Novel γ-cyclodextrin-metal-organic frameworks for encapsulation of curcumin with improved loading capacity, physicochemical stability and controlled release properties.

A safe and biodegradable γ-cyclodextrin-metal-organic-frameworks (γ-CD-MOFs) was successfully synthesized by using an improved hydrothermal method. In this study, curcumin (Cur) was chosen for testing the encapsulation stability and release performance of γ-CD-MOFs. Results of the crystal structure measurement indicated that the encapsulated curcumin within γ-CD-MOFs via van der Waals forces, hydrophobic interactions and hydrogen bonding was failed to disturb the inherent microtopography and crystallinity of γ-CD-MOFs. Compared to individual γ-CD, the γ-CD-MOFs exhibited improved loading capacity, physicochemical stability as well as controlled-release property in simulated digestion, and hence can be regarded as effective carriers for curcumin. Curcumin-loaded γ-CD-MOFs with a Cur : γ-CD-MOFs mass ratio of 2:3 (Cur-CD-MOFs/3), which showed the highest encapsulation efficiency (67.31 ± 2.25%), improved physicochemical stability and controlled-release performance, was selected for further research and industrialization. Our results demonstrate that γ-CD-MOFs can be regarded as a promising novel carrier for the delivery of curcumin or other hydrophobic nutraceuticals.

High-internal-phase emulsions (HIPEs) for co-encapsulation of probiotics and curcumin: enhanced survivability and controlled release.

Synergistic biological activities of probiotics and curcumin can be achieved based on the gut-brain axis. However, it is still a challenge for utilizing both of them in actual food products due to their high sensitivity to environmental conditions. In the present study, high-internal-phase emulsions (HIPEs) were fabricated to co-encapsulate the probiotics and curcumin in response to the customer demand for convenience. ß-Lactoglobulin-propylene glycol alginate composite hydrogel particles (ß-lgPPs) with proper size and intermediate wettability were prepared at ß-lg to PGA mass ratio of 2 : 1 and employed as particulate emulsifiers. Stable HIPEs with a fixed oil fraction (φ = 0.8) could be formed within a wide range of ß-lgPPs concentrations, ranging from 0.1 to 2.0 wt%. Confocal laser scanning microscopy (CLSM) images indicated that the interfacial structure of the oil droplets was composed of both ß-lg nanoparticles and a PGA network, which jointly contributed to the gel-like structures in HIPEs. An increase in elasticity and gel strength, as well as centrifugal stability, could be achieved by elevating the particle concentration as determined by diffusing wave spectroscopy and Lumisizer analysis. HIPEs with high particle concentrations showed a high resistance against pasteurization since no obvious flocculation or coalescence could be observed in these emulsions. HIPEs also provoked a significant reduction in the death of LGG as well as the chemical degradation of curcumin: up to 7.91 log CFU cm-3 of LGG and 93.0% of curcumin were retained after pasteurization treatment. Moreover, the HIPEs could also retard the release of curcumin and protect the LGG in simulated gastrointestinal tract conditions. The results from this work provide useful information for developing a promising delivery system for the co-encapsulation of curcumin and probiotics.

Stability and release performance of curcumin-loaded liposomes with varying content of hydrogenated phospholipids.

The aim of this study was to substitute part of soybean phospholipid (SPC) with hydrogenated soybean phospholipid (HSPC) in curcumin-loaded liposomes (Cur-LP), in order to further enhance stability and release performances of curcumin. When the SPC/HSPC mass ratio changed from 10:0 to 5:5, vesicle size, encapsulation efficiency and alkali resistance of curcumin increased, although a small decrease in centrifugal stability was observed. Salt stability became worse as more HSPC was used (3:7 and 0:10). Owing storage at 4 °C and 25 °C, Cur-LP at a SPC/HSPC mass ratio of 5:5 performed well considering vesicle size, lipid oxidation and curcumin retention. These vesicles displayed also the best sustained-release performance in simulated digestion, attributed to the tighter lipid packing in membranes as indicated by fluorescence probes, DSC and FTIR. This study can guide the development of a Cur-LP product with improved shelf-life stability by using HSPC.

Fabrication, Physicochemical Stability, and Microstructure of Coenzyme Q10 Pickering Emulsions Stabilized by Resveratrol-Loaded Composite Nanoparticles.

