Free radicals and reactive oxygen species (ROS) are highly reactive molecules that are generated by normal cellular processes, environmental stresses, and UV irradiation. ROS react with cellular components, damaging DNA, carbohydrates, proteins, and lipids causing cellular and tissue injury. Excess production of reactive oxygen species can also lead to inflammation, premature aging disorders, and several disease states, including cancer, diabetes, and atherosclerosis. Organisms have developed complex antioxidant systems to protect themselves from oxidative stress, however, excess ROS can overwhelm the systems and cause severe damage

ZenBio Antioxidant Assay Kits can be used to determine the total antioxidant capacity of biological fluids, cells, and tissue. They can also be used to assay the antioxidant activity of naturally occurring or synthetic compounds for use as dietary supplements, topical protection, and therapeutics.

All of the Antioxidant Assays are also offered as Contract Assay Services. Contact ZenBio for more information regarding testing of your samples.

• ABTS (TEAC) Antioxidant Assay Kit (AOX-1)
  The ZenBio ABTS Antioxidant Assay Kit measures ABTS•+ radical cation formation induced by metmyoglobin and hydrogen peroxide. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting the formation of the radical cation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present. This assay measures radical scavenging by electron donation and when combined with ZenBio's other antioxidant assay kits, can provide a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-1 kit contains everything required for performing the ABTS assay using one 96-well plate including Trolox standards.
• ORAC Antioxidant Assay Kit (AOX-2)
  The ZenBio ORAC (Oxygen Radical Absorbance Capacity) Antioxidant Assay Kit measures the loss of fluorescein fluorescence over time due to peroxyl-radical formation by the breakdown of AAPH (2,2'-azobis-2-methyl-propanimidamide, dihydrochloride). Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting fluorescein decay in a dose dependent manner. The ORAC assay is a kinetic assay measuring fluroescein decay and antioxidant protection over time. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present. This assay measures antioxidant activity by hydrogen atom transfer and when combined with ZenBio's other antioxidant assay kits, can provide a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-2 kit contains reagents sufficient for one 96-well plate test using the inner 60 wells. A larger, bulk kit (AOX-2RB) contains reagents for conducting the ORAC assay using five 96-well plates.
• DPPH Antioxidant Assay Kit (AOX-3)
  The ZenBio DPPH Antioxidant Assay Kit measures the reduction of the stable DPPH radical by electron transfer. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control reducing the DPPH radical in a dose dependent manner. The antioxidant activity in the test samples can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present. This assay measures radical scavenging by electron donation and when combined with Zen-Bio's other antioxidant assay kits, provides a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-3 kit contains reagents sufficient to test over 100-points in a 96-well plate format.
• Cu-TAC Antioxidant Assay Kit (AOX-4)
  The ZenBio Cu-TAC Antioxidant Assay Kit measures the reduction of Copper(II) to Copper(I) in the presence of the aromatic chelator, neocuproine. Uric acid or Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control for the reduction reaction in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Uric acid or Trolox units to quantify the composite antioxidant activity present. This assay measures antioxidant activity by electron transfer and when combined with Zen-Bio's other antioxidant assay kits, provides a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-4 kit provides the reagents necessary to test over 100 points in a 96-well plate format.
• TAC-BCS Antioxidant Assay kit (AOX-5)
  The ZenBio TAC-BCS Antioxidant Assay Kit measures the reduction of copper(II) to copper(I) in the presence of the aromatic chelator, bathocuproinedisulfonate (BCS). Uric acid or Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control for the reduction reaction in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Uric acid or Trolox units to quantify the composite antioxidant activity present. This assay measures antioxidant activity by electron transfer and when combined with Zen-Bio's other antioxidant assay kits, provides a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-5 kit contains reagents necessary to assay 100-points using a 96-well plate format.
