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Many dietary polysaccharides have been shown to protect against various harmful external stimuli by protecting the integrity of the intestinal barrier. Arabinogalactan (AG) is a high molecular weight polysaccharide composed of arabinose and galactose, which has good immunomodulatory, antioxidant and intestinal conditioning activities. Gastrointestinal injury caused by cisplatin (CP) is an inevitable damage during CP chemotherapy. This research explored the ameliorative effect of AG on cisplatin-induced intestinal toxicity and its possible molecular targets and mechanisms. The results showed that AG (200, 400 mg/kg) could significantly reverse the intestinal histopathological changes and oxidative stress injury caused by CP. Meantime, AG could target the IRE1α/JNK axis to inhibit the expression of apoptosis-related proteins and block the apoptotic cascade, thus reducing intestinal damage. In vitro , AG (10, 20, and 40 μg/mL) could regulate the IRE1α/JNK axis, inhibit apoptosis, and restore the antioxidant defense system damaged by CP to play a protective role in the intestine. In addition, 4-phenylbutyrate (4-PBA), a specific inhibitor of endoplasmic reticulum stress, was used to verify that AG also affected protein expression levels by regulating the IRE1α/JNK pathway-mediated endoplasmic reticulum stress signaling pathway, thereby alleviating CP-induced gastrointestinal dysfunction. Therefore, AG may be a potential drug to prevent CP-induced intestinal damage. [ABSTRACT FROM AUTHOR]

Plant polysaccharides can be used as bioactive natural polymers that provide health benefits, however high molecular weight neutral polysaccharides have not shown good bioactivity. In this study, high molecular weight neutral arabinogalactan was isolated and structurally characterized to investigate it antioxidant activity against IEC-6 cells. In this study, a neutral polysaccharide (AG-40-I-II) was obtained from the roots of Larix gmelinii (Rupr.) Kuzen. and purified using ethanol fractional precipitation and purification on a DEAE-52 cellulose column and a Superose 12 gel filtration column. The structural characteristics of AG-40-I-II was detected by chemical and spectroscopic methods. The results showed that the average molecular weight of AG-40-I-II was 18.6 kDa, the main chain was composed of →4)-β-D-Gal-(1, → 4, 6)-β-D-Gal-(1 and →4)-β- D-Glc-(1, the side chain is composed of T-β-L-Araf(1 → 6). The effect of AG-40-I-II on H 2 O 2 -induced IEC-6 cell injury was determined by MTT method. Besides, AG-40-I-II could reduce the level of MDA and increase SOD activity on IEC-6 cells, which could significantly inhibit the production of ROS. Importantly, AG-40-I-II inhibited the splicing of XBP1 by IRE1α through the ERS pathway and reduced the cell apoptosis induced by H 2 O 2. In summary, the results of this study indicate that AG-40-I-II, as a natural source of plant polysaccharides, has good antioxidant activity, and is expected to become a safe plant source of natural antioxidants, which has great potential in biomedicine potential. [ABSTRACT FROM AUTHOR]