Nuclear magnetic resonance and thermal studies on the interaction between salicylic acid and model membranes

Effect of propyl paraben on the dipalmitoyl phosphatidic acid vesicles

“…The model membranes used in this investigation, are in multilamellar vesicular (MLV) and unilamellar vesicular (ULV) forms. The method of preparation of the membrane sample in the MLV and ULV forms is the same as that detailed elsewhere [20][21][22]. The weight ratio of DPPA:cholesterol (ch) is 1:1.…”

“…However, at pH <9.3 DPPA do not form stable ULV (the dispersion remains milky indicating presence of MLV also). Hence the ULV of DPPA is prepared using pH 9.3 buffer as it formes stable ULV at pH 9.3 [20,22].…”

Interaction of keratolytic drug, salicylic acid with dipalmitoyl phosphatidylethanolamine vesicles

“…The -OH group of SA can form hydrogen bonding with the (a) vicinal water or (b) the -P¼O (DPPE) group or (c) the -C¼O (DPPE) group. 31 P NMR experiment with DPPE-SA-water ( e % 0) has shown that the phosphorous resonances are not affected by the presence of SA [33]. Thus, the interactions represented by (A) and (B) in figure 9 are more likely.…”

“…However, SA neither interacted with the methylene groups of the acyl chains nor with the ethanolamine (-CH 2 -CH 2 -N þ H 3 ) group of DPPE as these resonances was not affected by SA. 31 P NMR studies have shown that the polar groups of SA do not interact with the phosphate group of DPPE [33]. Hence, the SA molecules are expected to be located Interaction of keratolytic drug, salicylic acid with DPPE vesicles 373 Prolonged equilibration of SA-free and SA-doped MLV of DPPE-buffer pH 9.3 and DPPE-ch-buffer pH 7.4 systems resulted in the formation of a crystalline subgel phase(s).…”

Drug–Membrane Interactions: Molecular Mechanisms Underlying Therapeutic and Toxic Effects of Drugs

“…Dynamic properties such as diffusion, permeability, or fluidity of membranes are measured by NMR, X-ray, or fluorescence [80,123,124].…”