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Ionizing radiation (IR)‐induced intestinal injury is usually accompanied by high lethality. Intestinal stem cells (ISCs) are critical and responsible for the regeneration of the damaged intestine. Astragalus polysaccharide (APS), one of the main active ingredients of Astragalus membranaceus (AM), has a variety of biological functions. This study was aimed to investigate the potential effects of APS on IR‐induced intestine injury via promoting the regeneration of ISCs. We have established models of IR‐induced intestinal injury and our results showed that APS played great radioprotective effects on the intestine. APS improved the survival rate of irradiated mice, reversed the radiation damage of intestinal tissue, increased the survival rate of intestinal crypts, the number of ISCs and the expression of intestinal tight junction‐related proteins after IR. Moreover, APS promoted the cell viability while inhibited the apoptosis of MODE‐K. Through organoid experiments, we found that APS promoted the regeneration of ISCs. Remarkably, the results of network pharmacology, RNA sequencing and RT‐PCR assays showed that APS significantly upregulated the HIF‐1 signalling pathway, and HIF‐1 inhibitor destroyed the radioprotection of APS. Our findings suggested that APS promotes the regeneration of ISCs through HIF‐1 signalling pathway, and it may be an effective radioprotective agent for IR‐induced intestinal injury. [ABSTRACT FROM AUTHOR]

Functional group interconversion is of great significance in organic synthesis. However, aerobic cleavage of C=N bonds to access carbonyl compounds still suffered from some limitations such as harsh reaction conditions, stoichiometric oxidants, poor substrate scope and use of toxic reagents. Herein, we report a catalyst‐free and photo‐induced aerobic cleavage of C=N bonds to afford diverse carbonyl compounds using oxygen from air as green oxidant. This mild methodology permits N‐tosylhydrazones converted into the corresponding carbonyl compounds including ketones, aldehydes and carboxylic acids, showing broad functional group tolerance and compatibility. Moreover, the gram‐scale reaction and post‐modification of complicated molecules proved the applicability and efficiency of this strategy. Finally, a plausible mechanism was proposed based on spectroscopic investigations and detailed mechanistic studies. [ABSTRACT FROM AUTHOR]