Olive (Olea europaea L.) is recognized as a folk medicine for diabetes in Europe. The inhibitory action of an ethanol extract of olive leaves (OEE) on the activities of human amylases was examined in vitro. OEE inhibited the activities of ␣-amylases from human saliva and pancreas with IC 50 values of 4.0 and 0.02 mg/ml, respectively. Two anti-␣-amylase components were purified from a 50% ethanol soluble fraction of OEE using Sephadex LH-20 column chromatography. One was identified as luteolin-7-O-␤ glucoside and the other as luteolin-4¢ ¢ ¢ ¢-O-␤ glucoside. The 50% ethanol insoluble fraction of OEE was dissolved in 98% ethanol and fractionated using Cosmosil C18-OPN column chromatography. The anti-␣-amylase component purified by this chromatography was identified as oleanolic acid. Both luteolin and oleanolic acid have an inhibitory effect on postprandial blood glucose increase in diabetic rats. Olive leaves suppressed the elevation of blood glucose after oral administration of starch in borderline volunteers (fasting blood glucose: 110-140 mg/dl), and thus they may be a useful food supplement for the prevention of diabetes.

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Chem. 265, 6556 -6561) (identity: 99.6% in nucleotide sequence, 99.0% in amino acid sequence). That GlcNAc 2-epimerase is a RnBP was confirmed by its ability to bind porcine kidney renin and mask its protease activity. These findings provide unequivocal evidence that the enzyme GlcNAc 2-epimerase is a RnBP.

The effects of γ-aminobutyric acid (GABA) on sleep and its levels in blood after oral administration were investigated in humans. A randomized, single-blind, placebo-controlled crossover-designed study was conducted to evaluate the effect of GABA on sleep. Sleep was evaluated by electroencephalography (EEG) after oral GABA administration. GABA significantly shortened sleep latency and increased the total non-rapid eye movement (non-REM) sleep time. Questionnaires showed that subjects receiving GABA realized its effects on sleep. In addition, the blood level of GABA after administration was investigated, and the absorption and metabolism rates of GABA were determined. GABA was quickly absorbed, and the blood level of GABA was the highest 30 min after oral administration, with a subsequent decrease in concentration. As GABA strongly affected the early stage of sleep, the effect of GABA on sleep may be connected to its levels in blood.