Atractylodin, β-eudesmol, and (+)-hinesol in Atractylodes chinensis rhizomes improve glomerular injuries in high immunoglobulin A mice

Background: The rhizome of Atractylodes chinensis (Asteraceae), a crude drug of Japanese Kampo medicines, has been administered to patients with edema, nephrotic syndrome, and gastrointestinal disorders. Essential oils, such as sesquiterpenoids (e.g., β-eudesmol and hinesol) and atractylodin, are rich in the rhizomes. Previously, we discovered that atractylodin, a polyacetylene compound, found in an ethyl acetate (EtOAc)-soluble fraction from a methanol extract of A. chinensis rhizomes, possessed marked anti-inflammatory activities. Oral administration of the EtOAc-soluble fraction reduced immunoglobulin A (IgA) deposition in the renal glomeruli of high immunoglobulin A (HIGA) mice, a model of human IgA nephropathy. An increased serum IgA forms immune complexes and causes the deposition on renal glomeruli, leading to inflammation by the complement-mediated pathway. Objective: The aim of this study is to identify the compounds that reduce IgA deposition in an EtOAc-soluble fraction of A. chinensis rhizomes. Methods: Metabolites in the serum of HIGA and control BALB/c mice were analyzed by gas chromatography–mass spectrometry. A standard diet including each compound was fed to HIGA and BALB/c mice for 20 weeks to evaluate the improvement of glomerular IgA deposition. Results: Metabolomic analysis of serum suggested that the HIGA mice exhibit a state near the early stage of chronic kidney disease, compared with the BALB/c mice. When mice were orally administered each hydrophobic compound of A. chinensis rhizomes, it was revealed that atractylodin, as well as β-eudesmol and (+)-hinesol, efficiently inhibited glomerular IgA deposition. Furthermore, the renal levels of complement component 3 (C3) and proinflammatory cytokine mRNAs were decreased, when the hydrophobic compounds were orally administered to HIGA mice. Conclusion: Atractylodin, β-eudesmol, and (+)-hinesol may inhibit glomerular IgA deposition, probably by attenuating complement-mediated injuries and suppressing proliferation of mesangial cells in the renal glomeruli. These compounds might improve the pathological findings of human IgA nephropathy. Keywords: Atractylodes chinensis; Crude drug; Immunoglobulin A nephropathy; Metabolomics; Complement