Antioxidants - Science topic

What is the minimum amount of sample can be utilized in antioxidant activity ? As i have lesser amount of samples

Dear all, I carried out a research project to investigate the impact of different cooking methods and time on the antioxidant activity and bioaccessibility of bioactive components in pepper. While trying to use the mean values of my data to run the analysis, the result did not come out good, but when I used the raw data with three repetitions, it looked somehow good. PLEASE, I need your advice on the right thing to do. Thanks.

I conducted a cell culture study using primary fibroblast cells taken from the skin of baby mice, in the growth medium alfalfa plant extract was added. My main goal is to see the potential of alfalfa plants as antioxidants for healthy primary cells marked by increased viability and proliferation of fibroblast cells in the culture dish.

as a benchmark for comparison I need a positive control. the addition of vitamin C or vitamin E which functions as an antioxidant is my choice. can you help me in determining whether it is better to use vitamin C or vitamin E as a positive control?

I hope you understand the meaning of my question,

thank you, stay healthy

IC₅₀ (half-maximal inhibitory concentration) is a crucial parameter in antioxidant studies, representing the concentration of a substance required to inhibit 50% of free radicals (e.g., DPPH, ABTS, or FRAP assays)

With the growing scientific discourse on the role of antioxidants in health and disease, recent studies have raised intriguing questions about their long-term effects. Some findings suggest that antioxidant supplements may not always be beneficial and could even interfere with the body's natural adaptive responses to oxidative stress.

Given this, can the prolonged use of antioxidants (whether natural or synthetic) be considered a double-edged sword? Do we need to reconsider the concept of 'fighting free radicals' as a therapeutic strategy?

Dear Esteemed Researchers,

In assays evaluating antioxidant activity, is it plausible for a test compound to exhibit a lower IC50 value than the positive control, even when the positive control demonstrates a higher percentage of DPPH radical scavenging activity? Specifically, how can a compound with a lower overall inhibition rate at higher concentrations (as indicated by lower percentage inhibition) still possess a lower IC50 value, suggesting higher potency? What are the underlying mechanisms and potential factors contributing to this phenomenon?

I have synthesized a novel compound incorporating tamarind kernel powder (TKP) and a reagent containing nitrogen and sulfur functional groups. Given the known antioxidant potential of nitrogen- and sulfur-containing compounds, I aim to optimize its antioxidant activity for potential biomedical or industrial applications.

Are there established methods to enhance the antioxidant properties of such compounds? Would modifications in structural functionalization, improve its efficiency? Additionally, from a research perspective, is this approach novel and significant in the field of antioxidant materials?

I am studying on antioxidant activity of hydrogel ,hydrogel with drug, and single drug .i am facing problem for single group of drug its not giving any antioxidant effect .As it contain good antioxidant properties but i am confused why ...im using DPPH method and 10uM to 100uM concentration of drug i also tried other different concentration ..but still it did not give any effect ..can anyone please tell me some authentic reasons. that i need to follow for good results it would be highly appreciate

I don't use microplate, so I will make a dilution by volumetric flask. I also will do a triplo test, so can I do it all at once? like makin 3 times dilution of ascorbic acid and my 2 samples, incubated them together and check the abs together?

I have IC got IC 50 value. From this how can I calculate antioxidant activity or capacity

Hi everyone,

We performed this assay to evaluate the antioxidant properties of some compounds. The problem is we have very high standard deviations, even for the controls.

Dear All, In your opinion, what is the appropriate receptor and the corresponding active site for the docking of phenolic antioxidants ligands?

I am working on the antioxidant activity of phenolic compounds using DFT calculations, molecular docking, molecular dynamincs, ADMET and druglikeness properpties.

In your opinion, what is the appropriate receptor and the corresponding active site for the docking of phenolic antioxidants ligands ?

I am working on the antioxidant activity of phenolic compounds using DFT calculations, molecular docking, molecular dynamics, ADMET and drug-likeness properties.

Thank you in advance for your valuable responses.

