A great deal of okara is produced every year in Japan, but most of it is treated as industrial waste. Nowadays, people do not favor okara, which putrefies quickly and has a rough taste. However, okara contains several kinds of functional substances, such as dietary fiber, soybean protein and isoflavone. The effects of okara on blood cholesterol levels were investigated to show that okara may be used as a raw material for a functional food. When okara was given to rats fed a high- cholesterol diet, increases in plasma cholesterol level and accumulation of hepatic lipids were suppressed. Lowering of the plasma neutral fat level was not observed. Ingestion of okara over a period of more than 4 weeks was required to suppress the increase in plasma cholesterol.

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In order to develop a physiologically functional food material from Royal Jelly (RJ) proteins precipitated by ethanol, we tried to hydrolyze them using various proteases. As a result of 0.4wt%-2h Orientase ONS hydrolysis treatment of ethanol-insoluble RJ proteins at 50°C, a newly obtained hydrolysate exhibited strong angiotensin I-converting enzyme (ACE) inhibitory activity (IC₅₀ : 0.082mg/ml). Single-dose, oral administration of the hydrolysate (1g/kg of rat weight) in 13-week spontaneously hypertensive rats resulted in a significant reduction in the systolic blood pressure of ca. 12mmHg (P<0.05) at 2 and 6h after administration. By performing gel permeation chromatography of the hydrolysate, followed by reversed phase HPLCs, eight ACE inhibitory peptides were isolated and identified. Trp-Val-Leu (IC₅₀ : 32.4μM) and Tyr-Tyr-Ser-Pro (IC₅₀ : 1.3μM) were identified from natural resources for the first time. Some of the ACE inhibitory peptides were derived from the RJ-glycoprotein. Consequently, ethanol-insoluble RJ protein is thought to be a good resource as an antihypertensive food material.

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Sweetpotato shochu is a spirit that is mainly produced in the southern Kyushu area in Japan. During the course of our search for biologically active compounds in sweetpotato shochu distillery by-products, we reported that the extracts of a by-product inhibited lettuce seed germination. In the present study, in order to clarify the active compounds, the by-product was subjected to bioassay-guided fractionation using lettuce. A caffeic acid derivative was isolated from the by-product by bioassay-guided fractionation using high-performance liquid chromatography (HPLC). The derivative was identified as ethyl caffeate by ¹H-nuclear magnetic resonance (NMR) and electron impact mass spectrometry (EIMS). The inhibitory activity of ethyl caffeate on the growth of selected plants was examined in the laboratory. At a concentration of more than 0.62mM, ethyl caffeate significantly inhibited lettuce radicle elongation. However, seed germination was not affected. It was observed that the inhibitory activity of ethyl caffeate on lettuce radicle elongation was greater than that of caffeic acid. In the case of weeds, ethyl caffeate inhibited the seed germination of smooth pigweed by 29% and 48% at concentrations of 0.62 and 1mM, respectively ; however, southern crabgrass was not affected. In addition, ethyl caffeate inhibited radicle elongation of smooth pigweed by 79% and 85% at concentrations of 0.62mM and 1mM, respectively ; this inhibitory effect was greater than that observed in southern crabgrass. Caffeic, chlorogenic, 3-O-,4-O-dicaffeoylquinic (3,4-diCQA), 3-O-,5-O-dicaffeoylquinic (3,5-diCQA) and 4-O-,5-O-dicaffeoylquinic (4,5-diCQA) acids, together with ethyl caffeate in a filtrate of the by-product, were identified by retention times and on-line ultraviolet spectra in HPLC analysis. A filtrate of moromi before distillation and a filtrate of the by-product contained ethyl caffeate at concentrations of 13.7mg/L and 8.3mg/L, respectively. However, ethyl caffeate was not detected in the extract of the storage roots of Koganesengan, a sweetpotato cultivar from which shochu is prepared.

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6-O-caffeoylsophorose(CS) is a functional component of vinegar produced by the acetic fermentation of storage roots of purple sweet potato (cultivar Ayamurasaki). Large-scale preparation of CS was examined using a synthetic absorbent resin, Diaion HP20. The CS-rich preparation produced by heat cleavage in acidic conditions from purple sweet potato pigment (PSP) was purified by the HP20 open column method. However, a high purity of CS was not achieved due to the co-elution of chlorogenic acid. To remove the interfering chlorogenic acid, PSP was applied to the column and eluted with 15% ethanol, resulting in the elution of chlorogenic acid while the anthocyanins were absorbed to the resin. We were thus able to obtain chlorogenic acid-free PSP (CF-PSP) with a recovery ratio of approximately 66%. As a result of the purification of CS from heat-treated CF-PSP, we obtained CS with a purity of 80% at a recovery ratio of approximately 12%.

