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

Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology.

https://faculty.missouri.edu/~glaserr/3700s14/Antioxidant-Capacity_jf0502698.pdf

Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements

There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship. The bioavailability, metabolism, and biological activity of flavonoids depend upon the configuration, total number of hydroxyl groups, and substitution of functional groups about their nuclear structure. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. Most recent researches have focused on the health aspects of flavonoids for humans. Many flavonoids are shown to have antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, while some flavonoids exhibit potential antiviral activities. In plant systems, flavonoids help in combating oxidative stress and act as growth regulators. For pharmaceutical purposes cost-effective bulk production of different types of flavonoids has been made possible with the help of microbial biotechnology. This review highlights the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production.

/pdf/chemistry-and-biological-activities-of-flavonoids-an-483pb5vgo0.pdf

Chemistry and Biological Activities of Flavonoids: An Overview

Publisher Summary This chapter discusses ferric reducing/antioxidant power (FRAP) assay. The ferric reducing/antioxidant power (FRAP) assay is a recently developed, direct test of “total antioxidant power.” The FRAP assay is robust, sensitive, simple, and speedy and facilitates experimental and clinical studies investigating the relationship among antioxidant status, dietary habits, and risk of disease. Measurement of the total antioxidant power of fresh biological fluids—such as blood plasma—can be measured directly; the antioxidant content of various dietary agents can be measured objectively and reproducibly and their potential for improving the antioxidant status of the body investigated and compared. The FRAP assay is also sensitive and analytically precise enough to be used in assessing the bioavailability of antioxidants in dietary agents to help monitor longitudinal changes in antioxidant status associated with an increased intake of dietary antioxidants and to investigate the effects of disease on antioxidant status.

Ferric reducing/antioxidant power assay: direct measure of total antioxidant activity of biological fluids and modified version for simultaneous measurement of total antioxidant power and ascorbic acid concentration

https://aggie-horticulture.tamu.edu/faculty/cisneros/Papers/Thaipong_2006.pdf

Comparison of ABTS, DPPH, FRAP, and ORAC assays for estimating antioxidant activity from guava fruit extracts

Captopril has no significant scavenging antioxidant activity in human plasma in vitro or in vivo.

Background: Nutrition plays an important role throughout the life span. It is the interaction of nutrition and health that form part of the aging process. Nutrition affects the maintenance of physiological and biological process of aging, also, the risk of development of acute and chronic diseases.Objective: To examine dietary-related behaviors and lifestyle factors among non-institutionalized older persons in a local Chinese community.Design, setting & participants: It was a cross-sectional qualitative descriptive design. A convenience sample of 36 older persons (mean + SD age, 75±7.8 years) in a community center were approached and invited to complete a questionnaire regarding their dietary-related profile and the self-perceived nutritional and health status.Results: Results showed that 40% (n=14) of the older persons lived alone and ate alone on a regular basis, taking few fruit and vegetables per day, inadequate fluid and no dairy or bean curd products, and 48% (n=17) were overweight or obese. The self-perceived nutritional status correlated directly with perceived health status, which was high.Clinical relevance: The clinical relevance of this study is highlighted by the far from optimal dietary behaviors among this group of older persons. Nurses and health care providers working in the community should provide education on healthy diet and nutrition-related health problems, especially to older persons, for health maintenance and disease prevention.

Dietary-related profile of older persons in the Chinese community: An exploratory study

Hb-H disease is a form of alpha-thalassemia commonly found in south-east Asia. In this condition, numerous Hb-H bodies are found in erythrocytes using reticulocyte staining preparations. This is the first study addressing the possible interference of Hb-H inclusions in automated reticulocyte counting. In this study, seven Hb-H disease samples were tested. Results obtained by the visual method and the Technicon H*3 automated method agreed relatively well. This was in contrast to the Coulter STKS automated method which generally gave lower results. Furthermore, when the incubation time was extended to 180 min in the Coulter STKS method, two Hb-H disease samples gave results several-fold higher than those obtained using the 60 min incubation time. These discrepant results were likely to have been caused by the analyser using the wrong threshold to separate reticulocytes and mature erythrocytes. High and low interference in Hb-H disease samples was observed in the Coulter STKS automated reticulocyte method. Laboratories should be aware of this potential problem, particularly when samples are from patients of Asian origin.

Interference of Hb-H disease in automated reticulocyte counting

A storage and delivery vessel for a two-part medicament that has first deformable chamber for holding a first part of a medicament and a second chamber for holding a second part of the medicament The chambers are separated by a closure which opens when the first chamber is deformed by an external force, to mix the first and second parts of the medicament for dispensing through a dispensing aperture

Storage and delivery vessel for two-part medicament

Atherosclerosis
is the early stage of arterial disease, and underlies development of cardiovascular
disease (CVD) and stroke. Although sophisticated models for assessing CVD and
stroke risk have been derived based on large-scale
prospective studies, their abilities in detecting the presence or absence
of atherosclerotic plaque have not been investigated. This study aimed to
evaluate and compare discriminatory and risk stratifying abilities of 13 CVD
risk assessment models against the ultrasound detection of carotid plaques
in type 2 diabetes mellitus (T2DM) patients. Forty-nine T2DM subjects were
recruited with informed consent, and major anthropomorphic and biomarker data
for these models were collected. The model risk scores were evaluated against
the carotid plaques detected by Doppler ultrasound. Only the FHS-Lpts-CHD-10Y
model, which is a variant of the Framingham model, revealed an area under the
receiver operating curve (AUROC) that was significantly different from a
random scoring approach (AUROC: 0.681, p was able to stratify the risk
levels of carotid plaque presence (Chi-Square statistic: 5.99, p

/pdf/discrimination-and-stratification-tests-of-cardiovascular-3qtoo7ilgj.pdf

Discrimination and stratification tests of cardiovascular disease risk assessment models against ultrasound detection of carotid plaques in type 2 diabetics

Iris F.F. Benzie

Papers

Captopril has no significant scavenging antioxidant activity in human plasma in vitro or in vivo.

Dietary-related profile of older persons in the Chinese community: An exploratory study

Interference of Hb-H disease in automated reticulocyte counting

Storage and delivery vessel for two-part medicament

Discrimination and stratification tests of cardiovascular disease risk assessment models against ultrasound detection of carotid plaques in type 2 diabetics