Best Regards,

The DPPH (2,2-diphenyl-1-picrylhydrazyl) assay is a common method used to evaluate the antioxidant activity of a sample. It measures the ability of antioxidants to donate hydrogen atoms or electrons to neutralize free radicals, which can be indicators of the sample's antioxidant capacity.

How the DPPH Assay Works:

Steps in the DPPH Assay:

Expression of Results:

The results are typically expressed as a percentage of DPPH radical scavenging activity or as an IC50 value (the concentration required to reduce the initial DPPH concentration by 50%).

The DPPH assay is widely used due to its simplicity, speed, and ability to screen the antioxidant potential of various natural extracts, food products, and pure compounds.

I need a detailed protocol of any suitable method for ex., DPPH to determine antioxidant activity.

How many receptor sites does Vitamin C interact with?

Im doing biochemical analysis (phenols, flavonoids, and antioxidant) for wheat seeds, after i did all the steps i measured the absorbance of samples using spectrophotometer, so the question is how we can calculate the content of GAE for phenols, or quercetin for flavonoids in mg/g sample from the Abs?

Or how we can convert from abs to mg/g for both phenols (gallic acid standard) and flavonoids (quercetin standard)?

I use the IC50 to compare the antioxidant ablility among samples. However there are lots of article using % inhibition to make a conclusion of the antioxidant ability of a sample. They even do not draw a correlation linear or give any information about the concentration. However they still compare their results with the others. I wonder how can they do that. In my opinion we only can compare the % inhibition if the samples are in the same concentration. Moreover please giv me some pros and cons between those two method ( IC50 and % inhibition).

Please help me. I really need it as soon as possible.

Apparently the lack of tyrosinase:

"Inhibition of tyrosinase can reduce the production of melanin and achieve skin whitening, effectively solving pigmentation (Lall and Kishore, 2014). Therefore, the development of antioxidants, tyrosinase inhibitors, and elastase inhibitors play important roles in solving skin aging and pigmentation" ( https://www.google.com/url?q=https://www.sciencedirect.com/science/article/abs/pii/S0926669020309766&sa=U&ved=2ahUKEwjE4pTd0KyHAxUzHEQIHTzCCpIQFnoECAEQAw&usg=AOvVaw0gD_VQbHW1t1Go0zkPQyIW ).

Ming-Xiang Li, Jing Xie, Xue Bai, Zhi-Zhi Du,

Anti-aging potential, anti-tyrosinase and antibacterial activities of extracts and compounds isolated from Rosa chinensis cv. ‘JinBian’,

Industrial Crops and Products,

Volume 159,

2021,

113059,

ISSN 0926-6690,

https://doi.org/10.1016/j.indcrop.2020.113059.

(https://www.sciencedirect.com/science/article/pii/S0926669020309766)

Abstract: Rosa chinensis cv. ‘JinBian’, a cultivar of Rosa chinensis Jacq., is one of major raw material of rose tea and possesses sufficient plant resources in China. However, the studies on the chemical constituents and cosmetic activities of R. chinensis cv. ‘JinBian’ are almost blank. The main purpose of this study was to evaluate the anti-aging, skin-whitening, and antibacterial potentials of extracts and chemical constituents of the flower by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, elastase inhibition, anti-tyrosinase, and antibacterial assays. Bioassay results suggested both 95 % and 65 % ethanol extracts possessed significant antioxidant, elastase inhibition, and anti-tyrosinase activities. The combined active extract was studied with bioassay-guided fractionation to give a new compound, kaempferol 3-O-α-l-rhamnopyranosyl (1→6)-(2”,3”-O-digalloyl)-β-d-glucopyranoside (1) and fourteen known compounds (2–15). All compounds were firstly isolated from this species and subjected to the above mentioned bioassays. Ten compounds exhibited antioxidant activities with DPPH radical scavenging rate from 63.40 %–94.04 % under the concentration of 100 μg/mL. The antioxidant activities of 1, 2-phenylethyl 1-O-β-d-(6'-O-galloyl)-glucopyranoside (12), vomifoliol (14), and 4, 4'-dimethoxy-3'-hydroxy-7, 9': 7', 9-diepoxylignan-3-O-β-d-glucopyranoside (15) were firstly found with DPPH radical scavenging rate of 83.24 %, 91.10 %, 63.40 %, and 77.75 %, respectively. The moderate elastase inhibitory activities of 12, ethyl gallate (13), and 15 were firstly found with the inhibitory rate of 43.69 %, 43.25 %, and 35.34 % at the concentration of 100 μg/mL. Multiflorin B (3), 12, and 13 showed strong tyrosinase inhibitory activities with the inhibition rate at 43.83 %–55.80 %, comparing with the positive control, α-arbutin (22.15 %). In addition, 1 showed significant antibacterial activity against Staphylococcus aureus with the MIC50 of 8.51 ± 0.26 μg/mL. Compounds 2–4 and 12–14 showed moderate antibacterial activities against S. aureus. Compounds 6 and 13 also exhibited moderate inhibitory effects against Klebsiella pneumoniae. Above results manifested that R. chinensis cv. ‘JinBian’ possessed potential application values in the development of natural anti-aging, skin-whitening and antibacterial products.

