Development, characterization, and evaluation of the antioxidant activity of nanocarriers based on surfactant swollen micelles that encapsulate essential oils

This work aimed to compare the performance of two relatively underexplored methods for the swollen micelles (SMs) production as nanocarriers for essential oils (EOs). Origanum vulgare and Thymus vulgaris EOs were examined. The first method (SMs-1), involved a self-assembly process, while the second one (SMs-2), employed titration operation of an emulsion into a surfactant solution for SMs formation. Tween 80 and ethanol were used as surfactant and co-surfactant, respectively. The solubilization kinetics and the saturation concentration of EOs were determined. Particle size (measured by DLS) and encapsulation efficiency (EE) were the control parameters assessed, along with the EOs-loaded SMs' stability during 30 days of storage. Additionally, the EOs-loaded SMs' morphology was analyzed using atomic force microscopy (AFM). Finally, the antioxidant activity through the ABTS+ radical scavenging and the reducing power of EOs encapsulated in SMs was determined. The results showed that the solubilization of EOs in SMs was a rapid process with high EE. EOs-loaded SMs-2 systems exhibited greater colloidal stability and higher EE compared to EOs-loaded SMs-1 systems, showing smaller and more homogeneous particle sizes. Moreover, EOs-loaded SMs-2 systems maintained constant EE throughout the storage period. AFM imaging confirmed the rounded and heterogeneous morphology of EOs-loaded SMs-1 and the smaller, more homogeneous, and spherical morphology of EOs-loaded SMs-2. EOs-loaded SMs-2 showed high ABTS+ radical scavenging and reducing power when encapsulated in SMs. In conclusion, the SMs-2 method emerged as an effective approach for producing efficient nanocarriers for EOs, signifying a promising path for future developments in antioxidant delivery systems.

Squalene encapsulation by emulsification and freeze-drying process: Effects on bread fortification

In the present work, squalene (SQ) was encapsulated by a conventional emulsion method using egg white protein nanoparticles (EWPn) as a high molecular weight surfactant, followed by a freeze-drying process to obtain an SQ powder ingredient. EWPn was produced by heat treatment at 85°C, 10 min, and pH 10.5. EWPn showed higher emulsifying activity regarding native egg white protein (EWP), highlighting their potential to be used for the SQ encapsulation by an emulsification process. First, we explored the encapsulation conditions using pure corn oil as an SQ carrier. Conditions were oil fraction (0.1-0.2), protein amount (2-5 wt.%), homogenization pressure (100 and 200 bar), and maltodextrin amount (10-20 wt.%). At 0.15 oil fraction, 5 wt.%. protein concentration, 200 bar homogenization pressure, and 20% maltodextrin, the highest encapsulation efficiency (EE) was reached. Then, according to these conditions, SQ was encapsulated to obtain a freeze-dried powder ingredient for bread formulation. The total and free oil of SQ freeze-dried powder were 24.4% ± 0.6% and 2.6% ± 0.1%, respectively, resulting in an EE value of 89.5% ± 0.5%. The physical, textural, and sensory properties of functional bread were not affected by the addition of 5.0% SQ freeze-dried powder. Finally, the bread loaves showed higher SQ stability than the one formulated with unencapsulated SQ. Hence, the encapsulation system developed was suitable for obtaining functional bread based on SQ fortification.

Bioactive compounds: Application of albumin nanocarriers as delivery systems

Enriched products with bioactive compounds (BCs) show the capacity to produce a wide range of possible health effects. Most BCs are essentially hydrophobic and sensitive to environmental factors; so, encapsulation becomes a strategy to solve these problems. Many globular proteins have the intrinsic ability to bind, protect, encapsulate, and introduce BCs into nutraceutical or pharmaceutical matrices. Among them, albumins as human serum albumin (HSA), bovine serum albumin (BSA), ovalbumin (OVA) and α-lactalbumin (ALA) are widely abundant, available, and applied in many industrial sectors, becoming promissory materials to encapsulate BCs. Therefore, this review focuses on researches about the main groups of natural origin BCs (namely phenolic compounds, lipids, vitamins, and carotenoids), the different types of nanostructures based on albumins to encapsulate them and the main fields of application for BCs-loaded albumin systems. In this context, phenolic compounds (catechins, quercetin, and chrysin) are the most extensively BCs studied and encapsulated in albumin-based nanocarriers. Other extensively studied subgroups are stilbenes and curcuminoids. Regarding lipids and vitamins; terpenes, carotenoids (β-carotene), and xanthophylls (astaxanthin) are the most considered. The main application areas of BCs are related to their antitumor, anti-inflammatory, and antioxidant properties. Finally, BSA is the most used albumin to produced BCs-loaded nanocarriers.

In vitro gastrointestinal digestion and cytotoxic effect of ovalbumin-conjugated linoleic acid nanocomplexes

The aim of this work was to examine the behavior of conjugated linoleic acid (CLA) delivery systems based on ovalbumin (OVA) and their derived nanoparticles (OVA_n1 and OVA_n2), under static in vitro gastrointestinal digestion model. In addition, potential cytotoxic effect of these inclusion complexes on a human colon cancer cell line (HT-29) was evaluated. OVA was resistant to gastric and intestinal digestion, while OVA nanoparticles were very susceptible to digestive enzymes hydrolysis. Particle size distribution (PDS) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for OVA evidenced the presence of a protein fragment of similar size after simulated digestive process. Conversely, for nanoparticles, partial and total hydrolysis in gastric and intestinal phases, respectively, was evidenced. After in vitro gastrointestinal digestion, released CLA (R_CLA) was assayed. In case of OVA, as CLA carrier, R_CLA was 37%, while for OVA nanoparticles, lower R_CLA values (~10-20%) were obtained. From cytotoxic assays, it was observed that CLA molecule was responsible for cell death, whereas OVA or their derived nanoparticles were not cytotoxic on HT-29 cells. On the other hand, flow cytometry analysis revealed that main death mechanism for CLA, and their inclusion complexes was apoptosis. OVA-CLA and OVA_n1-CLA inclusion complexes displayed the highest potential cytotoxic activity and apoptotic index. Information derived from this work could be relevant for the design of CLA delivery systems as promising nanosupplements for production of new functional and excipient foods for both prevention and control of colon cancer.

