Purification, structural characterization, and anti allergic study of polysaccharides from white fresh skin
White fresh skin is the dried root skin of Dictamnus dasycarpus Turcz., a plant in the Rutaceae family. It contains polysaccharides, flavonoids, alkaloids, steroids, and other ingredients, and has the effects of clearing heat and dampness, treating damp heat sores, dispelling wind and detoxifying. It can be used to treat skin diseases such as tinea pedis, urticaria, skin itching, and eczema, and has strong anti allergic and anti itch effects. There are various types and complex structures of polysaccharides extracted from Chinese herbal medicine, and a large part of them have various biological activities such as promoting immune regulation, antioxidant, anti-inflammatory, antiviral, anti-tumor, etc.
Skin allergies caused by cosmetics have been a major safety concern for consumers in recent years. The main cause of skin allergies is IgE mediated type I hypersensitivity reactions, which undergo a series of complex processes such as allergen sensitization, mast cell activation and degranulation, and immune cell response, ultimately leading to the occurrence of allergic reactions. Mast cells are effector cells in allergic reactions and play an important role in allergic skin diseases and inflammatory processes. Skin allergies are closely related to the skin’s barrier function, neurological factors, and inflammatory reactions.
RBL-2H3 (at basophilic leukemia cells, RBL-2H3) is a subtype of rat basophilic tumor cell line, which is rich in IgE high affinity receptors on the cell surface and has various biological characteristics of mast cells. It is recognized as an in vitro replacement model for mast cells that can be passaged and cultured. β – Aminohexosyltransferase (β – HEX) is a hallmark granule of mast cells and a major mediator in the study of mast cell degranulation. Mast cells undergo degranulation when stimulated by the synthetic polyamine stimulant C48/80 (Compound 48/80). During this period, the release level of β – HEX is consistent with the degree of mast cell degranulation and positively correlated with histamine release. Therefore, it is often detected as an indicator of mast cell degranulation. The cell membrane is an important part of the skin barrier function, and the improved red blood cell (RBC) hemolysis test can determine the protective function of antimicrobial active substances on the cell membrane by the amount of hemoglobin leaked from the red blood cells. In addition, free radicals in the human body can attack cell membranes and proteins, leading to cell aging and death. Inhibiting the activity of free radicals can effectively alleviate cell aging caused by free radicals and maintain the skin barrier function.
Zhao et al. found that the crude extract of white fresh skin inhibits C48/80 induced degranulation of mast cells, reduces histamine and β – HEX release, and has anti allergic effects; Zhang et al. isolated a pure white fresh skin polysaccharide and verified its anti psoriasis effect after sulfation modification; Shi et al. validated its anti-inflammatory activity through mouse ear swelling experiments and mouse capillary permeability experiments; Cong et al. confirmed that the water extract of white fresh skin can inhibit DNCB induced delayed type hypersensitivity (DTH) in mice and has the function of inhibiting mouse specific cellular immunity. Up to now, although there have been some research progress on the anti allergic effect of crude extract of white fresh skin, there has been no study to verify the anti allergic effect of the main component in water extract of white fresh skin – white fresh skin polysaccharides. Therefore, this experiment extracted and isolated polysaccharides from Bai Xianpi, and conducted physicochemical analysis on its components; The inhibition of RBL-2H3 mast cell degranulation experiment and other detection and analysis were conducted with the aim of studying the anti allergic effect, providing a theoretical basis for the study of white fresh skin polysaccharides as anti allergic substances.

This study extracted and isolated white fresh skin, obtaining white fresh skin polysaccharide CDPS, and further purified it to obtain white fresh skin polysaccharide CDPS-1. Characterization of CDPS-1 was carried out using GFC, IC, and FT-IR methods. CDPS-1 is mainly composed of alpha glycosidic bonds, with a molecular weight of 2577Da. It is mainly composed of fucose, glucose, xylose, rhamnose, and galactose, with a molar ratio of 0.41:1.38:3:15:15.4:79.61. The inhibition rate, RBC hemolysis inhibition rate, and DPPH clearance rate of CDPS on the degranulation release of β – HEX from RBL-2H3 cells were determined. The results showed that within the concentration range of 0.5-1.0mg/mL, CDPS had a good inhibitory effect on β – HEX release and RBC cell membrane protection, with peak values of 28.54% and 62.1%, respectively, and a clearance rate of over 25% for DPPH. The white fresh skin polysaccharides extracted in this experiment have good anti allergic effects, and it is speculated that their protective and antioxidant abilities on cell membranes play a certain role in the anti allergic mechanism.