Antioxidants bioavailability

The aim of our project was to study phloem as a source of fiber and polyphenols, and to develop a method to improve its taste without losing the potentially bioactive polyphenols. In addition, we wanted to investigate the bioavailability, cholesterolemic and antioxidative effects and safety of phloem and its phytonutrients in humans in a randomised double-blind trial. 

Sies, H. and Stahl, W., Lycopene antioxidant and biological effects and its bioavail-abihty in the human, Proc. Soc. Exp. Biol. Med., 218, 121, 1998. 

Rao, A.V. and Agarwal, S., Bioavailability and in vivo antioxidant properties of lycopene from tomato products and their possible role in the prevention of cancer, Nutr. Cancer, 3, 199, 1998. 

Cyanidin is the most common anthocyanin in foods. In addition, anthocyanins are stabilized by the formation of complexes with other flavonoids (co-pigmentation). In the United States, the daily anthocyanin consumption is estimated at about 200 mg. Several promising studies have reported that consumption of anthocyanin-rich foods is associated with reductions of the risks of cancers - and atherosclerosis and with preventive effects against age-related neuronal and behavioral declines. These beneficial effects of anthocyanins might be related to their reported biological actions such as modulators of immune response and as antioxidants. Knowledge of anthocyanin bioavailability and metabolism is thus essential to better understand their positive health effects. 

Despite their potential health-promoting effects as dietary antioxidants, the fate of betalains in humans has been poorly studied. Betalain bioavailability was first demonstrated in humans by the appearance of betacyanins in urines after ingestion of beetroot extract" and red beet juice," indicating that these compounds are indeed absorbed. Although intact betacyanins (betanin and isobetaiun) appeared rapidly in human urine with a maximum excretion rate observed within 2.5 to 8 hr," betacy-anin recoveries in human urine were usually low (< 1% of the dose) over 24 hr postdose, suggesting that either the bioavailabifity of betacyaiuns from red beetroot is low or that renal clearance is a minor excretion route for these compounds. 

Explains the bioavailability, antioxidant and pro-oxidant action, and the influence of pigments on health and metabolism... 

Bioactive compounds, such as carotenoids have strong antioxidative properties and are used as efficient radical scavengers. In some natural sources several carotenoid isomers can be found, which differ in their biochemical activities such as bioavailability or antioxidation potency. Knowing the structure and concentration of each stereoisomer is crucial for an understanding of the effectiveness... 

There are also more complex hydroxycinnamic acids in cereals and other members of the Poaceae. These are cell wall-bound mono-, di- and tri-ferulates. Although they appear to have significant antioxidant activity, their bioavailability (release from cell walls and subsequent absorption in humans) is very low. 

Cerda B, Llorach R, Ceron JJ, Espin JC and Tomas-Barberan FA. 2003b. Evaluation of the bioavailability and metabolism in the rat of punicalagin, an antioxidant polyphenol from pomegranate juice. Eur J Nutr 42(1) 18—28. 

Hollman PC, van Trijp JM, Mengelers MJ, de Vries JH and Katan M B. 1997. Bioavailability of the dietary antioxidant flavonol quercetin in man. Cancer Lett 114(1—2) 139—140. 

Calcium antagonists are able to affect nitric oxide production and suppress the peroxyni-trite-induced damage. Thus, nifedipine enhanced the bioavailability of endothelial NO in porcine endothelial cell cultures supposedly through an antioxidative mechanism [288], Pretreatment with nisoldipine, a vascular-selective calcium blocker of dihydropyridine-type, of confluent bovine aortic endothelial cells suppressed the peroxynitrite-induced GSH loss and increased cell survival [289]. 

Because of human consumption of plant and plant products, there has been much interest on the impact of flavonoids on human health and this has been recently reviewed [149, 150 and ref therein]. Additionally, Passamonti et al. [151] have recently reviewed the issue of bioavailability of dietary flavonoids. Citrus flavonoids have been shown to have many beneficial effects on human health including anti-inflammatory activity, anticancer activity, antioxidant activity, and protection against coronary heart disease [reviewed in 152-154]. This has led to... 

The metabolism and bioavailability of isoflavonoids is likely to be of crucial importance to their ability to help protect human health against disease. Many studies have been published on the metabolism and bioavailability of isoflavones in adults. The metabolism of isoflavones is of particular interest because the potency of isoflavone metabolites differs from that of the parent compounds. The daidzein metabolite equol is three times as potent as is daidzein in an endometrial tumor line. Equol is also a more potent antioxidant in vitro (see Sections 7.3.5 and 7.4.2) ° and the clinical significance of the ability to form equol has been considered in depth. ... 

Bioactive peptides as products of hydrolysis of diverse marine invertebrate (shellfish, crustacean, rotifer, etc.) proteins are the focus of current research. After much research on these muscles and byproducts, some biologically active peptides were identified and applied to useful compounds for human utilization. This chapter reviews bioactive peptides from marine invertebrates in regarding to their bioactivities. Additionally, specific characteristics of antihypertensive, anti-Alzheimer, antioxidant, antimicrobial peptide enzymatic production, methods to evaluate bioactivity capacity, bioavailability, and safety concerns of peptides are reviewed. 

---