Akio Obata

Anti-allergic Activity of Naringenin Chalcone from a Tomato Skin Extract

The anti-allergic activity of a tomato extract was studied by using an in vitro histamine-release assay. The tomato skin extract exerted the strongest inhibition of histamine release. Chlorogenic acid, rutin and naringenin were identified in the 60% ethanol extract of tomato skin. However, the extract contained an unknown compound which strongly inhibited histamine release. This active compound in tomato skin was identified as naringenin chalcone (trans-2′4′6′4-tetrahydroxychalcone). Naringenin chalcone inhibited histamine release with an IC50 value of 68 μg/ml. The anti-allergic activity of the tomato skin extract was next investigated by the in vivo mouse ear-swelling response. We found that naringenin chalcone showed the strongest inhibitory effect of the polyphenols of the tomato skin extract. These results indicate that a tomato skin extract could inhibit allergic reactions.

Lactobacillus plantarum strain YU from fermented foods activates Th1 and protective immune responses.

Lactic acid bacteria (LAB) are known to have effects on immune function. From 203 strains of LAB isolated from fermented foods, we selected a beneficial strain, Lactobacillus plantarum strain YU (LpYU), which has high interleukin (IL)-12-inducing activity in mouse peritoneal macrophages. This activity of LpYU was partially mediated by Toll-like receptor (TLR) 2, but not TLR4 or TLR9. Oral administration of LpYU to ovalbumin (OVA)-immunized mice caused suppression of serum OVA-specific immunoglobulin E (IgE) levels, enhancing interferon (IFN)-γ production from spleen cells in response to OVA. Furthermore, LpYU enhanced natural killer cell activity in spleen cells and the production of IgA from Peyers patch cells. Because activation of Th1 immune responses and IgA production induce antiviral effects, we evaluated the inhibitory effects of LpYU against the influenza A virus (A/NWS/33, H1N1) (IFV). Oral administration of LpYU suppressed viral proliferation in the lungs and in bronchoalveolar lavage fluids (BALFs). Both levels of IFV-specific secretory IgA in BALF and feces and titers of IFV-specific neutralizing antibody in BALFs and sera were increased. These results indicate that LpYU has a protective effect against IFV replication. We conclude that this strain has a beneficial effect in activating Th1 immune responses and preventing viral infection.

Naringenin Chalcone Suppresses Allergic Asthma by Inhibiting the Type-2 Function of CD4 T Cells

BACKGROUND Some polyphenols possess anti-allergic activities. Naringenin chalcone is one of the polyphenols that is present in the skin of red tomatoes. In this study, we investigated the effect of naringenin chalcone in allergic responses in vivo using an experimental mouse model system of allergic asthma. METHODS Allergic airway inflammation was induced in mice by sensitization and challenge with ovalbumin. Naringenin chalcone was orally administrated every day during the course of the experiment. Airway hyperreactivity, the eosinophilic infiltration in the bronchioalveolar lavage fluid and Th2 cytokine production from splenic CD4 T cells were assessed. RESULTS Eosinophilic airway inflammation, airway hyperreactivity and Th2 cytokine production from CD4 T cells were significantly suppressed in mice that were treated with naringenin chalcone. Hyperproduction of mucus was slightly reduced. CONCLUSIONS The results of this study suggest that naringenin chalcone suppresses asthmatic symptoms by inhibiting Th2 cytokine production from CD4 T cells. Thus, naringenin chalcone may be a useful supplement for the suppression of allergic symptoms in humans.

Antihypertensive and Natriuretic Effects of Less-Sodium Soy Sauce Containing γ-Aminobutyric Acid in Spontaneously Hypertensive Rats

We investigated the mechanism of the antihypertensive effect of less-sodium soy sauce containing γ-aminobutyric acid (GABA) in spontaneously hypertensive rats (SHRs). When SHRs were given a diet with less-sodium soy sauce containing GABA (GABA-rich soy sauce group) for 6 weeks, the systolic blood pressure decreased as compared with that in rats fed diets with less-sodium soy sauce or a solution of salt. Renal sympathetic nerve activity (RSNA) and positive Na balance were reduced, and the urinary Na excretion tended to increase in the GABA-rich soy sauce group. Vascular hypertrophy of the thoracic aorta and the coronary and renal interlobular arteries tended to reduce in the GABA-rich soy sauce group. These results suggest that inhibition of Na retention by natriuresis, as a result of inhibition of RSNA by the GABA in the soy sauce contributed to the antihypertensive effect of GABA in the SHRs. Intake of less-sodium soy sauce containing GABA might help to reduce overall cardiovascular risk.

Lack of an Inducible Effect of Dietary Soy Isoflavones on the mRNA Abundance of Hepatic Cytochrome P-450 Isozymes in Rats

Modulation of the activity and content of cytochrome P-450 (CYP) in hepatic microsomes may be important to human health since these enzymes activate and inactivate a wide range of xenobiotics and food components. Regulation of the inducibility of most CYPs involves transcriptional regulation and post-transcriptional mRNA stabilization. We examined in the present study the effect of dietary soy isoflavone (0–300 mg of isoflavone/kg of diet) on the mRNA abundance of rat hepatic CYP1A1, CYP1A2, CYP2B1/2, CYP2C11, CYP2E1, CYP3A1, CYP3A2 and CYP4A1 by quantitative competitive RT-PCR and real-time monitored RT-PCR. A fermented soy extract containing 155 mg/g of genistein, 127 mg/g of daidzein, and other minor isoflavones was used as the isoflavone source. The dietary soy isoflavone had no affect on the hepatic mRNA abundance of these CYPs. The results by both methods were well matched and indicate that the dietary soy isoflavone did not cause the induction of CYPs by transcriptional step-up regulation or post-transcriptional mRNA stabilization.