Keywords: Rosa chinensis cv. ‘JinBian’; Antioxidant; Elastase inhibitory activity; Tyrosinase inhibitory activity; Antibacterial activity; Cosmetic potential

I conducted a DPPH experiment, and as the concentration of the sample, which is expected to have antioxidant activity, increases, the color of the reactant becomes lighter. However, the absorbance increases with increasing concentration.

The absorbance should decrease, so why is it measured to be higher?

My compounds are soluble In THF, so I woould like to know If for antioxidant activity I can prepare DPPH in THF. Before, I did a test in wich I had DPPH in ethanol, but when I Add my sample in THF, a precipitate starts to form.

Thank you

I have solubilized DPPH in methanol and used ascorbic acid as a positive control, and am testing the activity of pectins.

Would anyone be interested in collaborating on research focused on the antioxidant and antibacterial activity of medicinal plants?

Are there depletion experiments for these three antioxidants in Atlantic Salmon?

and

Why do double bonds reduce it ?

I need to analyse proximate composition in whole fish and antioxidant enzyme analysis. What is the protocol to store these samples for maximum efficiency in the results. I have -80 degree C storage facility. For how long I can store the samples?

H2O2 is an assay used to measure the antioxidant activity of an extract. There are different concentrations of H2O2 available. However, literature doesn't clearly cite the exact concentration of H2O2 that needs to be used.

Currently, there is a significant issue of iron deficiency among many people, leading to widespread use of iron supplements. However, many are unaware that iron can be toxic, and excessive iron poses substantial health risks. how effective is rosemary (Rosmarinus officinalis) as an antioxidant and its potential to prevent iron deposition within cells?

I am doing a meta-analysis, one of the outcomes is about blood antioxidant capacity, but one study has presented its outcome as biological antioxidant potential (BAP), while the others as Total Antioxidant capacity (TAC), my question is if I can pool all the results into one using standarized mean difference instead of mean difference to account for the different measurements.

Hi, I would like to perform the DHE assay to test antioxidant compounds on HT29. I am using antimycin A (100 microM) as a positive control (mitochondrial chain inhibitor). I have a good response with the positive control, but I am struggling to find a known antioxidant that works.

To specify, I'm using DHE as fluorescent probe and not MitoSox. Also, I use a confocal microscope.

Do you have any suggestions?

Thank you.

I'm trying to do a DPPH antioxidant test but when I mixed all the reagents with my polyphenol extract, some of the samples turned cloudy. Why does it happen and how can I prevent it? I am working on Dong Quai ginseng with different drying conditions.

I'm trying to incorporate curcumin in my polymer scaffold.

1. Is idea of soaking the 'scaffolds' in the curcumin solution is good?

2. will there not be any wastage of curcumin while incorporation in 'hydrogel solution' during fabrication? what should be done to avoid the wastage during fabrication process of the scaffolds?

