Suppressive effect of black tea polyphenol theaflavins in a mouse model of ovalbumin-induced food allergy.

Food allergy is recognized as a global medical problem with increasing prevalence in recent years. Currently, the treatment of food allergy mainly involves avoidance of allergens and allergen-specific immunotherapy. Barring the spontaneous resolution of food allergy during the growth process, this disease is difficult to treat fundamentally. In recent years, the use of functional food ingredients derived from natural products has been attracting attention for their prophylactic use in food allergy. Theaflavins, i.e., black tea polyphenols, are potent antioxidants that have inhibitory effects on a variety of diseases. However, little is known about the preventive effect of theaflavins on food allergy. In this study, we designed a mouse model of food allergy and examined the effect of theaflavins using the severity of diarrhea, a symptom of food allergy, as an indicator. The administration of a black tea extract rich in theaflavins or theaflavin 1 (subgroup of theaflavins) to mice reduced the severity of diarrhea when compared with a normal diet. A reduction in malondialdehyde levels, a key marker of lipid peroxidation, was also observed. Overall, these data suggest that theaflavins may potentially inhibit food allergy by alleviating oxidative stress in the colon and can be a potential food material for prevention of food allergy.

Physicochemical and Biochemical Evaluation of Amorphous Solid Dispersion of Naringenin Prepared Using Hot-Melt Extrusion.

Naringenin (NRG) is a plant-derived flavonoid. Due to its antioxidant, anti-inflammatory, and analgesic activities it is beneficial to human health and is often used as a functional food ingredient; however, it has poor water solubility and low in vivo bioavailability. Therefore, the efficacy of NRG can be improved by enhancing its water solubility to increase gastrointestinal absorption. Conventional methods for the formulation of NRG are very complex and use toxic organic solvents, making them impractical for the production of functional foods. The objective of this study was to develop a safe and effective NRG-based functional food material. Previously, we established a technology to prepare amorphous solid dispersions (SDs) from functional food ingredients with poor water solubility and used hot-melt extrusion technology that is comparatively simple and does not involve the use of organic solvents. In this study, we prepared NRG SD and evaluated them both physicochemically and biochemically. NRG SD had superior water solubility and gastrointestinal absorption relative to native NRG and showed higher analgesic efficacy in rats than crystalline NRG. NRG SD was administered to mice in a mixed diet for 28 days, and organ weights and hematological/clinical biochemical parameters were assessed. NRG SD did not demonstrate severe adverse effects. The results suggest that NRG SD is a safe and highly efficacious formulation that can be used as a functional food material in the future.

Examination of dissolution ratio of ß-carotene in water for practical application of ß-carotene amorphous solid dispersion.

ß-Carotene (BC) has an antioxidant effect that removes active oxygen in vivo and can reduce the risk of developing various diseases, but it is almost insoluble in water. Therefore, to develop highly effective BC functional food products, it is essential to increase its water solubility, which in turn can improve its absolute bioavailability. Recently, a BC amorphous solid dispersion (BC-SD) prepared using hot melt extruder technology had increased water solubility and improved absorption from the gastrointestinal tract. However, only a part of the BC in BC-SD could be dissolved in water. In this study, we evaluated whether the dissolution ratio of BC in water could be improved by examining the mixing ratio of BC and base materials in BC-SD. Results showed that by reducing the mixing ratio of BC to the base materials, the dissolution ratio of BC in water increased. It was also found that when BC-SD, which has the highest dissolution ratio, was intragastrically administered to rats, its absolute bioavailability was most increased. These results are useful findings that may help in reducing the costs associated with the BC-SD manufacturing process and will be an important part of our strategy for practical use in the future.

Improved Bioavailability of ß-Carotene by Amorphous Solid Dispersion Technology in Rats.

ß-Carotene (BC) is a natural lipophilic carotenoid mainly present in vegetables and fruits. Although it has various beneficial pharmacological activities, its bioavailability is low owing to its low water solubility. Recently, we reported that BC solid dispersion prepared using hot-melt technology with polyvinylpyrrolidone and sucrose fatty acid esters was in an amorphous state and showed the highest solubility. We hypothesized that the absorption of BC solid dispersion would be better because of its increased water solubility. To verify this, we conducted a pharmacokinetic analysis of BC for application in functional foods. Crystalline or amorphous BC was orally administered to rats. Blood was collected at various time points, and the BC concentration in the plasma was measured by HPLC. Oral administration of amorphous BC showed increased absorption in rats compared with that of BC crystals. Using blood samples from rats that were intravenously injected with the plasma of rats that had been orally administered BC, pharmacokinetic parameters could be calculated without using organic solvents or surfactants. It was possible to calculate various pharmacokinetic parameters under physiological conditions according to amorphous BC characteristics. Thus, we were able to determine the bioavailability of BC after oral administration. This simple technology to improve BC solubility without the use of organic solvents can be applied not only in the pharmaceutical industry but also in the food industry, and it therefore has high utility value.

ß-Carotene solid dispersion prepared by hot-melt technology improves its solubility in water.

ß-Carotene is a member of the carotenoid family and is a red-orange pigment abundantly present in many vegetables and fruits. As an antioxidant, it eliminates excessive reactive oxygen species generated in the body. Accordingly, it has potential to be used in the pharmaceutical, food, and cosmetic industries. ß-Carotene has a very low water solubility and low bioavailability; thus, there is a need to develop techniques to overcome these issues. In this study, we aimed to enhance the water solubility of ß-carotene by using hot-melt technology, a type of solid dispersions technology. When preparing ß-carotene solid dispersion using this method, suitable conditions for the emulsifiers and mixing ratios were investigated using water solubility as an index. Setting the weight ratio of ß-carotene:polyvinylpyrrolidone:sucrose fatty acid ester to 10%:70%:20% resulted in the poorly-water soluble ß-carotene showing improved water solubility (120 µg/mL). The physicochemical properties of the optimized ß-carotene solid dispersion were analyzed using field emission scanning electron microscopy, differential scanning calorimetry, and powder X-ray diffraction. The solid dispersion was found to have an amorphous structure. The improved solubility observed for ß-carotene in the solid dispersions developed in this work may make these dispersions useful as additives in foods or in nutraceutical formulations.

Antioxidative activity of microbial metabolites of (-)-epigallocatechin gallate produced in rat intestines.

The antioxidative activities of (-)-epigallocatechin gallate (EGCg) metabolites degraded by rat intestinal flora were investigated by a flow injection analysis coupled to an on-line antioxidant detection system with the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation. All of the metabolites were found to have antioxidative activity, suggesting that the EGCg metabolites may show antioxidative activity in the body.