Mechanistic Chemistry of Extraordinary Capacity of Salvianolic Acid B on Oxidatively-damaged Mesenchymal Stem Cells

As the main bioactive component of Chinese herbal medicine Danshen, salvianolic acid B (Sal B, or lithospermic acid B) was observed to maintain the viability of mesenchymal stem cells (MSCs) treated by Fenton's reagent in the study. Interestingly, at a higher concentration, Sal B could even increase the viability rate to 175.1%. In mechanistic analysis experiments, Sal B was found to resist DNA destruction by •OH radical, scavenge various radicals in vitro , reduce Cu 2+ → Cu + , chelate Fe 2+ to yield an absorption maximum at 710 nm. Based on these results, we concluded that, (1) Sal B can not only protect MSCs against •OH-induced damages, but also promote their proliferation. This extraordinary capacity makes Sal B an ideal candidate in MSCs transplantation especially when MSCs are polluted by iron-overload or other oxidative stress factors and, can partly be responsible for the versatile properties of Sal B in pharmacology. The possible mechanisms of its protective effect are hypothesized to include Fe 2+ chelating, and direct radical scavenging which is involved in electron transfer (ET) or hydrogen atom transfer (HAT) from the catechol moieties. Its proliferation-promoting effect is presumed to be from its ester group, carboxylic group, or benzofuran ring.