Physiological and morphological responses of green microalgae Chlorella vulgaris to silver nanoparticles

The toxic effects of silver nanoparticles (AgNPs) on the physiology and morphology of the green microalga Chlorella vulgaris were studied. AgNPs were characterized by particle size distribution, ζ potential measurement, and atomic force microscopy (AFM). Chlorella vulgaris was exposed to 90-1440 μg/L of AgNPs range in Bold's Basal Medium for 96 h. The inhibition of algae growth rate and changes in the concentrations of chlorophyll-a, chlorophyll-b, pheophytin, and carotenoids was determined at the beginning and end of the trial. Cell diameter and volume, carbohydrate, total lipids, and protein content were also determined. Our data strongly suggest that the toxic effects of the AgNPs resulted in concentration and time-dependent. AgNPs altered C. vulgaris growth kinetics and cell metabolism expressed in photosynthetic pigments and biochemical composition. Our study confirmed the cytotoxicity of AgNPs through the algal growth inhibition with an EC₅₀ value of 110 μg/L. Also, changes of chlorophyll-a, chlorophyll-b, pheophytin, and carotenoids concentrations were observed associated with a color shift from green to pale brown of algae cultures exposed to AgNPs for 96 h. Furthermore, algae cell concentration, diameter, and volume, plus total lipid, protein, and carbohydrates contents in the presence of AgNPs, were significantly altered compared to untreated cells. In synthesis, this study highlighted AgNPs toxic effects on morphological and physiological traits of C. vulgaris and warns about possible impacts on energy flow and aquatic food web structure, and on the transfer efficiency of energy to higher trophic levels.

Design of a biodegradable carrier for the application of controller bacteria on air-water interfaces

BACKGROUND

The formulation of a biodegradable carrier which effectively concentrates microorganisms on air-water interfaces is proposed. This avoids the dispersion of bacteria into the bulk liquid phase and at the same time prevents their sedimentation. This formulation can be used in biocontrol and bioremediation treatments where the target is at the position of the air-water interface, as in the case of the treatment of rice diseases caused by Sclerotium oryzae and Rhizoctonia complex. The carrier is an oil-in-water (O/W) emulsion which contains lecithin and chitosan in both phases at different proportions. In a stable formulation, bacteria that are adsorbed onto the surface of oil droplets are carried with them and flowed upward to the air-water interface, due to buoyancy forces.

RESULTS

When using the biodegradable carrier, it is possible to recover at least 15-fold more bacteria from the air-water interface than in the case of using the aqueous formulation.

CONCLUSION

The emulsion O/W is applied to the surface by dripping, resulting in a homogeneous two-dimensional film distribution. With this application device, the number of bacteria at the air-water interface is significantly increased. © 2019 Society of Chemical Industry.

Chrysin-loaded bovine serum albumin particles as bioactive nanosupplements

Freeze-dried Chrys-loaded BSAnp retained their properties after reconstitution and induced apoptosis on breast cancer cells. BSAnp-70-11 (smallest sized) was the most cytotoxic system with a gastrointestinal release of 14% Chrys.

Simulated gastrointestinal digestion of inclusion complexes based on ovalbumin nanoparticles and conjugated linoleic acid

Ovalbumin delivery system of conjugated linoleic acid resists in vitro gastrointestinal digestion with high percentages of bioactive retention.

Chromatographic fractionation and molecular mass characterization of Cercidium praecox (Brea) gum

BACKGROUND

Brea gum (BG) is an exudate from the Cercidium praecox tree that grows in semi-arid regions of Argentina. Some previous studies on BG have shown physicochemical characteristics and functional features similar to those of gum arabic. However, there is a need to elucidate the molecular structure of BG to understand the functionality. In this sense, BG was fractionated using hydrophobic interaction chromatography and the obtained fractions were analyzed by size exclusion chromatography.

RESULTS

Analysis of the fractions showed that the bulk of the gum (approx. 84% of the polysaccharides) was a polysaccharide of 2.79 × 10(3)  kDa. The second major fraction (approx. 16% of the polysaccharides) was a polysaccharide-protein complex with a molecular mass of 1.92 × 10(5)  kDa. A third fraction consisted of protein species with a wide range of molecular weights. The molecular weight distribution of the protein fraction was analyzed by size exclusion chromatography. Comparison of the elution profiles of the exudates in native and reducing conditions revealed that some of the proteins were forming aggregates through disulfide bridges in native conditions. Further analysis of the protein fraction by SDS-PAGE showed proteins with molecular weight ranging from 6.5 to 66 kDa.

CONCLUSIONS

The findings showed that BG consists of several fractions with heterogeneous chemical composition and polydisperse molecular weight distributions. © 2016 Society of Chemical Industry.