Interaction of quercetin with DPPC model membrane : Molecular dynamic simulation, DSC and multinuclear NMR studies †

Interaction between a drug and model membranes may be crucial for understanding the pharmacological activity. Quercetin (3,5,7,3w,4w-pentahydroxy flavone) possesses anti-inflammatory, anti-neoplastic and cardio-protective activity. In addition, it is a potent antioxidant and is known to act through cell membrane. The interaction of flavonoids with model membranes using various physical techniques is well documented. In this paper we report, the mode of interaction of quercetin with lipid bilayers prepared from dipalmitoyl phosphatidyl cho- line (DPPC). The techniques used are molecular dynamic (MD) simulations, 2D NMR and differential scanning calo- rimetry (DSC). The MD have been carried out in duplicate for 0.5 ns, 1.2 ns, 5 ns, 10 ns and 20 ns where quercetin shows the propensity of forming H-bonds with the acyl group in the polar head region of the lipid bilayer. The 2D NOESY experiments show the interaction of the 6wH, 5wH, 6H and 8H protons of quercetin with polar head group pro- tons of the lipid bilayer. The findings are further supported by the DSC, 31 P and 13 C NMR studies.