Antioxidant activity applying an improved ABTS radical cation decolorization assay.

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and “leads” which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Plant Products as Antimicrobial Agents

http://www.dietcan.net/docs/Polifenoles%20en%20alimentos%20y%20biodisponibilidad.pdf

Polyphenols: food sources and bioavailability

This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types:  assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include th...

The Chemistry behind Antioxidant Capacity Assays

Convincing evidence suggests that blood redox changes play a role in the development of various cardiovascular disorders including hypertension. Nutritional antioxidants have been suggested to play a role in cardiovascular disease prevention. In this study, we investigated in vivo changes in rat arterial blood pressure induced by acute exposition to an increased load of peroxyl radicals and by the administration of selected antioxidants after chemically induced oxidative stress. Hydrosoluble and liposoluble peroxyl radicals, generated by 2,2'-azobis-(2-amidinopropane) dihydrochloride and 2,2'-azobis 2,4-di-methylvaleronitrile, induced a dose-dependent decrease in rat blood pressure. All antioxidants tested (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, vitamin C, glutathione and dithiothreitol) returned peroxyl radical-induced hypotension to normal. Of the various antioxidants tested, glutathione was the most effective in restoring blood pressure after peroxyl radical generation. Treatment of rats with a thiol-chelating agent (N-ethylmaleimide) and an oxidizing agent (5,5'-dithiobis-2-nitrobenzoic) inhibited peroxyl radical-mediated hypotension. Our results suggest that acute exposition to peroxyl radicals have a hypotensive effect on blood pressure and that thiols play an active role in the redox regulation of blood pressure. Other experiments are needed to clarify the role played by oxidative potentials on blood pressure and the mechanism of action of nutritional antioxidants.

Effect on rat arterial blood pressure of chemically generated peroxyl radicals and protection by antioxidants.

A new methyl-cyclopentanoid monoterpene from linaria purpurea

dLLME-μSPE extraction coupled to HPLC-ESI-MS/MS for the determination of F2α-IsoPs in human urine.

:
It has been suggested that flavonoids, secondary metabolites widely present in the vegetable kingdom, are involved in the role played by plant foods in disease prevention. The immune-modulating action of flavonoids in vitro suggests a specific role in modulating cytokines and transcription factors such as nuclear factor kappa B (NFκB). However, the majority of studies have been conducted with non-physiological concentrations of flavonoids and without considering the nature of the metabolites found in the bloodstream. In humans, the number of studies is limited and the results are contrasting, leaving open the debate about the role of flavonoids as modulators of immune response.

Flavonoids and immune function

The existing data about the role of dairy foods in body weight management, as a physiological explanation are shown in this paper. There is accumulating evidence about inverse association between body weight and dairy intake. Research showed that obese individuals consume fewer dairies than normal weight people. Also three servings of dairy foods per day in a reduced calorie diet may help accelerate body fat loss when compared to a calorie-restricted diet low in dairy foods. Calcium plays the main role and is present in great amounts in dairy foods. Its anti-obesity effect is attributed to its impact on lypogenesis and lipolysis in adipocytes. Calcium supplements do not have such effect as dairy calcium, possibly due to the effects of other bioactive components in dairy foods such as conjugated linoleic acid, whey peptides, branched aminoacids and lactose which amplify anti-obesity effect. Cross-sectional epidemiological studies confirmed the hypothesis that high dairy food intake can act in a weight management, but prospective studies and randomised controlled intervention trials have yielded inconsistent results. Therefore there is a need of conducting more large population-based clinical trials and meta-analysis.

Mauro Serafini

Papers

Effect on rat arterial blood pressure of chemically generated peroxyl radicals and protection by antioxidants.

A new methyl-cyclopentanoid monoterpene from linaria purpurea

dLLME-μSPE extraction coupled to HPLC-ESI-MS/MS for the determination of F2α-IsoPs in human urine.

Flavonoids and immune function

Dairy foods and body weight management.