Synthesis and biological evaluation of novel leonurine-SPRC conjugate as cardioprotective agents.

The synthesis and biological evaluation of novel leonurine-SPRC conjugate, 3,5-dimethoxy-4-(2-amino-3-prop-2-ynylsulfanyl-propionyl)-benzoic acid 4-guanidino-butyl ester (1) is reported in this Letter. It is designed to improve the pharmacology efficiency by combining leonurine with S-propargyl-L-cysteine (SPRC), a cysteine analog, via a phenolic hydroxyl ester bond, which could be readily hydrolyzed to release bioactive leonurine and SPRC. Pharmacological evaluation has shown that 1 possesses potent cardioprotective effect against hypoxia-induced neonatal rat ventricular myocytes damage at lower molar concentration (10-fold less than leonurine required and 100-fold less than SPRC required). The mechanism is in partial related to improve hydrogen sulfide production, anti-oxidative stress and anti-apoptosis.