Correlation analysis between extracts and endogenous metabolites to characterise the influence of salt-processing on compatibility mechanism of 'Psoraleae Fructus & Foeniculi Fructus'.

Ethnopharmacological Relevance: 'Salt-processed Psoraleae Fructus & salt-processed Foeniculi Fructus' (sPF&sFF) is a common Chinese medicinal combination for treating diarrhoea. However, it is not clear how sPF and sFF work together, and why salt-processing is necessary.
Aim of the Study: To investigate the compatibility mechanism of sPF&sFF and the influence of salt-processing on it.
Materials and Methods: Firstly, the metabolomics approach was appliedto screen the differential components between four (s)PF&(s)FF extracts, i.e., sPF&sFF, sPF&FF, PF&sFF, and PF&FF extracts. Then, an in vivo metabolomics study was carried out to filter critical metabolites reflecting the curative effects of (s)PF&(s)FF, and construct a metabolic network. Finally, a correlation analysis between chemical components in extracts and critical metabolites in vivo was performed to find out the synergistic and/or antagonistic effects between herbs as well as the influence of salt-processing.
Results: Salt-processing had a direct influence on the contents of chemical components in sPF and sFF extracts, and there existed positive/negative correlations between the content change of chemical components and the effects of critical metabolites. Therefore, salt-processing indirectly affected on these correlations and was (i) conducive to the positive effects of sPF and sFF on bile acids, making sFF play a synergistic role, thereby, sPF&sFF could perform better than sPF and other three combinations and effectively relieve the symptoms of fatty diarrhoea, osmotic diuresis, malnutrition, and weight loss; (ii) conducive to the positive effects of sPF on triacylglycerol, 12(S)-hydroxyeicosatetraenoic acid, cholesterol, and arachidonic acid, and adverse to that of sFF, making sFF play an antagonistic role, thereby, sPF&sFF could prevent a series of side effects caused by over-regulation and suitably relieve the symptoms of osmotic diuresis, polyuria, malnutrition, and weight loss; and (iii) adverse to the positive effects of sPF and sFF on thromboxane A2, sphinganine and sphingosine, making sFF play a synergistic role, thereby, sPF&sFF could prevent a series of side effects and moderately relieve the symptoms of metabolic diarrhoea and polyuria.
Conclusions: Salt-processing indirectly affected on the correlations between chemical components in extracts and critical metabolites in vivo, and exhibited both conducive and adverse effects on the efficacy, making sPF and sFF cooperate with each other to moderately repair the metabolic disorders. Thereby, sPF&sFF could suitably relieve the diarrhoea and polyuria symptoms in the model and exert the most appropriate efficacy. Moreover, this novel strategy provided a feasible approach for further studying the compatibility mechanism of herbs.
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