Science topic

Antioxidant Activity - Science topic

Explore the latest questions and answers in Antioxidant Activity, and find Antioxidant Activity experts.
Questions related to Antioxidant Activity
  • asked a question related to Antioxidant Activity
Question
3 answers
Hello everyone. I need help regarding my DPPH assay.
I'm currently trying to measure the Antioxidant Activity of my sample, Water Kefir infused with Plant extract (Turmeric and Green Tea) using DPPH method.
My DPPH Assay protocols are as follows :
A DPPH stock solution was prepared by mixing 24 mg DPPH in 100 mL Methanol. The working solution was obtained by mixing 10 mL stock solution in 45 mL Methanol to obtain an absorbance of 1.1 0.05 units at 515 nm using ELISA plate reader (Bio-tek Instruments, USA). 50 µL of sample was allowed to react with 250 µL DPPH working solution in dark for 30 minutes. The absorbance was then read at 515 nm using ELISA plate reader (Bio-tek Instruments, USA). Trolox solution was used as positive control in this experiment.
However, I noticed that there is precipitate/sediment formed after I incubated my samples for 30 minutes.
Does anyone know what might be the possible cause and how can I minimize the occurrence of this precipitate/sediment?
Also, if I aliquot the supernatant to a new plate and get the absorbance reading, does it affect my result somehow?
I also attached this photo of my plate to give you a better idea on how does the precipitate/sediment looks like
Note : I serially diluted my samples (2 fold each, 6 times). I noticed that the higher the concentration, the more likely the precipitate/sediment to form (A = 1mL, B = 0.5 mL, C = 0.25 mL, D = 0.125 mL etc)
Relevant answer
Answer
you cam try to work with lower concentrations of kefir.
  • asked a question related to Antioxidant Activity
Question
4 answers
I intend to measure the antioxidant activity of plant extracts and oils using two devices (96 well plate reader and a double beam ultraviolet-visible (UV / vis) spectrophotometer). Which equation should I use to calculate?
Thank you
Relevant answer
Answer
Dear Masoumeh
These quotes are effective, but in a variety of ways. SOD and DPPH techniques.
What methodology was followed?
  • asked a question related to Antioxidant Activity
Question
4 answers
I was determining flavonoid concentration using AlCl3 method from natural product extract (based on Estimation of Total Phenols and Flavonoids in Extracts of
Actaea spicata Roots and Antioxidant Activity Studies; by Madan, Banshal, Kumar, Sharma; 2011) and used Sodium acetate instead of Potassium acetate (Evaluation of Antioxidant Activity, Total Flavonoids, Tannins
and Phenolic Compounds in Psychotria Leaf Extracts; Formagio et al, 2014).
EXPT-1.
I have prepared a calibration curve (With R^2=0.9918); by preparing different concentration of Quercetin (SRL chemicals) yellow powder in methanol. I did not notice any 'perceivable' colour change after I add reagents into Quercetin aliquot. However I prepared a conventional calibration curve.
It gave me a strange result. Very high flavonoid content in the test extracts; even greater than Total phenol content (by FCR method) of the test extracts
EXPT-2
Based on this ( https://chemistry.stackexchange.com/questions/35389/does-the-aluminium-chloride-assay-ordonez-et-al-2006-for-total-flavonoid-conte ) stackexchange post; I prepared a control set for the yellowish background correction (for each concentration of quercetin) where only water was added to quercetin aliquot (instead of same volume of AlCl3 reagent). This second experiment gave me weird result; the ODs increase with quercetin aliquot but OD(Reaction) - OD(Control) keeps fluctuating (positive and negative values at random).
Where I might be doing the mistake? Anybody else encountered similar problems?
Relevant answer
Answer
Hello Rajarshi. First check again - Does quercetin dissolved in methanol?. Second can you try using Rutin in place of quercetin for the calibration curve? Just prepare concentration of 20-100microgram of rutin using serial dilution. That will give you a straight line graph with equation for the estimation of your flavonoid content.
  • asked a question related to Antioxidant Activity
Question
8 answers
propolis (Bee Glue) and Evaluate Its Antioxidant Activity
Relevant answer
Answer
Propolis can interact with ACE2 and TMPRSS2, potentially blocking or reducing SARS-CoV-2 invasion of the host cell. Propolis has also shown promise as an aid in the treatment of various comorbidities that are particularly dangerous in COVID-19 patients, including respiratory diseases, hypertension, diabetes, and cancer.
  • asked a question related to Antioxidant Activity
  • asked a question related to Antioxidant Activity
Question
12 answers
Hello
I want to use the Hydroxyl Radical Scavenging method for a series of antioxidant tests.
In the written protocol, I should use iron sulfate, salicylic acid and 0.1% hydrogen peroxide.
Does 0.1% hydrogen peroxide mean by weight or by volume?
and What is the solvent of ferrous sulfate in this protocol? Is the Distilled Water?
Grateful
  • asked a question related to Antioxidant Activity
Question
16 answers
Hello
In the tests related to Hydroxyl Radical Scavenging, two different methods were used.
In some articles, EDTA, deoxyribose, etc. have been used, but in other articles, these two substances have not been used at all and salicylic acid has been used (Hydrogen peroxide and iron chloride are common in both methods).
What is the reason for this difference?
And what is the difference between these two methods? Are both valid?
Thanks a lot
Relevant answer
Answer
Dear Sahar
As Prof Shin wrote mostly we have more than one protocol , you should notice about the materials and all other points.
Deoxyribose assay is used to determine the hydroxyl radical scavenging activity in an aqueous medium. The reaction mixture containing FeCl3 (100 µM), EDTA (104 µM), H2O2 (1 mM) and 2-deoxy- D-ribose (2.8 mM) are mixed with or without the test sample (plant extract/fraction/compound) at various concentrations (10-250 µg) in 1 ml final reaction volume made with potassium phosphate buffer (20 mM, pH 7.4) and incubated for 1 hr at 37 0C. The mixture is then heated at 950C on water bath for 15 min followed by the addition of 1 ml each of Trichloroacetic acid (TCA) (2.8%) and Thiobarbituric acid (TBA) [0.5% TBA in 0.025 M NaOH containing 0.02% 2-Deoxy-D-ribose, butylated hydroxyanisole (BHA)]. Finally the reaction mixture is cooled on ice and centrifuged at 5000 rpm for 15 min. Absorbance of supernatant is measured at 532 nm. All readings are corrected for any interference from brown colour of the extract or antioxidant by including appropriate controls. The negative control without any antioxidant or sample is considered 100% deoxyribose oxidation. The % hydroxyl radical scavenging activity of test sample is determined accordingly in comparison with negative control. Ascorbic acid is taken as the positive control.
Hope it helps you.
