Present study was designed to investigate the role of acemannan acetyl group in murine model under radiotherapy. Acemannan, extracted from Aloe vera gel, has molecular weight of 1.02 × 10⁶ Da and mainly composed of mannose (84.9%), glucose (7.2%), and galactose (3.9%), with backbone of (1→4)-linked mannose/glucose. Acemannan (DS: 1.01) was over-acetylated and deacetylated to investigate the role of acetyl group. Acetylation enhances acemannan viscosity and thermal stability. Free radicals scavenging and Fenton reaction inhibition was mediated by acemannan acetyl and hydroxyl group respectively. Native or over-acetylated/deacetylated acemannan pre-treatment to mice has shown to reduce the γ-radiation-induced oxidative damage, and hematopoietic injuries by free radical scavenging and microphage activation to secrete pro-hematopoietic factors through TLR-4 respectively. Over-acetylated acemannan has stronger effects on immunomodulation/radioprotection. In summary, acemannan acetyl-group modulates immune system, while hydroxyl-group participate in free radical scavenging, and present finding can be employed in food and pharma industries for enhancing polysaccharide bioactivity.

本研究旨在研究乙酰甘露聚糖乙酰基在放疗小鼠模型中的作用。从芦荟凝胶中提取的Acemannan的分子量为1.02×10 ⁶Da主要由甘露糖（84.9％），葡萄糖（7.2％）和半乳糖（3.9％）组成，主链为（1→4）连接的甘露糖/葡萄糖。乙酰甘露聚糖（DS：1.01）被过度乙酰化和脱乙酰化以研究乙酰基的作用。乙酰化提高了甘露聚糖的粘度和热稳定性。自由基清除和芬顿反应抑制分别由乙酰甘露聚糖乙酰基和羟基介导。对小鼠的天然或过度乙酰化/脱乙酰化的甘露聚糖预处理已显示可通过自由基清除和微噬菌体活化分别通过TLR-4分泌γ辐射诱导的氧化损伤和造血损伤，从而分别分泌促造血因子。过度乙酰化的甘露聚糖对免疫调节/放射防护具有更强的作用。总之，乙酰甘露聚糖乙酰基可调节免疫系统，