A For dear researchers, we have a group of variables that were obtained in different units, which are the enzyme superoxide dismutase , Glutathione and Malondialdyhyde in micromol/liter and enzyme catalase In IU/milligram We need your help in knowing the appropriate mechanism or factor to convert these units to international units/liter Thank you for your presence in advance

Hi! I was going through the literature on Phospho-Molybdate Assay (Total Anti-oxidant Capacity) and I was puzzled by the formula for the percentage anti-oxidant capacity which is given below

%Antioxidant effect =(control absorbance - sample absorbance/ control absorbance)*100

To the best of my understanding, in this assay the anti-oxidant capacity increases as the absorbance increases. This should mean the control sample should have the lowest absorbance and hence the lowest anti-oxidant capacity. It would also mean that if I were to use the formula given above, the numerator would come out as negative. Can we use negative values? Is the formula correct? Or is my understanding of the basic principle of the assay flawed?

VIt.E&GSH An applied experiment was conducted on male rats exposed to oxidative stress induced by hydrogen peroxide, and the result of the vitamin E-treated group was that there were no significant differences regarding glutathione when compared to the control group Although the same group showed a significant increase in enzymatic antioxidants and a significant decrease in... Malondialdehyde

The product is a bread that is required to measure antioxidant activity by the DPPH and ABTS methodologies; However, the product contains phenolic compounds such as flavonoids and hydroxybenzoic acids.

I am currently setting up a two step treatment on HepG2 cells in a 96 well plate, using an antioxidant and a drug. Majority of the literature that I have consulted mention a pretreatment with the antioxidant, and then treatment using a drug. For the few treatments that I have set up, I give the tretament using antioxidant dissolved in media for 24 hours, remove the media, wash with PBS and then give the drug tretament (drug dissolved in media). My confusion here is : Is this protocol correct? Or do I keep the antioxidant containing media and just add the drug containing media on top of the antioxidant treatment, without removing the antioxidant and forgoing the PBS wash. Any clarification would be appreciated

5-Methoxytryptophol as a hormone

Hello,

I am doing a computational study with Gaussian software on certain compounds with antioxidant activity. I got the results of HOMO and LUMO energy. According to my results, the order of HOMO energy of my samples is T1>T2>T3>T4>T5

Does that mean the T1 sample has higher antioxidant activity than T5?

Moreover, In the articles that I have read, all mentioned that a compound with a low energy gap between HOMO and LUMO shows high antioxidant activity. But when I calculated the energy gap between HOMO and LUMO, the above order was not followed. The order for the energy gap is: T1<T4<T2<T5<T3

I am confused to interpret these data.

Hello everyone,

Im concerned about the bioactive properties of different natural powder extracts (botanicals and mainly rich in antioxidants) in a very alkaline environment, specifically during the saponification reaction in a cold process? The exposure will destroy or just lows the antioxidant properties? What happens with the vitamins?

I am running protein samples on SDS-PAGE that are tagged with fluorophores. If I place the gel in a destain solution of 60%water/30%methanol/10% acetic acid, the chemistry reverses and I lose the fluorophore. Is there an alternative storage solution I can use to get my gel to the imager to capture the fluorescence without chemical fixatives? After imaging, I then proceed to Coomassie Blue staining in acetic acid and methanol, at which point I am not worried about losing the fluorophore.

I have been working on antioxidant activity using FRAP assay. But, the correct way for calculate FRAP value is difficult to find, Can anyone help?

what is the optimum temperature for synthesis of tannic acid-metal complexes? we are synthesizing biocompatible antioxidants.

After successfully synthesizing selenium nanoparticles from plants using water my next objective is to assess their antioxidant activity. However, I encountered an issue during the drying process as the nanoparticles transformed into a powdered form that does not readily dissolve in water. To overcome this challenge, I am seeking guidance on how to dissolve the nanoparticles and which solvent would be most suitable for this purpose.

If you squeezewash a bitter leaf, with it take away all it's antioxidant?

Looking for methods or protocols on how to analyze Superoxide dismutase, Gluthoine-peroxidase, and Malandyhyde in dairy animals. Please share detailed steps.

