Effect of ultrasound assisted H2O2/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/cm2) on Lignosus rhinocerotis polysaccharide (LRP) degraded by ultrasound assisted H2O2/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.

Isolation, structural features, rheological properties and bioactivities of polysaccharides from Lignosus rhinocerotis: A review

L. rhinocerotis, an edible and medicinal mushroom, has long been utilized as folk medicine and nutritional food in Southeast Asia and southern China. Polysaccharides are the main bioactive substances of L. rhinocerotis sclerotia, and they have attracted extensive attention of researchers both at home and abroad. In the past few decades, various methods have been applied to extract polysaccharides from L. rhinocerotis (LRPs) and the structural features of LRPs are closely related to the used methods of extraction and purification. Many studies have confirmed that LRPs possess various remarkable bioactivities, including immunomodulatory, prebiotic, antioxidant, anti-inflammatory and anti-tumor activities and intestinal mucosa protective effect. As a natural polysaccharide, LRP has the potential to be a drug and functional material. This paper systematically reviews the recent studies on structural characteristics, modification, rheological properties and bioactivities of LRPs, and provides a theoretical basis for an in-depth study of the structure-activity relationship, and utilization of LRPs as therapeutic agents and functional foods. Additionally, the further research and development of LRPs are also prospected.

Ultrasound-induced changes in rheological behavior and hydrophobic microdomains of Lignosus rhinocerotis polysaccharide

Ultrasound is increasingly applied to modify the structures and physicochemical properties of polysaccharides. Hence, this work investigated the ultrasound-induced changes in the rheological behavior and hydrophobic microdomains of Lignosus rhinocerotis polysaccharide (LRP). With an increase in ultrasonic time, the apparent viscosity, storage modulus, loss modulus, and the final percentage recovery of LRP/water system increased to reach the maximum after 10 min treatment and then decreased. These results indicated that short-term (10 min) ultrasound could increase the strength of the network structure of LRP/water system, while longer-term ultrasound (30 and 60 min) weakened the network structure. The self-healing properties of LRP/water system was not affected by ultrasound treatment according to repeated strain and time sweep data. The critical aggregation concentration of the LRP/water system decreased from 2.5 to 1.8 mg/mL after 10 min ultrasound and the number of hydrophobic microdomains increased, suggesting that ultrasound promoted the hydrophobic aggregation of LRP.

Rheological properties and critical concentrations of a hyperbranched polysaccharide from Lignosus rhinocerotis sclerotia

The application of polysaccharides in the food industry mainly depends on their rheological properties and the polysaccharides in different concentration regions exhibit different rheological properties due to the interactions between polymer chains. Hence, this work investigated the concentration-dependent rheological behavior of Lignosus rhinocerotis polysaccharide (LRP) in water and determined the critical concentrations. The intrinsic viscosity of LRP was 378 ± 32 mL/g and the LRP exhibited more apparent shear-thinning behavior with increasing concentration. The LRP critical overlap and aggregation concentration in water was ~2.5 mg/mL, implicating the formation of hydrophobic regions may result from the aggregation and overlap between hyperbranched LRP molecules. The LRP/water system showed higher storage modulus than loss modulus with slight frequency dependence at the concentration of 15 mg/mL, exhibiting the structured liquid behavior. When the concentration increased from 10 mg/mL to 30 mg/mL, the compliance recovery percentage value increased from 58.51% to 92.30%, indicating the formation of a strong gel network in the LRP/water system. Furthermore, the micro-rheological test revealed that the LRP/water system exhibited a concentration-dependent increase in elasticity and viscosity and deterioration in fluidity.

A polysaccharide from Lignosus rhinocerotis sclerotia: Self-healing properties and the effect of temperature on its rheological behavior

This work investigated the self-healing properties of Lignosus rhinocerotis polysaccharide (LRP) and the effect of temperature on its rheological behavior. Dynamic sweep tests (strain sweep, frequency sweep, and time sweep) showed that the LRP/water system possessed self-healing properties due to the entangled network formed by hyperbranched LRP molecular chains. The flow activation energy of LRP solution calculated by Arrhenius equation was shown to decrease with increasing LRP concentration, indicating that LRP solution at higher concentration was less sensitive to temperature. Temperature ramp test exhibited that LRP had a glass transition temperature (T_g) determined as 49.35 °C and the temperature effect was irreversible. Microrheological test revealed that the LRP aqueous solution can form a gel at room temperature with the concentration ≥ 20 mg/mL. This work provided a theoretical basis for the development of LRP-based self-healing materials and facilitated a deep understanding of the temperature effect on rheological behavior of LRP.