Document Detail

Interaction of antimycobacterial and anti-pneumocystis drugs with phospholipid membranes.
MedLine Citation:
PMID:  2160335     Owner:  NLM     Status:  MEDLINE    
Liposomes can be used as carriers of drugs in the treatment of viral, bacterial and protozoal infections. The potential for liposome-mediated therapy of Mycobacterium avium-intracellulare complex infections, one of the most common opportunistic infections in AIDS, is currently under study. Here, we have investigated the effect of the lipid-soluble antimycobacterial drugs ansamycin, clofazimine and CGP7040 on the thermotropic behavior of liposomes composed of dipalmitoylphosphatidylcholine (DPPC) or dipalmitoylphosphatidylglycerol (DPPG) using differential scanning calorimetry (DSC). In the presence of ansamycin (rifabutine), the peak gel-liquid crystalline phase transition temperature (Tm) of DPPG was reduced, as was the sub-transition temperature (Ts), whereas the Tm of DPPC was reduced only slightly. The temperature of the pre-transition (Tp) of DPPC was lowered, while the pre-transition of DPPG was abolished. Ansamycin also caused the broadening of the transition endotherm of both lipids. Equilibration of the drug/lipid complex for 1 or 5 days produced different thermotropic behavior. In the presence of clofazimine, the cooperativity of the phase transition of DPPG decreased. Above 10 mol% clofazimine formed two complexes with DPPG, as indicated by two distinguishable peaks in DSC thermograms. The Tm of both peaks were lowered as the mole fraction increased. Clofazimine had minimal interaction with DPPC. In contrast, CGP7040 interacted more effectively with DPPC than with DPPG, causing a reduction of the size of the cooperative unit of DPPC even at 2 mol%. The main transition of DPPC split into 3 peaks at 5 mol% drug. The pre-transition was abolished at all drug concentrations and the sub-transition disappeared at 10 mol% CGP7040. These studies suggest that maximal encapsulation of clofazimine in liposomes would require a highly negatively charged membrane, while that of CGP7040 would necessitate a zwitterionic membrane. We have also investigated the interaction of the water-soluble antibiotic pentamidine, which has been used against Pneumocystis carinii, the most lethal of AIDS-related opportunistic pathogens. Aerosol administration of this drug leads to long-term sequestration of the drug in the lungs. The DPPG/pentamidine complex exhibited a pre-transition at 3.5 degrees C, an endothermic peak at 42 degrees C, and an exothermic peak at 44.5 degrees C, followed by another endothermic peak at 55 degrees C. The exotherm depended on the history of the sample, requiring pre-incubation for several minutes below the 42 degrees C transition. These observations suggest that upon melting of the DPPG chains at 42 degrees C, the DPPG crystallizes as a DPPG/pentamidine complex that melts at 55 degrees C.
M C Pedroso de Lima; B H Chiche; R J Debs; N Düzgüneş
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Chemistry and physics of lipids     Volume:  53     ISSN:  0009-3084     ISO Abbreviation:  Chem. Phys. Lipids     Publication Date:  1990 Mar 
Date Detail:
Created Date:  1990-06-27     Completed Date:  1990-06-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0067206     Medline TA:  Chem Phys Lipids     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  361-71     Citation Subset:  IM; X    
Cancer Research Institute, University of California, San Francisco 94143-0128.
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MeSH Terms
1,2-Dipalmitoylphosphatidylcholine / metabolism
Anti-Bacterial Agents / metabolism*
Antifungal Agents / metabolism*
Antitubercular Agents / metabolism
Calorimetry / methods
Clofazimine / metabolism
Hot Temperature
Lactams, Macrocyclic
Membrane Lipids / metabolism*
Mycobacterium avium Complex / drug effects*
Pentamidine / metabolism
Phosphatidylglycerols / metabolism
Phospholipids / metabolism*
Pneumocystis / drug effects*
Rifamycins / metabolism
Grant Support
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Antifungal Agents; 0/Antitubercular Agents; 0/Lactams, Macrocyclic; 0/Membrane Lipids; 0/Phosphatidylglycerols; 0/Phospholipids; 0/Rifamycins; 100-33-4/Pentamidine; 122188-44-7/CGP 7040; 2030-63-9/Clofazimine; 2644-64-6/1,2-Dipalmitoylphosphatidylcholine; 4537-77-3/1,2-dipalmitoylphosphatidylglycerol; 72559-06-9/Rifabutin

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