Good Luck
  • asked a question related to Antioxidant Activity
Question
14 answers
Hello
I wish you good health
I have a question:
In different articles, different volumetric ratios have been used for DPPH testing. For example, one paper used 0.5 cc of sample and 2.5 cc of DPPH solution, and another article used 1 cc of sample (ascorbic acid) and 1 cc of DPPH solution.
What is the reason for these different ratios and how do I know which method is correct?
Thanks for your response.
Relevant answer
Answer
Dear Dr Sahar, please kindly follow the attached article, hope it can be useful for you!
" according to reaction time (slow, fast kinetics), the linearity range of DPPH radical depending on the detection conditions as well as the kind of the investigated antioxidants (reference chemicals and the ground elder prepared from fresh and dry plants"
  • asked a question related to Antioxidant Activity
Question
3 answers
I'm performing antiplatelet aggregation induced by collagen, and I have only this manner, I can not test it by other methods such as ADP or TRAP-6 ...
And using different manners helps to confirm finding results and making a correlation. How can we deal with this kind of circumstances?
Relevant answer
Answer
I think this is the role of a researcher, to find new techniques to evaluate biological activity.
  • asked a question related to Antioxidant Activity
Question
7 answers
Can we give a little bit whether an explanation or interpretation of the potential played by essential oil against free radicals for example without saying only the synergistic effect?
Is there any in-depth way or theoretical study to confirm which compounds, in particular, are responsible for the activity?
  • asked a question related to Antioxidant Activity
Question
8 answers
I prepared a dose of 1200 ug/ml from my crude extract and doing a serial dilution 600,300,150,75 ug/ml then I poured 1 ml each dose in a 3 ml DPPH solution and final volume of solution was 4 ml. Finally my dose was 300,150,75, 37.5 and 18.75 ug/ml. Now, which doses  will I consider, final one or initial one? Most of the authors do not clarify it in their antioxidant article.
Relevant answer
Answer
Hi, Dear Yunus Ahmed
checking the attached papers can be useful to calculate DPPH.
M regards
  • asked a question related to Antioxidant Activity
Question
6 answers
As we know, when we increase the concentration, the percentage of inhibition gets increased until reaching the maximum point. But, is it necessary to reach 100% ? Because, sometimes even if we increase the concentration over and over, the value remains stable!
What leads this phenomenon and how can we interpret it?
C1= 1 mg gives 60 % of inhibition
C2= 1.5 mg gives 86 % of inhibition
C3= 3 mg gives 86.2 % of inhibition
C4= 10 mg gives 86.5 % of inhibition
Even increasing the concentration, inhibitions percentage started to look stagnated, no more progress!
Relevant answer
Answer
Depending on the inhibition test, it can reach 100%.
for example, in antibacterial tests it is easier to reach 100%.
In protein / enzyme inhibition tests it is more difficult, as there is the question of saturation and other parameters involved.
  • asked a question related to Antioxidant Activity
Question
1 answer
What about their potential role in postharvest qualities (resistance to decay, to chilling injuries, flavors)?
Relevant answer
  • asked a question related to Antioxidant Activity
Question
5 answers
Having a molecule containing double bonds (e.g Limonene), or a molecule containing a functional group (e.g citronellal). Which one of those are you expecting will have a good antioxidant activity? and why?
Note:
Limonene: containing 2 double bonds
Citronellal: containing 1 double bond + functional group ( aldehyde)
Relevant answer
Answer
Dear Alexander Sinko thank you for your interesting technical question. I assume that citronellal can be viewed as a modest antioxidant because the aldehyde functional group –CHO can be oxidized to a carboxyl functional group –C(=O)OH. For a relevant reference supporting this please have a look at the following article entitled
Assessment of antioxidant activity of citronellal extract and fractions of essential oils of Citrus hystrix DC
(see attached pdf file)
  • asked a question related to Antioxidant Activity
Question
3 answers
We determine the antioxidant activity through either donation H or donation of an electron.
Could you give deeply more details about this explanation?
Relevant answer
Answer
An antioxidant is a molecule capable of slowing or preventing the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as thiols, ascorbic acid or polyphenols.
For more information check the file bellow will help you a lot
  • asked a question related to Antioxidant Activity
Question
4 answers
As we know, an essential oil is a mixture of components playing a pivot role in various domains.
I'm carrying out the antioxidant activity using in vitro tests.
Before doing this task, can we predict the activity of my essential oil only from the compounds found in my sample?
Is there any software to make a theoretical study?
Relevant answer
Answer
Can done by molecular docking using computer program but it will take long time
  • asked a question related to Antioxidant Activity
Question
4 answers
In order to make a good comparison between your present work and the previous reported studies, we need to compare with results obtained below the same conditions.
Sometimes, we don't find works realised under the conditions that we used !
How can we valorize our work?
Are we allowed to compare even if the conditions are not alike?
Relevant answer
Answer
Official definitions by IUPAC
The terms “antioxidant activity” and “antioxidant capacity” have different meanings: antioxidantactivity deals with the kinetics of a reaction between an antioxidant and the prooxidant or radical itreduces or scavenges, whereas antioxidant capacity measures the thermodynamic conversion efficiencyof an oxidant probe upon reaction with an antioxidant.
"Methods of measurement and evaluation of natural antioxidant capacity/activity (IUPAC Technical Report)
  • January 2013
  • Pure and Applied Chemistry 85(5)
  • DOI:
  • 10.1351/PAC-REP-12-07
  • asked a question related to Antioxidant Activity
Question
4 answers
Recently, FRAP (Ferric Reducing Antioxidant Power Assay) is not accepted by some journals for the investigation of the antioxidant power of a sample like essential oil!
I don't know the reason behind this refusal!
Relevant answer
Answer
The performance antioxidant activity of essential oil (EOs) is the result of a complex interplay between components and the oxidizable tested material. ABTS and DPPH are antioxidant assays to measure the activity of the compounds to scavenge free radicals. The essential oil especially terpenoid groups containing phenolic skeleton can react rapidly with peroxyl radical, therefore could protect oxidation by those radicals. Most of the phenolic compounds capable of scavenging free radicals by donating their electrons or H (from a hydroxyl (—OH) in the benzene ring) to the radicals. On the other hand, non-phenolic terpenoids can not protect lipid from oxidation due to (for example alpha-pinene or its similar compounds) undergo auto-oxidation. Furthermore, not all EOs have the ability to reduce reduces Fe3+ to Fe2+ (as measured in FRAP assay), even the phenolic structure with ortho-dihydroxy moiety (ex. hydroxytyrosol) could chelate Fe2+ whereas the tyrasol that has only one OH does not show that ability.
