Abstract:

The synergistic solubilization of two major hydrophilic (vitamin C, ascorbic acid, AA) and lipophilic (vitamin E, D-$\alpha$-tocopherol, VE) antioxidants within reverse hexagonal (HII) mesophases is reported. The HII mesophases are composed of monoolein (GMO)/VE/AA/water. A wide range of VE concn. was examd. (on the expense of GMO concns.) while the AA and water concns. remained const. (4 and 12.5 wt %, resp.) in order to expand the HII mesophase. SAXS and DSC combined with ATR-FTIR techniques were utilized to study the interactions between each solubilizate and the HII component that enabled the synergistic accommodation of the hydrophilic and hydrophobic mols. It was revealed that up to 27 wt % VE solubilized within the HII mesophase. This hydrophobic additive localized at the lipophilic GMO tail region solvating the surfactant tails, thereby enabling the formation of the HII structure. As a result, the lattice parameter and the m.p. of the hydrophobic tails decreased. Above 27 wt % VE (up to 33 wt %), once the GMO lipophilic region was homogeneously solvated, addnl. VE mols. located closer to the interface. At this range of concns., new hydrogen bonds between O-H groups of VE and O-H groups of GMO were formed. Once 35 wt % VE was introduced, the HII structure transformed to face-centered reverse micellar cubic phase (Fd3m, Q227). [on SciFinder(R)]