Effect of particle size on dissolution of different chemical components in <scp><i>Codonopsis pilosula</i></scp>

Codonopsis pilosula (Franch.) Nannf. is a traditional herb for treating immunosuppression. C. pilosula boiling powder (CP-BP) contains particles of a small size made from C. pilosula decoction pieces (CP-DP). It is still unclear how changes in particle size during the decoction process affect the dissolution of various chemical components in C. pilosula. Herein, an ultra-high-performance liquid chromatography-quadrupole-Exactive Orbitrap mass spectrometry technique was established to characterize the components of CP-BP and CP-DP decoctions. The contents of the components were evaluated based on the relative peak area, extract yield, and alcohol solubility rate. A total of 71 compounds were finally identified, and their content in the CP-BP decoction was generally higher than that in the CP-DP decoction. Alkaloids had the highest average content, whereas terpenoids were the most affected by changes in particle size. In addition, immunosuppression was used as model to investigate whether these changes have practical significance. The results of network pharmacology suggested that the phosphoinositide 3-kinase (PI3K)-Akt pathway may be a potential pathway of C. pilosula for treating immunosuppression. The results of molecular docking indicated that compounds with large content variations have good docking affinity with key targets (epidermal growth factor receptor [EGFR], prostaglandin-endoperoxide synthase 2 [PTGS2], and peroxisome proliferator-activated receptor gamma [PPARG]). These results provide an important reference for further development and use of C. pilosula.