Takayuki Shibamoto

Antioxidant property of aroma extract isolated from clove buds [Syzygium aromaticum (L.) Merr. et Perry]

Abstract Aroma extract from dried clove buds [Syzygium aromaticum (L.) Merr. et Perry] was obtained by using steam-distillation under mild conditions (55°C and 95 mm Hg). The antioxidant property of the aroma extract was evaluated in two different assays. The aroma extract isolated from clove buds inhibited the oxidation of hexanal for 30 days at a level of 50 μg/ml. Clove bud extract inhibited malonaldehyde formation from cod liver oil by 93% at the 160 μg/ml level. Twenty-two compounds were identified in the extracts of clove buds by gas chromatography and gas chromatography/mass spectrometry. The major aroma constituents of clove buds were eugenol (24.371 mg/g) and eugenyl acetate (2.354 mg/g). Eugenol, eugenyl acetate, and benzyl alcohol inhibited the oxidation of hexanal by 99, 99, and 82%, respectively, for a period of 30 days at 500 μg/ml. Eugenol, eugenyl acetate, and benzyl alcohol inhibited malonaldehyde formation from cod liver oil by 88, 79, and 63%, respectively, at 160 μg/ml. The antioxidant activity of clove bud extract and its major aroma components, eugenol and eugenyl acetate, were comparable to that of the natural antioxidant, α-tocopherol (vitamin E).

Genotoxicity of safrole-related chemicals in microbial test systems

The genotoxicity of safrole, 9 compounds that are structurally similar to safrole (anethole, cinnamaldehyde, cinnamyl alcohol, estragole, methyl eugenol, eugenol, isoeugenol, isosafrole, piperonal), 5 essential oils, cassia oil, cinnamon bark oil, clove oil, fennel oil) which contain the chemicals tested, and 1 oleoresin was studies in 3 microbial test systems. Only anethole showed mutagenicity in the Ames Salmonella reversion assay. All chemicals except anethole, estragole and isosafrole were positive in the Bacillus subtilis DNA-repair test (Rec assay) without S9. All samples tested were negative in the Escherichia coli WP2 uvrA reversion test. The essential oils and pimenta oleoresin were positive in the DNA-repair test. The results obtained are discussed in relation to the nature of the problems encountered with each test method.

Antioxidant/Lipoxygenase Inhibitory Activities and Chemical Compositions of Selected Essential Oils

Twenty-five essential oils were tested for antioxidant activities using a conjugated diene assay, the aldehyde/carboxylic acid assay, the DPPH free radical scavenging assay, and the malonaldehyde/gas chromatography (MA/GC) assay. They were also tested for lipoxygenase inhibitory activities using the lipoxygenase inhibitor-screening assay. Thyme oil exhibited the greatest antioxidant effect in all assays (80-100%) except in the DPPH assay (60%). Clove leaf oil showed activities comparable to those of thyme oil (53-100%). Cinnamon leaf oil showed strong activities in the aldehyde/carboxylic acid assay (100%) and DPPH assay (84%), but only moderate activities in the conjugated diene assay (24%) and MA/GC assay (48%). Basil oil exhibited a strong effect in the DPPH assay (86%) and moderate activities in the MA/GC assay (35%). Bergamot oil exhibited 100% antioxidant activity in the aldehyde/carboxylic acid assay. Eucalyptus and chamomile oils showed appreciable activities only in the conjugated diene assay. Bitter orange oil exhibited moderate antioxidant activity (53%) only in the MA/GC assay. Aloe vera oil exhibited the greatest lipoxygenase inhibitory activity (96%), followed by thyme oil (86%) and bergamot oil (85%) at a concentration of 0.5 microg/mL. Chamomile oil showed slight lipoxygenase inhibitory activity at 0.5 microg/mL but strong lipoxygenase inducing activity at 5 microg/mL (-123%). Thyme and clove leaf oils contained high levels of thymol (23%) and eugenol (77%), respectively, as a principal of the antioxidant activity. The results obtained in the present study suggest that some essential oils possess strong medicinal activities, which can be utilized for treatment of certain diseases.

Role of Roasting Conditions in the Level of Chlorogenic Acid Content in Coffee Beans: Correlation with Coffee Acidity

Total chlorogenic acids of nine isomers from seven commercial green and roasted coffee beans ranged from 34.43 +/- 1.50 to 41.64 +/- 3.28 mg/g and from 2.05 +/- 0.07 to 7.07 +/- 0.16 mg/g, respectively. Methanol/water (7:3) extracts from four commercial green coffee beans roasted at different conditions (230 degrees C, 12 min; 24 degrees C, 14 min; 250 degrees C, 17 min; and 250 degrees C, 21 min) were also analyzed for chlorogenic acids. The total chlorogenic acid found in green coffee beans ranged from 86.42 +/- 2.04 to 61.15 +/- 1.40 mg/g. Total chlorogenic acids present were reduced in accordance with the intensity of roasting conditions. When green beans were roasted at 230 degrees C for 12 min and at 250 degrees C for 21 min, total chlorogenic acid content was reduced to nearly 50% and to almost trace levels, respectively. The results indicate that roasting conditions play an important role in chlorogenic acid content in roasted coffee beans. A general correlation between total caffeoylquinic acids and pH was observed.