The aim of this study was to develop a novel system for the co-delivery of resveratrol and coenzyme Q10 (CoQ10). It was achieved with a combination of resveratrol-loaded composite nanoparticles and CoQ10-loaded Pickering emulsions. Different levels of resveratrol (0.05-0.30%, w/v) were entrapped into composite nanoparticles by the method of emulsification-evaporation. The size of composite nanoparticles was around 300-600 nm, and the maximum loading capacity of resveratrol was up to 13.88% (w/w). Hydrogen bonds, hydrophobic effects, and electrostatic attraction participated in the self-assembly of composite nanoparticles. The stability of CoQ10 Pickering emulsions was monitored under simulated environmental stresses (pH, ionic strength, UV radiation, and heat) and accelerated storage conditions. The physical stability of Pickering emulsions was dependent on the particle compositions, and the CoQ10 entrapped was also protected by the resveratrol-loaded nanoparticles. The morphology of Pickering emulsions was observed with the aid of optical microscopy, confocal laser scanning microscopy, and cryo-scanning electronic microscopy. The nutraceutical Pickering emulsions were designed for the co-delivery of resveratrol and CoQ10, which has the potential to be a novel vehicle for bioactive ingredients.

Effect of ß-sitosterol on the curcumin-loaded liposomes: Vesicle characteristics, physicochemical stability, in vitro release and bioavailability.

In this work, the effect of ß-sitosterol (Sito) on vesicle characteristics, physicochemical stability as well as the in vitro release and bioavailability of curcumin-loaded liposomes (Cur-LP) was studied. When 20-33 mol% of Sito was incorporated, encapsulation efficiency of curcumin was improved due to the high amount of liquid-ordered domains in membranes. At 50 mol% Sito a lower encapsulation efficiency was observed possibly due to membrane defects. The physical, thermal and photo stability of curcumin in liposomes were markedly improved with increasing the amount of Sito. First-order kinetics fitted best the curcumin release dynamics of Sito containing liposomes, clearly showing that sustained release improved with increasing amounts of Sito in liposomes. Simulated digestion studies suggested that Sito concentration of about 20-33 mol% improved the bioavailability of curcumin in liposomes. These study shows that Sito is an applicable and potential route in forming healthier cholesterol-free curcumin-loaded liposomes for functional supplements.

Development of stable curcumin nanoemulsions: effects of emulsifier type and surfactant-to-oil ratios.

Curcumin, a natural polyphenolic compound, offers a wide range of pharmacological benefits such as antioxidant, anti-inflammatory and anti-cancer. The oil-in-water nanoemulsions containing curcumin were obtained by high pressure homogenization and effects of various emulsifiers (Tween-80, lecithin, whey protein isolate and acacia) and different surfactant-to-oil ratios (SOR) on physicochemical characteristics, physical stability and storage stability of curcumin loaded nanoemulsions were evaluated in this study. The result showed that smaller particle size, better physical and storage stabilities and higher curcumin content were found in curcumin loaded nanoemulsions stabilized with Tween-80 and lecithin. Compared with nanoemulsions prepared with lecithin, nanoemulsions fabricated with Tween-80 exhibited better uniformity and distribution as demonstrated by microscopic observations. It was found that SOR was positively correlated with particle size but negatively correlated with curcumin content in the emulsion droplets. Neither the emulsifier nor SOR values were found to have significant effects on zeta-potentials of the droplets. This result implied that curcumin loaded nanoemulsions prepared with Tween-80 and higher SOR values helped curcumin to achieve better physical stability and storage stability.

The effect of sterol derivatives on properties of soybean and egg yolk lecithin liposomes: Stability, structure and membrane characteristics.

The effects of three kinds of sterols (cholesterol, ß-sitosterol and ergosterol) on the stability, microstructure and membrane properties of soybean and egg yolk lecithin liposomes were investigated by light scattering, transmission electron microscope (TEM), atomic force microscope (AFM), fluorescence and Fourier transform infrared spectroscopy (FTIR). The vesicle size of cholesterol or ß-sitosterol incorporated liposomes was higher than that of the control and ergosterol incorporated ones, while the zeta-potential was similar when the same lecithin was used. Due to the excellent emulsifying capacity, Tween-80 was introduced into the system and which could obviously maintain the liposomal vesicle size in fetal bovine serum. According to TEM and AFM, the phenomena of membrane fusion and deformation were observed respectively in ergosterol-incorporated liposomes. Results of fluorescence probe spectra revealed the most compact membrane structure was found in cholesterol-incorporated liposomes, which was in accordance with the strongest intermolecular interaction in bilayers obtained by FTIR results. Conversely, the membrane of ergosterol-incorporated liposomes was the most fragile and fluid, which was also identified with the lowest physical stability obtained by Turbiscan. These results systematically illustrated the relationship between the structure of sterols and the liposomal membrane stability, and provided some meaningful information on the choice of sterols and lecithin in preparation of liposomes for different purposes.

