Synergistic cosolubilization of omega-3 fatty acid esters and CoQ10 in dilutable microemulsions

Water-dilutable microemulsions were prepared and loaded with two types of omega-3 fatty acid esters (omega-3 ethyl esters, OEE; and omega-3 triacylglycerides, OTG), each separately and together with ubiquinone (CoQ10). The microemulsions showed high and synergistic loading capabilities. The linear fatty acid ester (OEE) solubilization capacity was greater than that of the bulky and robust OTG.The location of the guest molecules within the microemulsions at any dilution point were determined by electrical conductivity, viscosity, DSC, SAXS, cryo-TEM, SD-NMR, and DLS.We found that OEE molecules pack well within the surfactant tails to form reverse micelles that gradually, upon water dilution, invert into bicontinuous phase and finally into O/W droplets. The CoQ10 increases the stabilization and solubilization of the omega-3 fatty acid esters because it functions as a kosmotropic agent in the micellar system. The hydrophobic and bulky OTG molecule strongly interferes with the tail packing and spaces them significantly – mainly in the low and medium range water dilutions. When added to the micellar system, CoQ10 forms some reverse hexagonal mesophases. The inversion into direct micelles is more difficult in comparison to the OEE system and requires additional water dilution. The OTG with or without CoQ10 destabilizes the structures and decreases the solubilization capacity since it acts as a chaotropic agent to the micellar system and as a kosmotropic agent to hexagonal packing. These results explain the differences in the behavior of these molecules with vehicles that solubilize them in aqueous phases.Temperature disorders the bicontinuous structures and reduces the supersaturation of the system containing OEE with CoQ10; as a result CoQ10 crystallization is retarded.

The location of the guest molecules within the microemulsions at any dilution point were determined by electrical conductivity, viscosity, DSC, SAXS, cryo-TEM, SD-NMR and DLS. Ternary phase diagram of system composed of Tween 80/propylene glycol/water. The water dilution line 70:30 is composed of 70 wt% Tween 80 and 30 wt% propylene glycol. Along the dilution line one can see the three main structures of W/O, bicontinuous, and O/W microemulsions. In addition, within the dilution line are marked the regions for which analytical tools were used; i.e. 0–100 wt% water – electrical conductivity, SAXS and SD-NMR; 0–60 wt% viscosity and SAXS (periodicity) and at 50 and 95 wt% water cryo-TEM.Figure optionsDownload as PowerPoint slideHighlights
► Fully dilutable microemulsions based on PG and Tween 80 were implemented to solubilize omega-3 fatty acid esters and ubiquinone.
► Upon water dilution, reverse micelles, formed in the presence of omega-3 fatty acid ethyl esters molecules, inverted into bicontinuous phase and finally into O/W droplets.
► The CoQ10 molecules, displaying kosmotropic properties in the micellar system, increased both the solubilization of the omega-3 fatty acid esters and its stability.
► Synergistic cosolubilization of the omega-3 fatty acid esters with CoQ10 was observed and well documented.