Interaction of N-acetylcysteine with DPPC liposomes at different pH: a physicochemical study

N-acetylcysteine is a commonly used mucolytic and antioxidant agent. Knowledge of the interactions of NAC with the cell membrane is important to understand its mechanism of pharmacological action at the molecular level. To gain a deeper insight into analyzing N-acetylcysteine (NAC) interaction with multilamellar liposomes of 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in hydrated states at different pH, we performed experimental studies by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy. The behavior asymmetric stretching band of the PO2- group was studied by FTIR following the changes that occur in the shape of this band in the pretransition and in the transition from the gel state to the crystalline liquid. The values of the pretansition temperature (Tp) for the different molar ratios of complex at the two pH studied, are coincident between the measurements of FTIR and DSC, these results reaffirm the importance of the PO2- group as a sensor not only of the state of hydration but also of the formation of new intermolecular bonds, which would lead to the formation of different domains. The vibrational behavior of the groups of the polar head of the lipid reveal the role of the lipid as an oxidant on the thiol site of the NAC. The results of these studies provide information on membrane integrity and physicochemical properties. From this aspect, this work has novelty and meaning in pharmacology and analytical chemistry.