Thermodynamics and 2H NMR study on the insertion of small quinones into a discotic nematic lyotropic liquid crystal.
A detailed description of the distribution, interaction, and dynamics of molecules with biological activity dissolved in a hydrophobic bilayer, a simple model of a biological membrane, provides valuable information for a better understanding of drug functioning, which can be very useful in drug design. Here we present an (2)H NMR and molecular dynamics study on the insertion, distribution, interactions, and thermodynamics of two biologically active molecules, 9,10-dihydroxy-4,4-dimethyl-1,4,5,8-tetrahydroanthracen-1-one (HQ), with anticancer activity, and 4,4-dimethyl-1,4,5,8,9,10-hexahydroanthracen-1,9,10-trione (Q) a fungicide, dissolved in a nematic discotic lyotropic liquid crystal (ndllc) composed of sodium dodecylsulphate (SDS), decanol (DecOH) and Na2 SO4 in water. (2)H NMR quadrupole splittings (ΔνQ ) and longitudinal relaxation times (T1) from HQ-d6, Q-d4, DecOH-α-d2, partially deuterated water, and SDS-d25 were measured and several molecular dynamics trajectories were also calculated. In particular, ΔG, ΔH, and ΔS profiles for the process of both molecules crossing the bilayer were estimated. It was evidenced that the insertion of both molecules into the aggregate is a spontaneous process, and the molecules are mainly distributed in the internal side of the interface. Addition of HQ or Q decreased the mobility of all aggregate components, but this effect was more pronounced for HQ. The rotational correlation time of Q allowed an estimate of 5.3 cP for the microviscosity inside the ndllc aggregate, in the order of previously measured values in similar environments. Both guest molecules display similar free-energy profiles for the process of crossing the bilayer, with a calculated barrier height of 25 and 36 kJ mol(-1) for HQ and Q, respectively.
Universidad de Chile, Facultad de Ciencias, Departamento de Química, Casilla 653, Santiago (Chile); Universidad Politécnica de Cartagena, Grupo de Bioinformatica y Macromoléculas (BioMac), Area de Química Física, Aulario II, Campus de Alfonso XIII, 30203 Cartagena, Murcia (Spain).
Víctor Eduardo
VE
Bahamonde-Padilla
José Javier
JJ
López-Cascales
Ramiro
R
Araya-Maturana
Maximiliano
M
Martínez-Cifuentes
Boris Enrique
BE
Weiss López
D050866:Liquid Crystals / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D011809:Quinones / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013816:Thermodynamics; D014783:Viscosity; D014867:Water / Q000737:chemistry
D011809:Quinones; D014867:Water; D012967:Sodium Dodecyl Sulfate
NMR spectroscopy; liquid crystals; microviscosity; molecular dynamics; quinones