  • asked a question related to Antioxidant Activity
Question
7 answers
I'm performing the antioxidant activity of essential oil by DPPH manner, and I was wondering about the value of IC50 it seems so high because that of reference which is ascorbic acid is around 0.018 mg/ml, whereas that of my sample is 2 mg/ml. There is a big difference!
When we can consider an essential oil as an antioxidant agent? Is there any intervale of IC50?
Is there any interest to say that this essential oil having an antioxidant activity?
Relevant answer
Answer
Harto Widodo The definition of antioxidant can't not be based on the mechanism. There area thousands of molecules which fit your definition, but they are not antioxidants. The concept of antioxidants belongs to life-sciences. In the field of chemistry dealing with oxidation by dioxygen the term "inhibitor" is commonly used. I think that the best definition of an antioxidant was given by Halliwell and Gutteridge: "an antioxidant is any substance that delays, prevents or removes oxidative damage to a target molecule”
  • asked a question related to Antioxidant Activity
Question
23 answers
We tested some new compounds and I would like to write a discussion and compare these with other similar compounds... but we used as standard trolox and in study I would like to use they used AA. Thanks for any answer!
Relevant answer
Answer
Trolox is best
  • asked a question related to Antioxidant Activity
Question
3 answers
I do flavonoid test for biscuit incorporated with muntingia fruit powder.
Sample extracted with metanol (1:10 ,w/v), macerated 24h, sentrifuged and filtered. Supernatan used for analysis.
I have done dpph, phenol earlier with the supernatan from the same extracts. Dpph done well. Phenol had white precipitation.
And now flavonoid have white cloudy like solution.
An aliquot supernatan, add with 0,15 ml nano2 5%, then 0,15 ml alcl3 10% and 1 ml naoh. Then read abs at 510 nm. Quercetin as standard.
But i have cloudy solution which make it difficult to read in spectro.
Do anyone could help me for these? Thanks before
  • asked a question related to Antioxidant Activity
Question
2 answers
hello
How to prepare a fruit juice sample to measure phenolic and antioxidant compounds by HPLC?
fot types of berries and grape?
Relevant answer
Answer
Fruit Juices may be extracted exhaustively by maceration with acidic methanol over 24 h at room temperature. The extract is filtered and concentrated in vacuo at 37C. The extract is partitioned sequentially with hexane and ethyl acetate, and the aqueous fraction containing phenolics may be lyophilized. Removal of other water-soluble constituents, such as sugars and ascorbic acid, is accomplished by column chromatography by applying the dried extract to a Diaion HP-20SS resin column and allowed to adsorb for 20 min. The column is sequentially eluted with 500 ml water to remove sugars etc. and then with 300 ml acidic methanol to elute all of the phenolic compounds (flavonoids/anthocyanins).
  • asked a question related to Antioxidant Activity
Question
6 answers
I will be thankful if anybody answer my question and send me a clear protocol to measure ABTS Radical scavenging activity of protein samples.I want to measure antioxidant capacity of my samples by ABTS assay. 
Relevant answer
Answer
Agree with Dr Santosh Kumar
  • asked a question related to Antioxidant Activity
Question
6 answers
to evalue the benefict of cheese on health as antioxydant activity in cheese coagulated by Lactic acid bacteria with out presure
Relevant answer
Answer
agree with Dr Ana Rojas
  • asked a question related to Antioxidant Activity
Question
3 answers
I made ice cream using red pitaya peel and i need to measure the DPPH inhibition percentage for both red pitaya peel and ice cream. As we know, red pitaya peel has such strong red purplish color meanwhile my ice cream is slightly pink color.
Can I use different sample volume for my DPPH assay? I've tried using 1,5 ml ice cream extract+2,5 ml DPPH solutions and 0,5 ml red pitaya peel extract+3,5 ml DPPH solution
But the ice cream gives bigger DPPH inhibition percentage than my red pitaya peel
Is it because of different sample's volume? I can't use 1,5 ml red pitaya peel extract like ice cream one because the color is too strong so it doesn't turn to yellow after incubation
Is there any solution? Because I already performed Phenolic content assay and my ice cream's phenolic lower than red pitaya peel's
Thank you
  • asked a question related to Antioxidant Activity
Question
5 answers
I read this paper - Introduction of Purple and Deep Purple F1 Carrot Hybrids to Egypt Showed High Antioxidant Activity and High Content of Total Flavonoids and Phenols
It mentions that carrots grow in Egypt. I am trying to find out whether the ancient Egyptians cultivated and used carrots. If so is there documentary or graphical evidence (e.g. tomb paintings) I can refer to.
I believe, without proper evidence, that they used the leaves and seeds for medicinal purposes.
Some history books refer to tomb paintings but never give detail.
Thanks
Relevant answer
Answer
You can find your answer through Ebers papyrus
  • asked a question related to Antioxidant Activity
Question
5 answers
I am using Ferric sulphate as standard and ascorbic acid as positive control
Relevant answer
Answer
Total Antioxidant Determination by FRAP Method
FRAP assay was carried out according to the previous study with some modification.[16] FRAP reagent was prepared from acetate buffer (1.6 g sodium acetate and 8 mL acetic acid makeup to 500 mL; (pH 3.6), 10 mM TPTZ solution in 40 mM HCL and 20 mM iron (III) chloride solution in proportion of 10:1:1(v/v), respectively. The FRAP reagent was prepared fresh daily and was warmed to 37°C in oven prior to use. A total of 200 μL of samples extract were added to 4 mL of the FRAP reagent and mixed well. The absorbance was measured at 593 nm using UV-VIS spectrophotometer (UV-VIS specord 205). Samples were measured in three replicates. Standard curve of ascorbic acid (125, 250, 500, 750, and 1000 μmol) and GA were prepared using a similar procedure.
  • asked a question related to Antioxidant Activity
Question
6 answers
Need to know from the community why we use Hippury-L-histidyl-L-Leucine as a substrate in ACE inhibitory activity
Relevant answer
Answer
Thank you Adam B Shapiro
So if i get 55% inhibition during ACE enzyme assay, what does it mean and correlate with substrate HHL and product hipuric acid
  • asked a question related to Antioxidant Activity
Question
10 answers
Does one use only one concentration of ascorbic acid and measure over time to get the linear equation? Or use several concentrations? Is it advisable to use dilutions of blank DPPH solutions as a standard curve and ascorbic acid as a positive control?
Relevant answer
Answer
  • asked a question related to Antioxidant Activity
Question
4 answers
Hi all,
In the determination of Antioxidant capacity of fruit samples, I used DPPH assay and have a few questions regarding the DPPH assay
1) why is it necessary to vortex and incubate in dark the sample and DPPH solution? Is it so the sample and the DPPH can mix and allow the redox reaction to take place?
2) Why must DPPH be mixed with methanol to form methanolic DPPH? What is the purpose of methanol?
