Article

Health promotion by flavonoids, tocopherols, tocotrienols, and other phenols: direct or indirect effects? Antioxidant or not? Am J Clin Nutr 81:268S-276S

Department of Biochemistry, Faculty of Medicine, Singapore.
American Journal of Clinical Nutrition (Impact Factor: 6.92). 02/2005; 81(1 Suppl):268S-276S.
Source: PubMed

ABSTRACT Foods and beverages rich in phenolic compounds, especially flavonoids, have often been associated with decreased risk of developing several diseases. However, it remains unclear whether this protective effect is attributable to the phenols or to other agents in the diet. Alleged health-promoting effects of flavonoids are usually attributed to their powerful antioxidant activities, but evidence for in vivo antioxidant effects of flavonoids is confusing and equivocal. This may be because maximal plasma concentrations, even after extensive flavonoid intake, may be low (insufficient to exert significant systemic antioxidant effects) and because flavonoid metabolites tend to have decreased antioxidant activity. Reports of substantial increases in plasma total antioxidant activity after flavonoid intake must be interpreted with caution; findings may be attributable to changes in urate concentrations. However, phenols might exert direct effects within the gastrointestinal tract, because of the high concentrations present. These effects could include binding of prooxidant iron, scavenging of reactive nitrogen, chlorine, and oxygen species, and perhaps inhibition of cyclooxygenases and lipoxygenases. Our measurements of flavonoids and other phenols in human fecal water are consistent with this concept. We argue that tocopherols and tocotrienols may also exert direct beneficial effects in the gastrointestinal tract and that their return to the gastrointestinal tract by the liver through the bile may be physiologically advantageous.

1 Follower
 · 
78 Views
  • Source
    • "Hindawi Publishing Corporation e Scientific World Journal Volume 2014, Article ID 306217, 10 pages http://dx.doi.org/10.1155/2014/306217 The Scientific World Journal of the body [10] [11] [12] "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to determine the composition and content of phenolic compounds in the ethanol extracts of apple leaves and to evaluate the antioxidant activity of these extracts. The total phenolic content was determined spectrophotometrically, as well as the total flavonoid content in the ethanol extracts of apple leaves and the antioxidant activity of these extracts, by the ABTS, DPPH, and FRAP assays. The highest amount of phenolic compounds and flavonoids as well as the highest antioxidant activity was determined in the ethanol extracts obtained from the apple leaves of the cv. Aldas. The analysis by the HPLC method revealed that phloridzin was a predominant component in the ethanol extracts of the apple leaves of all cultivars investigated. The following quercetin glycosides were identified and quantified in the ethanol extracts of apple leaves: hyperoside, isoquercitrin, avicularin, rutin, and quercitrin. Quercitrin was the major compound among quercetin glycosides.
    The Scientific World Journal 09/2014; 2014. DOI:10.1155/2014/306217 · 1.73 Impact Factor
  • Source
    • "Recently, there is growing interest in the role and usage of natural antioxidants as a strategy to prevent and protect oxidative damage in various health disorders with oxidative stress as a factor in their pathophysiology (Halliwell et al., 2005; Rathmanner et al., 2004; Mehmetçik et al., 2008). In Tunisia and other countries of the world, dates were regarded as a fruit with health benefits, and have been employed traditionally as detersive and astringent in intestinal troubles and counteract alcohol intoxication. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to investigate the protective effects of aqueous date extract (ADE) on dichloroacetic acid (DCA)-induced nephrotoxicity. In vitro, total phenolic content estimated in the ADE were 417.71 mg gallic acid equivalents/100g fresh weights (FW), while total flavonoid and tannins contents were 285.23 and 73.65 mg catechin equivalents/100g FW, respectively. The ADE has strong scavenging activity. Ferulic, caffeic and p-coumaric acids are the major's compounds. Nephrotoxicity was induced in male Wistar rats by the administration of 0.5 and 2 g/L DCA as drinking water. Some of these rats received also by gavage ADE (4 mL/kg) before the administration of DCA. After two months of experiment, DCA administration caused elevated levels of renal MDA, significant depletion of GSH levels, altered the antioxidant enzyme activities and deteriorated the renal functions as assessed by the increased plasma urea, uric acid and creatinine levels compared to control rats. The treatment with the ADE significantly normalized the increased plasma levels of creatinine, urea and uric acid, reduced the elevated MDA levels, significantly normalized the antioxidant enzyme activities and GSH level and restored the altered kidney histology in rats treated with DCA. Therefore, it was speculated that ADEprotects rats from kidney damage through its antioxidant capacity.
    Food and Chemical Toxicology 01/2014; DOI:10.1016/j.fct.2013.12.023 · 2.90 Impact Factor
  • Source
    • "Quercetin is linked with inhibition in growth of the fungus Neurospora crassa (Parvez et al., 2004). Reduced lipid peroxidation in treatment having combination of microbes (data not shown) may be correlated to accumulation of antioxidant quercetin and myricetin as they reduce oxidative modifications of membranes by restricting access of oxidants to the lipid bilayer and propagation of lipid oxidation in the hydrophobic membrane matrix (Halliwell et al., 2005). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to evaluate the potentiality of three compatible rhizosphere microbes, viz. fluorescent Pseudomonas aeruginosa (PHU094), Trichoderma harzianum (THU0816) and Mesorhizobium sp. (RL091), in community to mobilise antioxidant mechanisms in chickpea under the challenge of Sclerotium rolfsii. The microbes were applied as seed treatment in different combinations in two sets and the pathogen was inoculated in one of the sets after 3 weeks of sowing. A comparative study was conducted on the effect of the microbial combinations on host antioxidant mechanisms between the two sets. In pathogen challenged plants host defence responses included higher accumulation of hydrogen peroxide (H2O2) at petiolar and interveinal regions of leaf and high activities of catalase (CAT), glutathione reductase (GR) and guaiacol peroxidase (GPx) compared to unchallenged plants. The antioxidant enzyme activities increased 1.8-3.3 and 1.9-3.1 folds at 48 and 72 h, respectively, in the triple microbe treated challenged plants compared to unchallenged ones. Although, ascorbate peroxidase (APX) activity was significantly low, ascorbic acid (AA) and chitinase accumulation was high in the pathogen challenged plants. Antioxidant flavonols associated with host defence namely myricetin, quercetin and kaempferol also accumulated in high amounts in pathogen challenged plants. Among the microbial treatments, the triple microbe combination induced the highest response in all parameters as compared to dual or single application of the same microbes. The triple microbe consortium modulated the chickpea antioxidant mechanisms more efficiently and modulation of oxidative stress was directly correlated with lower plant mortality, thus demonstrating the synergistic behaviour of the microbes in protecting chickpea from the pathogen.
    Annals of Applied Biology 07/2013; 163(1). DOI:10.1111/aab.12030 · 1.96 Impact Factor
Show more