Abstract:

This study aims to compare the Bletilla striata gel (BSG) from fresh and dried from multiple aspects including physical and chemical properties, rheological properties, structural characterization and immunomodulatory activity. Gel of dried B. striata (BSG-1) and gel of fresh B. striata (BSG-2) were obtained using water-extraction and alcohol-precipitation method. The similarities and differences between BSG-1 and BSG-2 were primarily clarified through structural characterization and rheological properties, in conjunction with physicochemical properties, while exploring immune activity at the cellular level. BSG-1 and BSG-2 exhibited a wide range of molecular weights (3.90 ×10²-1.37×10⁸ Da). BSG-2 demonstrated a higher yield and richer monosaccharide composition, whereas BSG-1 exhibited better viscosity. Under varying concentrations, temperatures and pH conditions, the viscosity of BSG-1 and BSG-2 decreased with decreasing temperature. Partial acid or alkali treatment significantly reduced viscosity. Concentration emerged as a key factor influencing viscosity, with a notable increase in viscosity corresponding to higher BSG-1 and BSG-2 concentrations. It is noteworthy that when the sample concentration greater than 2 mg/mL or the ambient pH>9, the viscosity of BSG-1 is significantly higher than that of BSG-2 significantly. From a microscopic perspective, BSG-2 featured a smoother surface, a greater variety of structure types, and a unique filamentous and porous network structure compared to BSG-1. In terms of immunomodulatory activity, differences were observed in the activities of BSG-1 and BSG-2 at various concentrations. Research indicates that there are distinct difference in physicochemical properties, structural characterization and immune activity regulation between the gels from fresh and dried B. striata, which can provide the theoretical basis for the application of BSG in various fields.