Development of a soy protein isolate-carrageenan-quercetagetin non-covalent complex for the stabilization of ß-carotene emulsions.

The current study investigated the application of a soy protein isolate (SPI), κ-carrageenan (CG) and quercetagetin (Qut) non-covalent complex in stabilizing ß-carotene emulsions. The ternary complex was formed through a mild mixing and incubation process. FTIR measurement indicated the formation of hydrogen bonds in the non-covalent complex. SPI-CG and SPI-CG-Qut complexes had a much smaller particle size when redispersed in water after spray drying, compared to those in the original dispersions (p < 0.05). Dynamic light scattering analysis revealed that the emulsion stabilized with the ternary complex had a bigger particle size, higher surface charge, and improved creaming stability compared to those stabilized with SPI or SPI-Qut (p < 0.05). The ternary complex allowed less degradation of ß-carotene in the emulsions when exposed to light or thermally treated at 37 °C or 55 °C. Therefore, the SPI-CG-Qut non-covalent complex might work as a novel ingredient in designing delivery systems for ß-carotene.

Physicochemical and in vitro antioxidant properties of pectin extracted from hot pepper (Capsicum annuum L. var. acuminatum (Fingerh.)) residues with hydrochloric and sulfuric acids.

BACKGROUND: Transformation of hot pepper residues to value-added products with concomitant benefits on environmental pollution would be of great value to capsicum oleoresin manufacturers. Pectin, a soluble dietary fiber with multiple functions, from hot pepper residues was investigated in this study. RESULTS: The extraction of hot pepper pectin using hydrochloric acid was first optimized using response surface methodology (RSM). The most efficient parameters for maximum hot pepper pectin yield (14.63%, dry basis) were a pH of 1.0, a temperature of 90 °C, an extraction time of 2 h and a liquid-to-solid ratio of 20 L g-1 . The pectin was mainly composed of uronic acids, and the major neutral sugars were galactose and glucose. The structure of hot pepper pectin was characterized by homogalacturonan and rhamnogalacturonan I elements. The physicochemical properties of hot pepper pectin extracted by sulfuric acid and hydrochloric acid were further investigated. The content of protein and degree of esterification in hot pepper pectin extracted with sulfuric acid solution (SP) were higher (P < 0.05) than those in that extracted with hydrochloric acid solution (HP), while the mean molecular weight of SP was lower than that of HP. Compared with HP, SP exhibited higher viscosity and better emulsifying property. CONCLUSION: Based on the yield and physicochemical properties of hot pepper pectin, hot pepper residues would be a new source to obtain pectin, and SP would be more preferred than HP. © 2017 Society of Chemical Industry.

In vitro antioxidant, anti-diabetic and antilipemic potentials of quercetagetin extracted from marigold (Tagetes erecta L.) inflorescence residues.

Quercetagetin, the major flavonoid in marigold (Tagetes erecta L.) inflorescence residues was extracted and purified. The content of quercetagetin after the purification was 89.91 ± 0.26 %. The in vitro antioxidant activity of quercetagetin and its potential in controlling diabetes mellitus and obesity were investigated and compared to quercetin and rutin. The 50 % inhibitory concentration (IC50) values of quercetagetin on scavenging 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS) and hydroxyl radicals were 27.12 ± 1.31 µmol/L, 12.16 ± 0.56 µmol/L and 1833.97 ± 6.66 µmol/L, respectively. The IC50 values of quercetagetin on α-glucosidase, α-amylase and pancreatic lipase were 180.11 ± 3.68 µmol/L, 137.71 ± 3.55 µmol/L and 2327.58 ± 12.37 µmol/L, respectively. These results indicated that quercetagetin exhibited strong in vitro antioxidant, anti-diabetic and antilipemic activities. Lineweaver-Burk plots analysis elucidated that quercetagetin inhibited α-glucosidase and α-amylase non-competitively, while its inhibition against pancreatic lipase was involved in a mixed-type pattern. Moreover, strong correlations were found between ABTS(·+)/DPPH(·) scavenging activities and lipase inhibitory activity (R (2) > 0.90), as well as ·OH scavenging activity and α-amylase inhibitory activity (R (2) = 0.8967).