Carrageenan (CRG) is a kind of linear sulfated polysaccharide that emerging as a promising substituent in food, pharmaceutics, and cosmetics. In recent years, biological properties of CRG polysaccharides such as antiviral, immunomodulatory, anticoagulant, antioxidant, and anticancer have been broadly studied, however, systematical summary of their structure-property relationships is scarce. Moreover, chemical modification is of great significance to explore biological and physiochemical properties of CRG polysaccharides which should be focused on. Chemical modification of CRG polysaccharides, e.g., carboxymethylation, thiolation, acetylation, phosphorylation, oversulfation, oxidization, and cationic or other derivatives, can improve their bioactivities and facilitate their applications in different biological systems. Hence, this review aims to elucidate structure-property relationships of CRG and its chemically modified derivatives with different structures and bioactivities, so as toxicity of CRG as food additive for the guidance of its clinical application.

角叉菜胶（CRG）是一种线性硫酸化多糖，在食品，药品和化妆品中作为有希望的取代基出现。近年来，对CRG多糖的生物学特性（例如抗病毒，免疫调节，抗凝，抗氧化剂和抗癌）进行了广泛的研究，但是，关于它们的结构-性质关系的系统总结却很少。此外，化学修饰对探索应重点关注的CRG多糖的生物学和理化性质具有重要意义。CRG多糖的化学修饰，例如羧甲基化，硫醇化，乙酰化，磷酸化，过硫酸盐化，氧化和阳离子或其他衍生物，可以改善其生物活性并促进其在不同生物系统中的应用。因此，