Cinnamon and paprika oleoresins (CPO) are by-products of the spice Cinnamomum zeylanicum Blume and the fruit Capsicum annuum L., respectively. They present a hydrophobic nature and various active compounds that can act synergistically. However, they are both susceptible to degradation by light, oxygen, and temperature. This work aimed at identifying the synergistic effect of these oleoresin mixtures, incorporating them into emulsions and characterizing the obtained systems. The CPO concentration was 10%, and whey protein isolate (WPI), gum Arabic (GA), or maltodextrin (MD) were used as wall materials in different proportions, totalizing 30% solids. The synergistic effect was observed in the FRAP assay at a 1:1 CPO ratio, with its expected value being significantly higher than the values for individual oleoresins (p < 0.05). Emulsions containing GA were unstable, while the emulsions containing MD and WPI showed reduced droplet size and viscosity, remaining stable for 7 days. The sample with a 1:3 proportion of MD:WPI as wall material showed higher FRAP and ORAC antioxidant values (24.74 ± 0.83 and 28.77 ± 1.23 mmol TE/g of oleoresin, respectively) and 4.18 mg total carotenoids/g sample. These results suggest the emulsions have a protective effect on active compounds content and can be used as efficient delivery systems for food product applications.

OBJECTIVE: The development of vehicles for the co-encapsulation of actives with diverse characteristics and their subsequent controllable co-delivery is gaining increasing research interest. Predominantly centred around pharmaceutical applications, the majority of such co-delivery approaches have been focusing on solid formulations and less so on liquid-based systems. Simple emulsions can be designed to offer a liquid-based microstructural platform for the compartmentalised multi-delivery of actives.
METHODS: In this work, solid lipid nanoparticle stabilised Pickering emulsions were used for the co-encapsulation/co-delivery of two model actives with different degrees of hydrophilicity. Lipid particles containing a model hydrophobic active were prepared in the presence of either Tween 20 or whey protein isolate, and were then used to stabilise water-in-oil or oil-in-water emulsions, containing a secondary model active within their dispersed phase.
RESULTS: Solid lipid nanoparticles prepared with either type of emulsifier were able to provide stable emulsions. Release kinetic data fitting revealed that different co-delivery profiles can be achieved by controlling the surface properties of the lipid nanoparticles. The current proof-of-principle study presents preliminary data that confirm the potential of this approach to be utilised as a flexible liquid-based platform for the segregated co-encapsulation and independent co-release of different combinations of actives, either hydrophobic/hydrophilic or hydrophobic/hydrophobic, with diverse release profiles.

Calcium and vitamin D3 were co-encapsulated in three types of water-in-oil-in-water (W/O/W) double emulsions stabilized with biopolymers: gum arabic, sodium alginate (Alg) and chitosan (Ch). Three calcium salts with different solubility were used: calcium carbonate (CaC), tricalcium phosphate (CaP) and calcium gluconate (CaG). In order to study the bioavailability of calcium and vitamin D3, the W/O/W double emulsions were subjected to digestion in simulated conditions using in vitro gastrointestinal models. The size of the oil droplets of all double emulsions increased in oral phase and decreased in gastric and intestinal phases. In the intestinal phase, the average diameter of oil globules in the W/O/W(Alg) and W/O/W(Ch) was d23 = 6.56 ± 0.09 and d23 = 5.33 ± 0.01 and the electro-kinetic potential was: ζ ≈ -25 mV and ζ ≈ -17 mV, respectively. Presence of calcium ions in the intestinal fluid decreased the free fatty acids content and decreased the bioaccessibility of vitamin D3 due to the inhibition of micellization process.

Combined therapy with corticosteroids and immunosuppressant-loaded nanostructured lipid carriers (NLC) could be useful in the treatment of skin diseases. To circumvent NLC loading capacity problems, loaded drugs should have different physicochemical characteristics, such as tacrolimus (TAC) and clobetasol (CLO). Therefore, in the present study, TAC and CLO were encapsulated in NLC (TAC-NLC, CLO-NLC and TAC+CLO-NLC), coated or otherwise with chitosan. Electron paramagnetic resonance (EPR) spectroscopy of different spin labels was used to investigate the impact of drug and oil incorporation on the lipid dynamic behavior of the lipid matrices. In addition, the impact of co-encapsulation on drug release and skin permeation was evaluated. Entrapment efficiency was greater than 90% for both drugs, even when the maximum drug loading achieved for TAC-NLC and CLO-NLC was kept at TAC+CLO-NLC, because TAC is more soluble in the solid lipid and CLO in the liquid lipid. EPR data indicated that both drugs reduced the lipid fluidity near the polar surface of the lipid matrix, which suggests their presence in this region. In addition, EPR data showed that liquid lipid is also present in more superficial regions of the nanoparticle matrix. CLO was released faster than TAC from TAC+CLO-NLC, probably because it is more soluble in the liquid lipid. TAC skin penetration was affected by CLO. A 5-fold increase in TAC penetration was observed from TAC+CLO-NLC when compared to TAC-NLC formulations. Coating also increased TAC and CLO permeation to deeper skin layers (1.8-fold and 1.6-fold, respectively). TAC+CLO-NLC seems to be an effective strategy for topical delivery of TAC and CLO, and thus constitutes promising formulations for the treatment of skin diseases.