Systematic characterization of the metabolites of defatted walnut powder extract in vivo and screening of the mechanisms against NAFLD by UPLC-Q-Exactive Orbitrap MS combined with network pharmacology.

ETHNOPHARMACOLOGICAL RELEVANCE: Walnut kernel, a well-known TCM, is often used after being defatted in tradition. And defatted walnut powder extract (DWPE) has the actions of tonifying the liver and kidney, dissipating stagnation and removing blood stasis, which has the effect on non-alcoholic fatty liver disease (NAFLD). However, the effective components of DWPE in vivo were unclear and the multiple mechanisms of DWPE against NAFLD have not been explored. AIM OF THE STUDY: The studies were performed to screen the effective substances in vivo by identification of the metabolites of DWPE in rats and to seek the potential mechanisms of DWPE on NAFLD by construction of the network pharmacology based on metabolites and verification of the highly correlated pathway. MATERIALS AND METHODS: To explore the effective substances in vivo, the metabolites of DWPE were identified in SD rats' bio-samples through UPLC-Q-Exactive Orbitrap MS. To analyze the mechanisms of DWPE on NAFLD, a Metabolite-Target-Disease network was established and the potential mechanisms were predicted. Then, highly correlated pathway was verified in animal and cells studies. RESULTS: A total of 52 metabolites of DWPE were identified in vivo, which were derived from gallic acid, ellagic acid (EA) and glansreginin A (Gla A). The possible metabolic pathways were phase Ⅰ (hydroxylation, hydrolyzation, etc) and phase Ⅱ metabolic reactions (methylation, sulfation and glucuronidation). Furthermore, in the network pharmacology, 54 core targets were enriched into pathways in cancer, nitrogen metabolism and other 9 pathways, which were essential pathways of DWPE against NAFLD. And the mechanism of nitrogen metabolism was verified in both of animal and cells studies. The results showed that DWPE could decline the concentration of ammonia and increase the expressions of carbonic anhydrase 2 (CA2) and carbamoylphosphate synthetase (CPS1) in nitrogen metabolism. CONCLUSION: Taken together, the study revealed the absorption components and their metabolic pathways and demonstrated the mechanism of nitrogen metabolism of DWPE on anti-NAFLD.

Anti-NAFLD effect of defatted walnut powder extract in high fat diet-induced C57BL/6 mice by modulating the gut microbiota.

ETHNOPHARMACOLOGICAL RELEVANCE: Walnut kernel has the actions of removing meteorism, dissipating stagnation and removing blood stasis and is used after being defatted in TCM. Defatted walnut powder extract (DWPE) has the abilities of anti-oxidation and lowering lipid levels in vivo. However, the effects and the potential mechanisms of DWPE on NAFLD have not been explored. AIM OF THE STUDY: The study were to investigate the anti-NAFLD effect of DWPE in high fat diet-induced C57BL/6 mice and demonstrate that whether DWPE developed the effect on anti-NAFLD by remodeling the compositions and abundances of gut microbiota. MATERIALS AND METHODS: The inhibitory effect of DWPE on the development of NAFLD was conducted on C57BL/6 mice with a high fat diet and the regulation effect of DWPE on gut microbiota was verified on pseudo-sterile mice with treatment of broad spectrum antibiotics. RESULTS: The results showed that the oral administration of DWPE remarkably alleviated hepatic lipid accumulation by decreasing the levels of TG, TC, LDL, MDA and increasing HDL. Meanwhile, the expressions of NF-κB and MAPKs family proteins were reduced by DWPE compared with HFD group. Otherwise, the efficacy of anti-NAFLD of DWPE was significantly decreased after treatment of antibiotics, which indicated the key role of gut microbiota in the therapeutic process. Furthermore, sequencing of 16S rRNA gene revealed that DWPE could revert the decreased relative abundance of gut microbiota caused by the long term of a high fat diet. And the disordered microflora was remodeled by DWPE including the reduction of Erysipelotrichia, Firmicutes and Actinobacteria as well as the increment of Bacteroidetes, Clostridiales, Bacteroidales S24-7, Prevotellaceae and Bacteroides. CONCLUSION: Taken together, DWPE had a preventing effect on NAFLD, which might be associated with the regulation of gut microbiota.