由于富含高营养价值，火龙果花（Hylocereus undatus (Haw.) Britton et Rose）的花被广泛认可为一种具有药食同源特征的资源。然而，对火龙果花多糖（FHRP）的提纯、结构、抗氧化和免疫调节活性的研究尚相对缺乏深入探究。本研究的目的是使用水提取和层析纯化方法，研究从火龙果花中提取的多糖的初级结构、抗氧化和免疫调节活性。共得到三种多糖分离物，命名为FHRP-1、FHRP-2和FHRP-3。结果表明，对RAW246.7细胞进行200-800 μg/mL的FHRP-1、FHRP-2和FHRP-3处理24小时，能显著增加超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性，减少H2O2诱导的细胞内丙二醛（MDA）的产生。此外，这三种多糖分离物均表现出免疫调节活性，增强RAW264.7细胞的液泡摄取作用，并促进一氧化氮（NO）、白细胞介素6（IL-6）和肿瘤坏死因子α（TNF-α）的产生。在这三种多糖分离物中，FHRP-3表现出最具有希望的抗氧化和免疫调节性质，这归因于其较高的醛酸含量、中等分子量和三螺旋构象。这些发现为FHRP的初级结构信息和生物活性提供了初步的见解。版权所有©2023 Elsevier B.V.出版。

The flower of Hylocereus undatus (Haw.) Britton et Rose is widely recognized as a kind of medicine-food homologous resource due to its high nutritional value. However, there is a lack of in-depth studies on the purification, structure, antioxidative and immunoregulatory activities of polysaccharides from H. undatus flowers (FHRP). The objective of this study was to investigate the primary structure, antioxidative and immunoregulatory activities of the polysaccharides extracted from Hylocereus undatus flower using water extraction and chromatogram purification. Three polysaccharide fractions named FHRP-1, FHRP-2 and FHRP-3 were obtained. The results showed that FHRP-1, FHRP-2 and FHRP-3 (200-800 μg/mL) treatment for 24 h significantly increased the activities of superoxide dismutase (SOD) and catalase (CAT), and reduced the malondialdehyde (MDA) production in RAW246.7 cells under H2O2-induced oxidative stress. Additionally, all three fractions exhibited immunoregulatory activities by enhancing the pinocytosis of RAW264.7 cells and promoting the production of nitric oxide (NO), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α). Among three polysaccharide fractions, FHRP-3 exhibited the most promising antioxidative and immunoregulatory properties, which was attributed to its higher content of uronic acid, moderate molecular weight, and triple-helix conformation. These findings provide preliminary insights into the primary structural information and biological activities of FHRP.Copyright © 2023. Published by Elsevier B.V.