Protective Effect Of Danshensu - Cysteine ​​conjugate On Oxidative Damage Of Vascular Endothelial Cells

Background and purpose:Cardiovascular disease is still the main threaten for human health. Danshensu,(R)-(+)-3-(3,4-dihydroxyphenyl)-2-hydroxypropanoic acid, is one of the main hydrosoluble active ingredients of Radix Salviae Miltiorrhizae (Danshen) which has been applied in clinical practice for centuries in Asia. A series of novel amide and thioester conjugates between Danshensu and cysteine derivatives have been designed and synthesized. The pharmacological activities and the possible mechanism of these compounds were investigated in this study.Experimental approach:After growing to sub-confluence, human umbilical vein endothelial cells were pretreated with various concentrations of danshensu-cysteine conjugates (5,50,100μmol/L) and N-acetyl-L-cysteine (5mmol/L, as positive control) for4h and then exposed to H2O2for12h. Then measurements of different indexes were carried out.Key results:Pharmacological evaluation indicated that the amide conjugates3a/4a/17a and thioester conjugates6a-b exhibited obvious protective effects on H2O2-induced human umbilical vein endothelial cells (HUVECs). Pretreated with these conjugates could decrease lactate dehydrogenase (LDH) leakage, increase glutathione (GSH) activity and decrease malondialdehyde (MDA) level. Further study on4a showed that it dose-dependently restored the mitochondrial potential that decreased due to H2O2exposure, attenuated H2O2-induced apoptosis in HUVECs. Western blot results showed that4a up-regulated the level of Bcl-2markedly and down-regulated the levels of Bax and p53. H2O2-induced activation of caspase-9and caspase-3, increased p53and Bax expression, as well as the cleavage of PARP were all inhibited by pretreated4a significantly.Conclusions and implications:The pharmacological evaluation of a series of novel amide and thioester conjugates between Danshensu and cysteine derivatives have been carried out and3a/4a/17a/6a-b demonstrated significant protective effect on H2O2-induced HUVECs. Pharmacological evaluation has shown that these conjugates exhibit well-ordered structure-activity relationship. For amide conjugates3a/4a/17a, the phenolic acetyl protective groups and2-acetoxy substitution are favorable to their activity. For thioester conjugates6a-b, the scaffold of caffeic acid were more privileged than saturated analogs. The protective mechanism of these conjugates may be related to their anti-oxidative and anti-apoptotic properties. Further study are in progress as these promising results demonstrate that these Danshensu-cysteine analog conjugates merit further investigation as potential cardiovascular-protective agents.