Check these links and publications:

https://www.researchgate.net/post/can_anyone_guide_on_how_best_to_quantify_the_phytochemicals_in_a_crude_plant_extract?_tpcectx=post_detail_recommendations&tpr_view=8f382a13-d93d-49b2-90a5-cc2db2cf5a61_2&_trid=849f61e9-e846-4464-bcef-b908f09fab5f_2

https://www.researchgate.net/post/Can_someone_list_out_the_methods_of_extraction_crude_extract_compounds_isolation_purification_identification_and_structural_elucidation?_tpcectx=profile_questions

https://www.researchgate.net/go.Deref.html?url=http%3A%2F%2Fwww.slideshare.net%2Frahulbs89%2Fextraction-of-plant-contituents

First you will need to extract the plant with different solvents sequentially using Hexane, Chloroform, Ethyl acetate and Methanol in that order. You will need DPPH (2,2-diphenyl-1-picrylhydrazyl) for the antioxidant assay. Do TLC for the fractions and spray with DPPH; spots on the TLC plate that turn yellow to the spray have antioxidant potential. Look up the book "Natural Product Isolation (Satyajit Sarker eds)" for a rigorous procedure. Thanks

Check this informative and interesting link:

http://www.slideshare.net/rahulbs89/extraction-of-plant-contituents

Following Jecinta advices I suggest you to try DPPH assays on any extract you prepare to know which one have positive reaction and then make the separation of the components on that extract through chromatography. This chromatographic separation provides you many fractions which have to be assayed again by DPPH  until you get the more active fractions which have to be purified. To start from a crude extract to get the  active compounds and it's chemical  characterization  really means many more steps and you have to go step by step. Good luck.

Good question. I agreed with J M Anowu and Olga lock.Any unexploited herb or plant, the first concern is to isolate and characterize the biochemical constituents, so wew can further study the use of particular constituents in food, medicinal or cosmetic products.

Thanks to all 

I have worked a lot on such phytochemical characterization and the first thing you must do is get a MS analysis done and compare it with references that you may have come across. After that we may discuss the purification of specific compounds.

First of all try to find out the required activities of your crude extract , if it has the activities then go further for fractionation.  

Kalpna am currently on this area of research, extraction, isolation and identification research are very demanding and expensive in countries like Nigeria that I reside, but I advice you do activity guided extraction first based on the polarity index of solvents. On the fractions obtained, YOU carried out antioxidant or antimicrobial assay, choose fraction with the highest activity for the isolation (Liquid chromatography, TLC and preparative TLC). For structure elucidation of your compounds, GC-MS, FTIR and NMR are suggested. Goodluck

Dear Kalpna D. Rakholiya,

GCMS gives only the volatile compounds,

You can not identify some unknown phytochemicals in the extracts only from FTIR and UV,

NMR is very complicated,

You can proceed with HPTLC and LC-MS,

Sincerely,

Gharavi