α-Tocopherol oxalate (TO), a tocopherol ester derivative, was investigated for its effect on the structural changes of fully hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes, as a function of concentration and temperature, by applying differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and DPH fluorescence anisotropy methods. The DSC and DPH anisotropy data indicated that TO embedded into DPPC membrane lowered the enthalpy (ΔH_m) and temperature (T_m) of the main phase transition as well its cooperativity. Fluidization of the membrane at a lowered temperature was accompanied by formation of mixed structures of tocopherol-enriched domains. SAXS studies showed the formation of various ordered structures in DPPC gel-phase during incorporation of TO into the bilayer, as evidenced by the existence of lamellar phases with repeat distances (d) of 6.13 and 6.87 nm, assigned to TO-enriched domains and a lamellar, liquid-ordered DPPC phase with d = 8.45 nm at increasing TO concentrations with lowering and broadening of the Bragg peaks, and diffuse scattering, characteristic of a fluid L_α phase, were observed. In DPPC fluid-phase, the increasing presence of TO at low concentrations resulted in the appearance of a liquid-ordered phase with repeat d = 6.9 nm coexistent with a lamellar structure with d = 9.2 nm, assigned to liquid-disordered structures. An increasing repeat distance observed with raising the TO amount in the DPPC bilayer evolved from an increasing interlamellar water layer of increasing thickness. Presence of TO facilitated penetration of water molecules into the acyl chain region which decreased van der Waals interactions in the bilayer. The DSC, SAXS, and fluorescence anisotropy data established that TO exhibited pronounced disruptive activity in DPPC membranes compared to α-tocopherol. The driving force of the observed action was attributed to electrostatic and dipole interactions of the acidic moiety with the polar head group of phospholipids in the interface region of the bilayer.

研究了生育酚酯衍生物α-生育草酸酯（TO）对完全水合的1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）脂质体的结构变化的影响，该作用是浓度和温度的函数，通过应用差示扫描量热法（DSC），小角度X射线散射（SAXS）和DPH荧光各向异性方法。的DSC和DPH各向异性数据表明，TO嵌入DPPC膜降低了焓（ΔH_米）和温度（T_米）以及它的合作性。膜在较低温度下的流化伴随着生育酚富集域的混合结构的形成。SAXS研究表明，在将TO掺入双层膜期间，DPPC凝胶相中形成了各种有序结构，这由层状相的存在证明，该层状相的重复距离（d）为6.13和6.87 nm，分配给富含TO的结构域和a层状液体有序的DPPC相，d = 8.45 nm，随着TO浓度的增加，布拉格峰的降低和展宽以及扩散散射，这是流体_Lα的特征阶段，进行了观察。在DPPC液相中，低浓度TO的增加导致出现重复d = 6.9 nm的液相有序相与d = 9.2 nm的层状结构共存（分配给液相无序结构）。随着DPPC双层中TO含量的增加，观察到的重复距离增加，这是由厚度增加的层间水层引起的。TO的存在促进水分子渗透进入酰基链区域，这降低了双层中的范德华相互作用。DSC，SAXS和荧光各向异性数据确定，与α-生育酚相比，TO在DPPC膜中表现出明显的破坏活性。