Nobutaka Suzuki

Preparation and antioxidant properties of water extract of propolis

A water extract was prepared from fresh propolis from Brazil. Antioxidant activity was measured using a lipid peroxidation model system. The activity was very strong and, at 1 and 5 mg/ml, higher than that of 5 mM ascorbic acid. The scavenging activity against superoxide anion radical of water extract of propolis was high, and the extracts, at 50 and 100 mg/ml, completely inhibited the production of superoxide. The extracts, at 50 and 100 mg/ml, completely inhibited the hydroxyl radical. This suggests that the water extract of propolis has potential as a pharmaceutical for patients with various diseases such as cancer, cardiovascular diseases, and diabetes.

Antioxidative Activities and Angiotensin I-Converting Enzyme Inhibition of Extracts Prepared from Chum Salmon (Oncorhynchus Keta) Cartilage and Skin

The extracts from cartilage and skin of chum salmon were prepared using a pressure cooker. As a result, protein and collagen contents in extracts from cartilage and skin was higher than those only in cartilage. The inhibition activity of linoleic acid oxidation was high in extract from cartilage. The scavenging activity of cartilage extract was higher than those of cartilage and skin against all reactive oxygen species, such as superoxide anion, hydroxyl, and DPPH radicals. On the other hand, angiotensin I-converting enzyme inhibitory activity of cartilage extract was about seven times as high as that of cartilage and skin extract. The present studies indicate that the extracts, particularly from cartilage, have angiotensin I-converting enzyme inhibitory activity that functions to depress hypertension, and antioxidant activity, which acts to prevent of life-style related diseases such as cancer, cardiovascular diseases, and diabetes. The data should be useful for developing a novel type of functional seasoning.

Antioxidative Activities and Angiotensin I-converting Enzyme Inhibitory Activities of Enzymatic Hydrolysates from Commercial Kamaboko Type Samples

Enzymatic hydrolysates were prepared from commercially available kamaboko type samples using three gastrointestinal proteases and protein proteases. The yields of these hydrolysates were about 10–31% and these protein contents ranged from 62 to 533 g/mg per sample powder on their wet weight basis. The hydrolysates showed higher antioxidative activities and scavenging activities against active oxygen species such as hydroxyl radical and superoxide anion radical. Moreover, these hydrolysates exhibited high angiotensin I-converting enzyme inhibitory activites that were similar or higher than those from various fermented foods such as fish sauce, sake, soy sauce, vinegar, miso and natto. The antioxidative and antihypertensive activities of commercially available kamaboko type samples were not related to the colour of the samples. The results indicated that enzymatic hydrolysates from commercially available kamaboko type samples, whose health benefits are scientifically supported, have the potential to be an increasingly important component of a healthy lifestyle and to be beneficial to the public and the food industry.

Antioxidative Activity Against Superoxide of Anticarcinogenic Tea-Leaf Catechins: Measurement by the Cypridina Chemiluminescence Method

The reaction constants between superoxide (O2 -) and tea-leaf catechins, whose anticarcinogenic activity to stomach cancer has been confirmed, were measured using the Cypridina chemiluminescence method for measuring rate constants between O2 - and antioxidants established in our previous report. The quenching experiments of chemiluminescence of a Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA) in 25mM buffer solution (pH 7.0) at 25°C were used. Small amounts of antioxidants were needed for the measurement (<10mg). The activities are expressed in quenching constants so we can compare them quantitatively. Tea-leaf catechins showed reaction rate constants ranging from 104 to 106M-1s-1 (as large as ascorbic acid). Some teas showed reactivity to superoxide as well as peroxide values. The results were compared with the data in the literature. They prove that tea-leaf catechins have strong antioxidative activity against O2 - in aqueous solutions and suggest that superoxide can cause stomach cancer. We also found that the present measuring method is applicable to the measurement of reaction rate constants of antioxidative samples against superoxide even when the samples are fairly unstable.

Purification and Partial Characterization of Major Viscous Protein from Yam (Dioscorea opposita Thunb.) Tuber Mucilage tororo

Viscous protein was purified from yam (Dioscorea opposita Thunb.) tuber mucilage tororo by Phenyl-Toyopearl 650M, DEAE-Toyopearl 650M, and CM-Toyopearl 650M column chromatographies, and partially characterized. The molecular weight of the purified protein was estimated to be about 200 kDa, by Native-PAGE and Toyopearl HW-55F gel filtration. Moreover, it had identical subunits of molecular weight of about 32 kDa, either without or with 2-mercaptoethanol, respectively. This protein was identified as dioscorin, the major storage proteins in yam species tubers, when comparing the sequence obtained in an automatic Edman sequencer with the database using FASTA WWW System. On the other hand, the purified protein showed carbonic anhydrase activity and the activity was not inhibited by 2,6-pyridinedicarboxylic acid: zinc atoms were absent in the purified protein. The optimum pH in viscosity was about 5.8 and optimum temperature 20–30°C. Heat denaturation of the protein occurred at about 40°C, but the protein retained more than 66 % of the original viscosity at 70°C for 30 min.