Abstract: Iron deficiency anemia (IDA) is a common iron deficiency disease. IDA has become one of the major public health problems worldwide. Our previous studies have shown that Auricularia auricula melanin (AAM) can alleviate IDA, but the mechanism is not clear. In this study, the role of the intestinal microflora in the improvement of IDA by AAM was studied by elimination of gut bacteria using an antibiotic cocktail as well as using metabonomics. The results showed that AAM treatment significantly alleviated anemia symptoms of IDA mice in terms of body mass, hemoglobin concentration, hematocrit, mean erythrocyte volume and platelet count, and this effect was lost when the intestinal flora was eliminated. Totally 76 differential metabolites were identified by metabolnomics analysis. Pathway enrichment analysis identified seven pathways including tryptophan metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, ascorbic and uronic metabolism, glutathione metabolism, tyrosine metabolism, pentose and glucuronate interconversion and steroid hormone biosynthesis. Among these, tryptophan metabolism was most significant. In the presence of intestinal microflora, tryptophan metabolites such as 5-hydroxyindole acetic acid and N-formyl kynurenine were significantly accumulated in IDA mice supplemented with AAM, indicating that AAM could mitigate IDA, which may be related to activation of tryptophan metabolism through the intestinal flora. This study may provides a theoretical basis for further research on the mechanisms by which AAM improves IDA and for the development of anti-IDA products.

Key words: Auricularia auricula melanin; removal of intestinal flora; intestinal metabolites; non-targeted metabonomics; iron deficiency anemia