A simple and widely applicable method for the simultaneous determination of 5 kinds of catechins, i. e., epigallocatechin (EGC), epigallocatechin gallate (EGCg), epicatechin (EC), epicatechin gallate (ECg) and catechin (C), and 3 kinds of methylxanthines, i. e., theobromine (TB), theophylline (TP) and caffeine (CA), by semi-micro high performance liquid chromatography was developed.
The sample was extracted with 40% aqueous ethanol and cleaned up by use of a Sep pak C₁₈ cartridge. The extract was chromatographed on asemi-micro size Inertsil ODS-2 column (2.1mm i. d.×250mm) with a mobile phase of methanol-water-0.2M phosphate buffer pH 3.0 (12:33:5). The detection was achieved with a UV monitor set at 207nm.
The recoveries from sencha (common grade green tea), maccha icecream (icecream containing finely ground green tea), maccha senbei (Japanese cracker containing finely ground green tea), maccha jelly (jelly containing finely ground green tea) and candy containing oolong tea extract were 90.9-120.4% (CV 0.8-6.4%) for EGC, 91.8-117.3% (CV 0.4-6.3%) for EGCg, 91.2-96.7% (CV 0.9-3.1%) for EC, 83.2-104.3% (CV 1.5-9.4%) for ECg, 90.2-101.6% (CV 3.1-5.6%) for C, 53.0-106.4% (CV 1.0-11.0%) for TB, 74.6-101.6% (CV 0.8-3.3%) for TP and 88.4-98.8% (CV 0.9-4.1%) for CA.
The detection limits were 0.1μg/g for each compound.

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The effect of brewer's yeast (BY) on the absorption of ferrous sulfate from the intestinal tract was investigated by using ⁵⁹FeSO₄ in an in vivo rat model.
The absorption was significantly elevated by the simultaneous administration of BY. The elevation was also observed in glutathione and cysteamine (2-aminoetanethiol) with a strong anti-oxidative potency. BY showed almost the same anti-oxidative potency as that of glutathione or cysteamine. These data suggest that the anti-oxidative potency of BY may play a role in the mechanism of the elevation of ferrous sulfate absorption by BY.

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To detect trace amounts of total mercury in vegetables and fruits, the wet digestion-cold vapor atomic absorption spectrometry method was improved.
The recoveries and the coefficients of variation for total mercury added to vegetables and fruits were 94-103% (average 99%) and 2.0-11% (average 5.6%) at 0.5ppb, and 97-101% (average 99%) and 2.8-6.3% (average 4.1%) at 2.5ppb. The detection limit was 0.1ppb in the samples.
The improved method was adapted to the determination of trace amounts of total mercury in 27 kinds of vegetables and fruits (81 samples) collected from markets in Nara Prefecture. The obtained mean amounts of total mercury were less than 0.1ppb for 10 species, 0.1-1.0ppb for 12 species and 1.0-2.4ppb for 5 species. These values are lower by 1-2 orders of magnitude than those reported by other researchers.

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The addition of borates to foods is not permitted in Japan. However, agar may contain boron derived from boric acid. In order to study whether or not the bioavailability of agar-bound boron is different from that of free boric acid, rats that had been subjected to a 16hr fasting period were given a 5% (w/v) suspension of agar, a 2% carboxymethylcellulose solution containing boric acid, or a boric acid solution, by oral intubation. For 24hr after the treatment, only water was given to the animals ad libitum, then the rats were killed. The amount of boron excreted in the urine within 24hr was significantly higher in the three treated groups than in the control group that received only distilled water. However, no significant differences were observed among the three boron-treated groups. The difference in the urinary boron content between the boron-treated groups and the control group was equivalent to approximately two-thirds of the administered dose. No significant differences in the boron contents of the feces and the cecum contents were detected among the four groups. Consequently, there appeared to be no difference in gastrointestinal absorption and urinary excretion of boron between boron in agar and free boric acid.

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The decarboxylation of gallate by cell-free extracts of Streptococcus faecalis and Klebsiella pneumoniae isolated from the feces of rats was studied.
Gallate decarboxylase in K. pneumoniae seemed to be identical with the constitutive enzyme in K. aerogenes (EC 4.1.1.59). On the other hand, it was found that enzyme in S faecalis was inducible by gallate in both growing and resting cells, and the induction was inhibited by chloramphenicol. The enzyme was partially purified by (NH₄)₂SO₄ fractionation from the extracts of S. faecalis grown with gallate. This enzyme catalyzed the decarboxylation of gallate and 3, 4-dihydroxybenzoic acid (protocatechuic acid). From the differences in substrate specificity, optimum pH and constitutive or inducible character between the enzymes from S. faecalis and other bacteria, the S. faecalis enzyme seems to be novel.
Thus, decarboxylation of gallate by intestinal bacteria was confirmed in experiments at the enzyme level.

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[in Japanese]

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[in Japanese]

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