Comparative analysis of anti-osteoporosis efficacy in Radix Dipsaci before and after processing with salt based on spectrum-effect relationship

Radix Dipsaci (RD) is the dry root of the Dipsacus asper Wall. ex DC., which has the effect of strengthening muscles and bones. The purpose of this study was to find the main active ingredients that could improve the anti-osteoporosis efficacy of RD after processing with salt. The fingerprints of raw and salt-processed RD were established by HPLC-DAD to determine the common components. Then, an experimental study on the anti-osteoporosis efficacy was carried out to compared the difference in the efficacy between raw and salt-processed RD. Pharmacological results showed that, compared with the model group, both the raw and salt-processed RD were able to increase the Ca, bone mineral content, bone mineral density, trabeculae bone area and number of trabeculae bone of rats, and reduce the P, alkaline phosphatase, osteocalcin and trabecular bone separation of rats. Under the same dose, the pharmacological effect of salt-processed RD group was better than that of raw RD group. Finally, spectrum-effect relationship between fingerprints and anti-osteoporosis efficacy of RD was assessed by grey relational analysis and entropy method to screening out the ingredients that affect the anti-osteoporosis efficacy in RD after processing with salt. The results showed that the anti-osteoporosis efficacy of salt-processed RD was stronger than that of raw RD, and the pharmacologically active ingredients that improved its anti-osteoporosis efficacy after processing with salt were peak 4, peak 7 (caffeic acid), peak 8 (loganin), peak 12 (isochlorogenic acid C), peak 13 (dipsanoside A) and peak 14. As far as we known, this was the first time to establish the spectrum-effect relationship between RD and anti-osteoporosis efficacy, which laid the foundation for the follow-up research on the pharmacodynamic components and molecular mechanism of RD.