Solvent-free synthesis of δ-carbolines/carbazoles from 3-nitro-2-phenylpyridines/2-nitrobiphenyl derivatives using DPPE as a reducing agent

A green and efficient preparation of functionalized δ-carbolines/carbazoles via reductive ring closure by 1,2-bis(dipenylphosphino)ethane under solvent-free conditions is described. The starting materials 3-nitro-2-phenylpyridines/2-nitrobiphenyl derivatives are readily prepared through Suzuki-Miyaura cross-coupling reaction from commercially available compounds. And the polar by-product ethane-1,2-diylbis(diphenylphosphine oxide) is easily removed from the relatively polar reaction mixture. Various substituted δ-carbolines/carbazoles are obtained in acceptable yields. It is particularly worth mentioning that substrates with electron-withdrawing groups (EWG) also give the desired products in good yield.     

Interaction of FtsZ protein with a DPPE Langmuir film

FtsZ is the key protein in cell division in bacteria. We have proposed that lipid domains in the cytoplasmic membrane play a role in the localisation of FtsZ. In order to test this hypothesis, we used a model system based on Langmuir films to simulate the bacterial membrane. In this simple system we used a single phospholipid, dipalmytoylphosphatidylethanolamine, which is the major constituent of the inner membrane in Escherichia coli. The first results show clearly the importance of the GTP-controlled assembly process in the appearance of circular or fibrillar structures.     

N,N-二丁基甲酰胺的制备-二正丁胺存在下二氧化碳催化氢化反应的研究

研究了在二正丁胺存在下RuCl3/DPPE催化二氧化碳氢化反应, 探讨了N,N-二正丁基甲酰胺的制备新途径, 考察了温度、溶剂、二氧化碳及氢气压力等对催化氢化反应的影响, 产物的结构及量用核磁共振波谱、气相色谱分析测定. 反应的催化效率随温度的升高(120 ℃)先上升后降低; 在4 MPa二氧化碳压力下催化效率随氢气的压力升高而升高; 在4 MPa氢气压力下, 催化效率随二氧化碳压力的升高(6 MPa)先升高后降低, 在10 MPa氢气压力下, 催化效率随二氧化碳的压力升高而升高. 二氧化碳压力的非线性效应可能是由于二丁胺与二氧化碳反应, 导致二丁胺对甲酸的稳定化效应随二丁胺的量的变化而变化的结果, 该假设得到对照实验的验证.     

Interaction of keratolytic drug,salicylic acid with dipalmitoyl phosphatidylethanolamine vesicles

Salicylic acid (SA), a keratolytic drug, is used to treat skin disorder like corns, warts, and acne. To understand the mechanism by which SA interacts with the cell membranes, we have investigated its interaction with dipalmitoyl phosphatidylethanolamine (DPPE) vesicles using DSC, ¹H NMR and Raman spectroscopy. Presence of drug asymmetrically broadened the acyl chain melting transition and shifted the transition temperature, T _m, to lower value. Both, NMR and DSC studies indicate that the drug molecules are located in the glycerol backbone region of the lipid bilayer and increase the membrane headgroup fluidity. At high drug concentration, additional transitions are observed whose intensity increases with increasing drug concentration. In cholesterol doped DPPE dispersion the interaction of SA with DPPE bilayer is more. The transformation of the gel phase of DPPE dispersion to a stable crystalline subgel phase(s) is accelerated by the presence of SA.     

Influence of the leprosy drug, dapsone on the model membrane dipalmitoyl phosphatidylethanolamine

The influence of the sulfone drug, diamino diphenyl sulfone (DDS or dapsone) on the phase transitions and dynamics of the model membrane, dipalmitoyl phosphatidylethanolamine (DPPE)-water/buffer has been studied using DSC and (¹H and ³¹P) NMR. These investigations were carried out with DPPE dispersion in both multilamellar vesicular (MLV) and unilamellar vesicular (ULV) forms for DDS/DPPE molar ratio, R, in the range 0-0.5. DSC results indicate that the mechanism by which DDS interacted with the DPPE membrane is independent of the morphological organization of the lipid bilayer and the solvent (water or buffer) used to form the dispersion. DDS affected both the thermotropic phase transitions and the molecular mobility of the DPPE membrane. Addition of increasing amounts of DDS to the DPPE dispersion, resulted in the lowering of the gel to liquid-crystalline phase transition temperature (T_m) hence increased membrane fluidity. At all concentrations, the DDS is located close to the interfacial region of the DPPE bilayer but not in the acyl chain region. The interesting finding with MLV is that the gel phase of DPPE-water/buffer both in presence and absence of DDS, on prolonged equilibration at 25 °C, transforms to a stable crystalline subgel phase(s). The DPPE-water system forms both crystalline subgel L_LC (with transition temperature T_LC < T_m) and L_HC (with transition temperature T_HC ≥ T_m) phases, while the DPPE-buffer system forms only subgel L_LC phase. The presence of the drug seems to (i) increase the strength of the subgel L_LC phase and (ii) decrease the strength of subgel L_HC (for R < 0.5) phase. However, the value of the transition temperatures T_LC and T_HC does not change significantly with increasing drug concentration.