Respected expert, as I have done antioxidant assay for zinc oxide nanoparticle using medicinal plant Serriphidium kurramense. In this assay I have used Ascorbic acid as standard and DPPH as free radical. In the assay for control 2ml methanol and 1ml DPPH is used, and different concentrations of nanoparticles and plant extract are used as test samples against DPPH. The question is, my test sample that is nanoparticle always give higher absorption value then control due which I get wrong result and my sample showing no antioxidant activity while the plant used in the synthesis show antioxidant activity. Is it possible that the plant showed antioxidant activity but the nanoparticles synthesized from that plant show no antioxidant activity. The change from pinkish color of DPPH to yellow or colorless is completely done in case of Plant Extract and standard Ascorbic acid but show antioxidant activity not more than 80% when calculated although color change is 100% in both plant extract and standard and in case of NPs no color change occurred.

File is attached for reference. Please help what should I do in this case?

I have repeated the assay many time but got no positive result.

Your precious time and comments will be highly appreciated.

Respected expert, as I have done antioxidant assay for zinc oxide nanoparticle using medicinal plant Serriphidium kurramense. In this assay I have used Ascorbic acid as standard and DPPH as free radical. In the assay for control 2ml methanol and 1ml DPPH is used, and different concentrations of nanoparticles and plant extract are used as test samples against DPPH. The question is, my test sample that is nanoparticle always give higher absorption value then control due which I get wrong result and my sample showing no antioxidant activity while the plant used in the synthesis show antioxidant activity. Is it possible that the plant showed antioxidant activity but the nanoparticles synthesized from that plant show no antioxidant activity. The change from pinkish color of DPPH to yellow or colorless is completely done in case of Plant Extract and standard Ascorbic acid but show antioxidant activity not more than 80% when calculated although color change is 100% in both plant extract and standard and in case of NPs no color change occurred.

File is attached for reference. Please help what should I do in this case?

I have repeated the assay many time but got no positive result.

Your precious time and comments will be highly appreciated.

I have synthesized AgNps using medicinal plant extract. I am facing a problem with their antioxidant activity. The antioxidant activity of the plant extract is higher whereas plant-mediated synthesized AgNps show a decrease in antioxidant activity. As per the reported literature, AgNps show good antioxidant activity. But my findings are totally against the already reported studies. Can anyone suggest me why there is decrease in antioxidant activity of AgNps.

M-type calcium hexaferrite (CaFe12O19) was synthesized using Azadirachta indica and Murraya koenigii leaves extracts, followed by calcination. Phytochemicals in the extracts influenced the structural, optical, microstructural, magnetic, and dielectric properties. Characterization techniques included FT-IR, XRD, UV–Vis, SEM, VSM, and dielectric measurements. The plant extracts exhibited phenolic content and antioxidant properties, contributing to the formation of a pure hexagonal phase. SEM revealed a spongy appearance in the modified ferrites. Samples prepared with Murraya koenigii leaves extract had higher saturation magnetization (11.78 Am2/kg) compared to Azadirachta indica (3.56 Am2/kg). Both samples exhibited a magnetically soft nature with a multidomain structure. The energy bandgap was 2.01 eV, and dielectric measurements showed distinct values for the two extracts.

research paper :

#research #materialscience

#calcium

Science Red seaweeds have a good quantity of water-soluble phycobiliprotein, which may precipitate during extraction with some of the solvents. Thus, I am searching for a better solvent to estimate the antioxidant activities of red seaweeds.

Hello,

I am studying non-enzymatic, dietary antioxidants but I am having a hard time finding information about the differences between hydrophilic and lipophilic compounds (besides methods of detection).

Any information or suggestion of literature is highly appreciated!

Thank you!

If we treat NHDF cells with ascobic acid for 1 hour at 33ug/mL and then irradiate the cells with a low dose of UVA we see a good antioxidant response and cell viability does not change compared to non-irradiated NHDF cells. However, if we followed this procedure but with a incubation of ascorbic acid for 24 hours, after irradiation we were unable to detect an antioxidant effect and we also observed an increase in cell viability.

We know that ascorbic acid can reduce our cell viability reagent, but we do not know why its antioxidant effect and viability depend on its incubation time. Do you have any idea?

