Theaflavins, polyphenolic ingredients of black tea, were observed to inhibit in vitro lipid peroxidation in the erythrocyte membrane ghost and microsomal systems. Theaflavins also showed inhibition of DNA single-strand cleavage and mutagenicity, both induced by hydrogen peroxide. These results suggest that theaflavins scavenge radicals to produce antioxidative and antimutagenic effects. It was also found that the gallic acid moiety of theaflavins is essential for their potent antioxidative activities.

Animals↗

PubMedDate not supplied

Inhibition of glutathione S-transferase P type-positive foci development by linolic acid hydroperoxides and their secondary oxidative products in a rat in vivo mid-term test for liver carcinogens.

The effects of linolic acid hydroperoxides (product A) and secondary oxidative products of product A (product B), were examined in an in vivo mid-term test for hepatocarcinogens or hepatopromoters in rats. The number of placental type of glutathione S-transferase (GST-P)-positive foci of the liver was significantly reduced in rats given diethylnitrosamine (DEN) followed by products A (4.64 +/- 1.09, P less than 0.05) or B (3.62 +/- 1.65, P less than 0.01) as compared to the controls given carcinogen alone (6.31 +/- 2.82). The area of GST-P positive foci was also significantly reduced in rats given DEN followed by product B (0.30 +/- 0.21, P less than 0.05) as compared to the controls (0.47 +/- 0.23). These results suggest that linolic acid hydroperoxides or their secondary oxidative products are not hepatocarcinogens and rather may possess inhibitory potential for liver carcinogenesis.

Animals↗

PubMedDate not supplied

Chemical aspects of mutagen formation by sorbic acid-sodium nitrite reaction.

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Chemical Phenomena↗

PubMedDate not supplied

Influence of glucose infusion on levels of phosphomonoesters and adenosine triphosphate as detected by magnetic resonance spectroscopy in a new model of core-cooling of the rat liver in situ.

This preliminary study was undertaken to ascertain whether our newly developed model of the cold ischemic rat liver in situ is applicable to studies designed to assess the metabolism of nutrients. Ischemia of the whole liver of 12 Wistar rats was induced by clamping all supply and drainage vessels. The ischemic liver was perfused in situ. The duration of ischemia of the liver was 20 minutes. Saline was infused into six rats throughout the experiment (group A). An intravenous infusion of glucose at a rate of 0.75 g/h per rat was begun immediately after the induction of blood-reflow to the liver (group B, n = 6). Six rats (group C) did not undergo the procedure for induction of hepatic ischemia and received glucose at the same rate as rats in group B. Changes in hepatic levels of sugar phosphates (phosphomonoesters [PMEs]), inorganic phosphorus, and beta-positioned phosphorus in adenosine triphosphate (beta-ATP) were monitored by 31P magnetic resonance spectroscopy. Ischemia caused a significant increase in levels of PMEs and a decrease in levels of beta-ATP. The infusion of glucose caused a further increase in levels of PMEs and a further decrease in levels of beta-ATP in group B. In contrast, in group C such infusion did not induce any changes in levels of PMEs or beta-ATP. In group A, PMEs and beta-ATP returned to basal levels 5 hours after the induction of blood-reflow to the liver. The changes in levels of PMEs were similar to those in levels of inorganic phosphorus in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMedDate not supplied

Protective role of rice polyphenols in oxidative stress.

The oxidative breakdown of membrane polyunsaturated fatty acids is known to be accompanied by the formation of a complex mixture of lipid hydroperoxides and secondary products. These compounds are highly reactive and are capable of rapid reaction with cellular nucleophiles such as phospholipids and proteins; we found that these reaction products are candidates as important biomarkers to evaluate the antioxidative activity of dietary antioxidants. We have been involved in developing immuno-chemical detection methods for oxidative stress by the application of polyclonal and monoclonal antibodies. From our hypothesis that endogenous antioxidants in plants must play an important role in antioxidative defense systems against oxidative stress, an intensive search for novel natural antioxidants has been carried out on numerous plant materials, including those used as foods, and we have isolated and identified a number of lipid-soluble and water-soluble dietary antioxidants from crop seeds, sesame seeds and some spices. In this paper, we review the recent progress of research on functions of rice polyphenols.

Antioxidants↗

PubMedDate not supplied

The inhibitory effect of DL-alpha-tocopheryl ferulate in lecithin on melanogenesis.

Oral vitamin E (alpha-tocopherol) supplementation has been reported to improve facial hyperpigmentation. The compound of alpha-tocopherol and ferulic acid, also an antioxidant connected with an ester bond, alpha-tocopheryl ferulate (alpha-TF) can absorb ultraviolet (UV) radiation and thus maintain tocopherol in a stable state. Our aim was to determine whether alpha-TF can be applied to improve and prevent facial hyperpigmentation induced by UV as a whitening agent as well as an antioxidant. In this study, the effects of alpha-TF on melanogenesis were examined using cultured human melanoma cells and normal human melanocytes in vitro. alpha-TF solubilized in 0.5% lecithin inhibited melanization significantly at the concentration of 30 micrograms/ml compared with arbutin (100 micrograms/ml), kojic acid (100 micrograms/ml), ascorbic acid (600 micrograms/ml), and tranexamic acid (600 micrograms/ml). alpha-TF had no effect on the protein amounts of tyrosinase, TRP (tyrosinase related protein)-1, and TRP-2 of human melanoma cells exposed to UV radiation, but inhibited tyrosine hydroxylase activity. alpha-TF neither directly inhibited tyrosinase activity of the large granule fraction extracted from melanoma cells, nor modulated glycosylation of tyrosinase. These results suggest that alpha-TF may be a candidate for whitening agent which suppresses melanogenesis, possibly by inhibiting tyrosine hydroxylase activity in an indirect manner. Further, alpha-TF decreased the amount of 8-hydroxydeoxyguanosine produced indirectly through active oxygen species (AOS) in guinea pig skin exposed to 2 times the minimal erythema dose of UVB radiation, but did not suppress the direct formation of cyclobutane pyrimidine dimers and (6-4) photoproducts. Thus alpha-TF may reduce AOS-induced DNA damage and thereby contribute at least in part to suppressing or retarding skin cancer development.

8-Hydroxy-2'-Deoxyguanosine↗

PubMedDate not supplied

Emptying of the jejunal pouch as a gastric substitute after total gastrectomy for cancer.

BACKGROUND/AIMS: The reservoir and transit capacity of the post-gastrectomy jejunal pouch was evaluated, using a radioisotopic method, to examine the relationship of the gastric emptying to postprandial symptoms and to the food intake status. METHODOLOGY: Thirty-seven patients who had undergone total gastrectomy for cancer (Roux-Y reconstruction, 8; Hunt- Lawrence pouch and Roux-Y, 15; pouch interposition, 5; modified pouch interposition, 9) were retrospectively studied. Based on the percent retention in the gastric substitute, the emptying curves were classed as showing delayed, intermediate, and rapid emptying types. RESULTS: All of the patients with pouch reconstruction showed either delayed or intermediate emptying. High frequency of the sensation of epigastric fullness, nausea, or vomiting was demonstrated in the patients with delayed emptying (p < 0.01). The patients with delayed emptying showed poor food intake compared to those with intermediate emptying (p < 0.05). Given the X-ray video film and endoscopic findings, the delayed emptying was thought to be due to poor drainage of the efferent loop resulting from the post-operative adhesions. CONCLUSIONS: The present study revealed that delayed emptying is associated with postprandial symptoms and with poor food intake. The examination of gastric emptying is useful in evaluating or predicting the postoperative status.

Adult↗