Kikue Kubota

6-Shogaol and 6-gingerol, the pungent of ginger, inhibit TNF-α mediated downregulation of adiponectin expression via different mechanisms in 3T3-L1 adipocytes

In this study, we demonstrated that the two ginger-derived components have a potent and unique pharmacological function in 3T3-L1 adipocytes via different mechanisms. Both pretreatment of 6-shogaol (6S) and 6-gingerol (6G) significantly inhibited the tumor necrosis factor-alpha (TNF-alpha) mediated downregulation of the adiponectin expression in 3T3-L1 adipocytes. Our study demonstrate that (1) 6S functions as a PPARgamma agonist with its inhibitory mechanism due to the PPARgamma transactivation, and (2) 6G is not a PPARgamma agonist, but it is an effective inhibitor of TNF-alpha induced c-Jun-NH(2)-terminal kinase signaling activation and thus, its inhibitory mechanism is due to this inhibitory effect.

A nonpungent component of steamed ginger--[10]-shogaol--increases adrenaline secretion via the activation of TRPV1.

Abstract We investigated the components of ginger that are involved in increasing body temperature. Gingerols ([6,8,10]-gingerols) and shogaols ([6,8,10]-shogaols) having different alkyl carbon chain lengths were targeted. All the gingerols and shogaols increased intracellular calcium concentration in rat transient receptor potential vanilloid subtype 1 (TRPV1)-expressing HEK293 cells via TRPV1. In this regard, the shogaols were more potent than the gingerols. Aversive responses were induced by [6]-, [10]-gingerol, and [6]-shogaol (5 mmol/l) in rats when these compounds were applied to the eye; however, no response was observed in response to [10]-shogaol (5 and 10 mmol/l). [10]-Shogaol induced nociceptive responses via TRPV1 in rats following its subcutaneous injection into the hindpaw; the pungent compound capsaicin (CAP) and [6]-shogaol were observed to have similar effects. Moreover, adrenal catecholamine secretion, which influences energy consumption, was promoted in rats in response to [6]- and [10]-gingerols and [6]- and [10]-shogaols (1.6 μmol/kg, i.v.). [10]-Shogaol-induced adrenaline secretion was inhibited by administration of capsazepine, a TRPV1 antagonist. In conclusion, gingerols and shogaols activated TRPV1 and increased adrenaline secretion. Interestingly, [10]-shogaol is the only nonpungent compound among the gingerols and shogaols, suggesting its usefulness as a functional ingredient in food.

Pungent Qualities of Sanshool-Related Compounds Evaluated by a Sensory Test and Activation of Rat TRPV1

The detection threshold and taste characteristics of sanshools were examined by sensory evaluation, after isolating four sanshools (α-, β-, γ-, and δ-), and two hydroxy sanshools (α- and β-) from the pericarp of Japanese pepper. The Scoville unit (SU) values of the four sanshools were in the range of 80,000–110,000, while those of hydroxy sanshools were 3–5 fold lower than corresponding sanshools. The pungent qualities of each sanshool were different. Burning and tingling were predominantly perceived and lasted for the longest time with α-sanshool. Burning and fresh for γ-sanshool, and tingling and numbing for hydroxy α-sanshool were perceived. Tests on the activation of rat TRPV1 were also performed. All of them were weak agonists. Among them, γ-sanshool was the most potent agonist, although its EC50 value of 5.3 μM was 230 fold higher than that of capsaicin. These results indicate that it would be difficult to explain the pungent quality of each sanshool simply in terms of TRPV1 activation.

Comparison of aroma characteristics of 16 fish species by sensory evaluation and gas chromatographic analysis

Abstract The aroma properties of fish broths prepared from 16 fish species (10 saltwater, three freshwater, two anadromous and one brackish water species) were described quantitatively by reference to 10 sensory attributes. Principal component analysis (PCA) and cluster analysis of sensory attributes classified the fish into four groups. Group 1, characterised by a strong ‘green’ odour, comprised all three freshwater species (loach, pond smelt and carp), two saltwater whitefish species (snapper and conger) and eel. Group 2 included migratory coastal species (sardine, banded blue‐sprat and mackerel) and was distinguished by strong ‘fish oil’ and ‘grilled fish’ notes. Group 3 consisted of swordfish, sablefish and salmon, which exhibited a strong ‘fried chicken’ note. Group 4 included flounder, cod, tuna and goby, which were scored high for ‘cooked fish’, ‘roasted soy sauce’, ‘canned tuna’ and ‘sweet’ aromas. Partial least squares regression (PLSR) models derived from selected influential peaks in the gas chromatograms of the volatile components in the broths for each attribute were highly predictive (R 2 ≥ 0.936). The selected peaks corresponded well to each sensory attribute.

Analysis of glycosidically bound aroma precursors in tea leaves. 2. changes in glycoside contents and glycosidase activities in tea leaves during the black tea manufacturing process

Glycosides are known to be precursors of the alcoholic aroma compounds of black tea. They are hydrolyzed by endogenous glycosidases during the manufacturing process. Changes in the amounts of these glycosides during the manufacturing process were investigated by using a capillary gas chromatographic--mass spectrometric analysis after trifluoroacetyl derivatization of the tea glycosidic fractions. Primeverosides were 3-fold more abundant than glucosides in fresh leaves, but they decreased greatly during the manufacturing process, especially during the stage of rolling. After the final stage of fermentation, primeverosides had almost disappeared, whereas glucosides were substantially unchanged. These results show that hydrolysis of the glycosides mainly occurred during the stage of rolling and confirm that primeverosides are the main black tea aroma precursors. This was also supported by the changes in the glycosidase activities in tea leaves. The glycosidase activities remained at a high level during withering but decreased drastically after rolling.

