Abstract: In this paper, the effects of chemical modification on the chemical properties and cadmium adsorption capacity of pectin from the peel of finger citron fruit were studied. The cadmium adsorption capacity and adsorption process were analyzed by kinetic and thermodynamic studies. Furthermore, a 20-day gavage experiment using ICR mice was performed to explore the preventive effect of pectin on cadmium-induced liver and kidney injury. The esterification degree of the modified pectin was significantly lower than that of the unmodified one. The modified pectin had stronger cadmium adsorption capacity than its unmodified counterpart. The adsorption process of cadmium mainly involved ion exchange and physical adsorption. In addition, the pectin significantly alleviated the increased aspartate aminotransferase, alanine aminotransferase, total bilirubin, γ-glutamyl transpeptidase, urea nitrogen, and creatinine in plasma, and urinary albumin level (P < 0.05). Moreover, the activities of superoxide dismutase, catalase and glutathione peroxidase in the liver and kidney of the mice treated with either the unmodified or the modified pectin were significantly higher than those in the cadmium exposure group (P < 0.05). The pectin significantly alleviated cadmium-induced oxidative stress, and mitigated the morphological changes of the liver and kidney. In conclusion, the chemical modification process reduces the esterification degree and enhances the cadmium adsorption capacity of finger citron pectin. The pectin can effectively relieve cadmiuminduced liver and kidney injury.

Key words: finger citron peel residue pectin, ultrasonic-assisted acid extraction, modified pectin, cadimium adsorption, liver and kidney injury