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Context: The petroleum ether extract (PET) of Amygdalus mongolica (Maxim.) Ricker (Rosaceae) has an ameliorative effect on renal fibrosis (RF)., Objective: To evaluate the antifibrotic effects of A. mongolica seeds PET on RF by serum metabolomics, biochemical and histopathological analyses., Materials and Methods: Sixty male Sprague-Dawley rats were randomly divided into the sham-operated, RF model, benazepril hydrochloride-treated model (1.5 mg/kg) and PET-treated (1.75, 1.25, 0.75 g/kg) groups, and the respective drugs were administered intragastrically for 21 days. Biochemical indicators including BUN, Scr, HYP, SOD, and MDA were measured. Haematoxylin and eosin and Masson staining were used for histological examination. The serum metabolomic profiles were determined by UPLC-Q-TOF/MS and metabolism network analysis. Acute toxicity test was performed to validate biosafety., Results: The PET LD 50 was >23.9 g/kg in rats. PET significantly alleviated fibrosis by reducing the levels of Scr (from 34.02 to 32.02), HYP (from 403.67 to 303.17) and MDA (from 1.84 to 1.73), and increasing that of SOD (from 256.42 to 271.85). Metabolomic profiling identified 10 potential biomarkers, of which three key markers were significantly associated with RF-related pathways including phenylalanine, tyrosine and tryptophan biosynthesis, amino sugar and nucleotide sugar metabolism and tyrosine metabolism. In addition, three key biomarkers were restored to baseline levels following PET treatment, with the medium dose showing optimal effect., Conclusions: These findings revealed the mechanism of A. mongolica PET antifibrotic effects for RF rats on metabolic activity and provided the experimental basis for the clinical application.

Ethnopharmacological Relevance: Renal fibrosis (RF) is a common outcome of various progressive chronic kidney diseases (CKDs) and, thus, seriously endangers human health. As the active ingredient of Amygdalus mongolica, amygdalin inhibits RF. Furthermore, our previous studies demonstrated that n-butanol extract (BUT) and petroleum ether extract (PET), which are effective components of A. mongolica, have an anti-renal fibrosis effect. However, their potential mechanisms of action are unclear and need further verification., Aims of the Study: The aims of this study were to further investigate the effects and potential mechanisms of A. mongolica extracts in the treatment of RF., Materials and Methods: The animals were divided into the control group, RF model group, PET group and BUT group. The RF rat model was established through unilateral ureteral obstruction (UUO). Biochemical indicators, including blood urea nitrogen (BUN), serum creatinine (Scr), and hydroxyproline (HYP, a routine marker of fibrosis), and the antioxidant index (including superoxide dismutase (SOD) and malondialdehyde (MDA)) were measured to evaluate the anti-RF effects of the extracts of A. mongolica. The histomorphology of renal tissue was observed and scored by HE and Masson staining. A serum metabonomic analysis based on UPLC-Q-TOF/MS was performed to assess the changes in the metabolic profile among the different groups., Results: The results showed that PET and BUT significantly improved tubulointerstitial damage and fibrosis by reducing the levels of Scr, BUN, HYP, and MDA and increasing the level of SOD. Moreover, no significant differences in efficacy were observed between the BUT and PET groups. According to the metabolomics analysis, seventy-four potential biomarkers were identified, and eight crucial biomarkers were further selected. These key biomarkers significantly contributed to RF progression by participating in six metabolic pathways, including pathways involved in arginine and proline metabolism, histidine metabolism, nicotinamide metabolism, pentose and glucuronate interconversion, ascorbate and aldarate metabolism, and amino sugar and nucleotide sugar metabolism. In addition, eight key biomarkers and six crucial biomarkers were restored to levels similar to those observed in controls following the treatment with PET and BUT, respectively., Conclusions: The outcomes of these studies demonstrate the renoprotective effects of A. mongolica extracts in rats with RF and revealed the mechanism underlying these antifibrotic effects on metabolic activity for the first time., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)