Fumio Yamaguchi

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.

Efficient Production of γ-Polyglutamic Acid by Bacillus subtilis (natto) in Jar Fermenters

The large scale fermentation of γ-polyglutamic acid (γ-PGA) by Bacillus subtilis (natto) was done using a 30-liter jar fermenter. A stable cultivation without foaming could be done with addition of 3% NaCl to the medium. The γ-PGA productivity became higher with increasing speed of agitation and amounts of glutamic acid added to the broth. Finally, we were able to obtain about 35 mg/ml of γ-PGA under the optimum conditions. The glutamic acid added to the medium was efficiently converted into γ-PGA in the stationary phase. To discover the role of l-glutamic acid added to the medium for γ-PGA biosynthesis by Bacillus subtilis (natto), the radioactivity incorporated into γ-PGA from (14)C-l-glutamic acid was measured. As a result, radioactive γ-PGA was detected in the medium. Then, the glutamic acid in the medium was transported into the cells and actually polymerized as the glutamic acid unit of γ-PGA.

Detection of γ-Polyglutamic Acid (γ-PGA) by SDS-Page

γ-Polyglutamic acid (γ-PGA) produced by Bacillus suhtilis (natto) was detected by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and basic dye staining. Using this method, the molecular weight of γ-PGA was estimated at 275,000. This value was almost the same in all bacterial strains tested. As other applications of this SDS-PAGE method, degradation of γ-PGA by acid and heat treatment and a cross-linking reaction with carbodiimide and ethylenediamine were made visible in acrylamide gel. In the growth curve of the bacteria, γ-PGA production was detected in early stationary phase by SDS-PAGE.