Modification, analysis and properties of Piper nigrum polysaccharide

Currently, researchers have not yet found the antioxidant activity and structure of Piper nigrum L. polysaccharides (PNLP) and their modified derivatives. PNLP possesses advantages such as simple and stable structure, ease of separation and purification, high carbohydrate content, and excellent antioxidant activity, yet it remains largely undeveloped. This study aims to investigate the antioxidant activity and fundamental structure of PNLP and its three derivatives, and to provide a theoretical explanation for the relationship between them. Three derivatized polysaccharides, namely acetylated polysaccharides prepared from PNLP (Ac-PNLP), carboxymethylated polysaccharides prepared from PNLP (CM-PNLP) and phosphorylated polysaccharides prepared from PNLP (P-PNLP), which had degree of substitution (DS) of 0.41, 0.48, 0.11, and carbohydrate contents of 37.19%, 53.97%, and 36.83%, respectively. P-PNLP was shown to have good scavenging ability in DPPH radical scavenging and hydroxyl radical scavenging assays, and it was hypothesized that the antioxidant activity of the chemically modified PNLP was increased, which may be attributed to the introduction of the new functional groups and its altered structure-activity relationship resulted. This experiment provides insights into the structure and activity of PNLP and its derivatives, offering explanations for the relationship between the two. It establishes a theoretical foundation for the application of PNLP in the food and pharmaceutical industries.