Inhibitory effect of anthocyanins and colored rice on diabetic cataract formation in the rat lenses

Abstract In the course of our screening for diabetic cataract inhibitors from edible plants using a rat lens organ culture system under 15 mM xylose condition, five anthocyanin monomers isolated from the extract of grape skins showed the inhibitory activities for lens opacity. Malvidin 3-glucoside and delphinidin 3-glucoside showed stronger inhibitory activities than cyanidin 3-glucoside (C3G), petunidin 3-glucoside (P3G) and peonidin 3-glucoside in this assay system. Concerning a continuous intake of anthocyanins from daily foods, colored rice is one of the good candidates among the Asian countries. Red rice and black rice have been eaten traditionally in China, Japan, India, etc. Thus, we started to collect strains of colored rice from the Asian countries; finally, 48 stains were collected. After extended screening of the collected strains of colored rice, two excellent strains, asamurasaki-2 (AS2, Japanese black rice) and chikushi-akamochi-2 (CH2; Japanese red rice), were selected as potential inhibitory strains for the rat lens opacity. The content of anthocyanins (mainly C3G) and the other important polyphenols (ferulic acid (FA), caffeic acid (CA) and protocatechuic acid (PA)) of these strains were quantified.

Analysis of glycosidically bound aroma precursors in tea leaves. 3. Change in the glycoside content of tea leaves during the oolong tea manufacturing process.

A direct qualitative and quantitative determination of the glycosides of tea aroma compounds at the four stages of the oolong tea manufacturing process (plucking, solar withering, indoor withering, and oolong tea product) was carried out by a capillary gas chromatographic-mass spectrometric analysis after trifluoroacetyl derivatization of the glycosidic fractions. Sixteen glucosides and primeverosides were identified and quantified in cv. Chin-shin-oolong and cv. Chinhsuan-oolong. A comparison of the glycosides in dried fresh leaves between the two cultivars showed significant differences. During the manufacturing process, the amounts of most of these glycosides increased from the solar-withering stage, reaching the highest level at the final stage of oolong tea production. It was noted that no glycoside decreased in its content during the manufacturing process, this being quite different from the manufacture of black tea. In addition, the contents of these alcoholic aroma compounds in the free aroma concentrate from each cultivar remained almost unchanged or slightly decreased, and they constituted only about 12 and 17% in amount of the whole oolong tea aroma compounds. However, jasmine lactone and indole were markedly higher in the final oolong tea products.

Sensory characteristics and volatile components in aromas of boiled prawns prepared according to experimental designs

Abstract Comparing samples prepared according to a two-level fractional-factorial design, parts of prawns and pH were selected as essential factors for generating boiled prawn aroma. Aroma characteristics in samples prepared based on a three-level full-factorial design for pH (2, 7, and 12) and parts (shell: S, meat: M, and meat with shell: W) were quantitatively described using 10 attributes. “Sweet”, “cooked fish”, “roasted shrimp” and “boiled prawn” scores were higher in M and W samples at pH 7, but “sewage” scores were higher in all S samples. Response surfaces in statistically significant models obtained for seven attributes clearly visualized how parts and pH influenced them. Partial least squares regression models composed of selected influential peaks for seven attributes were highly predictable.

The formation mechanism by yeast of 4-hydroxy-2(or 5)-ethyl-5(or 2 ) -methyl -3 (2H) -furanone in miso

The mechanism of the formation of 4-hydroxy-2(or 5)-ethyl-5-(or 2)-methyl-3(2H)-furanone (HEMF) with yeast under caltivation in a medium containing amino-carbonyl reactants of ribose and glycine was investigated using stable isotopes of the corresponding compounds. It was confirmed that the skeleton of the five-membered ring and the methyl group of the side chain of HEMF was formed from ribose, and that the ethyl group was derived from the glucose metabolite by yeast. The formation of HEMF was confirmed when acetaldehyde as the glucose metabolite and a cell-free extract from yeast were added to the medium containing amino-carbonyl reactants. These results suggest that the role of yeast in HEMF formation is not only to provide the glucose metabolite, but also in combining the amino-carbonyl reactants with the glucose metabolite.

Quantitative Analysis of Sanshool Compounds in Japanese Pepper (Xanthoxylum piperitum DC.) and Their Pungent Characteristics

The distributions of each sanshool in the Japanese pepper plant grown in various regions and the change in composition of sanshools during maturation of the fruit were investigated. The degree of pungency, defined as the amount of a sanshool/the threshold value, was calculated, and the pungent qualities of the products were evaluated and compared. The degree of pungency and amount of a sanshool showed a positive correlation. In young leaves and flowers, the degree of pungency was less than that in the fruits, the main compound being α-sanshool, while the two hydroxy sanshools were detected only in trace amounts. The main compound in fruits was hydroxy α-sanshool, whose threshold value was higher than that of α-sanshool. It is concluded that the pungency of Japanese pepper should be evaluated not only by the threshold values, but also by the pungent qualities, the composition of sanshools, and the usage of each product of Japanese pepper.