Effect of ultrasound assisted HO/Vc treatment on the hyperbranched Lignosus rhinocerotis polysaccharide: Structures, hydrophobic microdomains, and antitumor activity.

The effect of ultrasonic intensity (28.14, 70.35, and 112.56 W/cm) on Lignosus rhinocerotis polysaccharide (LRP) degraded by ultrasound assisted HO/Vc system (U-H/V) was investigated. U-H/V broke the molecular chain of LRP and improved the conformational flexibility, decreasing the molecular weight, intrinsic viscosity ([η]) and particle size. The functional groups and hyperbranched structure of LRP were almost stable after U-H/V treatment, however, the triple helix structure of LRP was partially disrupted. With increasing ultrasonic intensity, the critical aggregation concentration increased from 0.59 mg/mL to 1.57 mg/mL, and the hydrophobic microdomains reduced. Furthermore, the LRP treated with U-H/V significantly inhibited HepG2 cell proliferation by inducing apoptosis. The increase in antitumor activity of LRP was closely associated with the reduction of molecular weight, [η], particle size and hydrophobic microdomains. These results revealed that U-H/V treatment facilitates the degradation of LRP and provides a better insight into the structure-antitumor activity relationship of LRP.