Screening of peptidyl arginine deiminase 4 inhibitors in traditional herbal medicines

Abstract

Peptidyl arginine deiminase 4 (PAD4) is a promising target for the treatment of metabolic diseases associated with autoimmune and central nervous system disease. By now there are limited numbers of PAD4 inhibitors, and no one is ready for clinical use. This study aims to find efficient and specific PAD4 inhibitors from traditional herbal medicines and to investigate their inhibitory mechanisms. The inhibitory effects of forty-eight extracts from sixteen traditional herbal medicines which are widely used in traditional herbal medicines were investigated. Salvia miltiorrhiza was found to have the most potent PAD4 inhibitory activity. After that, a practical bioactivity-guided fractionation coupling with a chemical profiling strategy was used to identify the fractions from Salvia miltiorrhiza with strong PAD4 inhibition activity, and the major constituents in these bioactive fractions were characterized by LC-MS/MS. Seven compounds were found to have inhibition on PAD4 with IC50 values ranging from 33.52 μM to 667 μM, in which salvianolic acid A showed the most potent inhibitory activity, with an IC50 value of 33.52 μM. Inhibition kinetic analyses indicated that salvianolic acid A effectively inhibited PAD4 in a mixed inhibitory manner, and computer simulation analyses demonstrated that salvianolic acid A binds to PAD4 mainly using hydrogen bonding. Overall, our results suggest that salvianolic acid A from Salvia miltiorrhiza is a potent inhibitor of PAD4, and that salvianolic acid A can be used as a promising lead compound for the development of more potent PAD4 inhibitors.