Synthesis And Anti-ED Pharmacological Activity Studies Of Ligustrazine's Derivatives

Objective: The ligustrazine derivatives were synthesized from ligustrazine, followed by oxidation, chlorination and amidation. The aim of this experiment is to study the effects of ligustrazine derivatives on intracellular free calcium([Ca2+]i )in cultured penis corpus cavernosum smooth muscle cells(PCSMC)in Man, and explore the Pharmacological mechanism of anti-ED .Methods:Two of tetramethylpyraze metabolites(2-carboxyl-3,5,6-trimethyl-pyrazine and 2-hydroxymethyl-3,5,6-trimethyl-pyrazine)were synthesised from ligustrazine. According to hypridization principle and prodrug principle in medicinal chemistry, the ligustrazine derivatives were prepared starting from the intermediate 2- carboxyl-3, 5,6-trimethyl-pyrazine in this synthesis. Screening the compounds of anti-ED pharmacological activity in vitro: By using laser scanning confocal microscope (LSCM),the[Ca2+]i Fluorescence signal changes was investigated in cultured PCSMC loaded with Ca2+ indicator Fluo-3/AM. Compared with TMP and the classical calcium antagonist Ver, Effects of ligustrazine derivatives were observed in the same concentrations on [Ca2+]i increase induced by NE.Results: By searching SciFinder, the newly four synthesized compounds have not been reported in literature, and their chemical structures were characterized by IR, 1H-NMR and MS. Compared with TMP, ligustrazine derivatives on PCSMC cytopasm had no significant impact at resting state (p>0.05). The peak inhibition rates of ligustrazine derivatives were 49.03%,54.83%,51.48%,50.31% respectively induced by NE at the concentration of 0.2mmol/L. Compounds A4 presents an excellent inhibition rate of normal cell, which is more potent than ligustrazine(18.96%), much better than Ver(16.51%)(p<0.05). Conclusions: The ligustrazine derivatives were synthesized from ligustrazine, followed by chlorination and amidation of 2-carboxyl-3,5,6-trimethyl-pyrazine and Piperazine derivatives,Methods are simple. Ligustrazine derivatives can inhibit man PCSMC [Ca2+]i, significantly by suppressing voltage dependent calcium channel, Their effects are better than ligustrazine. These results indicate that Ligustrazine derivatives possess the trait of calcium antagonist. It deserves to be studied further that Ligustrazine derivatives may have important effect in the treament of ED.