3) How did the equation %Inhibition= [(A0-A1)/A0] × 100 come about? Why is it not using beer-lambert law of calibration curve instead?
Please help! Thank you(:
Relevant answer
Answer
I agree with the previous speakers. Voltexing ensures that the mixture is homogeneous. Dropping off in a dark place is to trigger a reaction.
The standard DPPH assay uses methanol as solvent, to keep the hydrophobic hydrazyl radical soluble while offering sufficient buffering capacity.
Best regards,
Aldona Adamska-Szewczyk
  • asked a question related to Antioxidant Activity
Question
1 answer
I am finding a way to determine the all the possible derivatives of a certain compound (say derivatives of curcumin). And, I am having a hard time pointing out possible pathways and for novel product derivatives. Can anyone suggest how I can do it systematically or any technique at all, is there a software for this? Thanks
Relevant answer
Answer
I suggest using pressurized fluid to extract the samples, then centrifuge for 10 min at 20000 ppm, separate by microfilter and bring HPLC-Mass to 10000 ppm
  • asked a question related to Antioxidant Activity
Question
8 answers
I´m looking for the best diluent for total antioxidant capacity in serum or plasma.
Relevant answer
Answer
For ABTS radical scavenging assay, 0.1 M potassium phosphate buffer (pH 7.4) is the preferred diluent followed by methanol.
Regards
  • asked a question related to Antioxidant Activity
Question
13 answers
Carried 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid (ABTS), Cupric Reducing Antioxidant Capacity (CUPRAC), Total phenolic content (TPC), Reducing Power (RP), Hydroxyl radical scavenging assay (HRSA), Total Antioxidant Activity (TAA) in standard and sample. In DPPH, TPC, CUPRAC and HRSA standard was superior than sample. What may be the reason for this result?
Relevant answer
Answer
Thank you Jan Homolak
  • asked a question related to Antioxidant Activity
Question
4 answers
I'm looking for laboratories working with oxidative stress to test nitrocellulose redox permanganometry (NRP). NRP is a simple method for reductive capacity assessment based on the analysis of the MnO2 precipitate following redox reaction between KMnO4 and biological samples fixed onto the nitrocellulose. This method estimates how well the sample can give up its electrons to KMnO4, so it estimates the amount of chemical antioxidants. In other words this method can be used to measure total chemical antioxidant capacity of biological samples. Advantages of the method are: great precision and accuracy; the possibility to measure a lot of samples simultaneously; simplicity; cost (you only need a piece of nitrocellulose membrane and KMnO4). Moreover, the method can be used to obtain information on the spatial distribution of antioxidant capacity in tissue sections (both cryosections and FFPE can be used), providing unique information on the redox status of the tissue.
As the method is new, and we proposed it just recently, I'm looking for laboratories that are working with oxidative stress to test the method in their samples. We conducted thorough analyses and the method seems to be very robust. Nevertheless, I believe additional independent testing is always a good idea. Also, I believe comments of researchers closely working with oxidative stress would be beneficial for further development of this simple method.
The original paper can be found here:
A step by step protocol can be found here:
Best,
Jan
Relevant answer
Answer
In my opinion, there are no simple methods to evaluate antioxidizing capacities of potential antioxidants. General tests like DPPH, ABTS... only (roughly) measure the ability of the antioxidants to scavenge free radicals. An antioxidant is much more than that; it can act as a scavenger of free radicals, repair of the oxidized species (reduction by one electron transfer) or by cascade (cumulative) effect . Furthermore, the antioxidant capacity can also depend on the agent responsible for the oxidative stress conditions (selective antioxidants).I recommend the evaluation of the mutual behavior of both antioxidant and the target to be protected in every specific oxidizing environment.For details see e.g.:
  • Santos, P.M.P.; Telo, J.P.; Vieira, A.J.S.C. "Structure and Redox Properties of Radicals Derived from One-electron Oxidised Methylxanthines", Redox Report (2008), 13(3), 123; DOI: 10.1179/135100008X259231
  • Santos, P.M.P.; Antunes, A.M.M.; Noronha, J.; Fernandes, E.; Vieira, A.J.S.C. "Scavenging activity of aminoantipyrines against hydroxyl radical", Eur. J. Med. Chem. (2010), 45, 2258-2264; DOI: 10.1016/j.ejmech.2010.01.071
  • Santos, P.M.P.; SILVA, S.A.G., JUSTINO, G.C.; VIEIRA, A.J.S.C. "Demethylation of Theophylline (1,3-Dimethylxanthine) to 1-Methylxanthine: the First Step of an Antioxidising Cascade", Redox Report (2010), 15(3), 138; DOI: 10.1179/174329210X12650506623726
  • SANTOS, P.M.P.; VIEIRA, A.J.S.C.Antioxidising activity of cinnamic acid derivatives against oxidative stress induced by oxidising radicals”, J. Phys. Org. Chem. (2013), 26, 432; DOI: 10.1002/poc.3104
  • VIEIRA, A.J.S.C.; SANTOS, P.M.P. “A Tentative Classification of Antioxidants: Which Role They Play when Protecting Biological Targets from Oxidative Stress Induced Damage?”, J Med Chem Drug Des (2017), 1, 1-3; DOI: 10.16966/jmcdd.101
  • VIEIRA, A.J.S.C.; GASPAR, E.M.; SANTOS, P.M.P. “Mechanisms of potential antioxidant activity of caffeine”, Rad. Phys. Chem. (2020), 174, 108968; DOI 10.1016/j.radphyschem.2020.108968
  • asked a question related to Antioxidant Activity
Question
10 answers
How many receptor sites does Vitamin C interact with?
Relevant answer
Answer
Anti scorbut properties. When deficiency is not so low to cause scorbut, a low vit C status leads to impaired wound healing. In our own hospital we saw several examples in post-surgery patients.
  • asked a question related to Antioxidant Activity
Question
4 answers
I am trying to measure the antioxidant activity in food samples. Which is the best way to express Antioxidant capacity - %DPPH inactivation or Trolox Equivalent Antioxidant Capacity? How do they differ? I see the usage of two ways of representations in a same article.
Relevant answer
Answer
DPPH and TEAC (ABTS radical) are important methods belonging to single Electron transfer (sEt) based assays. In my opinion, you have to consider to apply both methods in order to test the antioxidant capacity with two different radicals. Your results can be expressed as value showing the concentration caused 50% scavenging of DPPH• radical (IC50 ) in  μg/ml
You can check also the following paper.
  • asked a question related to Antioxidant Activity
Question
7 answers
what are the best plant extract dilution concentrations used in Antioxidant Activities?any well known dilution procedure and concentration for Antioxidant activities?
