Dear Kiran, thank you very much for posting this interesting technical question. For some general information about the topic please have a look at the following potentially useful article which might help you in your analysis:

Preparation of Medicinal Plants: Basic Extraction and Fractionation Procedures for Experimental Purposes

Article Preparation of Medicinal Plants: Basic Extraction and Fracti...

Fortunately this article has been posted by the authors as public full text on RG, so you can freely download it as pdf file. The same is true for the following two articles which show that you can directly use the methanolic extracts:

Biological activity of methanolic and aqueous extracts of Glycosmis mauritiana and Streblus asper

Article Biological activity of methanolic and aqueous extracts of Gl...

and

Evaluation of biological activities and chemical constituent of storage medicinal plant materials used as a traditional medicine in Nepal

Article Evaluation of biological activities and chemical constituent...

It might also be worth having a look at the answers given to the following closely related question which has been posted earlier on RG:

How can I prepare a stock solution from a plant extract?

https://www.researchgate.net/post/How-can-I-prepare-a-stock-solution-from-a-plant-extract

(10 answers)

I hope this helps answering your question. Good luck with your research and best wishes, Frank Edelmann

Dear all, the question is a litle bit unclear, but if you want to prepare a dose as you said directly from the extraction solution, then you consider this later as a mother solution, get its concentration via UV-Vis spectroscopy or any other technique, after that you have to delute if a lower concentration is needed or evaporate if higher concentration is needed. My Regards

You must bring your extract to dryness to weigh it and prepare your solution. For biological activities, you want to dissolve the extract preferably in saline or water, so you should verify that your extract is soluble. If your extract does not solubilize in either saline or water, you will have to mix it with tween 80 for example, it all depends on your extract.

Methanol extracts are rich in polar constituents, in that way you must use polar solvent to prepare the dose. However, to evaluate biological assay, organic solvents are not recommended due to their toxicity. Dimethyl Sulfoxide (DMSO) is more used in bioassays as a solvent but must have low concentrations to not interfere with your results. I suggest you test the safer concentrations of DMSO in your target, in order to define the non-toxical concentration and realize a solvent control group in your experiments.