I am working on the antioxidant activity of samples. I did the ORAC assay and DPPH assay. My samples work well in ORAC assay, and they have shown higher antioxidant activity than Trolox and Ascorbic acid. However, in the DPPH assay, they have not shown any activity and in some cases, the absorbance of DPPH increases when I add my samples.

Can we conclude that my samples do not have the ability to scavenge RNS?

The sample are Clitoria ternatea where methanol and aqueous extract. The total inhibition show the aqueous extract have higher antioxidant than methanol. why? the methanol extract have higher phenolic,flavanoid content but have lower antioxidant than aqueous extract

I want to estimate the antioxidant, flavonoid and phenolic compounds of the fortified yogurt.

I want to do the antioxidant test for C.ternatea flower aqueous extract but im not sure how to prepare the sample? Should i dissolve in distilled water or methanol? There will be several concentration such as 1mg/ml,0.5mg/ml,0.25mg/ml and 0.125mg/ml.. For standard, can I use ascorbic acid?

Does water have a role in increasing the effectiveness of enzyme antioxidants?

Generally, the rate of antioxidant reactions (activity) seem unrelated to total antioxidant effect (capacity); the latter is perhaps governed by thermodynamic considerations (pls. cf. redox reactions, Nernst equation etc.) and the complicated mess of real-world antioxidant reactions [1]. This is one justification cited for combining both rate and end-point measurements in order to get more representative antioxidant evaluations. Consistent with this approach, there is the general chemistry principle which states: the kinetics and thermodynamic properties of reaction are unrelated [2]. But why not? Some research (now quite old) shows that the rate of autoxidation reactions vary linearly as function of the net changes redox potential [ref. 3]. Marcus theory shows kinetic and thermodynamic "cross-overs" occur for single electron transfer reactions and (perhaps) other linear free energy relations [ref. 2]. Professor R.A. Marcus won the 1992 chemistry Nobel prize for the research completed initially in 1956; this model follows-on from Eyring's absolute reaction rate theory (cf. Activation free energy narrative) but in addition delta-G# is shown to be a function of Gibbs free energy (cf. delta-Go = n F Eo) plus a term for the solvent reorganization energy (L) – Marcus in brief!

Questions

Q1. Why is Marcus' theory not finding itself into standard chemistry texts?

Q2. Is there evidence for kinetics and thermodynamic cross-relations for single electron transfer reactions involving real-world antioxidants?.

Acknowledgement.

this discussion was prompted by this post on the Marcus theory.

References

[1]. Campos, A., Duran, N., Lopez-Alarcon, C., Lissi, E., 2012. Kinetic and stoichiometric evaluation of free radicals scavengers activities based on diphenyl-picryl hydroxyl (DPPH) consumption. Journal of the Chilean Chemical Society 57, 1381–1384. http://dx.doi.org/10.4067/S0717-97072012000400010

[2]. Silverstein, T.P., 2012. Marcus theory: thermodynamics CAN control the kinetics of electron transfer reactions. Journal of Chemical Education 89, 1159–1167.

[3]. Kurimura, Y., Ochiai, R., Matsuura, N., 1968. Oxygen oxidation of ferrous Ions induced by chelation. Bulletin of the Chemical Society of Japan 41, 2234–2239. https://doi.org/10.1246/bcsj.41.2234

I want to perform Antioxidant assay for Iron oxide NPs synthesized through green synthesis method from leaves extract and also wants to check the antioxidant capability the plant extract which is used the synthesis of these NPs. I have also used Ascorbic acid as standard antioxidant.

Thanks!

Good morning,

I am trying to study the antioxidant activity of ZnO NPs. I have already performed some methods, such as DPPH and ABTS assay, but without success.

When I search in the literature for methods to measure antioxidant activity of ZnO NPs, the syntheses of these ZnO NPs are biosyntheses (green synthesis), always with extracts of something natural. Which makes me question if it is really the ZnO NPs that have the antioxidant activity or if this activity comes from the extracts used in the syntheses.

Can anyone help me how to measure the antioxidant activity of ZnO NPs that have not been synthesized by natural methods? Does anyone have knowledge on this matter?

