Performing biological tests like MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) or DPPH (2,2-diphenyl-1-picrylhydrazyl) on insoluble samples can present challenges due to the limited solubility of the samples. However, there are approaches you can consider to overcome this issue. Here are some general strategies for conducting these tests on insoluble samples:

Remember to perform validation and replication of the assay to ensure reliability and reproducibility of the results. Additionally, it is important to consider the potential interference of the solvent, extraction process, or other sample components on the assay system and carefully interpret the obtained data in the context of the sample's characteristics.

Abdullah S. Seddiek thanks alot for your response

Hello,

I totally agree with abdullah's very comprehensive answer.

In order to perform these tests, it is essential to dissolve the chromogenic substrate in the same solvent in which you finish to dissolve your extract.

Most antioxidant tests, like MTT or DPPH or others, are based on reductions or oxidations of chromogenic substrates. They are therefore totally dependent on the electronic state of the chromogenic substrate. They are therefore particularly sensitive to anything that might modify this state, and of course to the solvent in which they are dissolved. The solvent will of course impose, among other things, its polarity and a "pH equivalent" (as we are in a non-aqueous phase).

Good luck.

all the best.

Marc