Study On The Synthesis Of 8-alkyl-coptisine Homologues And Their Pharmacological Activities

The isoquinoline alkaloids coptisine, is an important active component of Rhizoma Coptidis, and seldom used in clinic. Modern scientific research indicated that coptisine has not only antimicrobial activity in vitro and in vivo, has hypoglycemic antioxidant, Gastric-Mucous Membrane Protection anti-diabetic and Antibacteria Activity To increase the pharmaceutica activity of coptisine 8-alkylcoptisine homologues with seriate different lipophilic property were synthesized in our laboratory by introducing different length alkyl at C8 position, some pharmacological effects of 8-alkyl-coptisine homologues were studied including the antimicrobial activity, glucose consumption effect and toxicity. The methods and results are as follows:1. The synthesis and molecular structure identification of 8-alkyl-berberine homologuesThe synthesis approaches to 8-alkyl-dihydro coptisine were carried out in tetrahydrofuran. The result showed that the highest recovery of the compound had been achieved when synthesized in tetrahydrofuran. The structure of 8-alkyl-coptisine homologues synthesized was affirmed with,1H NMR and 13C NMR.2. The antimicrobial activity of 8-alkyl- coptisine homologues in vitroThe sensitivity of 5 microorganism come from G+ bacteria, G- bacteria and fungus to 8-alkyl- coptisine homologues respectively were evaluated by inhibition zone method and MICs of 8-alkylcoptisine homologues against 5 sensitive microorganisms were determined by turbidimetric method respectively.The result showed that G+ bacteria and fungus were more sensitive than G- bacteria. The antimicrobial activity increased as the length of aliphatic chain elongated and then decreased gradually when the alkyl chain exceeded 8 carbon atoms.8-octyl- coptisine showed the highest antimicrobial activity among all compounds.3. The antimicrobial mechanism of 8-alkyl-berberine homologues in vitroThe mechanism of the interactions of coptisine analogues with lysozyme was studied by fluorescence quenching method. The result had revealed that there was a strong fluorescence quenching effect of coptisine analogues binding to lysozyme. The quenching constants of the synthesized compounds with lysozyme were measured and calculated at different temperatures. The data had indicated both dynamic and static quenchings were involved in the quenching process. The thermodynamic parameters of Gibbs free energy change(ΔG), Enthalpy change(ΔH), Entropy change(ΔS) were calculated. NegativeΔG value(ΔG<0) had found the interactions were spontaneous; PositiveΔH value(ΔH>0) had showed the benefit to the binding. UV absorption of lysozyme was more negatively affected by a longer alkyl chain. Cop-C8 had the highest binding constant which is 206.3×105 and two binding sites which is higher than othersbility to whole cells of B. subtilis (G+) and E. coli (G-) is nearly same while same compound.4. investigate the glycometabolism of 8-Alkylberberine in vitroTo investigate the glycometabolism of 8-Alkyl coptisine in vitro. HepG2 cell s similar to human hepatic cells were used to test the glucose consumption (GC), MTT assay was used to monitor the proliferation of the HepG2 cells, The results indicated that In moderate high glucose concentration (10 mmol/L), the amounts of Glucose consumption of 8-hexyl coptisine is the highest by Glucose- consumption test in vitro. Glucose-Lowering Effect increased as the length of the aliphatic chain increased and we discovered the Glucose-Lowering Effect decreased when the length of the aliphatic chain exceeded six atoms,while a long aliphatic chain is beneficial for Glucose-Lowering Effect of HepG2. 8-hexyl Coptisine is a potential Hypoglycemic leading compound8-Alkyl coptisine could effectively decrease the blood glucose of the mouse t rel. It could aslo improve the glucose tolerance, body weight and food intake of diabetes rats. Moreover, 8-Alkyl coptisinein had ability to regulate the level of SOD, MDA and GSH-Ps in the secrum.5. Preliminary study on toxicity of 8-alkyl coptisine homologues in vivoWith kuming mouse o rats as animal model, the LD50 was determined to evaluate the toxicity of8-alkylcoptisine according to Karber, The route of administration is aintraperitoneal injection..inject 4ml drug one mouse every day according to different concentrations and groups, Result showed that the toxicity of 8-alkyl coptisine derivatives was stronger than that of coptisine. However, by elongating the aliphatic chain, toxicity decreased gradually.