Thank you very much.

Ana Rita Mendes

For my research paper, I will be studying on the antibacterial, antioxidant, and antitumor activities of the plant species shown in the photo. However, I am not sure of its full scientific name. It was collected in Pandan, Antique Province, Philippines. It has a local name of "libut" and is known as a medicinal plant for headaches and toothaches. Thank you very much in advance.

I have used the MTT Assay to measure cancer cells' viability under an antioxidant compound's influence. But contrary to expectations, with the increase of antioxidant concentration from 5 μM to 150 μM, the viability not only did not decrease but also increased. In other words, with the increase in the concentration, the amount of light absorption increased. In your opinion, what is the reason for this technical error? Or what kind of problems could have occurred during the MTT Assay?

Hi guys, i want to ask you something. I'm doing some study on antioxidant activity in Palm Kernel Cake (PKC) by using DPPH assay method. I observed that my the color of my bio-oil extracted from PKC was appeared in likely clear colour. Last time, I saw someone wrote that it's better to use 0.1mM of DPPH instead of 0.6mM of DPPH for a clear solution sample. Is that true? Can someone give me some opinion how can i know how much concentration for dpph i should use? It's okay if I use 0.6mM DPPH? Thankyou. 😁

Dear all,

I wonder whether you use antioxidants for cells before cryopreservation. Would you suggest a specific antioxidant? I found that (N-acetyl cysteine) was used for cryopreservation of human cord blood nucleated cells. I want to try it on PBMCs, do you have any ideas about the best concentration?

Thank you very much.

Why natural polyphenols (like proanthocyanidins from berries) decrease their antioxidant activity in a lipid environment? vs an aqueous environment?

I know that existing research suggests that the lipid solvent lowers polyphenol antioxidant activity. But why? It is because their favored the prooxidation of lipids?

Thanks guys.

I am using ABTS assay to investigate the antioxidant capacity on sorghum flour but I'm having issues with the calibration curve (trolox stock 0,025g in 100ml MetOH 50%) ranging from 5 to 900 µmol/L.

For the ABTS solution I am mixing

- 5mL of 2.6mM potassium persulphate

- 5mL of 8mM ABTS

and after letting them react for 16h at room temperature in the dark I adjust the absorbance at 743nm between 0.7 and 0.8 with 80% EtOH (HPLC grade).

The problem is that the curve is not linear with an R2 lower than 0.98 (the standards are fine and already checked) but I do not understand what I am doing wrong.

Within the scope of my research, I am currently engaged in conducting an estimation of antioxidant power using the FRAP (Ferric Reducing Antioxidant Power) method. To establish a standard curve for this particular method, I have meticulously prepared a stock standard solution comprising 278mg FeSo4 and 10 mL of distilled water, resulting in a concentration of 100mM. Subsequently, I have generated several dilutions (1000 uM, 500 uM, 250 uM, 125 uM, 62.5 uM) for the working standard by diluting the aforementioned stock standard solution. By capturing readings for each of these standards and constructing a corresponding curve, I have visually represented the acquired data. I am eagerly seeking your esteemed suggestions and recommendations pertaining to the precautions and measures that need to be taken during the execution of the standard procedure for the FRAP assay. Your input would be immensely valuable to my research, as it would help to verify the accuracy of my steps, values, and standard curve. These are my primary inquiries regarding this assay.

1. According to the procedure, considering the nature of the reaction as kinetic. How many measurements should be taken to observe changes in absorbance, and at what intervals should these measurements be made?

2. I have obtained R2 values of 0.8105 and 0.847. Are these values considered acceptable?

3. Are there any other methods available to assess the total antioxidant power, or is this the only one?

4. When measuring FeSO4.7H2O for the preparation of the stock standard, are there any specific precautions or considerations that need to be taken into account?

I need to evaluate the antioxidant and cytotoxicity activity for polymeric material . It doesnt dissolve in common organic solvents even dmso. Is there is a way to do such test!

Hey everybody. I have done amino acids analysis by LCMSMS. I am looking for a list of secondary amino acids in order to see antioxidant capacity in these molecules.

anyone have a such list????

