Chitosan-glucose conjugates: influence of extent of Maillard reaction on antioxidant properties.

Chitosan-glucose conjugates were prepared using Maillard reaction chemistry. Water-soluble and acid-soluble chitosan-glucose mixtures were heated at pH 4.9 and 6.0 at 98 °C. Mixtures at pH 6.0 containing acid-soluble chitosan gelled when heating was continued after reaching 98 °C and withstood gelation for only 30 min at pH 4.9. In contrast, mixtures containing water-soluble chitosan could be heated without gelation at pH 6.0 and 4.9. Examination of the extent of Maillard reaction and antioxidant properties showed that acid-soluble chitosan reacted for 30 min at pH 4.9 had the highest extent of reaction as judged by increased absorbance, the highest degree of modification to the amino group as evidenced by Fourier transform infrared and shifts of the endotherms by differential scanning calorimetry, and the highest antioxidant activity as indicated by ferric reducing power and oxygen radical absorbance capacity. There were significant correlations (p < 0.05) between indices of browning and antioxidant activity.

Chemical modification of gelatin by a natural phenolic cross-linker, tannic acid.

Chemical modification of gelatin by a natural phenolic compound tannic acid (TA) at pH 8 was studied, and the properties of the modified gelatin materials were examined. The cross-linking effect was predominant when the TA content was lower, resulting in the formation of a partially insoluble cross-link network. The cross-linking structure was stable even under boiling, and the protein matrix became rigid, whereas the mechanical properties were enhanced. An effective cross-linking effect on gelatin matrix was achieved when the amount of TA was around 3 wt %. Further increase in the TA content enhanced the grafting and branching reactions between gelatin and TA in conjunction with the hydrogen bonding between gelatin and TA molecules. These effects produced an increase in molecular mobility of gelatin matrix, and the materials displayed a behavior similar to that of plasticized protein materials.

Consumption of grape seed extract prevents amyloid-beta deposition and attenuates inflammation in brain of an Alzheimer's disease mouse.

Polyphenols extracted from grape seeds are able to inhibit amyloid-beta (Abeta) aggregation, reduce Abeta production and protect against Abeta neurotoxicity in vitro. We aimed to investigate the therapeutic effects of a polyphenol-rich grape seed extract (GSE) in Alzheimer's disease (AD) mice. APP(Swe)/PS1dE9 transgenic mice were fed with normal AIN-93G diet (control diet), AIN-93G diet with 0.07% curcumin or diet with 2% GSE beginning at 3 months of age for 9 months. Total phenolic content of GSE was 592.5 mg/g dry weight, including gallic acid (49 mg/g), catechin (41 mg/g), epicatechin (66 mg/g) and proanthocyanidins (436.6 mg catechin equivalents/g). Long-term feeding of GSE diet was well tolerated without fatality, behavioural abnormality, changes in food consumption, body weight or liver function. The Abeta levels in the brain and serum of the mice fed with GSE were reduced by 33% and 44%, respectively, compared with the Alzheimer's mice fed with the control diet. Amyloid plaques and microgliosis in the brain of Alzheimer's mice fed with GSE were also reduced by 49% and 70%, respectively. Curcumin also significantly reduced brain Abeta burden and microglia activation. Conclusively, polyphenol-rich GSE prevents the Abeta deposition and attenuates the inflammation in the brain of a transgenic mouse model, and this thus is promising in delaying development of AD.

Grape seed polyphenols and curcumin reduce genomic instability events in a transgenic mouse model for Alzheimer's disease.