Relevant answer
Answer
Dear Dr. Zaha:
This question is very relevant, in specific for times of COVID 19, since some antioxidant compounds are also anti-inflammatory compounds in some cases, in this sense, by hypothesis, natural antioxidant/anti-inflammatories would be a natural armor to mitigate the fast propagation of the virus in the organism, perhaps.
There are several classes of antioxidant, a priori four most present in the day-by-day. Some are them can be soluble in part in water, hydrosoluble, while another are strictly fat-soluble. This character is important in an analysis. Also, the aspect of biodisponibility is relevant. A great part of antioxidant compounds are absorbed by human organism is very small amount. However, a synergetic phenomenon can occurs and absorption can be further incremented. As example, there is a classical antioxidant called curcumin, fat-soluble as lycopene, that can be absorbed by organism in an amount 1000 times highest when piperine is associated. The actuation of similar phenomenon above mentioned between two antioxidant compounds might occur, possibilities.
Is high that some antioxidant can be used to induce the production of another in human organism, see:
Also, the pH parameter is relevant, when absorption is considered.
with best regard
Marcos Nobre
  • asked a question related to Antioxidant Activity
Question
3 answers
What is the criteria should I follow to study the antioxidant effect of an extract of marine algae?
I mean determination of the concentration that recommended to be administrated in water.
Is there a standard method should I follow?
Should I perform a toxicity test first?
Could I use the concentration to the its effect on amino acids and fatty acids metabolism of adult Zebrafish?
Relevant answer
Answer
Have you checked whether the extract from the marine algae has potential antioxidant properties?
If No, You may go with spectrophotometric analysis (Antioxidant assays- DPPH,ABTS,ORAC,NO).
Further, you may proceed with cell lines or any normal cells to check the reduction in intracellular Reactive oxygen species of your extract.
Now, for the concentration you may start with the a higher say 1000uM and reduce it to lower concentrations based on the literature .
However, when you go for in Vivo model it is necessary to go for toxicity analysis to check the different parameters like mortality, malformations, heart rate etc. so that you can set a concentration. Also, the concentrations set for in vitro and Vivo antioxidant activity will vary.
You can go with DCFDA analysis. Further SOD,CAT,GPx for you in Vivo antioxidant studies.
  • asked a question related to Antioxidant Activity
Question
10 answers
I would like to have an idea of which cell-based assays have been used in different laboratories to assess antioxidant activity.
Relevant answer
Answer
To measure oxidative stress and the ability to oxidize in the plant is preferred to use
As for the animal, it is preferred to use clotathione
  • asked a question related to Antioxidant Activity
Question
4 answers
Dear scientist:
I want to measure the antioxidant capacity of cosmetic creams and lotions with the DPPH and
ABTS methods, but I am not sure how to prepare the samples. Will dissolving them in a mixture of methanol or ethanol and water work?
Thank you in advance for your collaboration
Relevant answer
Answer
  • asked a question related to Antioxidant Activity
Question
21 answers
Can anybody suggest me one/more plant names for doing project either in alone or combination therapy of diabetic mellitus, wound healing and anti oxidant property?
  • asked a question related to Antioxidant Activity
Question
3 answers
antioxidants studies in C. quinoa in different parts of the plant
Relevant answer
  • asked a question related to Antioxidant Activity
Question
13 answers
i use ethyl acetat and ethanol as solvent for extraction fruit of mangrove Avicennia marina. I have a problem with crude extract from ethanol solvent contain liquids that are very similar like oil. I did DPPH test from the extract of both solvents, and the results for ethanol have very weak activity IC50 = almost 2000 µg/mL. Does the liquid like oil affect the value of the activity obtained?
Relevant answer
Answer
yes is effect on antioxidant activity by many way......
these articles have a good informations about your question
  • asked a question related to Antioxidant Activity
Question
7 answers
How can I calculate and express total phenolic content as mg GAE/g DE? Below are the details: 1. I dissolved 10mg dry extract in 1ml methanol 2. 200 micro was taken for folin ciocalteu assay 3. The absorbances for one sample were: (0.915, 0.917 & 0.919) 4. i used (0, 10, 30, 50, 70 & 90 micro g/ml) and got the equation (y = 0.0193x + 0.047)
Relevant answer
Answer
Dear Duried Alwazeer ,
If I dissolved (10) g of dried pomegranate peel with (25) ml of boiled distilled water to prepare aqueous extract of pomegranate peel, my question is how I can calculate the concentration of extract solution.
Thanks in advance.
  • asked a question related to Antioxidant Activity
Question
6 answers
Hi, I am trying to estimate total flavonoid content in crude extract, can you please provide any protocol to prepare catechin standard curve.
Thank you in advance.
Relevant answer
Answer
you can use this research
in this research we used Querciten
the protocol is one
  • asked a question related to Antioxidant Activity
Question
14 answers
The systemic antioxidant therapy is one of the therapeutic options for oral mucosal lesions. In Localized delivery of antioxidant molecules to the oral mucosal lesion, will the oral mucosal cells uptake/absorb the antioxidant molecules? Will the antioxidant molecules perform their action when delivered locally? Which route of delivery (systemic/local) of antioxidant molecules can have better activity?
Relevant answer
Answer
Antioxidants can be used topically on oral mucosal tissues, as many antioxidant agents are composed of some materials that aid in upcoming of the components by oral mucosal parts. For example, Aloe vera is an active antioxidant in which Lignin is used to be absorbed into deeper tissues of oral mucosa.
In addition, to prevent chemotherapy induced oral mucositis from taking place, topical use of some agents are studied. My last research wss about topical application of olive oil in order to prevent chemotherapy induced oral mucositis. Antioxidant proerties was one of the most important justifications of olive oil effectiveness as it was effective in prevention.
This is the url of that article
  • asked a question related to Antioxidant Activity
Question
10 answers
Dear Sir/Madam, I invited as a guest editor from high quality journals to handle special issues. If anyone can prepare a review similar to my review papers, particularly about a natural product in cancer prevention with focus on the structure activity relationship and mechanism of action, please kindly let me know to send an official letter. At this stage you should just send the title, authors and affiliation and abstract. Please kindly let me know as soon as you can. The suggested deadline for sending review is about 3 month. Best wishes, Suggeted topic: Genotoxicity of different agents and possble protection. Reducing side effects of radiotherapy and chomotherapy. Next generation of cancer therapy; Natural products. Natural products as novel therapeutic compounds. Radiation protection.
Relevant answer
Answer
What is names of the journals
  • asked a question related to Antioxidant Activity
Question
4 answers
Based on my research journals say that fermentation can increase antioxidant activity because the acid lactid bacteria will form primary and secondary metabolites which the secondary metabolite is polyphenol, can someone explain how that happen? Thankyou
Relevant answer
Answer
Lactic acid bacteria don't produce in primary or secondary metabolic pathways phenolic compounds. The response provided by @Vineet Sharma is logical, but this phenomenon could be happen by different microorganisms including fermentative ones.
