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

With the aim to expand the Italian total antioxidant capacity (TAC) database, the TAC values of 11 spices, 5 dried fruits, 7 sweets, 18 cereal products, 5 pulses, and 6 nuts were determined using three different assays and considering the contribution of bound antioxidant compounds in fiber-rich foods (i. e. cereals, legumes, and nuts). Among spices, saffron displayed the highest antioxidant capacity, whereas among dried fruits, prune exhibited the highest value. The TAC values of all the chocolates analyzed were far higher than the other sweet extracts measured. Among cereal products, whole meal buckwheat and wheat bran had the greatest TAC. Among pulses and nuts, broad bean, lentil and walnuts had the highest antioxidant capacity, whereas chickpeas, pine nuts and peanuts were less effective. The contribution of bound phytochemicals to the overall TAC was relevant in cereals as well as in nuts and pulses. The complete TAC database could be utilized to properly investigate the role of dietary antioxidants in disease prevention.

Total antioxidant capacity of spices, dried fruits, nuts, pulses, cereals and sweets consumed in Italy assessed by three different in vitro assays.

Total Antioxidant Capacity (TAC) considers the cumulative action of all the antioxidants present in plasma and body fluids, thus providing an integrated parameter rather than the simple sum of measurable antioxidants. The capacity of known and unknown antioxidants and their synergistic interaction is, therefore, assessed, thus giving an insight into the delicate balance in vivo between oxidants and antioxidants. There is new evidence indicating the importance of understanding the mechanisms of the homeostatic control of TAC in plasma and tissues and its modification during oxidative stress development. Recently, the epidemiological application of TAC has been proposed as a new tool for investigating the relationship between dietary antioxidants and cancer risk in population studies. This review outlines the pros and cons of the more common assays for measuring plasma TAC and the latest findings on dietary modulation of plasma redox status. Finally, the feasibility of the 'TAC concept' as an innovative tool for investigating the association between diet and oxidative stress is discussed.

https://www.tandfonline.com/doi/pdf/10.1179/135100004225004814

Understanding the association between dietary antioxidants, redox status and disease: is the Total Antioxidant Capacity the right tool?

https://www.gastrojournal.org/article/S0016-5085(02)00201-9/pdf

Total antioxidant potential of fruit and vegetables and risk of gastric cancer

Background— Dark chocolate has potent antioxidant properties Coronary atherosclerosis is promoted by impaired endothelial function and increased platelet activation Traditional risk factors, high

/pdf/dark-chocolate-improves-coronary-vasomotion-and-reduces-5ltqsg72sq.pdf

Dark Chocolate Improves Coronary Vasomotion and Reduces Platelet Reactivity

Ten healthy human subjects consumed 500 mL of Choladi green tea, containing 648 mumol of flavan-3-ols after which plasma and urine were collected over a 24 h period and analysed by HPLC-MS. Plasma contained a total of ten metabolites, in the form of O-methylated, sulphated and glucuronide conjugates of (epi)catechin and (epi)gallocatechin, with 29-126 nM peak plasma concentrations (C(max)) occurring 1.6-2.3 h after ingestion, indicative of absorption in the small intestine. Plasma also contained unmetabolised (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate with respective C(max) values of 55 and 25 nM. Urine excreted 0-24 h after consumption of green tea contained 15 metabolites of (epi)catechin and (epi)gallocatechin, but (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate were not detected. Overall flavan-3-ol metabolite excretion was equivalent to 8.1% of intake, however, urinary (epi)gallocatechin metabolites corresponded to 11.4% of (epi)gallocatechin ingestion while (epi)catechin metabolites were detected in amounts equivalent to 28.5% of (epi)catechin intake. These findings imply that (epi)catechins are highly bioavailable, being absorbed and excreted to a much greater extent than most other flavonoids. It is also evident that flavan-3-ol metabolites are rapidly turned over in the circulatory system and as a consequence C(max) values are not an accurate quantitative indicator of the extent to which absorption occurs.

Mauro Serafini

Papers

Total antioxidant capacity of spices, dried fruits, nuts, pulses, cereals and sweets consumed in Italy assessed by three different in vitro assays.

Understanding the association between dietary antioxidants, redox status and disease: is the Total Antioxidant Capacity the right tool?

Total antioxidant potential of fruit and vegetables and risk of gastric cancer

Dark Chocolate Improves Coronary Vasomotion and Reduces Platelet Reactivity

Absorption, metabolism and excretion of Choladi green tea flavan-3-ols by humans