Effect of nanoparticles on the male reproductive system of mice

The effects of nanoparticles toward on the male reproductive system of mice were investigated. Three sizes (14, 56 and 95 nm) of carbon black nanoparticles were intratracheally administered (0.1 mg/mouse for 10 times every week) to ICR male mice to investigate their adverse effects on the reproductive function. The serum testosterone levels were elevated significantly in the 14- and 56-nm carbon nanoparticles-exposed groups. Histological examination showed partial vacuolation of the seminiferous tubules. In addition, the effects of particle number towards the male reproductive system were investigated. The particle number controlled 14-nm nanoparticles-exposed group (14 N group, which has approximately the same particle number per unit volume as the 56-nm nanoparticles) showed fewer effects than did the 56-nm nanoparticles-exposed groups. These results suggest that carbon nanoparticle-exposure has adverse effects on the mouse male reproductive function. Furthermore, the effects of nanoparticles on the male reproductive system depend on particle mass rather than particle number.

Quantitative analysis by gas chromatography of volatile carbonyl compounds in expired air from mice and human

Formaldehyde, acetaldehyde and acetone expired from tumor-bearing transgenic mice and formaldehyde exhaled from breast cancer patients were analyzed using gas chromatography. The tumor-bearing mice expired significantly more formaldehyde per unit metabolic size (1.43-2.98 micromol) than did control mice (0.77-1.01 micromol). There was no detectable difference in the levels of expired acetaldehyde and acetone between the two groups of mice. The exhaled formaldehyde levels from three women with breast cancer and from three healthy women were satisfactorily determined using the method developed in this study. The results suggest that these carbonyl compounds may be used as a biomarker.

Bioactivity of essential oils and their volatile aroma components: Review

The bioactivity of essential oils and their flavor and fragrance components have been known since ancient times. Essential oils are a mixture of numerous compounds characterized by an essence of aromatic plants. Currently, approximately 3000 essential oils are known, 300 of which are commercially important, in particular for the pharmaceutical, food, household and cosmetic industries. Essential oils have been known to have various bioactivities including antibacterial, antiviral, anti-inflammatory, antifungal, antimutagenic, anticarcinogenic, and antioxidant as well as other miscellaneous activities. Consequently, studies on the biological activities of essential oils have become increasingly important in the search for natural and safe alternative medicines in recent years. This review discusses various biological activities of essential oils and their components that have been reported in scientific references.

Investigation of pyrazine formation pathways in sugar-ammonia model systems

Model systems of d-glucose and ammonia with metal ions, oxygen, antioxidants, and sodium hydroxide were reacted at 100°C (solution temp.) for 2~18 hr to investigate pyrazine formation pathways. Pyrazines identified in these model systems were unsubstituted-, 2-methyl-, 2,5-dimethyl-, 2,6-dimethyl-, 2-ethyl-, 2,3-dimethyl-, 2-ethyl-5-methyl-, 2-ethyl-6-methyl-, 2,3,5-trimethyl-, 2-ethyl-3-methyl-, 2-vinyl-, 2-ethyl-3,5-dimethyl-, 2-ethyl-3,6-dimethyl- and ethyl vinyl-. Results show that α-amino carbonyl compounds acted as intermediates to form various pyrazines. For example, 2-methylpyrazine may be formed from the condensation of α-amino-α-hydroxy acetaldehyde and α-amino acetone following the elimination of a water molecule.We propose that the formation of a pyrazine ring from dihydropyrazine is due to the dehydration of hydroxy dihydropyrazine rather than the dehydrogenation of dihydropyrazine. This explains the formation of an alkyl group (e.g., an ethyl group) from the sugar moiety.We propose ten α-ami...

TOXICOLOGY AND ANTIOXIDANT ACTIVITIES OF NON-ENZYMATIC BROWNING REACTION PRODUCTS: REVIEW

This article summarizes toxicity and antioxidative activity of non-enzymatic browning reaction products. The subject focuses on the formation and toxicity testing of mutagenic Maillard reaction products (MPRs) formed in food model systems and in actual foods. The MRPs have also been investigated for nutritional, physiological, and biological activities. The antioxidant properties of MRPs are also reviewed in terms of protection potential against oxidative damage associated with a wide variety of diseases such as diabetes and cancer, and pathological conditions such as aging.

Formation of Carcinogenic 4(5)-Methylimidazole in Maillard Reaction Systems

4(5)-Methylimidazole has received the attention of federal and state regulatory agencies because of its carcinogenicity and common presence in foods and beverages. In the present study, the formation of 4(5)-methylimidazole in Maillard reaction model systems consisting of D-glucose/NH(3), L-rhamnose/NH(3), methylglyoxal/NH(3), and methylglyoxal/formaldehyde/NH(3) was investigated. 4(5)-Methylimidazole was formed at levels ranging from 0.49 to 0.71 mg/mL in the d-glucose/NH(3) model system. The formation of 4(5)-methylimidazole was slightly higher in the L-rhamnose/NH(3) system (0.91 mg/mL) than in the d-glucose/NH(3) system (0.71 mg/mL) under the conditions used in the present study. A methylglyoxal/NH(3) system produced significantly higher levels of 4(5)-methylimidazole (5.70 mg/mL), suggesting that methylglyoxal is an important precursor of 4(5)-methylimidazole. Ammonolysis of methylglyoxal, which is one of the glucose degradation products, was proposed to form formamide, which subsequently reacted with 2-aminopropanal (α-aminocarbonyl intermediate) formed from methylglyoxal to give 4- or 5-methylimidazole. The levels of 4(5)-methylimidazole found in commercial cola soft drinks range from 0.30 μg/mL (brand 3) to 0.36 μg/mL (brands 1 and 5).