Effect of xanthones on lipid membranes

CEJAS, J.; ALARCÓN,L.; GERBINO, D.; ANIBAL EDGARDO DISALVO; FRIAS, M DE LOS ANGELES

Buenos Aires

Congreso; Reunión Conjunta De Sociedades De Biociencias; 2017

LA SOCIEDAD ARGENTINA DE BIOFÍSICA

Xanthones are heterocyclic compounds with the dibenzo-γ-pyrone structure. In nature xanthones are a class of secondary metabolites that produced commonly in several plant families. The fused rings that form the xanthonic system and the eight possible types of substitution provide an interesting framework from which different systems can be designed. Interest in their chemical and structural properties has increased due to many biological activities such as inhibitory activity in tumor cell lines. The interest in this compound is related to its possible integration to biological membrane in order to design lipid particles for drug delivery. Thus, it is of interest to study the effect it may have on membrane structure. For this reason we investigated the insertion of Xanthone (9H-xanthen-9-one) and Hydroxy-xanthone (1-hydroxy-9H-xanthen-9-one) in lipid monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), di-Oleoylphosphatidylcholine (DOPC), 1,2-di-O-tetradecyl-sn-glycero-3-phosphocholine (etherPC), Phosphatidylethanolamine (16:0 DPPE) by measuring the changes in the dipole potential, the area per lipid and compressibility properties. In addition, the changes in packing and membrane polarity was studied by measuring Generalized Polarization in gel and liquid crystalline states. The experimental results show that xanthone inserts in DPPC membrane interface orienting the CO group with the oxygen towards the aqueous media normal to membrane surface that explains the dipole potential. The aromatic ring locates parallel to the first C atoms of the acyl chains apparently by interaction with the non bound populations of the CO groups of the phospholipid. This produces a modest area increase and a depolarization of the interface. This was confirmed by molecular dynamics analysis. The presence of OH group attenuates the increase in the dipole potential demonstrated that it is essential the full insertion of the non polar moiety in the membrane phase to produce the dipole potential increase.