Assessment of the Effects of Structural Modification of Gastrodia elata Polysaccharide on Anti-Breast Cancer Activity Using Asymmetrical Flow Field-Flow Fractionation.

Gastrodia elata ("Tian Ma" in Chinese) is used as a food and medical ingredient in traditional Chinese medicine. In this study, to enhance the anti-breast cancer activity of Gastrodia elata polysaccharide (GEP), GEPs were modified via sulfidation (SGEP) and acetylation (AcGEP). The physicochemical properties (such as solubility and substitution degree) and structural information (such as molecular weight Mw and radius of gyration Rg) of GEP derivatives were determined by Fourier transformed infrared (FTIR) spectroscopy and asymmetrical flow field-flow fractionation (AF4) coupled online with multiangle light scattering (MALS) and differential refractive index (dRI) detectors (AF4-MALS-dRI). The effects of the structural modification of GEP on the proliferation, apoptosis, and cell cycle of MCF-7 cell were studied systematically. The ability of MCF-7 cell for the uptake of GEP was studied by laser scanning confocal microscopy (LSCM). The results suggested that the solubility and anti-breast cancer activity of GEP were enhanced and the average Rg and Mw of GEP decreased after chemical modification. The AF4-MALS-dRI results showed that the chemical modification process simultaneously caused the degradation and aggregation of GEPs. The LSCM results revealed that more SGEP can enter the MCF-7 cell interior compared with AcGEP. The results indicated that the structure of AcGEP could play a dominating role in antitumor activity. The data obtained in this work can be used as a starting point for investigating the structure-bioactivity of GEPs.

Study on effects of preparation method on the structure and antioxidant activity of protein-Tremella fuciformis polysaccharide complexes by asymmetrical flow field-flow fractionation.

Oxidation is an essential biological process for human life. In this study, low density lipoprotein-Tremella fuciformis polysaccharide (LDL-TFP) complexes were prepared by electrostatic and covalent methods. The effects of preparation method on the structure and antioxidant activity of LDL-TFP complexes were investigated by asymmetrical flow field-flow fractionation (AF4) coupled with ultraviolet-visible (UV/Vis), multiangle light scattering (MALS), and differential refractive index (dRI) detectors. The results showed that the electrostatic LDL-TFP complexes had a spherical structure, while the covalent LDL-TFP complexes had a rod-like structure as indicated by the ratio of Rg (radius of gyration) to Rh (hydrodynamic radius). Moreover, the results revealed that the antioxidant activity of the LDL-TFP complexes on the HepG2 could be related to the structure of LDL-TFP complexes. The antioxidant activity of LDL-TFP complexes formed by LDL modified with phospholipase A2 was further enhanced. This study would help expand the application of TFP.

Towards a better understanding of the relationships between the structure and antitumor activity of Gastrodia elata polysaccharides by asymmetrical flow field-flow fractionation.

To better understand the structure-function relationship of Gastrodia elata polysaccharides (PGEs), PGEs were extracted by ultrasound-assisted extraction method and the effects of extraction time on the structure and conformation of PGEs were evaluated by asymmetrical flow field-flow fractionation (AF4) coupled online with multiangle light scattering (MALS) and differential refractive index (dRI) detectors (AF4-MALS-dRI). Besides separation, AF4-MALS-dRI can provide more information about PGEs, such as size and molecular weight (Mw) distributions, apparent density, and conformation. The effects of PGEs on the proliferation, apoptosis, and cell cycle of MCF-7 cells were investigated. The cell activity assay indicated that the PGEs can inhibit the growth of MCF-7 cells by inducing late apoptosis. The results indicated that PGEs with a spherical conformation and compact structure seem to be beneficial to inducing MCF-7 cells late apoptosis. Moreover, results demonstrated that the information obtained by AF4-MALS-dRI is valuable for better understanding of the relationship of structure-activity of PGEs.