It is usually found that the reducing power assay is concentration dependent and increases with increase in concentration. However in my experiment taking different parts of the same plants (in triplicate) at a conc. of 20, 40, 60, 80 and 100, I found that in all the cases the highest reducing power activity was found at a conc. of 40 and then decreased at 60 followed by gradual increase at 80 and 100.
Please provide your valuable suggestions.
Thank you
Well it would increase dose-wise until a certain concentration (and not forever) due to decreased solubility of compounds in a limited reaction volume. Happens in all reactions. The increase during later concentrations would be false readings- OD increases from polyphenols/ compounds itself than reaction- kind of interference. If the concentrations are in mg/ ml, then they are too huge, try lower at say ug/ ml and so on. Also, the clue is to do experiments in repliates, starting from new diutions, and extractions, than just once, and diluting it again and again from a same stock. Repetitiveness to make sure n= 8 or 10 makes readings more stable and patterns more interpretable. best wishes. Biswa
Well it would increase dose-wise until a certain concentration (and not forever) due to decreased solubility of compounds in a limited reaction volume. Happens in all reactions. The increase during later concentrations would be false readings- OD increases from polyphenols/ compounds itself than reaction- kind of interference. If the concentrations are in mg/ ml, then they are too huge, try lower at say ug/ ml and so on. Also, the clue is to do experiments in repliates, starting from new diutions, and extractions, than just once, and diluting it again and again from a same stock. Repetitiveness to make sure n= 8 or 10 makes readings more stable and patterns more interpretable. best wishes. Biswa
Though you are not mentioning which sorts of reducing tests did you performed, I guess it is oxidation reduction experiment. Many compounds such as flavonoids and polyphenols have anti-oxidant efficacy at lower concentration and pro-oxidant efficacy in higher concentration. Forexample The mechanism of cell protection by T. chebula extract, against H2O2 induced cell death is largely due to the antioxidant efficacy of polyphenols present in T. chebula, such as quercetin, gallic acid and ellagic acids. These polyphenols are reported to show pro-oxidant activity at higher concentrations. However compounds having high low and again high effect in concentration dependent manner can not be scientifically explained. Might have some experimental error also. Following links may help you.
http://www.mdpi.com/1420-3049/18/3/3529
http://onlinelibrary.wiley.com/doi/10.1002/iub.7510450510/abstract
http://www.ncbi.nlm.nih.gov/pubmed/9119242
It could depend on method and technique you have made. If it is spectrophotometric assay you may find it wrong with results are above 0,900 absorbance. On the other hand, you should remember about antioxidant paradox- too high concentration results in lower antioxidant activity, also in reducing power test.
Generally in spectrophotometric analyses or assays there are threshold or maximum absorption value for each analyte above which there would be no linear relationship between absorbance and the concentration of the test compound when it is in high concentration. For example, absorbance value of 1.0 more may not represent accurate concentration of the compound.Similarly, high concentration of the solute compound may results in lower antioxidant activity and reducing power index.
In my view dose response curve reflect your answer.It is not necessary increase the concentration ,the response will increase because receptor is saturated. Other think Tachyphylaxis .
It is due to allelopathy. You can view publication
Article Allelopathy: Natural and an environment friendly-unique tool...
- Badges
- Science topic
- Similar topics
- Biological Science
- Plant Sciences
- Ethnobotany