Hello everybody,
I have some complex extracts that I am using to test antioxidant activity. I wanted to compare the antioxidant activity of an extract to a synthetic mixture with the same components and the same concentrations. My main problem is that some of the components are not commercially available, so I am thinking about using statistics to put a model to measure the interaction type between the components (antagonistic, additive or synergistic) and the contribution of each component. Is it possible to put that model?
Can anyone guide me through this step?
Thanks a lot.
What is the purpose of the comparison between the extract and the synthetic mixture? Are you looking to show that there are interactions in the extract that are not present in the synthetic sample? And when you say you have a synthetic mixture, you have replicated all of the metabolites from the extract? Or do you have a mixture of the principal ones (by concentration) that you are using to compare the two?
Looking at interaction type could be done singly, using a checkerboard assay and isobologram construction, but for very complex mixtures this can be tedious and time-consuming. We have been working on a metabolomics approach to this question... see
Article Biochemometrics to Identify Synergists and Additives from Bo...
Article Biochemometrics for Natural Products Research: Comparison of...
as examples. I'd be happy to help guide you through it more thoroughly... feel free to PM me.
At first step by ANOVA you can analyze the data statistically. At next step, if you have you have control in your system, you can compare the treatments with controls by LSD (least significant differences). If you do not have control, you can use Duncan for your means comparison.
@Josh Kellogg
Actually, I am interested in studying the contribution of single components to the total activity measured. You are right, my samples are so complex and it is not easy to simulate them or prepare similar synthetic mixtures. I am not expert in working with models and statistics, that's why I am asking about the possibility of applying the idea then I can dig more and more. I will go through the suggested articles and contact you back.
Thanks a lot Josh :)
Do you have in detail the chemical composition of your extracts? You may start examine separately the antioxidant activity of each single compound at the concentration you find them in extracts, and a mixture of all you are capable to find them commercially. From this point you can see if there is antagonism or synergism in terms of antioxidant activity
Why are you planing to copy your extract with a synthetic mixture. You have the original one. You can use a bioguided isolation. Then analyse just the active fraction. You will minimise the number of compounds and just deal with the most interesting regarding antioxidant activity.
@Efstathia
I have lot and lots of compounds in my extracts. I am trying to identify most of them, but a number of them are not commercially available. There are recent research pointing out the compound can behave differently in single and mix solutions according to which compounds are there in its mix. It is a bit of complicated :)
Thanks for the suggestion.
@Fatma,
I understand, and with such complex mixtures it is often not possible to quantify/identify everything. We take an untargeted approach, that uses PLS modeling with some subsequent feature identification methods. This can be easier in some respects than bioassay guided fractionation/isolation, but more data analysis. But we've been pleased with our results so far... let me know your thoughts.
@Segueni
I am not looking for the active fractions. I want to study the antioxidant of the extract mixture as it is and try to assess the role of the compounds in the extract itself. The compound may behave differently if it is in combination with different compounds.
Thanks for the suggestion :)
@ Josh
I went through one of the papers you suggested to go through. Actually, the work is amazing. It is kind of new to me, so I am going through more readings to see how can I do something similar with my extracts.
I will need your guidance and help at some point if you don't mind :)
Thanks a lot.
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