Assay for lipid peroxides in animal tissues by thiobarbituric acid reaction

Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.

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Plant phenolics: extraction, analysis and their antioxidant and anticancer properties.

Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer.

The biochemistry and medical significance of the flavonoids.

The induction of expression of genes for xenobiotic metabolizing enzymes in response to chemical insult is an adaptive response found in most organisms. In vertebrates, the AhR is one of several chemical/ligand-dependent intracellular receptors that can stimulate gene transcription in response to xenobiotics. The ability of the AhR to bind and be activated by a range of structurally divergent chemicals suggests that the AhR contains a rather promiscuous ligand binding site. In addition to synthetic and environmental chemicals, numerous naturally occurring dietary and endogenous AhR ligands have also been identified. In this review, we describe evidence for the structural promiscuity of AhR ligand binding and discuss the current state of knowledge with regards to the activation of the AhR signaling pathway by naturally occurring exogenous and endogenous ligands.

Activation of the aryl hydrocarbon receptor by structurally diverse exogenous and endogenous chemicals.

Polyphenols, which have beneficial effects on health and occur ubiquitously in plant foods, are extremely diverse. We developed a method for simultaneously determining all the polyphenols in foodstuffs, using HPLC and a photodiode array to construct a library comprising retention times, spectra of aglycons, and respective calibration curves for 100 standard chemicals. The food was homogenized in liquid nitrogen, lyophilized, extracted with 90% methanol, and subjected to HPLC without hydrolysis. The recovery was 68-92%, and the variation in reproducibility ranged between 1 and 9%. The HPLC eluted polyphenols with good resolution within 95 min in the following order: simple polyphenols, catechins, anthocyanins, glycosides of flavones, flavonols, isoflavones and flavanones, their aglycons, anthraquinones, chalcones, and theaflavins. All the polyphenols in 63 vegetables, fruits, and teas were then examined in terms of content and class. The present method offers accuracy by avoiding the decomposition of polyphenols during hydrolysis, the ability to determine aglycons separately from glycosides, and information on simple polyphenol levels simultaneously.

Simultaneous determination of all polyphenols in vegetables, fruits, and teas.

A strong water-soluble antioxidant was identified in the popular commercial banana Musa cavendishii. It is dopamine, one of the catecholamines. For suppressing the oxygen uptake of linoleic acid in an emulsion and scavenging a diphenylpicrylhydrazyl radical, dopamine had greater antioxidative potency than glutathione, food additives such as butylated hydroxyanisole and hydroxytoluene, flavone luteolin, flavonol quercetin, and catechin, and similar potency to the strongest antioxidants gallocatechin gallate and ascorbic acid. Banana contained dopamine at high levels in both the peel and pulp. Dopamine levels ranged from 80-560 mg per 100 g in peel and 2.5-10 mg in pulp, even in ripened bananas ready to eat. Banana is thus one of the antioxidative foods.

High content of dopamine, a strong antioxidant, in Cavendish banana.

The purpose of this study was to examine whether hesperidin inhibits bone loss in ovariectomized mice (OVX), an animal model of postmenopausal osteoporosis. Forty 8-wk-old female ddY mice were assigned to five groups: a sham-operated group fed the control diet (AIN-93G), an OVX group fed the control diet, an OVX+HesA group fed the control diet containing 0.5 g/100 g hesperidin, and an OVX+HesB group fed the control diet containing 0.7 g/100 g alpha-glucosylhesperidin and an OVX+17beta-estradiol (E(2)) group fed the control diet and administered 0.03 micro g E(2)/d with a mini-osmotic pump. After 4 wk, the mice were killed and blood, femoral, uterine and liver were sampled immediately. Hesperidin administration did not affect the uterine weight. In OVX mice, the bone mineral density of the femur was lower than in the sham group (P < 0.05) and this bone loss was significantly prevented by dietary hesperidin or alpha-glucosylhesperidin. The Ca, P and Zn concentrations in the femur were significantly higher in the hesperidin-fed and E(2) groups than in the OVX group. Histomorphometric analyses showed that the trabecular bone volume and trabecular thickness in the femoral distal metaphysis were markedly decreased (P < 0.05) by OVX, and alpha-glucosylhesperidin significantly prevented this bone loss. Furthermore, hesperidin decreased the osteoclast number of the femoral metaphysis in OVX mice, as did E(2). Serum and hepatic lipids were lower in mice that consumed the hesperidin-containing diets (P < 0.05) than in the OVX group fed the control diet. These results suggest a possible role for citrus flavonoids in the prevention of lifestyle-related diseases because of their beneficial effects on bone and lipids.

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Hesperidin, a Citrus Flavonoid, Inhibits Bone Loss and Decreases Serum and Hepatic Lipids in Ovariectomized Mice

Obesity is a serious health problem, and its prevention is promoted through life style including diet and exercise. In this study, we investigated the suppressive effects of tea catechin on the differentiation of 3T3-L1 preadipocytes to adipocytes. (-)-Catechin 3-gallate (CG), (-)-epigallocatechin (EGC), (-)-epicatechin 3-gallate, and (-)-epigallocatechin 3-gallate at 5 muM suppressed intracellular lipid accumulation. The suppressive effects of CG and EGC were stronger than the others, and CG and EGC also suppressed the activity of glycerol-3-phosphate dehydrogenase as a differentiation marker. These catechins inhibited the expression of peroxisome proliferator-activated receptor (PPAR) gamma2 and CCAAT/enhancer-binding protein (C/EBP) alpha, both of which act as key transcription factors at an early stage of differentiation, followed by the expression of glucose transporter (GLUT) 4 at a later stage. In addition, the catechins did not affect the phosphorylation status of the insulin signal pathway. Thus, catechin suppressed adipocyte differentiation accompanied by the down-regulation of PPARgamma2, C/EBPalpha, and GLUT4. These results suggest that tea catechin prevents obesity through the suppression of adipocyte differentiation.

https://www.tandfonline.com/doi/pdf/10.1271/bbb.68.2353

Tea Catechin Suppresses Adipocyte Differentiation Accompanied by Down-regulation of PPARγ2 and C/EBPα in 3T3-L1 Cells

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2800%2901730-0

Kazuki Kanazawa

Papers

Simultaneous determination of all polyphenols in vegetables, fruits, and teas.

High content of dopamine, a strong antioxidant, in Cavendish banana.

Hesperidin, a Citrus Flavonoid, Inhibits Bone Loss and Decreases Serum and Hepatic Lipids in Ovariectomized Mice

Tea Catechin Suppresses Adipocyte Differentiation Accompanied by Down-regulation of PPARγ2 and C/EBPα in 3T3-L1 Cells

Flavones and flavonols at dietary levels inhibit a transformation of aryl hydrocarbon receptor induced by dioxin.