component isolated from the herb, had an average molecular mass of 160 kDa and 5 kinds of monosaccharides as acid-splitting products. Its HPLC showed a main sharp peak at 162 kDa.

The kinetic effects of RGP-b on IL-2 secretion, cytotoxic T-lymphocyte (CTL) activities and L3T4+, lyt-2+ T-lymphocyte subset in mice bearing S180 were observed.

RGP-b 10 or 20 mg kg-1 ip obviously attenuated the decrease of CTL cytotoxity caused by excessive tumor growth on d 9 after the administration, but only partly ameliorated the descent of IL-2. Its effect on lyt-2+ subset was quite parallel with that on CTL cytotoxity. RGP-b kept the ratio of L3T4+ to lyt-2+ subset lower than that of control.

Improving the production of lyt-2+ CTL and its cytotoxity were an essential immuno-antitumor mechanisms of RGP-b.