Hirotomo Ochi

Biomarker evidence of DNA oxidation in lung cancer patients: association of urinary 8‐hydroxy‐2′‐deoxyguanosine excretion with radiotherapy, chemotherapy, and response to treatment

Ratios of urinary 8‐hydroxy‐2′‐deoxyguanosine to urinary creatinine (8‐OHdG/creatinine) have been considered as a good biological indicator of DNA oxidation. Urinary 8‐OHdG/creatinine levels of lung cancer patients were evaluated by enzyme‐linked immunosorbent assay using a monoclonal antibody N45.1 during radiotherapy and chemotherapy. An increase in urinary 8‐OHdG/creatinine was found in non‐small‐cell carcinoma (non‐SCC) patients during the course of radiotherapy. SCC patients showed higher levels of urinary 8‐OHdG/creatinine than the controls. Furthermore, SCC patients with complete or partial response to the chemotherapy showed a significant decrease in urinary 8‐OHdG/creatinine while patients with no change or progressive disease showed an increase.

THE CONTRIBUTION OF PLANT FOOD ANTIOXIDANTS TO HUMAN HEALTH

Abstract We have been actively involved in the isolation and characterization of endogenous plant antioxidants that are believed to inhibit lipid peroxidation and offer protection against oxidative damage to membrane functions. Antioxidants have been isolated from conventional food sources, such as tea (green and black), sesame and wild rice, and also from other plant sources, such as rice hulls, and crude plant drugs. Data on new types of water-soluble and lipid-soluble plant antioxidants are provided, and the biological activity and functionality of these antioxidants are discussed.

New biomarker evidence of oxidative DNA damage in patients with non-insulin-dependent diabetes mellitus

Urinary 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG) has been reported to serve as a sensitive biomarker of oxidative DNA damage and also of oxidative stress. We have investigated oxidative DNA damage in patients with non‐insulin‐dependent diabetes mellitus (NIDDM) by urinary 8‐OHdG assessments. We determined the total urinary excretion of 8‐OHdG from 24 h urine samples of 81 NIDDM patients 9 years after the initial diagnosis and of 100 non‐diabetic control subjects matched for age and gender. The total 24 h urinary excretion of 8‐OHdG was markedly higher in NIDDM patients than in control subjects (68.2±39.4 μg vs. 49.6±37.7 μg, P=0.001). High glycosylated hemoglobin was associated with a high level of urinary 8‐OHdG. The increased excretion of urinary 8‐OHdG is seen as indicating an increased systemic level of oxidative DNA damage in NIDDM patients.

Antioxidative activity of heterocyclic compounds formed in Maillard reaction products

Abstract Typical heterocyclic compounds substituted with various functional groups found in Maillard reaction were examined for antioxidant activity. Pyrroles exhibited the greatest antioxidant activity among all heterocyclic compounds tested. All pyrroles inhibited hexanal oxidation by almost 100% at a concentration of 50 μg/ml over 40 days. Addition of a formyl group to the pyrrole ring enhanced antioxidative activity remarkably. Pyrrole-2-carboxaldehyde inhibited hexanal oxidation by about 90% at 5 μg/ml. Unsubstituted furan exhibited the greatest antioxidant activity among furans tested. Addition of all functional groups tested to the furan decreased antioxidative activity. Antioxidant activity of thiophene was increased by the addition of methyl groups, but addition of formyl groups to thiophene decreased antioxidant activity. Thiazoles and pyrazines were ineffective antioxidants at all concentrations tested.

A sensitive method to screen for hydroxyl radical scavenging activity in natural food extracts using competitive inhibition ELISA for 8-hydroxy deoxyguanosine

Representative endogenous antioxidants and natural food extracts were screened for hydroxyl radical scavenging activity by an ELISA. Whereas conventional assays for hydroxyl radical scavenging activity use either spin traps following the induction of Fenton reaction or measure thiobarbituric acid-reactive substances, this assay measures 8-hydroxy deoxyguanosine liberated from the hydroxylation of deoxyguanosine by Cu2+/ascorbate system.

Superoxide Radical Scavenging Activities of Wines, and Antioxidative Properties of Fractions Recovered from Merlot Wine Pomace

Wine samples (n = 43) differing in origin, grape variety, and vintage were analyzed for total phenolic content, sulfur dioxide content, color (OD520), and superoxide radical scavenging activities (SOSA). A direct correlation between the wine color (r = 0.7517), its phenolic content (r = 0.9686), and the ability of the wine constituents to scavenge superoxide radicals was established using a simple regression analysis. Distribution of the SOSA in wines was further examined by fractionating 12 wines into three fractions with a C18 Sep-pak cartridge. The correlation coefficient between SOSA and total phenol content in the fractions was r = 0.2705 in fraction A (containing phenolic acids, sugars, organic acids, amino acids, and salts) r = 0.9575 in fraction B (containing procyanidins, flavonols, and catechin) and r = 0.9785 in fraction C (containing anthocyanins and tannins), respectively. As the phenolic content of fraction C was about twofold higher than that of fraction B, fraction C contributed most to the SOSA value in wine. Phenolic compounds were extracted with 50% ethanol from Merlot wine pomace. The extract showed high antioxidant activities, and also scavenged the superoxide and hy-droxyl radicals quite efficiently.

Antioxidative Defense System and Free Radical Scavenging Potentials of Cereals

Cereals occupy an important place in the human diet. In addition to being the primary source of carbohydrates, cereals also provide us with vitamins, trace minerals, and dietary fibers. With the recent increase in interest in the intake of dietary antioxidants, cereals have also been investigated for their antioxidant defense potentials. This review focuses on the description of a phenolic antioxidant defense system in the rice hull that has been demonstrated to offer chemical protection to the rice grain from undergoing oxidative damage. In addition, data are presented to demonstrate the free radical scavenging potentials of the hot aqueous extracts of some of the selected cereal grains. Information is also provided on the newly identified antioxidants in wild rice, and in the green leaves of young barley plants.

Effect of L-Carnosine on 8-OH Deoxyguanosine Release by H2O2 in 3Y1 Rat Embryo Fibroblasts

L-Carnosine is abundantly present in vertebrate skeletal muscles. Its antioxidant role in the body has been of interest to nutritional biochemists. We investigated the release of 8-hydroxydeoxyguanosine (8-OH dG), one of the markers for in vivo oxidative DNA damage, by rat embryo fibroblasts in response to oxidative stressor H2O2 and L-carnosine. When fibroblasts were exposed only to H2O2 (10–500 μM) for 120 minutes varying patterns of 8-OH dG release were observed with increasing concentration of H2O2. At a concentration of 100 μM, H2O2 produced a dose-dependent increase in 8-OH dG release into the medium. Exposure of fibroblasts to 500 μM of H2O2, even for 30 minutes, resulted in irreversible cell death. The antioxidant effect of L-carnosine was measured by exposing the fibroblasts simultaneously to H2O2 (250 μM) and L-carnosine (10 or 30 mM) for 60 minutes. The 8-OH dG release from the fibroblasts treated with H2O2 and L-carnosine was markedly lower than that of fibroblasts treated with H2O2 only. We conclude that the antioxidant role of L-carnosine is probably executed via its inhibition of the formation of 8-OH dG.