Catalpol from <italic>Rehmannia glutinosa</italic> Targets Nrf2/NF-κB Signaling Pathway to Improve Renal Anemia and Fibrosis.

<italic>Rehmannia glutinosa</italic> is widely recognized as a prominent medicinal herb employed by practitioners across various generations for the purpose of fortifying kidney yin. Within <italic>Rehmannia glutinosa</italic>, the compound known as catalpol (CAT) holds significant importance as a bioactive constituent. However, the protective effects of CAT on kidneys, including ameliorative effects on chronic kidney disease — most prominently renal anemia and renal fibrosis — have not been clearly defined. In this study, the kidney injury model of NRK-52E cells and C57BL/6N male mice was prepared by exposure to aristolochic acid I (AA-I), and it was discovered that CAT could ameliorate oxidative stress injury, inflammatory injury, apoptosis, renal anemia, renal fibrosis, and other renal injuries both <italic>in vivo</italic> and <italic>in vitro</italic>. Further treatment of NRK-52E cells with Nrf2 inhibitors (ML385) and activators (ML334), as well as NF-κB inhibitors (PDTC), validated CAT’s ability to target Nrf2 activation. Furthermore, the expression of phosphorylated NF-κB p65, IL-6, and Cleaved-Caspase3 protein was inhibited. CAT also inhibited NF-κB, and then inhibited the expression of IL-6, p-STAS3, TGF-β1 protein. Therefore, CAT can regulate Nrf2/NF-κB signaling pathway, significantly correct renal anemia and renal fibrosis, and is conducive to the preservation of renal structure and function, thus achieving a protective effect on the kidneys. [ABSTRACT FROM AUTHOR]