Hi

Absolutely no. 

it depends on, plant and active compound.

For example, a plant material extracted with methanol is more bioactive than any other solvent used. some with Aq: EtoH, some with EA etc etc..

so, it depends on polarity and solubility of the targeted active and it is potency on target benefit.

you have to choose the solvent system by, maximum extractability, maximum assay or Biological activity and convenient to handle and less toxic.

All the best

Dear Hira

It depends upon the Active molecule of that herb. For example Guggulsterone is in high concentration in Ethyl Acetate fraction of Commiphora Mukul(Guggulu),Farskolin is also the same case. Many phytosterone,Phytosterols,Fatty Acid,Terpenes  having biological activity are not a part of Hydro Alcohol Extract of that herbs. 

it is always best to extract your plant in methanol or 20% aqueous methanol

I have prepared aqueous ethanolic extract of a plant and further fractionated it in various organic solvents.

Now when I tested the aqueous ethanol extract and all of its fractions for their pharmacological effect , the crude extract (aqueous ethanol) showed more significant effect on same dose as compared to any of its fraction. Is it logical ?

Dear  Michael Päch

yes I have read all answers and your answer was quite relevant to my question and it could be possible reason (synergistic effect) of more pronounced effect of crude extract than its fractions.

Thanks a lot Sir.

yes it is possible and its logical...

I am agree with the above comments for example ethanolic extract is the total extract, for sure it will have active compounds. But when do fractionation, among fractions the active compounds you will find in subfractions, that might be EtOAc , Chloroform or butanol Fr etc. Then you can evaluate the activity by comparing Total extract and fractions. For example, EtOAc Fr showed potent activity it means your active compounds are in EtOAc Fr. then you can start isolation from that fraction and finally you will get active compound.

Thanks

Agree with Dr. Jayaram and Dr. Naveed A it depend on the target compound

Dear Hira,

In addition to above, that's why we ask our students to develop the method before action.  For example,  to optimize the solution of extraction that assumed to be best solution with suitable antioxidant added. To open this area a little bit not all antioxidant should be used to prevent more oxidation during extraction process that may take 2 hours. For example,  TBHQ in aqueous methanol will produce two peaks in HPLC system while diethyldithiocarbamic acid sodium salt (DETC) will produce null. To come to this  surfing review of literature is a basic thing to build your own extraction solution.

All the best

Aly R Abdel-Moemin

Dear Abdel-Moemin AR

Thanks  a lot Sir

I will keep it in mind for the next time as am on initial phase of research work and learning.

Regards

Good luck

Absolutely it is possible. That is the "beauty" of holistic or nature characteristic.

Let say that if there are complex of active, contain of polar and non-polar compounds; so when you do the fractionation, you would only get part of it's efficacy.

Also, don't forget about the interaction between compounds. Even the main compound is the most active, but it could be enhanced by the others.

So, knowing what is target and what are in the sample, would give you the best answer

Dear investigator,

Selection of the solvent extract depends on the what kind of phytol ingredients ur are interested  to purify .

if it is highly polar u select polar solvent like methanol or water but some time  what happen Phyto ingredients r distributed in all solvent but concentration varies.

r t mahajan 

I agree with Jayaram M and Naveed A

What is the ratio of your aqueous ethanolic mixture??

Now u'v got many replies but in my opinion most of the pharmaceuticals r either water soluble or prepared salt to soluble in water. Ur aqueous ethanolic extract contain mostly water soluble compounds or partially water soluble compounds which gives u activity/potency, it does not means other fractions containing inactive or impotent compounds eg. most of the alkaloids are found in Chloroform extract! So solubility is required for activity/potency. U may use PSS, ethanol, DMSO & twin-80 up to some extent & chq with blank/control, how much % is not inter-fairing results.

Considering one solvent at a time, this may be possible, if there are bioactive compounds in the extract. The higher potency compared to the single bioactive compound may be due to synergistic effect on a particular biochemical or physiological function.

Thank you all.

Thank you very much Thamere Cheriet