• HORAC Antioxidant Assay Kit (AOX-6)
  The ZenBio ORAC (Hydroxyl (HO•) Radical Absorbance Capacity) Antioxidant Assay Kit measures the loss of fluorescein fluorescence over time due to hydroxyl-radical formation by the mixture of hydrogen peroxide and oxidizable metal ions (Co(II)). Gallic Acid [3,4,5-Trihydroxybenzoic acid], a simple phenolic compound, serves as a positive control inhibiting fluorescein decay in a dose dependent manner. The HORAC assay is a kinetic assay measuring fluorescein decay and antioxidant protection over time. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Gallic Acid units to quantify the composite antioxidant activity present. This assay measures antioxidant activity by hydrogen atom transfer and when combined with Zen-Bio's other antioxidant assay kits, provides a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-6 kit contains reagents sufficient for one 96-well plate test using the inner 60 wells.
• NORAC Antioxidant Assay Kit (AOX-7)
  The ZenBio NORAC (Peroxynitrite [ONOO-] Radical Absorbance Capacity) Antioxidant Assay Kit measures the increase in rhodamine 123 fluorescence over time due to the oxidation of dihydrorhodamine 123 by peroxynitrite radicals formed through SIN-1 (3-morpholinosydnonimine) degradation. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting DHR123 oxidation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present in each sample. While the NORAC assay can be performed as a kinetic assay, typically it is performed as an endpoint assay due to the linear nature of the oxidation reaction over time.
  The AOX-7 kit contains reagents sufficient for one 96-well plate test using the inner 60 wells.
• CLORAC Antioxidant Assay Kit (AOX-8)
  The ZenBio CLORAC (hypoChLORite [ClO-] Absorbance Capacity) Antioxidant Assay Kit measures the decrease in fluorescein fluorescence due to the oxidation of fluorescein by hypochlorite ions. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting fluorescein oxidation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present in each sample. The CLORAC assay is performed as an endpoint assay due to the rapidity and linear nature of the oxidation reaction over time.
  The AOX-8 kit contains reagents sufficient for one 96-well plate test.
• CAA Cellular Antioxidant Assay Kit (AOX-9)
  The Zen-Bio CAA (Cellular Antioxidant Activity) Assay Kit measures the capacity of antioxidants to inhibit the oxidation of the nonfluorescent probe, DCFH to the fluorescent species, DCF, by intracellular reactive oxygen species (ROS). Cellular ROS is induced by peroxyl radical formation from the Radical Initiator and leads to a gradual increase in fluorescence due to oxidation of DCFH within the cell. Cell permeant antioxidants inhibit this reaction by interfering with ROS activity, leading to a reduction in cellular fluorescence over time. The fluorescence signal is measured over 60 minutes by excitation at 485 nm, emission at 538 nm. The CAA assay is a kinetic assay measuring increasing fluorescence and antioxidant protection over time. The antioxidant activity in the test samples can be normalized to equivalent quercetin units to quantify the composite antioxidant activity present.
  The AOX-9 kit provides the necessary reagents for testing in two 96-well plates.
• FRAP Assay Kit (AOX-11)
  The Zen-Bio FRAP (Ferric Reducing Antioxidant Power) Assay Kit measures the increase in absorbance due to the reduction of Fe(III) to Fe(II) at low pH in the presence of a chelating probe, tripyridyltriazine (TPTZ). An Fe(II) solution serves as the positive control comparator to determine the sample's reducing capacity. The FRAP assay is an endpoint assay measuring the increase in blue absorbance at 540-600nm. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Fe(II) units to quantify the composite antioxidant activity present. This assay measures antioxidant activity by electron donation and when combined with Zen-Bio's other antioxidant assay kits, provides a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-11 kit provides everything necessary for the test in a 96-well plate format.
• SOAC Antioxidant Assay Service (AOX-12)
  The ZenBio SOAC (Singlet Oxygen (1O2) Absorbance Capacity) Antioxidant Assay measures the increase in fluorescence caused by singlet oxygen oxidation of dihydroethidium (DHE) over time. Singlet oxygen is generated by a reaction between sodium molybdate and hydrogen peroxide in N,N-dimethylacetamide. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting DHE oxidation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, synthetic compounds and natural extracts can be normalized to equivalent Trolox units to quantify the antioxidant activity present in each sample. The SOAC assay can be performed as a kinetic assay or endpoint assay due to the linear nature of the oxidation reaction over time.
  The SOAC assay is offered only as a contract service.
