Dear Ismail,

I think that when you obtain your crude aqueous extract, you can use organic solvents such as hexane, dichloromethane, ethyl acetate and n-butanol to extract it again before column separation. The choice of the organic solvents depends on the class of secondary metabolites you want to isolate.

Best regards,

Dear Ismail,

The suggestion given by Remy Bertrand Teponno is correct. Firstly you have to be clear about the property of compound which you are desired to isolate. Afterward you can easily select the most appropriate solvent for extraction and isolation via column separation.

Dear Ismail,

You must clear about the chemical properties of the chemical constituent which you need to isolate. After that you can select the required solvent (hexane, methanol, dichloromethane, butanol and ethyl acetate) for the extraction and isolation process.

Thanks for your suggestion, the method of preparation in folklore is via infusion, having shown activity, I intend to probe further through activity guided to determine the active principles, being water extract (polar), I cannot obtain any constituents using hexane, chloroform OR DCM. however, little or nothing from EToAc, what is the best way forward? 

Dear Ismail,

With an  aqueous extract in hands I would first try column chromatography over Sephadex LH-20.  There are many solvent systems you can try.  In order to analyse the isolated fractions I would use TLC developed with BAW (buthanol:acetic acid:water).

Best wishes,

Joao

The sequential TLC should give you a better idea as well