  • asked a question related to Antioxidant Activity
Question
5 answers
Hello everyone, You know what is the blank for the FRAP Assay?, to calibrate to zero the FRAP solution, or What is the absorbance of FRAP solution?, (control absorbance, for example in DPPH is around 0.6).
Thank you for the answers
Relevant answer
Answer
Hello Manju Tembhre, thanks for the answer, but can you tell me what is the blank to read the absorbance only for the FRAP solution?, without the analyte, because I am working with a methodology that requires the absorbance of only the initial reagents (FRAP solution). Get my kind regards.
  • asked a question related to Antioxidant Activity
Question
6 answers
I've a question regarding lipid oxidation - there are secondary products with truncated chains (like PoxnoPC and PazePC). The question is if they are stable, since I can't find any publication regarding the problem.
Relevant answer
Answer
to my knowledge the product is unstable so it is difficult to measure thank you
  • asked a question related to Antioxidant Activity
Question
2 answers
In seedlings it is important to verify that ozone does not cause damage, because plants are more sensitive to ozone in juvenile stages (Timonen et al., 2004).
Ozone, applied diluted in water and sprinkled on seedlings of ornamental perennial species such as Salix integra, Hydrangea paniculata or Spiraea japonica, has proven to be a very effective treatment against fungal foliar diseases, ultimately causing a saving of chemical products. This fact in a world that increasingly requires more ecological treatments, and in which the demands for reducing the residues of fungicides and other pesticides are increased not only in fruits but also in foods processed with them (Edder et al., 2009 ).
Ozone is considered as a possible organic biocide because apart from not leaving chemical residues, it acts in two ways, a direct and an indirect way through the ROS species (Zotti et al., 2008). Toxic doses in sprinkler irrigation were observed from 1.5 ppm on the mentioned perennial seedlings, in applications of 7.5 minutes of irrigation / day (approx 1L per plant / day) for 6 weeks. The non-toxic dose was observed in concentrations below 1.5 ppm, such as 0.5 ppm. At these levels, an elimination of algae and biofilm is ensured, without showing phytotoxic effects (Graham et al., 2009).
In hydroponic or semi-hydroponic systems, water (30%) and fertilizer (40%) were saved by recycling leached or closed-circuit water (Runia, 1988, 1993, 1994; McDonald, 2007).
In hydroponic tomato cultivation with nutritive solution + ozone, larger tomato plants were obtained than in nutritive solution - ozone. It was demonstrated in this work that the concentration of macro and micronutrients of the nutrient solution is not modified: there is no variation in the levels of Calcium, Potassium, Magnesium, Phosphate, Ammonium, Nitrate, Copper, Molybdenum or Zinc depending on the dose increasing ozone up to 10 ppm. There is a drastic decrease in Manganese (from 0.5 ppm) and Iron (from 5 ppm). To avoid that, Terazoe (2001) proposed the ozonation of the water in a separate tank before adding the nutrients or separating the irrigation with ozone and the irrigation of nutrients. Despite this drastic decrease in the irrigation solution, there are no differences in the content of these nutrients in the leaves, which is not negatively affecting their normal development. There is a notable decrease in the incidence of root rot, typical of hydroponic cultivation (Ohashi-Kaneko et al., 2009).
Questions:
So, everything seems quite good in that way, but many questions comes to my mind:
1) Given the potential of this tool, why is ozone not an essential tool in agriculture today?
2) Are we still in a time of transition to tools such as ozone in agriculture? Or, on the other hand, do people distrust this technology due to unethical actions carried out by certain companies in the manufacturing sector of ozone generators and other innovative technologies?
3) Are there few studies in agriculture with ozone application? Or perhaps the studies show very contradictory results among them?
Feel free to discuss and propose your own questions/answers,
Thank you!
JD
References:
Edder, P., Ortelli, D., Viret, O., Cognard, E., Montmollin, A. D., & Zali, O. (2009). Control strategies against grey mould (Botrytis cinerea Pers.: Fr) and corresponding fungicide residues in grapes and wines. Food Additives and Contaminants, 26(5), 719-725.
Graham, T., Zhang, P., Zheng, Y., & Dixon, M. A. (2009). Phytotoxicity of aqueous ozone on five container-grown nursery species. HortScience, 44(3), 774-780.
Ohashi-Kaneko, K., Yoshii, M., Isobe, T., Park, J. S., Kurata, K., & Fujiwara, K. (2009). Nutrient solution prepared with ozonated water does not damage early growth of hydroponically grown tomatoes. Ozone: Science & Engineering, 31(1), 21-27.
Timonen, U., Huttunen, S., & Manninen, S. (2004). Ozone sensitivity of wild field layer plant species of northern Europe. A review. Plant Ecology, 172(1), 27-39.
Zotti, M., Porro, R., Vizzini, A., & Mariotti, M. G. (2008). Inactivation of Aspergillus spp. by ozone treatment. Ozone: Science and Engineering, 30(6), 423-430.
Relevant answer
Answer
Were your experiments done with ozone generated from air or from oxygen? If from air, you may find other molecules formed in the generator, are interfering with your results.
In answer to question 1, I would guess that it is the same as why ozone is not more used in Medicine i.e. there have been lo large scale trials. The reason for the lack is the same. There is no way of protecting your investment in a trial nor large money to be made.
It certainly is a cheap biocide. Even the equipment needed is cheap.
I have had saline ozone IVs and my condition did improve although it's back to where it was prior to treatment 2yrs ago.
  • asked a question related to Antioxidant Activity
Question
5 answers
What are the genes involved in Polycystic ovary syndrome (pco), what is the role of oxidative stress in progression of PCO?
Relevant answer
Answer
Please take a look at the following RG link.
  • asked a question related to Antioxidant Activity
Question
6 answers
I am read this sentence in artical paper >
(( Successive extraction with petroleum ether (6×50 mL), ethyl acetate (3×100 mL), and n-butanol (3×50 mL) afforded fractions))
Relevant answer
Answer
I would interprete these numbers as: 6 times extraction with 50 ml petroleumether, 3 times with 50 ml ethylacetate and 3 times with 5 ml n-butanol.
I doubt whether 6 extrations is essential. I learned that after 3 extractions (nearly) all has been removed.
  • asked a question related to Antioxidant Activity
Question
6 answers
I am using the dpph test for some plant extracts, the extracts are colored and they interfere with the resulted absorbance and I get an absorbance above the negative control....if any one could give me the protocol I'll be very thankful
Relevant answer
Answer
Dear Dima Depp
Followed standard protocol for DPPH assay and additionally measure your sample colour absorbance for each dilution without DPPH (You need to do the same dilution as your DPPH addition). Then subtract the sample colour from reaction mixture colour(With DPPH).
