Purification, Structural Characterization, and Anticancer Activity of the Polysaccharide From Sea Red Rice Bran

ABSTRACT Three novel polysaccharides (SRBP‐I, SRBP‐II, and SRBP‐III) were purified from sea red rice bran polysaccharide (SRBP) using a DEAE‐52 anion exchange column. Their physicochemical properties were identified through high‐performance liquid chromatography (HPLC), UV‐visible spectrophotometry, Fourier transform infrared spectrometry (FT‐IR), and scanning electron microscopy (SEM). The anticancer effects of these polysaccharides on four types of tumor cells (HepG2, A549, MCF7, and Hela cells) were investigated using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. Further mechanism studies were conducted employing wound healing experiments, Transwell chamber experiments, Annexin V/PI double staining, and Western blot techniques. The results indicated that the molecular weights of SRBP‐I, SRBP‐II, and SRBP‐III were 4112.16, 4242.82, and 16311.09 Da, respectively. SRBP‐I, SRBP‐II, and SRBP‐III were identified as heteropolysaccharides because they were composed of mannose, glucose, galactose, and rhamnose. Moreover, SRBP‐I exhibited stronger inhibitory effects on the growth of the four types of tumor cells compared to SRBP‐II and SRBP‐III, with the inhibitory effect on Hela cells being more pronounced than on the other three types of cells. Further research into the mechanism revealed that SRBP‐I inhibits the proliferation of Hela cells by suppressing cell migration and inducing apoptosis. These results provide data support for the application of SRBP in the field of anti‐tumor research and promote the diversification and development of high‐value‐added products from sea red rice bran.