Insights into the Mechanism of Supramolecular Self-Assembly in the Astragalus membranaceus–Angelica sinensis Codecoction

[Image: see text] Astragalus membranaceus (Fisch.) Bge. (AM) and Angelica sinensis (Oliv.) Diels (AS) constitute a classic herb pair in prescriptions to treat myocardial fibrosis. To date, research on the AM–AS herb pair has mainly focused on the chemical compositions associated with therapeutic efficacy. However, supermolecules actually exist in herb codecoctions, and their self-assembly mechanism remains unclear. In this study, supermolecules originating from AM–AS codoping reactions (AA-NPs) were first reported. The chemical compositions of AA-NPs showed a dynamic self-assembly process. AA-NPs with different decoction times had similar surface groups and amorphous states; however, the size distributions of these nanoparticles might be different. Taking the interaction between Z-ligustilide and astragaloside IV as an example to understand the self-assembly mechanism of AA-NPs, it was found that the complex could be formed with a molar ratio of 2:1. Later, AA-NPs were proven to be effective in the treatment of myocardial fibrosis both in vivo and in vitro, the in-depth mechanisms of which were related to the recovery of cardiac function, reduced collagen deposition, and inhibition of the endothelial-to-mesenchymal transition that occurred in the process of myocardial fibrosis. Thus, AA-NPs may be the chemical material basis of the molecular mechanism of the AM–AS decoction in treating isoproterenol-induced myocardial fibrosis. Taken together, this work provides a supramolecular strategy for revealing the interaction between effective chemical components in herb-pair decoctions.