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The amounts of anthocyanins and chlorogenic acid in eggplants (Solanam melongena L.) having different peel colors (senryo-nigo, local name of naga-nasu ; kurowashi, local name of bei-nasu ; green-peel eggplant (midori-nasu) ; white-peel eggplant (siro-nasu)) were measured by HPLC. Extracts were obtained by extracting the peels, flesh and petals of each type of eggplant with 3% trifluoroacetic acid (crude extracts). The extracts and their Sep-pack Plus C18 cartridge-adsorbable fraction (partially purified extracts) were used for measuring the amounts of anthocyanins and chlorogenic acid by HPLC, and the DPPH radical scavenging activity. The relationships between the amounts of these compounds and the radical scavenging activity were also investigated. The results were as follows. (1) Anthocyanin was not detected in the peels of green- and white-peels eggplants, although the petals of these eggplants contained nasunin as a major anthocyanin. A major anthocyanin in the peels of the bei-nasu was identified as delphinidin 3-O-rutinoside, while delphinidin 3-O-rutinoside-5-O-glucoside was identified as a minor component. (2) The DPPH radical scavenging activity of both crude and partially-purified extracts showed strong correlations with the amount of chlorogenic acid present in eggplants, suggesting that the radical scavenging capacity of eggplants may be mainly determined by chlorogenic acid concentration levels.

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Using a placebo-controlled single blind study, we examined the effect of dried skipjack soup stock (DSSS) on the mood and emotional states of middle-aged Japanese subjects. Thirty-eight subjects (19 female, 19 male) were divided into two groups, and one group consumed “miso soup” containing 5.0g/day of DSSS (test group), and the other group consumed “miso soup” without DSSS (placebo group) for 2 weeks. In the analysis performed on all subjects, the eye fatigue score of the emotional questionnaire (EQ) significantly decreased in week 1 (p<0.05), and the depression score of the profile of mood states (POMS) significantly decreased in week 2 (p<0.05) for the Test group. In the analysis performed on subjects who had fatigue symptoms, the fatigue score and the concentration score of the EQ significantly decreased (improved) in the Test group(p<0.05). The tension score of POMS significantly decreased (p<0.05) in the Test group. The TMD change in the Test group was significantly lower than that of Placebo group (p<0.05). These results suggested that the intake of DSSS has a beneficial effect on the moods and emotional states of middle-aged Japanese.

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Functional foods which have α-glucosidase inhibitory activity are effective in controlling blood sugar levels in persons with a risk of diabetes. We have developed a simple method for screening of functional foods which is useful for colored samples. In this method, we use the slope of the liner regression curve of the absorbance of product in a 96-well microplate as an index of activity. This was applied to the measurement of α-glucosidase inhibitory activity in beverages such as tea. Mulberry leaf tea had the highest inhibitory activity and Guava tea had the second highest activity of all samples used in this experiment. Green teas showed little α-glucosidase inhibitory activity, and coffee had no activity. In order to confirm the effectiveness of this method, we undertook addition and recovery of 1-Deoxynojirimycin in a coffee sample. The regression curve obtained showed good linearity. This method seems to be useful and convenient for measurement of α-glucosidase inhibitory activity in colored beverages.

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The polyphenol components and radical scavenging activity of Geneva (Malus niedzwetzkyana) fruit were determined. Geneva is a Canadian native crab apple with deep red skin and flesh, and is grown in the Asahi region, Yamagata prefecture. The contents of malic acid and polyphenols in Geneva fruit juice were higher than those of several other apple juices such as Fuji, Ohrin, and Kogyoku, but the Brix value of Geneva was lower than those of other apples. Chlorogenic acid, (+) catechin, (-)epicatechin, procyanidin B2, procyanidin B1, and phloridzin were identified as major polyphenol compounds in Geneva by HPLC and ESI-MS spectrometry. The DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity of Geneva fruit juice was the highest of all the apple juices, and the activities of all juices were proportionate to their total polyphenol contents. It was concluded that the major components responsible for high DPPH radical scavenging activity were chlorogenic acid, catechins (monomeric forms), and procyanidins (oligomeric and polymeric forms).

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[in Japanese]

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