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.

b-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. b-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 b-carotene by using hot-melt technology, a type of solid dispersions technology. When preparing b-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 bcarotene:polyvinylpyrrolidone:sucrose fatty acid ester to 10%:70%:20% resulted in the poorly-water soluble b-carotene showing improved water solubility (120 lg/mL). The physicochemical properties of the optimized b-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 b-carotene in the solid dispersions developed in this work may make these dispersions useful as additives in foods or in nutraceutical formulations. Keywords b-Carotene Á Emulsifier Á Water solubility Á Hot-melt technology Á Solid dispersion Á Amorphous Kenji Ishimoto and Shohei Miki have contributed equally to this work.

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To examine the biotransformation of (ϩ)-catechin by the plant cultured cells of Eucalyptus perriniana, three new biotransformation products, (ϩ)-catechin-3Ј-O-b-D-glucoside, (ϩ)-catechin-5-O-b-D-glucoside and (ϩ)-catechin-7-O-b-D-glucoside were isolated after 3 days incubation. The cultured cells of E. perriniana were found to be capable of glycosylation at the 5, 7-positions on the A ring and the 3Ј-position on the B ring of (ϩ)-catechin.

Not applicable *Consent to participate -(include appropriate consent statements) Not applicable *Consent for publication -(appropriate statements regarding publishing an individual's data or image) Not applicable *Availability of data and material -(data transparency)The datasets during and/or analysed during the current study available from the corresponding author on reasonable request.

It is well known that black and green tea extracts, particularly polyphenols, have antimicrobial activity against various pathogenic microbes including viruses. However, there is limited data on the antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), which emerged rapidly in China in late 2019 and which has been responsible for coronavirus disease 2019 (COVID‐19) pandemic globally. In this study, 20 compounds and three extracts were obtained from black and green tea and found that three tea extracts showed significant antiviral activity against SARS‐CoV‐2, whereby the viral titre decreased about 5 logs TCID50 per ml by 1·375 mg ml−1 black tea extract and two‐fold diluted tea bag infusion obtained from black tea when incubated at 25°C for 10 s. However, when concentrations of black and green tea extracts were equally adjusted to 344 µg ml−1, green tea extracts showed more antiviral activity against SARS‐CoV‐2. This simple and highly respected beverage may be a cheap and widely acceptable means to reduce SARS‐CoV‐2 viral burden in the mouth and upper gastrointestinal and respiratory tracts in developed as well as developing countries.

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.

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.