Ultrasonic treatment of Dendrobium officinale polysaccharide enhances antioxidant and anti-inflammatory activity in a mouse D-galactose-induced aging model

Utilization of the biological macromolecule Dendrobium officinale polysaccharide (DOP) as a functional ingredient is limited by its high intrinsic viscosity and molecular weight. The goal of the present study was to improve rheological properties of DOP by ultrasonic treatment. Such a treatment resulted in the degradation of DOP and consequent reduction of rheological properties. Among DOP samples treated with ultrasonication at low (L), medium (M), and high (H) power intensities (25, 50, 75 w/cm(2)), M-DOP displayed the highest reactive oxygen species (ROS) and reactive nitrogen species (RNS) radical scavenging activity in vitro. In a mouse D-galactose (D-Gal)induced aging model, M-DOP significantly increased activities of antioxidant enzymes and reduced levels of pro-inflammatory cytokines in liver. Real-time polymerase chain reaction (RT-PCR) analysis indicated that M-DOP upregulated messenger RNA (mRNA) expression of anti-inflammatory/antioxidant proteins such as Nrf2 (nuclear factor erythroid 2-related factor), hemeoxygenase-1 (HO-1), and NAD(P)H:quinone oxidoreductase (NQO1) in liver. In summary, M-DOP displayed a strong radical scavenging activity in vitro, and ameliorated liver injury in the mouse aging model through the promotion of Nrf2/HO-1/NQO1 signaling pathway.

Automated summary

This study indicates that ultrasound treatment can improve the rheological properties of Dendrobium officinale polysaccharide (DOP). Among the samples treated with ultrasound, M-DOP shows the highest capability in scavenging reactive oxygen and nitrogen species radicals in vitro. In a mouse aging model, M-DOP increases antioxidant enzyme activity and reduces pro-inflammatory cytokine levels in the liver. Moreover, M-DOP upregulates the expression of anti-inflammatory/antioxidant proteins through the Nrf2/HO-1/NQO1 signaling pathway.