SUSS

In analyzing the total antioxidant content, what is the triazine complex ferric made of?

• TPTZ, acetate buffer, and iron

• acetate buffer, tripyridyltriazine, hydrochloric acid, and iron (III) chloride

• Ferrous ion, ferric ions, and TPTZ

• acetate buffer, tripyridyltriazine, hydrochloric acid, and iron (II) chloride

Answer explanation

The triazine complex ferric is a reagent from the Ferric Reducing Antioxidant Power Assay (FRAP) that is made from acetate buffer, tripyridyltriazine, hydrochloric acid, and iron (III) chloride.

Which of the following statements about the Ferric Reducing Antioxidant Power (FRAP) assay is true?

• The FRAP assay measures the ability of antioxidants to reduce ferric ions Fe³⁺ to Fe²⁺.

• The FRAP assay primarily measures the total phenolic content of a sample.

• In the FRAP assay, the color change from yellow to blue is due to the reduction of ferrous to ferric ions.

• The FRAP assay is exclusively used to quantify vitamin C in biological samples.

Answer explanation

The FRAP is the process where the ferric ions Fe³⁺ are reduced to Fe²⁺ and the Distractor 2 is incorrect because it switched the defined process of the said assay.

In a study focused on evaluating the radical chain-breaking antioxidant activity of a compound, the method used measures the transfer of hydrogen atoms during the reaction. Which assay is most appropriate for this analysis?

• SET- and HAT-based assay

• Hydrogen-based assay

• Electron-based assay

• Hydrogen electron transfer-based assay

Answer explanation

The hydrogen electron transfer-based assay is a suitable antioxidant assay type for this situation, as it involves the donation of hydrogen atoms to neutralize reactive oxygen species effectively.

An antioxidant assay is essential for evaluating the effectiveness of substances in protecting cells from oxidative damage. The principle of this is the following:

1. I. This involves assessing how well an antioxidant can neutralize free radicals or reactive oxygen species (ROS), which can potentially lead to oxidative damage in cells and tissues.

2. II. These are substances that prevent oxidative damage caused by reactive oxygen species by interacting with free radicals or quenching molecular oxygen.

3. III. This evaluates the ability of antioxidants to donate electrons or hydrogen atoms to stabilize free radicals, thereby neutralizing their harmful effects.

Which of the following statements is correct?

• Statements I and III are correct

• Statement I is correct

• Statement I and II are correct

• Statements I, II, and III are correct

Answer explanation

Statement II is incorrect because it misrepresents the principle of antioxidant assays. Antioxidants are substances that prevent oxidative damage caused by reactive oxygen species (ROS) by neutralizing free radicals or quenching molecular oxygen. Antioxidant assays, on the other hand, are analytical methods designed to measure the capacity of these antioxidants to inhibit or prevent oxidative damage, rather than being mechanisms of action themselves.

When a food sample (e.g. cranberry juice) was tested for its antioxidant capacity using the Trolox Equivalent Antioxidant Capacity Assay and the blue-green solution became light in color to almost colorless, what does it mean?

• The food sample has no antioxidants

• The food sample is low in antioxidants

• The food sample is high in antioxidants

• The assay used was not suitable and inconclusive

Answer explanation

TEAC assay uses a generated radical cation chromophore acting as ABTS+ which is blue-green in color. When antioxidants are reacted with the chromophore, the chromophore will return to its colorless, neutral form. The higher the level of antioxidants in the sample, the more power it has to change the chromophore’s color.

You are analyzing the antioxidant capacity of a citrus fruit using TEAC assay and you realized that when compared to other antioxidant assays, it does not accurately reflect the antioxidant activity of your sample. Why?

• The TEAC assay only generates a free radical solution and does not represent a physiological radical source.

• The TEAC assay is a single-electron transfer-based assay

• TEAC assay is only used for other foods and is not applicable to citrus fruits.

• The method used was full of errors.

Answer explanation

One of the TEAC assay’s limitations is that it does not represent a physiological radical source because it only generates a free radical-like substance, not a naturally occurring one. This can be a disadvantage of the assay among other assays that use a naturally occurring one as it can affect the accuracy of a food sample in a real biological/chemical system

What molecule generates detectable signals in ELISA to quantify the target antigen?

• Enzyme

• Detection antibody

• Enzyme substrate

• Capturing antibody

Answer explanation

The enzymes are the molecules that generate a detectable signal by converting a colorless substrate into a colored soluble product in the solution.

What determines the high  Oxygen Radical Absorbance Capacity (ORAC) value indicating a high amount of antioxidants neutralizing the free radicals?

• Decrease of fluorescence signal in the probe

• Increase in temperature of the sample

• Decrease in temperature of the sample

• Increase of fluorescence signal in the probe

Answer explanation

The fluorescence signal in the probe will increase with the presence of antioxidants in it. If the probe has high amount of free radicals, the fluorescence signal will decrease.

What does the ORAC assay measure?

• The concentration of Reactive Oxygen Species (ROS)

• The amount of Trolox® in a sample

• The antioxidant capacity of a substance

• The production of free radicals in the body

Answer explanation

The ORAC assay measures the amount of antioxidants present in the substance, and wil determine if the amound of antioxidants present can help neutralize the free radicals as a byproduct of metabolic process where the body uses oxygen to convert food into energy.

What is the primary target of reactive oxygen species (ROS) in the LDL oxidation assay?

• Proteins in the LDL structure

•  Cholesterol in the LDL particle

•  Polyunsaturated fatty acids (PUFAs) in the lipid layer

• Antioxidants in the surrounding medium

Answer explanation

Because of their numerous double bonds, PUFAs in the lipid layer of LDL particles are particularly vulnerable to oxidation by reactive oxygen species (ROS). Since the oxidative modification of PUFAs is crucial to the mechanism under investigation, this is the assay's main focus.