TNX

Hello everyone

I'm using BHT and ascorbic acid as a standard curve to study the antioxidant activity of my lichen species (by the DPPH radical scavenging assay), but my BHT graph's curve is not linear. When I display the regression equation, the R-squared value is 0.72, which is far from 1, but if I display it as a logarithmic equation it equals 0.95, this time is good, is that normal to choose the trendline as a logarithmic equation or not?

I analyzed the caffeine antioxidant activity with 100 µL serial concentration 1;1.5;2;2.5;3;3.5 mg/mL of caffeine add with 100 µL DPPH 0.2mMolar (Ethanol as solvent) using 96 wall plate while 100 µL DPPH solutions as blank. After 30 minutes incubation, the absorbances of the caffeine + DPPH showed higher value compare to DPPH solutions and the colour of caffeine mixture still remains in purple colour with wavelength settings of microplate readers at 516nm.

So I wonder, is there any possibility of colour interferences during the preparation or do you think if DPPH assays might be not suitable assay for caffeine

Can anyone have this answer so please let me know, Signalling pathway of enzymatic antioxidant and non enzymatic antioxidants in plants like millet?

I am working in my PhD about one medicinal plant doing extraction and isolation the phytochemical and check their biological activities and the last objective of my work Biosynthesis of ZnO Nanoparticles using same plant extract as a reducing agent and a stabilizing agent then charcterisation the ZnO NPs and check their antimicrobial antioxident activites. Is that ok or it is not mached?

Is the green ZnO NPs activity will differ from plant to other plant extract?

Thank you in advance

Therapeutics such as probiotics exert a beneficial effect on host gut microbiota after consumption and may be capable to prevent several diseases such as Alzheimer’s disease. Fermented dairy foods, cheese whey and buttermilk whey offer suitable matrices for the growth and viability of probiotic microorganisms and are potential sources for the development of probiotic dairy-based beverages. The literature shows that the heterogeneous food matrices of non-dairy food carriers are the major constraints for the survival of the probiotics and the use of antioxidants in yogurt manufacture. Dairy consumption such as sour/fermented milk, yogurt, cheese, butter/cream, ice cream, and infant formula need to be assessed for the content of microbial diversity. The role of fermentation, freezing/thawing, room temperature modification and probiotic shelf life may have a critical effect on the generation of LPS from gram negative bacteria that may lead to dysbiosis. The association between high fat/high cholesterol diets have been shown to be linked to the increased incidence for Alzheimer’s disease (AD). The literature shows strong evidence with relevance to changes in cholesterol metabolism and transport that is associated with AD pathogenic processes. The safety of probiotic therapy for AD patients requires investigation with relevance to the induction of dyslipidemia and the release of bacterial lipopolysaccharides and amyloid beta from gram-negative bacteria needs to be controlled in these probiotic formulations.

RELEVANT REFERENCES:

Hai, can someone help. I want to use the DPPH method to analyze lipstick's antioxidant activity. But, can I dissolve lipstick in methanol? Is it possible for lipstick to dissolve in methanol?? Sorry for my bad English :)

ow can i quantify the TPC and test the antioxidant activity of non polar extract and polar extract of seeds oil extracted by ethyl acetate?

Well, I found a paper pretty old, 2001, that shows a decrease in the DCFH-DA signal. Is this decrease a quenching effect? Or another phenomenon but never a measurement of antioxidant enzymatic.

What do you think?

help me a little bit whit this, OP

I am working on a project looking at the cytotoxic effects of lipid oxidation products on caco-2 cells. I would like to include a sample group with added antioxidants as a 'negative control'. What commercially available antioxidants might be suitable or have been used before? What concentrations are generally used? Are there other considerations to keep in mind? Thanks!

FRAP is an antioxidant test that measures the reducing activity of an extract. it can be expressed in mgEstandard/100 g. with different concentrations how do you calculate EC50?

It can act as an anti-inflammatory, energy-booster, antioxidant to strengthen your body's immunity and memory.

view: https://rasayanam.in/

microencapsulation, chitosan and maltodextrin, antioxidant extract