  • asked a question related to Antioxidant Activity
Question
14 answers
Coffee is a simple beverage, but it’s full of complex compounds with health benefits. It contains hundreds of bioactive components including vitamins, minerals, and anti-inflammatory polyphenols such as flavonoids. The amount of caffeine in a cup of coffee can vary, depending on factors ranging from the type of bean used. So, What about the healthy daily amount of caffeine was recommended to be healthy with no risk?
  • asked a question related to Antioxidant Activity
Question
3 answers
I need the full protocol for analysis Chlorophyll a and b, and Anthocyanin for hydroponics lettuce and the ideal solvent for analysis such as acetone for cholophyll and methanol for anthocyanin.
Relevant answer
Answer
  • asked a question related to Antioxidant Activity
Question
3 answers
Why is methanol used for dpph assay as control? Shouldn't it be dpph+methanol solution?
Relevant answer
Answer
Absorbance of DPPH + methanol is used as negative control,
A-B
% of inhibition= -------------------X 100
A
here A is the negative control, B is the absorbance of test or standard
  • asked a question related to Antioxidant Activity
Question
7 answers
For the experimental study we would like to use Thymoquinone. Is there anyone who could explain the dissolving procedure and dose before irradiation?
Relevant answer
Answer
To be used for in vivo (e.g Wistar rats), What is the percentage of minimum DMSO that can be use to dissolve thymoquinone?
  • asked a question related to Antioxidant Activity
Question
3 answers
Estoy evaluando actividad antioxidante de un extracto de hojas de ortiga para ello quiero determinar el IC50 por lo cual prepare diferentes concentraciones del extracto para lo cual tuve que disolverlo por lo que las concentraciones están expresadas en mg/mL por lo tanto al calcular el IC50 este tendrá las mismas unidades (mg/mL) sin embargo revisando un articulo científico encuentro que el IC50 esta expresado en mg/g como logro esto? y como se interpreta estos resultados.
Relevant answer
Answer
Las unidades de mg/g se refiere a los mg de antioxidante que se necesita para inhibir el 50% del radical ABTS o DPPH y los gramos (g) se refiere a gramos de hojas de ortiga, se reporta en mg/mL o mg/uL ya que se va a comprar con un estándar que esta disuelto en medio liquido por eso se utilizan estas unidades.
  • asked a question related to Antioxidant Activity
Question
7 answers
Hello everybody!
is it possible to measure 8-OHDG biomarker molecule in frozen sperm sample (epididymal) or it has to be a fresh sample necessarily?
thank you
Relevant answer
Answer
Hello Maryam Haqparast
Indeed, sperm cells are sensitive to freezing regarding to levels of DNA damages as measured by 8-OHdG immunostaining. Frozen samples have higher levels of DNA damages than fresh ones.
Considering this information, I must recommend to establish distinct norms for cryoconserved samples in one hand and fresh samples in the other hand. Furthermore, to ensure easier and reliable interpretation of your datas, it seems really important not to mix these two types of samples.
To answer entirely, I must add that the protocole of freezing, and particularly the cryoprotectant solution seems to be a key point and variation in its composition may have critical effect on DNA damages.
Regards,
Benoît
  • asked a question related to Antioxidant Activity
Question
10 answers
I want to determine some extracts' antioxidant activity but I am looking for methods which do not need to spectrometery.
Please let me know if you have any idea. Thanks.
Relevant answer
Answer
Dear Meysam Shahrashoub
Please find the attached file : A new colorimetric DPPH scavenging activity method with no need for a spectrophotometer applied on synthetic and natural antioxidants and medicinal
Best regards
Dr. Bensouici Chawki
  • asked a question related to Antioxidant Activity
Question
3 answers
I am conducting a experiment for antioxidant activity. For example let a sample X( Containing alpha-Tocopherol and ascorbyl palmitate) giving 250 (mM/g)(TEAC) for ABTS and 450((mM/g) ) for DPPH for a single sample. But most of research publication shows DPPH values have always less than ABTS for a single sample. Is there possible reason behind my result being high in terms of DPPH than ABTS.
Relevant answer
Answer
Dear Debi Prasad Sahoo,
The antioxidant power can be evaluated in vivo or in vitro by applying methods that measure the antioxidant capacity of a molecule or a natural extract. Given the complexity of the oxidation processes and the diverse nature of antioxidants, with both hydrophilic and hydrophobic components, there is not a universal method by which antioxidant activity can be quantitatively measured accurately. Most often, the responses of different and complementary tests must be combined to give an indication of the antioxidant capacity of the test sample.
Regards
Dr Benkhaled A
  • asked a question related to Antioxidant Activity
Question
8 answers
Hi
As far as I know, ascorbate peroxidase enzyme (APX) is the major enzyme involved in H2O2 scavenging. It is specific to plants and algae.
Recently, I was shocked when I came across an article in which APX and guaiacol peroxidase (GPOX) from fungi were unusually assayed !
In fact, GPOX activity monitoring in fungal cells is not surprising since the famous class II peroxidases such as lignin peroxidase that is found in fungi can use guaiacol as electron donor. However, APX assay is well conducted and APX activity was even higher than catalase that is well reported in fungi !
Although ascorbate (or erythroascorbate) could be a natrural substrate for many peroxidases, what do you think about the presence of APX enzyme in non-photosynthetic organisms and especially in fungi ?
Your contributions will be welcomed.
Mohammad
Relevant answer
Answer
Hello, can't be evidence of ascorbate peroxidase in fungi. Peroxidase structures have significantly increased our understanding of the evolutionary and functional relationships within the plant peroxidase superfamily.
Three distantly related structural classes have emerged:
1. mitochondrial yeast cytochrome c peroxidase, chloroplast and cytosol ascorbate peroxidases, and gene duplicated bacterial peroxidase class I
2.secretory fungal peroxidases classII
3. classical, secretory plant peroxidases (class III).
So ascorbate peroxidase is class I peroxidase enzyme and catalyse the H2O2-dependent oxidation of ascorbate in plants, algae and certain cyanobacteria but not fungi. For this type of peroxidase your culture shuld be photosynthetic. My be we will see this activity in future in Radiotrophic fungus.
Good luck!
  • asked a question related to Antioxidant Activity
Question
4 answers
I'm using "Use of a Free Radical Method to Evaluate Antioxidant
Activity W. Brand-Williams, M. E. Cuvelier and C. Berset" as reference.
I' m trying to measure antioxidant activity on garlic extract but something react with metoh so the solution isn't clear and can't be read on spectrophotometer .
thanks a lot
C.Orefice
Relevant answer
Answer
I've checked and in literature they freeze-dry the sample but I'have to use the extract in this way. I'm thinking to use FRAP method to overcame this problem or to dilute the extract before the DPPH analysis.
