Transformation of salvianolic acid B to salvianolic acid a in aqueous solution and the in vitro liver protective effect of the main products.

Salvianolic acid A (Sal A) was considered to be the compound with highest activity in Salvia miltiorrhiza (danshen). Due to its low content in raw materials, many studies reported its preparation from salvianolic acid B (Sal B). However, the process of this transformation is still unknown. Our objective was to find the chemical change of the transformation from Sal B to Sal A. The results showed that Sal B was hydrolyzed to lithospermic acid (LA) first, and the latter was transformed into Sal A in thermal aqueous solution. The radical scavenging ability of Sal A, Sal B, and LA was tested through DPPH, and Sal A showed higher radical elimination ability compared to Sal B and LA. In vitro liver damage was induced by CCl4 in human hepatic WRL68 cell line. Sal A, Sal B, and LA showed liver protective ability in a dose-dependent manner, while Sal A possessed a much higher ability compared to Sal B and LA.