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

Prevention of Oxidative Damage to Cellular DNA by Mushroom-Derived Components

Incense burning is common in Southeast Asia, where it is a traditional and ceremonial practice in deity worship and paying respect to ancestors. However, incense emissions are an important source of indoor air pollution in Asia, and may induce health problems to those exposed. In this in vitro study the effects of incense emissions on human DNA were investigated using the comet assay. Particulates in smoke from six kinds of incense were trapped in saline or ethanol and human lymphocytes were exposed under controlled conditions. Results showed that DNA damage, including strand breaks, was induced by both aqueous and ethanolic extracts of two samples. The ethanolic extract of one sample induced DNA damage, while no significant DNA damage was found in the remaining three samples. The mechanisms underlying DNA damage induced by incense emissions were also investigated. Catalase (CAT), sodium azide, and superoxide dismutase (SOD) were co-incubated with extract, which exerted significant DNA damaging effects. R...

Effects of Incense Smoke on Human Lymphocyte DNA

Electronic Health Record (EHR) provide clinical evidence for identifying subclinical diseases and supporting decisions on early intervention. Simple string matching cannot link up the conceptually similar but verbally different clinical terms in patient records, limiting the usefulness of EHR. A novel ontological similarity matching approach supported by the Systematized Nomenclature of Medicine Clinical Terms (SNOMED-CT) is proposed in this paper. The disease terms of a patient record are transformed into a vector space so that each patient record can be characterized by a feature vector. The similarity between the new record and an existing database record was quantified by a kernel function of their feature vectors. The matches are ranked by their similarity scores. To evaluate the proposed matching approach, medical history and carotid ultrasonic imaging finding were collected from 47 subjects in Hong Kong. The dataset formed 1081 pairs of patient records and the ROC analysis was used to evaluate and compare the accuracy of the ontological similarity matching and the simple string matching against the presence or absence of carotid plaques identified in ultrasound examination. It was found that the simple string matching randomly rated the record pairs but the ontological similarity matching provided non-random rating.

Is the inter-patient coincidence of a subclinical disorder related to EHR similarity?

To the Editor:

We were surprised by the effects of lercanidipine reported by Taddei et al1 on the plasma antioxidant capacity, with the ferric reducing (antioxidant) power (FRAP) value increasing from 305.0±31.3 to 435.7±142.9 μmol/L. Typical FRAP values for human plasma usually range from 800 to 1200 μmol/L.2 The apparently low baseline values may be related to the use of ascorbic acid or Trolox™ (rather than a solution of ferrous ions) as calibrator without correcting for their stoichiometric factor, which is 2.0 in the FRAP assay. However, it is more difficult to explain the almost 50% increase in plasma FRAP values after lercanidipine treatment. We have found that lercanidipine itself has no in vitro antioxidant effect in the FRAP assay, but it does undergo extensive first-pass metabolism, and some metabolites could have a direct antioxidant effect. The peak plasma concentration (Cmax) of S-lercanidipine is, at most, around 15 nmol/L,3,4 and although the Cmax for total metabolites was >40 times higher than that of the parent drug,5 this still amounts to <1 μmol/L of total …

Antioxidant Effect of Lercanidipine

Multi-disciplinary platform is created to store and integrate DICOM objects from various clinical disciplines. With artificial intelligence, clinical decision support system is built to assess risk of disease complications using the features extracted from the DICOM objects and their interrelationship. Diabetes Mellitus is considered as the disease of interest and the risks of its complications are assessed based on the extracted features. The synergy of the DICOM-based multi-disciplinary platform and the clinical decision support system provides promising functions for extracting and interrelating consistent features of clinical information.

Iris F.F. Benzie

Papers

Prevention of Oxidative Damage to Cellular DNA by Mushroom-Derived Components

Effects of Incense Smoke on Human Lymphocyte DNA

Is the inter-patient coincidence of a subclinical disorder related to EHR similarity?

Antioxidant Effect of Lercanidipine

DICOM-Based Multidisciplinary Platform for Clinical Decision Support: Needs and Direction