Lipidic peptides X. Synthesis, structural and physico-chemical elucidation of lipidic amino acid conjugates with hydrophilic compounds
作者:Istvan Toth、Graeme J. Anderson、Rohanah Hussain、Ian P. Wood、Esther del Olmo Fernandez、Peter Ward、William A. Gibbons
DOI:10.1016/s0040-4020(01)88194-1
日期:——
Lipidicaminoacids 1a, c and dimer 1b were coupled to highly hydrophilic compounds, lactic, glycolic and gluconic acids and protected gulonic acid, yielding conjugates 1d,f,h,i,j,l and o. After carboxyl deprotection, acids e,g and m and were obtained. Physico-chemical investigations of these compounds were carried out using proton nuclear magnetic resonance. Plots of chemical shift versus concentration
Hussain, Rohanah; Toth, Istvan; Gibbons, William A., Liebigs Annalen der Chemie, 1991, # 9, p. 963 - 966
作者:Hussain, Rohanah、Toth, Istvan、Gibbons, William A.
DOI:——
日期:——
Unsymmetrical Azo Initiators Increase Efficiency of Radical Generation in Aqueous Dispersions, Liposomal Membranes, and Lipoproteins
作者:Sean M. Culbertson、Ned A. Porter
DOI:10.1021/ja9934605
日期:2000.5.1
Lipid peroxidation studies often employ the use of azo initiators to produce a slow, steady source of free radicals, but the lack of initiators capable of efficiently generating radicals in lipid aggregates such as micelles and membranes has created persistent problems in these investigations. We report here the synthesis and study of unsymmetrically substituted (hydrophilic/hydrophobic) azo initiators C-8, C-12, and C-16 that increase the efficiency of radical generation in lipophilic regions of aqueous emulsions such as micelles and liposomes. Radical generation from these initiators was monitored in micelles? liposomes, and lipoproteins by the use of two radical scavengers, one that scavengers lipophilic peroxyl radicals and one that scavenges hydrophilic peroxyls. The lipophilic radical scavenger used was the well-known antioxidant alpha-tocopherol and thr hydrophilic radical scavenger used was uric acid. Two peroxyl radicals are trapped by each of these scavengers, tocopherol presumably being biased toward reacting with lipid soluble radicals, uric acid presumably reacting preferentially with water-soluble radicals. In Triton X-100 micelles the unsymmetrical initiators C-8 and C-16 display an increase in both alpha-TOH (alpha-tocopherol) trapping and in overall radical generation efficiency compared to the symmetrical initiators C-0 (hydrophilic) and MeOAMVN (lipophilic). The unsymmetrical azo initiators performance in liposomes was excellent (increased cage escape with lipid compartment access). In low-density lipoprotein oxidations, the initiators C-8, C-12, and C-16 also provided advantages over C-0 and MeOAMVN. The hydrophilic/hydrophobic character of the two radicals generated from the unsymmetrical initiators is an important factor for separating the geminate radical pair, These initiators, when compared to the widely used symmetrical azo initiators, provide an advantage of free radical production, lipophilic access, and constant radical generation in the investigation of lipid peroxidation in various media.
Abderhalden; Tanaka, Fermentforschung, vol. 7, p. 155
作者:Abderhalden、Tanaka
DOI:——
日期:——
Lipophilic methotrexate conjugates with antitumor activity
作者:Rosario Pignatello、Giuseppina Spampinato、Valeria Sorrenti、Claudia Di Giacomo、Luisa Vicari、John J McGuire、Cynthia A Russell、Giovanni Puglisi、Istvan Toth
DOI:10.1016/s0928-0987(00)00062-2
日期:2000.5
Lipophilic methotrexate (MTX)-lipoamino acid conjugates coupled with amide or ester Linkages (1a-1r) were synthesised. The inhibitory activity of the conjugates was evaluated on bovine Liver DHFR. The in vitro growth inhibitory effect against MTX-sensitive human lymphoblastoid CCRF-CEM cells and an MTX-resistant sub-line (CEM/MTX), which displays defective intracellular transport of MTX, was determined under short-term and continuous (120-h incubation) exposure conditions. The alpha, gamma, or alpha,gamma amide conjugates showed different activity in inhibiting the growth of parent cells. CEM/MTX cells were much less susceptible than CCRF-CEM cells to inhibition by alpha or alpha,gamma-substituted lipoamino acid conjugates, whereas both cell lines were almost equally sensitive to the MTX-gamma conjugates. Although less potent than MTX, they could partially circumvent the impaired transport system. These findings confirm that lipophilic MTX conjugates may be good lead compounds on the drug development for the treatment of some MTX-resistant tumors. Ester-type conjugates displayed an interesting activity against parent CCRF-CEM cells, although they were less potent against the transport-resistant sub-line. Stability studies on these molecules indicated that they are not degraded into MTX in the culture medium, thus suggesting that they are not able to over-cross cell resistance despite of their lipophilicity. (C) 2000 Elsevier Science B.V. All rights reserved.