Enhancement of the solubility and antioxidant capacity of α-linolenic acid using an oil in water microemulsion

Abstract

The applications of α-linolenic acid (ALA) in the food industry are restricted due to its poor water solubility and antioxidant stability. This study concentrates on developing an ALA-loaded microemulsion (ALA-ME) to enhance its solubility and antioxidant capacity. The formulation of the microemulsion was investigated based on pseudoternary phase diagrams. The ALA-ME was characterized by using electrical conductivity, viscosity and transmission electron microscopy (TEM). The microstructure of the ALA-ME was probed using nuclear magnetic resonance (H-NMR). The results proved that ALA-ME consisted of spheroidal droplets with 20-40 nm diameter. A structural transformation from water in oil (W/O) to oil in water (O/W) occurred, as seen from the electrical conductivity determination. The H-NMR results revealed a transition of the ALA position encapsulated from the core area of the microemulsion to the lipophilic layer of the surfactant. Furthermore, two microstructural models of ALA-ME were proposed. The antioxidant evaluation demonstrated that the ALA antioxidant capacity in microemulsions was enhanced to about 80% compared with that of ALA in oil solution.

Preparation of α-Linolenic-Acid-Loaded Water-in-Oil-in-Water Microemulsion and Its Potential as a Fluorescent Delivery Carrier with a Free Label

“…As already demonstrated in Figure –, it could be seen that a mixed surfactant was more effective to enlarge the microemulsion area by controlling oil–water interfacial distribution in contrast to single-component surfactants . Similarly, this phenomenon provided further evidence that a co-surfactant is a crucial factor, which can increase the interfacial curvature to make interface bending easier, enhance interfacial film fluidity, and alter the HLB value to promote the phase transition . Moreover, as demonstrated, this explanation is well in agreement with the phenomenon that the total area of the microemulsion in the presence of ethanol is higher than that of pure Cremophor EL.…”

“…To further interpret the encapsulated mechanism of ALA, we considered that it may be due to the medial oil layer in W/O/W microemulsion being thin enough, leading to the simultaneous occurrence of both aggregation and diffusion, which was significantly different from the O/W microemulsion of pre-aggregation and re-diffusion. In addition, the chemical shifts of W/O/W microemulsion pronounced decreased in contrast to the O/W microemulsion prepared by Chen at al . The results on basis of these changes may be attributed to the fact that a multilayer interfacial structure improved the oil phase of the intermediate layer, resulting in a large interfacial curvature and specific surface area, thus weakening the attractive force and positional pressure of the water–oily interface.…”

“…In our previous work, the pseudo-ternary phase diagrams of O/W microemulsion were established by means of four identical constituents. Hence, the preparation process of O/W microemulsion had been modified slightly to fabricate W/O/W microemulsion under room temperature . The original oil phase was replaced by primary W/O microemulsion and then, in combination with Cremophor EL and ethanol, was redispersed in aqueous media, whose proportion of Cremophor EL/W/O microemulsion/ethanol was 7:2:1.…”

Oral delivery of lycopene-loaded microemulsion for brain-targeting: preparation, characterization, pharmacokinetic evaluation and tissue distribution

“…With good biocompatibility and proven safety profile (Rowe et al., 2009), this co-emulsifier has been commonly used in the construction of orally administered ME formulations (Wu et al., 2015; Guo et al., 2016). Furthermore, the surfactant to co-surfactant weight ratio is a key factor affecting S mix interactions and ME formation (Chen et al., 2017), and the appropriate ratio was fixed at 2:1.…”

“…Owing to manifold advantages of slight materials requirement, easy manufacture, smaller size and monodispersibility, ME has been extensively used to deliver drugs (Ghosh et al., 2006; Sane et al., 2013). More importantly, it is known to have higher solubilization capacity, especially for hydrophobic substances (Amar et al., 2003; Chen et al., 2017), and the system possesses promising stability to protect bioactive components from undesired damage (Chen et al., 2017; Tao et al., 2017).…”