The study set out to determine (a) whether DNA damage is elevated in mice that carry mutations in the amyloid precursor protein (APP695swe) and presenilin 1 (PSEN1-dE9) that predispose to Alzheimer's disease (AD) relative to non-transgenic control mice, and (b) whether increasing the intake of dietary polyphenols from curcumin or grape seed extract could reduce genomic instability events in a transgenic mouse model for AD. DNA damage was measured using the micronucleus (MN) assay in both buccal mucosa and erythrocytes and an absolute telomere length assay for both buccal mucosa and olfactory bulb tissue. MN frequency tended to be higher in AD mice in both buccal mucosa (1.7-fold) and polychromatic erythrocytes (1.3-fold) relative to controls. Telomere length was significantly reduced by 91% (p=0.04) and non-significantly reduced by 50% in buccal mucosa and olfactory bulbs respectively in AD mice relative to controls. A significant 10-fold decrease in buccal MN frequency (p=0.01) was found for AD mice fed diets containing curcumin (CUR) or micro-encapsulated grape seed extract (MGSE) and a 7-fold decrease (p=0.02) for AD mice fed unencapsulated grape seed extract (GSE) compared to the AD group on control diet. Similarly, in polychromatic erythrocytes a significant reduction in MN frequency was found for the MGSE cohort (65.3%) (p<0.05), whereas the AD CUR and AD GSE groups were non-significantly reduced by 39.2 and 34.8% respectively compared to the AD Control. A non-significant 2-fold increase in buccal cell telomere length was evident for the CUR, GSE and MGSE groups compared to the AD control group. Olfactory bulb telomere length was found to be non-significantly 2-fold longer in mice fed on the CUR diet compared to controls. These results suggest potential protective effects of polyphenols against genomic instability events in different somatic tissues of a transgenic mouse model for AD.

Chitosan microspheres for encapsulation of alpha-lipoic acid.

Encapsulation of alpha-lipoic acid (LA) was carried out using chitosan as an encapsulant matrix. Placebo and LA-loaded chitosan microspheres were prepared by a spray-drying process. Scanning electron microscopy (SEM) studies confirmed the spherical particle geometry and the smooth surface morphology of LA-loaded particles. The particle size distribution (PSD) analysis of the placebo and LA-loaded microspheres has shown that 50% of the microspheres were less than 3.53 and 7.89 microm, respectively. The structural interactions of the chitosan matrix with the encapsulated LA were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) which revealed structural interactions of lipoic acid with the encapsulant matrix. The antioxidant activity of encapsulated lipoic acid was studied using the free-radical scavenging assay. This study demonstrated significant retention of antioxidant activity of lipoic acid (75%) after encapsulation in the chitosan matrix. Encapsulation efficiency of lipoic acid obtained in this study was 55.2% when ethanol and acetic acid (1:1 v/v) was used as incubation/extraction medium.

Liposomal delivery systems for encapsulation of ferrous sulfate: Preparation and characterization.

Liposomal delivery systems for water-soluble bioactives were prepared using the pro-liposome and the microfluidization technologies. Iron, an essential micronutrient as ferrous sulfate and ascorbic acid, as an antioxidant for iron were encapsulated in the liposomes. Liposomes prepared by the microfluidization technology using 6% (w/w) concentration of the lipid encapsulated with ferrous sulfate and ascorbic acid had particle size distributions around 150 to 200 nm, whereas liposomes from the pro-liposome technology resulted in particle sizes of about 5 microm. The encapsulation efficiency of ferrous sulfate was 58% for the liposomes prepared by the microfluidization using 6% (w/w) lipid and 7.5% of ferrous sulfate concentrations, and it was 11% for the liposomes from pro-liposome technology using 1.5% (w/v) lipid and 15% of ferrous-sulfate concentration. Both the liposomes exhibited similar levels of oxidative stability, demonstrating the feasibility of microfluidization-based liposomal delivery systems for large-scale food/nutraceutical applications.

Colon targeted delivery systems: review of polysaccharides for encapsulation and delivery.

Colon-targeted delivery of bioactives has recently gained importance in addressing specific needs in the therapy of colon-based diseases. Many approaches have been attempted for the development of colon-specific delivery systems, with not much success in the past. Recent research into the utilization of the metabolic activity and the colonic microenvironment in the lower gastrointestinal tract has attained great value in the design of novel colon-targeted delivery systems based on natural biodegradable polymers. In the current article, special emphasis has been placed on polysaccharide systems, with minimal chemical modification, that have been exploitedfor colon targeting. These polysaccharide based encapsulation and targeted delivery systems are envisaged to have an immense potential for the development of food/nutraceutical formulations for colon-based diseases, including colorectal cancer.