Okay..Thank u so much..!

Hi

Here, the  IC50 values are calculated by means of a linear regression between the concentration in μg.mL–1 (axis of the abscissas) and the mean percentage of antioxidant activity, (ordinal axis), according to the formula

%AA = 100 - { [( Abs sample – Abs blank) X 100] / Abs control}

We plot the corresponding inhibition and concentration curve following the formula y = ax + b where y = 50 and calculate X which is the value of IC 50 (like Mr Giuseppe Lubes ).

I agree with Giuseppe Lubes … in this range of antioxidant activity 18 to 35%, you do not have a good safety results. Ideally is get a larger range 10 -90% cc would be perfect.

Good luck

Solange

Hi, from what I'm seeing, since the highest concentration tested (1000ug/ml) didnt inhibit by 50% or more then there's no need to calculate the IC50 valur but rather report that the IC50 value for that specific sample was >1000 ug/ml. Going on to test above 1000 ug/ml might not be feasible since ideal bioactivity for crude extracts should be observed at +/-100 ug/ml or less

Thank u all for ur answers..! 

So do i have to repeat the procedure with greater concentration or should i just mention that the ic50 value is >1000mcg/ml in my thesis..?

Both options are fine. But i strongly go for indicating that ic50 is >1000, clearly explaining in your thesis that 1000 was the highest concentration tested in your study. The other problem with testing higher concentrations of crude extracts is the issue of masking. Highly concentrated crude extracts have the ability to mask molecules being tested then you end up with false positives; thinking that your sample is inhibiting while it's actually just masking radicals or proteins in the case of enzymes, or even cells in the case of cytotoxicity testing. 

Thank you so much Petrina Kapewangolo mam...!

Please note that before you use Ms excel to calculate your IC50, R value needs to be closed to 1. I mean the equation of line y=mx+c. I hope this information will help.

It is better to repeat the experiment with concentrations ranging from 100µg-2000µg as you got less than 50% inhibition even at the highest concentation used in the current study. Do the experiment in triplicate, calculate IC50 value separately and express the value with SD. This will ensure reliability of your data,

In case using the current data, it is better to use Graphpad Prism software for regression analysis if possible.