• SORAC Antioxidant Assay Service(AOX-13)
  The ZenBio SORAC (Superoxide Radical (O2•-) Absorbance Capacity) Antioxidant Assay measures the increase in fluorescence caused by superoxide radical oxidation of dihydroethidium (DHE) over time. Superoxide radicals are formed by the enzymatic reaction of xanthine oxidase and xanthine substrate. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control inhibiting DHE oxidation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, synthetic compounds and natural extracts can be normalized to equivalent Trolox units to quantify the antioxidant activity present in each sample. The SORAC assay is performed as a kinetic assay taking fluorescence measurements over the course of 10 minutes.
  The SORAC assay is offered only as a contract service.
• Activated ABTS Antioxidant Assay Kit(AOX-14)
  The ZenBio Activated ABTS Antioxidant Assay Kit improves upon the AOX-1 kit by generating the highly colored ABTS•+ radical cation prior to testing samples for their antioxidant activity. This isolates a sample's ability to reduce the pre-formed ABTS•+ radical cation from also interacting with ferryl metmyoglobin or HO• to overestimate its antioxidant activity. Trolox [6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid], a water soluble vitamin E analog, serves as a positive control reducing the pre-formed radical cation in a dose dependent manner. The antioxidant activity in biological fluids, cells, tissues, and natural extracts can be normalized to equivalent Trolox units to quantify the composite antioxidant activity present. This assay measures radical scavenging by electron donation and when combined with ZenBio's other antioxidant assay kits, can provide a comprehensive analysis of a test sample's antioxidant activity.
  The AOX-14 kit contains everything required for performing the Activated ABTS assay using two 96-well plates including Trolox standards.
• Ferrous Iron Chelating (FIC) Assay Kit (AOX-15)
  Excess transition metal ions, such as Fe(II), can generate hydroxyl radicals [OH•] in biological systems through Fenton-like reactions. Some antioxidants are able to chelate Fe(II) thereby inhibiting the formation of hydroxyl radicals and oxidative damage. The ZenBio Ferrous Ion Chelating (FIC) Assay measures the capacity of test samples to chelate free ferrous ions in solution thereby inhibiting Fe(II) binding to ferrozine which generates a highly colored complex. EDTA serves as a positive control capable of chelating ferrous ions in a dose dependent manner. The FIC assay is an endpoint assay measuring absorbance of the ferrous-ferrozine complex at λ = 562nm. FIC activity is determined as the percent of total ferrozine / Fe(II) binding.
  The AOX-15 kit contains everything required for performing the FIC assay using two 96-well plates including EDTA controls.
• Cupric Ion Chelating (CIC) Assay Kit (AOX-16)
  Excess transition metal ions, such as Cu(II), can generate hydroxyl radicals [OH•] in biological systems through Fenton-like reactions. Some antioxidants are able to chelate Cu(II) thereby inhibiting the formation of hydroxyl radicals and oxidative damage. The ZenBio Cupric Ion Chelating (CIC) Assay measures the capacity of test samples to chelate free cupric ions in solution thereby inhibiting Cu(II) binding to pyrocatechol violet (PV) which generates a highly colored complex. EDTA serves as a positive control capable of chelating cupric ions in a dose dependent manner. The CIC assay is an endpoint assay measuring absorbance of the Cu(II)-PV complex at λ = 632nm. CIC activity is determined as the percent of total PV / Cu(II) binding.
  The AOX-16 kit contains everything required for performing the CIC assay using two 96-well plates including EDTA controls.
• Total Phenolic Content Assay Kit (AOX-17)
  Phenolic compounds are present in fruits, vegetables and medicinal plants and can impart antioxidant capacity to reduce the effects of reactive oxygen species. These compounds also can provide UV protection, are anti-inflammatory and anti-microbial. The ZenBio Total Phenolic Content Assay uses the Folin-Ciocalteu Reagent to react with phenolic compounds in a test sample producing a highly colored molybdenum species. The phenolic content of a sample can be normalized to equivalent Gallic Acid units. The total phenolic content assay is an endpoint assay measuring absorbance at λ = 765nm.
  The AOX-17 kit contains everything required to perform the total phenolic content assay using two 96-well plates including Gallic Acid standards.

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