Dear Bhavesh,

Choice of plants for new bioactive natural products is based not only on ethnopharmacology. To cite an example:  If you find a plant species that is used in ethnomedicine and quite extensively studied for its efficacy and chemistry, the next logical choice would be to look at related genera within the family, eventhough, there is no mention of their use in ethnomedicine.  To extend it further, if you find a compound or a chemical group expressed in an ethnomedicinal plant, the logical choice would be to look for a plant species (even if they are not taxonomically related) that produces very similar chemistries.  The best example that comes to mind is 'trans-resveratrol' from grape skins, intially talked about in 'French paradox'.  Now we find an unrelated plant, Polygonum cuspidatum, which is used more and more in commercial herbal medicines for 'trans resveratrol'.  Extension of this is the interest to look for related stilbenoid chemistry in conifers and woody  angiosperms that produce a variety of stilbenes. Again, a related and yet new area of research is by utilising the phylogenetic links between species that throw lot more information in drug discovery.  I remember an excellent paper on phylogenetic space illustrating species belonging to different plant families that produce COX-2 inhibitors, that are phylogenetically related.  You could google for this work, which is available for free download.

Regards

Please read the Compendium of Materia Medica of China.

Dear Hong, thanks for the suggestion made. The compedium is not available with me or my institution. Kindly help.

Dear Bhavesh,

Choice of plants for new bioactive natural products is based not only on ethnopharmacology. To cite an example:  If you find a plant species that is used in ethnomedicine and quite extensively studied for its efficacy and chemistry, the next logical choice would be to look at related genera within the family, eventhough, there is no mention of their use in ethnomedicine.  To extend it further, if you find a compound or a chemical group expressed in an ethnomedicinal plant, the logical choice would be to look for a plant species (even if they are not taxonomically related) that produces very similar chemistries.  The best example that comes to mind is 'trans-resveratrol' from grape skins, intially talked about in 'French paradox'.  Now we find an unrelated plant, Polygonum cuspidatum, which is used more and more in commercial herbal medicines for 'trans resveratrol'.  Extension of this is the interest to look for related stilbenoid chemistry in conifers and woody  angiosperms that produce a variety of stilbenes. Again, a related and yet new area of research is by utilising the phylogenetic links between species that throw lot more information in drug discovery.  I remember an excellent paper on phylogenetic space illustrating species belonging to different plant families that produce COX-2 inhibitors, that are phylogenetically related.  You could google for this work, which is available for free download.

Regards

You just may find a new compound that may be useful later. The plants that exhibit activity have been studies fairly well. Other plants? They may have compounds that are useful but the plant isn't used because other compounds in the plant are toxic, or there are other reasons the plant isn't used. You are doing basic research, which isn't a bad thing.

One of the difficulties with using traditional knowledge is that rural people frequently only have water available as extractant.  We have found repeatedly that the compounds responsible for antimicrobial activity in plants, have intermediate polarity and are not extracted by cold water.  Over a long time we have determined the antibacterial and antifungal activity of  leaf extracts of more than 700 trees.  We could show that there are statistically significant differences between different tree taxa.  Certain families and genera have much higher activity than others.  Some have higher activity against fungi and there are also differences between the activities  of different tree taxa between Gram negative and Gram positive bacteria. The first manuscript on these results Pauw and Eloff is in press in BMC Complementary and Alternative Medicine.

The answer to your question, as Suresh has already stated, is that taxonomically closely related species may have similar activities.  If someone in Africa finds that a certain species has excellent activity a related species in India may also have a high activity.  

When you are looking for new active compounds, then you are not restricted for ethnopharmacology results, because most of these plants are extensively studied. In my institution we conducted a survey to investigate the biological activity of wild plants, and we screened more than 1400 plant extracts belonging to 600 plant species, and we had some promising results from plants which have not been studied before.   

Dear All Thank you very much for your suggestions.

Dear Rana M. Jamous, What justification should be given for the plant not traditionally claimed for a particular biological activity but showing promising biologically activity during the experiment?

Dear Jacobus Nicolaas Eloff and Suresh Govindaraghavan,

What justification should be given regarding the selection of a plant not traditionally claimed for a particular biological activity but showing promising biologically activity during the experiment?

The justification is clear to me.  People have not used these plants for a specific disease in the past.  Even if they tried and could not extract the active compounds, there would not have been activity.  If it was not active in their hands, the knowledge would not have been passed on to next generations.

Dear All,

I would be grateful to you all if you ponder your thoughts over this question which i just asked on Research gate.

Which part of a medicinal plant should be selected for research?

All parts since different parts produce different compounds. Compounds may also be produced during part of the growing season too, and not during other portions of the growth cycle.

The Compendium of Materia Medica in English may give you help in ethno pharmacological basis

Dear Bhavesh,

you can't restrict your selection for a specific part in medicinal plants, the leaves might be active in some plants while in others the activity is in the fruits or seeds. Thus, it should be better to screen different parts of the plants to estimate the active part.

Good luck

Dear Rana,

Thanks for your kind and valuable suggestions.

Using only ethnopharmacology as criteria   for choice of research plants presupposes that all existing plants and parts have been put to use at one time or the other which may not be totally true. Randomn selection is therefore justified in order to acess some that might have been missed out and may likely have activities. Your criteria in random selection may shift to geographical area, families, genuses, morphological parts etc.

Dear Samuel,

I was also thinking in the same direction that what if some plant or their parts have missed traditional claims.

Thank you so much for addressing in this direction too.

Dear Bhavesh Tiwari

Your repeated insistence on ethonopharmacological use indicates that you are working on specific funded project and you are unable to include a plant of your choice since you are not yet successful in finding any ethnopharmacological use through your literature search for your test plant. There are databases on such uses of medicinal plants. You may check NAPRALERT (natural product alert) database. You can also contact FRLHT, Bangalore or MS Swaminathan Foundation, Chennai for help.

Good luck.

Thank you so much Rao sir.