Design, Synthesis And Metabolism Of Danshensu Brain Targeting Derivatives

Danshensu (DSS) is a major active component of Salvia miltiorrhiza, and is used to treat ischemic cardiovascular and cerebrovascular diseases in clinic. However, the brain targeting of DSS is poor because of the unstable chemical properties and the short half-life in vivo. This limits the use of DSS as cerebral vascular disease drug. Therefore, design and synthesis of DSS brain targeting derivatives, stability in vitro, and brain targeting evaluation in vivo were carried out in this thesis. The results are as follows:1. The brain targeting parameters of 14 disigned derivatives were predicted by computer drug prediction software, and the DTI, DT3 and DT4 were selected as the target molecules for chemical synthesis and characterization.14 kinds of DSS brain targeting derivatives were designed by using the P-glycoprotein (P-gp) inhibitor tetramethylpyrazine and its derivatives as carriers. Lipid-water partition coefficient (logP), brain blood concentration ratio (BB) and P-glycoprotein affinity of the derivatives were predicted by computer drug prediction software and the better compounds DT1, DT3 and DT4 were chosen for the next synthesis by the consideration of the prediction parameters and the difficulty of synthesis.The target compound DTI was synthesized by esterification of chemically synthesized DSS with 2-bromomethyl-3,5,6-trimethylpyrazine. DT3 and DT4 were synthesized by total acetylation or phenolic hydroxyl acetylation of DTI. The structures of DTI, DT3 and DT4 were confirmed by mass spectrum, infrared spectrum and nuclear magnetic resonance analysis.2. The research of metabolic stability of DTI, DT3 and DT4 in vitro showed that the brain targeting potential of DT3 was higher.The quantitative HPLC detection method of DT 1, DT3, DT4 and the metabolite TMPM in rat plasma and brain homogenate was established. The method realized the synchronous detection of each compound.The stability of DTI, DT3 and DT4 in rat plasma and brain homogenate was investigated by using the method. The result showed that he degradation of DT3 and DT4 in rat plasma and brain homogenate always goes through the process:DT3 → DTI→the active metabolite. Compared with DTI and DT4, DT3 slowed down the formation of the active metabolite in rat plasma, the T1/2 of TMPM were 1.68 min,0.77min and 1.71 min respectively. The active metabolite of DSS and TMPM can be quickly metabolized by DT3 in rat brain homogenate, and the concentration showed a steady increase, the T1/2 of TMPM was 222.88 min.3. It was confirmed that the brain targeting of DT3 was better than that of parent drug DSS by studying the pharmacokinetics iv in rat.The quantitative HPLC detection method of DT3 and DSS in rat plasma and brain homogenate was established. The method realized the synchronous detection of each compound in rat.The pharmacokinetics of DT3 in rat plasma and brain homogenate was studied by using the method. After intravenous injection of DT3, the half-life (t1/2) and the mean residence time (MRT) of the parent drug DSS metabolized by DT3 were longer than that of SDSS (MRT:46.177 min vs.9.412 min; t1/2:29.823 min vs.7.571 min) in rat plasma. It shows that the metabolic property of DT3 have been greatly improved. At the same time, the distribution of DSS metabolized from DT3 have greater improvement than injection of DSS (AUC:13.701 mg/L×min vs.2.783 mg/L×min) in rat brain homogenate. The t1/2 and MRT of DSS metabolized from DT3 were both extended (MRT:41.798 min vs.13.226 min; t1/2:26.531 min vs.9.148 min) and the clearance rate (CL) was decreased (CL:1.460 L/min/kg vs.22.277 L/min/kg) in rat brain homogenate. This shows that DT3 has brain targeting function in vivo.The calculated drug targeting index (DTI) value of DT3 was 18.66. The research shows that the brain targeting of DT3 has been greatly improved and the goal of brain targeting derivatives design was achieved.