Dietary Soy Isoflavone–Aglycone Lowers Food Intake in Female Rats With and Without Ovariectomy

Objective: Estrogens downregulate eating behavior, and soy isoflavones are known to be estrogenic agents. We aimed to examine whether the estrogenic property of soy isoflavones can affect food intake and body weight.

A sulfated polysaccharide, fucoidan, enhances the immunomodulatory effects of lactic acid bacteria

Fucoidan, a sulfated polysaccharide contained in brown algae, has a variety of immunomodulatory effects, including antitumor and antiviral effects. On the other hand, lactic acid bacteria (LAB) also have immunomodulatory effects such as anti-allergic effects. In this study, we demonstrated that fucoidan enhances the probiotic effects of LAB on immune functions. By using Peyers patch cells and spleen cells in vitro, fucoidan amplified interferon (IFN)-γ production in response to a strain of LAB, Tetragenococcus halophilus KK221, and this activity was abolished by desulfation of fucoidan. Moreover, this IFN-γ response was abolished by interleukin (IL)-12 neutralization. These results indicate that fucoidan enhanced IL-12 production in response to KK221, resulting in promoting IFN-γ production. In an in vivo study, Th1/Th2 immunobalance was most improved by oral administration of both fucoidan and KK221 to ovalbumin-immunized mice. These findings suggest that fucoidan can enhance a variety of beneficial effects of LAB on immune functions.

Metabolite profiling of soy sauce using gas chromatography with time-of-flight mass spectrometry and analysis of correlation with quantitative descriptive analysis

Soy sauces, produced from different ingredients and brewing processes, have variations in components and quality. Therefore, it is extremely important to comprehend the relationship between components and the sensory attributes of soy sauces. The current study sought to perform metabolite profiling in order to devise a method of assessing the attributes of soy sauces. Quantitative descriptive analysis (QDA) data for 24 soy sauce samples were obtained from well selected sensory panelists. Metabolite profiles primarily concerning low-molecular-weight hydrophilic components were based on gas chromatography with time-of-flightmass spectrometry (GC/TOFMS). QDA data for soy sauces were accurately predicted by projection to latent structure (PLS), with metabolite profiles serving as explanatory variables and QDA data set serving as a response variable. Moreover, analysis of correlation between matrices of metabolite profiles and QDA data indicated contributing compounds that were highly correlated with QDA data. Especially, it was indicated that sugars are important components of the tastes of soy sauces. This new approach which combines metabolite profiling with QDA is applicable to analysis of sensory attributes of food as a result of the complex interaction between its components. This approach is effective to search important compounds that contribute to the attributes.

Analysis of the correlation between dipeptides and taste differences among soy sauces by using metabolomics-based component profiling

Characterizing the relationships between the components and taste differences among soy sauces can help evaluate and improve the quality of soy sauces. Although previous studies have reported that certain taste-active dipeptides, the relationships between taste differences and dipeptides of soy sauces are unknown. Therefore, our objective in this study was to investigate the correlations between the dipeptides and the taste differences among soy sauces. To analyze the dipeptides, we constructed an analytical method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) in multiple reaction monitoring mode. Based on this method, we detected 237 dipeptides, the largest number ever detected in soy sauce research. Next, orthogonal projections to latent structures regressions were performed. The data matrix of components, including dipeptides and other low-molecular-weight hydrophilic components obtained from gas chromatography/mass spectrometry (GC/MS), served as explanatory variables (366 in total), whereas a sensory data matrix obtained using quantitative descriptive analysis served as the response variable. The accuracy of models for the sweetness and saltiness differences constructed using the LC/MS/MS and GC/MS data matrix were higher than did models constructed using only the GC/MS data matrix. As a result of investigation of the correlation between the dipeptides and taste differences among soy sauces by using variable importance in the projection (VIP) score, many dipeptides showed the high correlation with taste differences. Specifically, Ile-Gln, Pro-Lys, Ile-Glu, Thr-Phe, and Leu-Gln showed the high VIP score on sweet differences. This study is the first report that reveals the correlations between the dipeptides and taste differences among soy sauces.

Anti-influenza virus effects of elderberry juice and its fractions.

Elderberry (Sambucus nigra L.) has traditionally been used for treating influenza and colds. We evaluated the antiviral effect of concentrated juice of elderberry (CJ-E) on the human influenza A virus (IFV). CJ-E had a relatively strong effect on IFV-infected mice, although its anti-IFV activity was weak in a cell culture system. The in vivo anti-IFV activities of the fractions were determined after separating CJ-E by ultrafiltration and anion-exchange chromatography. Oral administration of the high-molecular-weight fractions of CJ-E to IFV-infected mice suppressed viral replication in the bronchoalveolar lavage fluids (BALFs), and increased the level of the IFV-specific neutralizing antibody in the serum, as well as the level of secretory IgA in BALFs and feces. Fr. II from high-molecular-weight fraction HM, which contained acidic polysaccharides, showed relatively strong defense against IFV infection. We conclude that CJ-E had a beneficial effect by the stimulating immune response and preventing viral infection.