  • asked a question related to Antioxidant Activity
Question
5 answers
I want to conduct a theoretical study in which the antioxidant activity and capacity of a phenolic chemical compound is supposed to be evaluated. The number of atoms of the compound is less than 40. I am absolutely in need of a computational method to use in the molecular modeling. Moreover, for doing the calculation, I need an open-source computational software, preferably a windows version. I thank you in advance for your valuable suggestions.
Relevant answer
Answer
You can go for Autodock 4 version for docking studies with PDB suitable for antioxidant potentials..Good luck
  • asked a question related to Antioxidant Activity
Question
7 answers
Some polymer additives are added during polymerization reactions in petrochemical plants while masterbatchs are added to the final polymer out of the plent.
Is the above sentence right?
Actually i cannot get the proper list of polymer additives added in petrochemical plants.
I google it but there is not any specific term yet i confuse with masterbatch and additives.
Relevant answer
Answer
A great number of companies offer polymer additives of various types for different properties.
Master batches can be like taking some liters of your intermediate liquid product and mixing in some additives before adding it all to the polymerization reactor. It makes mixing easier and can help with heat management.
Different master batch added after polymerization is usually a paint or other coating that is to be added to the surface of a product.
  • asked a question related to Antioxidant Activity
Question
26 answers
Suggest some best journals which offer speedy publication of research articles covering physio-chemical, sensory and antioxidant analysis of a developed food product. The journals should be impacted.
Thanks in anticipation
Relevant answer
Answer
you can choose the journal according to your work from the below links
  • asked a question related to Antioxidant Activity
Question
6 answers
I'm a total newbie on antioxidant assay. Trying to determine antioxidant activity of an encapsulated polyphenolic compound
So I was looking at some journals for ABTS Assay procedures, and got quite confused as below:
&
This is the confusion part for me:
For (1), 7mM ABTS solution mixed with K2S2O8 solution. In that mixture, the concentration of K2S2O8 is 2.45mM.
Whereas for (2) equal amount of 7mM ABTS solution is mixed 2.45mM K2S2O8 solution. Doesnt that mean the final concentration of K2S2O8 in that mixture is 1.225mM.
Is (2) correct. Are they trying to get final concentration of 1.225mM. Or am I reading it incorrectly?
Relevant answer
Answer
I agree Parthiban Ezhumalai
  • asked a question related to Antioxidant Activity
Question
31 answers
Actually, I'm trying to extract Spirulina microalgae using ethyl acetate to evaluate antioxidant activity. I want the ethyl acetate to be 50% diluted, meaning that I'm planning to add 50 ml water into 50ml of ethyl acetate. Is this applicable, because ethyl acetate has a low solubility in Water? Will this work?
Relevant answer
Answer
Dr. Pagandai Vaithianathan Pannirselvam, noted.
Actually as you said I did tried with all different solvents. I used Methanol, 50% diluted methanol, ethyl acetate, hexane and distilled water to extract phenolic compounds separately and made comparison. And Yes as suggested methanol was very productive compared to other solvents. Thank you for the suggestions.
  • asked a question related to Antioxidant Activity
Question
20 answers
Hello everyone,
I have a query regarding ''the possible reasons behind the higher phenolic content but lower antioxidant activity''. I used the raw bamboo shoots and it showed good amount of phenolic/flavonoid content and antioxidant activity but when I prepare candies from it without adding any other antioxidant rich ingredient, processing decline the phenolic content but antioxidant activity increase significant higher. Kindly suggest what could be the reason behind it.
Relevant answer
Answer
Dear Vikas,
Individual phenolic compounds may exhibit low to high antioxidant activity. This depends on aspects involving its structure and chemical function. In order for you to make sure that the antioxidant activity is low analyze several antioxidant methods FRAP, DPPH, CUPRAC and ABTS (for example). These methods have different principles and evaluate different forms of antioxidant activity.
Regards,
Alessandro
  • asked a question related to Antioxidant Activity
Question
9 answers
LED treated plants gave lower concentrations on APX, SOD and CAT antioxidant activities than fluorescent light...what does it tell from the concentration of the enzymes? which is better?
Relevant answer
Answer
the most importnat parameters is balance between ROS production and scavenger. Enzyme activity is only ROS scavenger in certain compartments (3 SOD, 3 different APX). The best conclusion you will made if you can measure balance of the ROS (H2O2 and superoxide accumulations) in different compartments. This parameter give you real level of oxidative stress.
My best wishes!
  • asked a question related to Antioxidant Activity
Question
4 answers
I am trying to measure a snapshot of the hydrogen peroxide levels in plasma using a quick assay that consists of Horse Radish peroxidase (HRP).
Whenever I spike the plasma samples to be tested, with a specific concentration of hydrogen peroxide, the hydrogen peroxide is undetectable when measured 15 minutes later. This suggests that any endogenous hydrogen peroxide in the plasma will decompose just as fast as soon as the plasma samples are brought to room temperature.
Is there a way to stop hydrogen peroxide levels in my plasma samples from decomposing that wouldn't affect HRP activity of the assay?
Relevant answer
Answer
Dr. Armindo Salvador gave good reasons to suggest that H2O2 measurements will be prone to error, But before doing anything, Noha, ask yourself: OK, I have some number, what does it mean? What does it add to our understanding Oxidative stress? Surprisingly (for you) this information will be useless. To explain why, would take too much time and space in this notice. The main reason, H2O2 is not dangerous, particularly in the blood..
  • asked a question related to Antioxidant Activity
Question
5 answers
I am performing DPPH assay test of citrate and ammonium based compounds. While performing DPPH assay test color of solution changes from violet to brown after incubation. Peak at 417 nm disappears and shifted 425 nm while increasing overall intensity at 417 nm. now colour change is happening BUT why intensity is increasing after adding my samples to DPPH solution. Any particular reason?
P.S using absolute EtOH as solvent. and incubation time is 60 min.
Relevant answer
Answer
Then, the color changes are related to products of oxidation of your sample. You need to perform a full analysis of spectra after the reaction with DPPH, not just at several wavelengths.
  • asked a question related to Antioxidant Activity
Question
5 answers
I use quercentin as a standard and reacting the sample with NaOH, AlCl3 and NaNO2
Relevant answer
Answer
Aluminium chloride in presence of sodium hydroxide may form insoluble aluminium hydroxide.
  • asked a question related to Antioxidant Activity
Question
4 answers
I saw some journal about antioxidant activity with extract in aquades, but i'm still confused about that.
Relevant answer
Answer
Use DPPH assay; Take ethanol also as control and subtract ethanol if it scavange.
  • asked a question related to Antioxidant Activity