Extract out the volatile principle using hydrodistillation method by clavenger assembly. Then check its bioactivity. If found active then go for GCMS identification of compounds.

Try with a MSMS analysis. This could indicate what molecules (protein) there are in the extract.

To obtain volatile organic compounds you can use supercritical fluid extraction.

And fractionation can performed by column chromatography using silica gel as stationary phase.

The most potent method is the solvent extraction gradient in polarity and then measure the activity as antioxidants for example and followed by GC MS. Thanks

Dear Nabil

It's very depend to chemical class of compounds that you are interested in and also amount of plant material and etc.

Dear Nabil

Essential oils isolated from aromatic plants (see the threads) by different methods and aroma compounds isolated by fractional distillation are biocompounds and have been reported to have antibacterial, antifungal, antiviral, insecticidal and pharmacological properties.

https://www.researchgate.net/post/Which_methods_can_be_used_to_identify_and_authenticate_essential_oil_constituents

https://www.researchgate.net/post/What_are_the_techniques_used_for_the_extraction_of_essential_oils_from_a_plant