Integrated metallomic and metabolomic profiling of plasma and tissues provides deep insights into the protective effect of raw and salt-processed Achyranthes bidentata Blume extract in ovariectomia rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Achyranthes bidentata Blume (AB) is a well-known traditional Chinese medicine for treating osteoporosis and bone fracture. In the current, researches on pharmacological mechanism of AB mostly focused on molecular pathways, knowledge about its metabolic signatures is largely unclear. This study aims to develop an integrative metabolomics and metallomic approach for deciphering the biochemical basis of anti-osteoporosis effects of raw and salt-processed AB.

METHOD: Gas chromatography-mass spectrometry (GC-MS) and inductively coupled plasma mass spectrometry (ICP-MS) were combined for metabolomic and metallomic profiling of rats serum, liver and kidney derived from the sham group, model group, E2, raw and salt-processed AB treated groups. Meanwhile, micro-CT and biomechanical analysis were carried out to ensure the success of the osteoporosis model and to validate the anti-osteoporosis effect of raw and salt-processed AB. Partial least squares discriminant analysis (PLS-DA) was employed to screen potential biomarkers and the MetaboAnalyst and KEGG PATHWAY Database were used to investigate the metabolic pathway.

RESULTS: Raw and salt-processed AB protected the rats against osteoporosis, as evidenced by the restoration of the alkaline phosphatase activity, osteocalcin concentration, urine calcium/creatinine ratio and urine phosphorus/creatinine ratio. The combination of PCA and PLS-DA revealed deviations in ninety-four differential biomarkers between raw AB treated group and model group. The identified biomarkers were primarily engaged in the metabolic pathways including galactose metabolism, urea cycle, arginine and proline metabolism, alanine metabolism, lactose degradation, ammonia recycling and glycine and serine metabolism. The levels of these biomarkers showed significant alterations and a tendency to be restored to normal values in raw and salt-processed AB treated osteoporosis rats. Of note, the levels of trace elements, such as Zn, Se, Mn, Cu and Fe, were elevated after raw and salt-processed AB treatment. Finally, a correlation network diagram was constructed to show the biomarkers perturbed by raw and salt-processed AB.

CONCLUSION: Our findings indicate that raw and salt-processed AB has positive effects on osteoporosis rats. Meanwhile, metabolomic and metallomic method coupled with metabolites enrichment analysis and pattern recognition serves as a useful tool for revealing the action mechanism of traditional Chinese medicine.