Dear Friends

We have a mixed bag of opinions. We have 4 combinations here Medicinal and aromatic plants and extraction and isolation. If we search the large body of literature on medicinal plants the general procedures adopted are collection of plant part, drying, powdering and extraction with water or solvents (polar, non-polar or both). We get a crude extract by evaporating the solvent. The extract is further purified or concentrated and used for isolation or separation of classes of compounds from the extract (alkaloids, tannins, phenolics, terpenoids etc.) or pure compounds by further processing the extract. The word isolate has not been used for the extract.

In the case of aromatic plants, the essential or volatile oil is isolated from the collected fresh or dried aromatic plant biomass by distillation (hydro, steam or hydro-cum-steam). While employing the distillation technique, the term extraction has rarely been used in the essential oil literature. Most of the times the term distilled (essential oil was distilled from the aromatic plant) has been commonly used. However, essential oil and other non-volatile aroma compounds can also be obtained from aromatic plants by using other techniques. While using solvents, the term extraction (solvent extraction) has been widely used for flower concretes or spices oleoresins. For costly/expensive aromatic products (essential oils, concretes, oleoresins) super-critical fluid extraction has been used. Expression (cold extraction of citrus peels), enfleurage (extraction of pomades from aromatic flowers using fats/oils), microwave distillation with and without solvents, simultaneous distillation and solvent extraction are the other techniques employed in aromatic plants for isolating essential oils.

By further processing or distilling oleoresins essential oils can be separated or isolated. Similarly through fractional distillation of essential oils, aroma compounds can be separated or isolated from the essential oil. 

It is possible in some papers these 2 terms have been used synonymously.

I thank all the RG members who have shared their views for the benefit of young researchers.

Best wishes and good luck.

Extraction is simple use of solvent to leach out natural plant product, it may be from any plant part. Extraction is a simple term which is used to indicate something has been obtained by solvent treatment from two different polar substances mainly by using separatory funnels. But it does not apply for the essential oil, it needs crushing, distillation, steaming and collection. Certainly the terminology which should be used in case of essential oil is isolation. Separation implies for separation of compound on TLC. Sohxlet extraction is also used to leach out the substances in solvent with rotation. 

The most scientific term that used to get essential oils from plants wherever the essential oils found (stem, root, leaves, buds, oil gland, .....) is extraction. There are many different methods of essential oils extraction from plants; steam distillation, water distillation, water-steam distillation, solvent extraction (concrete), extraction with wax (hot wax, cold wax), cold press (like citrus oils), SFE (super critical fluid extraction). these methods are used to get essential oils from plants and called "extraction".

For essential oil,,extraction is the right word while active compounds isolation is the best word. This is to the best of my understanding

Extraction is a general term used for a group of compounds maybe related or unrelated which come out of the plant matrix while using some solvent whereas isolation looks for a specific biomolecule among the mixture.

I agree with D Chakraborty suggestion.

I am agree with Ravi Kant Sir. But Extract word is used for separating out compounds using solvents and isolation is used to separate individual molecule from a mixture of compounds present in extract.

To extract the EO from the aromatic plants you can uses the methods that Mohamed have indicated. If you want to extract non volatile compounds from medicinal plants , normally solvents is used. In both cases you have extracts. If you separate one or many components of the extracts you are isolating the compounds. 

Extraction of EO means, leaching of complete chemical flora responsible for aromaticity of the plant. On the other hand isolation means leaching of individual component of extract in pure form.

Ms. Thelma E. Ihedioha

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Good luck.

Extraction is a process used to obtain compounds which may be unrelated from  plant material (stem bark, leaves, roots), while isolation is a process of separation to obtain a pure compound from plant extract.

Extraction by a solvent mostly gives a mixture of compounds soluble in extracting solvent. Further purification of the extrat to get a pure component is isolation. Essential oils are a mixture of compounds having closely related properties and applications. Hence are isolated as single class of compounds.

Dear Friends

We have a mixed bag of opinions. We have 4 combinations here Medicinal and aromatic plants and extraction and isolation. If we search the large body of literature on medicinal plants the general procedures adopted are collection of plant part, drying, powdering and extraction with water or solvents (polar, non-polar or both). We get a crude extract by evaporating the solvent. The extract is further purified or concentrated and used for isolation or separation of classes of compounds from the extract (alkaloids, tannins, phenolics, terpenoids etc.) or pure compounds by further processing the extract. The word isolate has not been used for the extract.

In the case of aromatic plants, the essential or volatile oil is isolated from the collected fresh or dried aromatic plant biomass by distillation (hydro, steam or hydro-cum-steam). While employing the distillation technique, the term extraction has rarely been used in the essential oil literature. Most of the times the term distilled (essential oil was distilled from the aromatic plant) has been commonly used. However, essential oil and other non-volatile aroma compounds can also be obtained from aromatic plants by using other techniques. While using solvents, the term extraction (solvent extraction) has been widely used for flower concretes or spices oleoresins. For costly/expensive aromatic products (essential oils, concretes, oleoresins) super-critical fluid extraction has been used. Expression (cold extraction of citrus peels), enfleurage (extraction of pomades from aromatic flowers using fats/oils), microwave distillation with and without solvents, simultaneous distillation and solvent extraction are the other techniques employed in aromatic plants for isolating essential oils.

By further processing or distilling oleoresins essential oils can be separated or isolated. Similarly through fractional distillation of essential oils, aroma compounds can be separated or isolated from the essential oil. 

It is possible in some papers these 2 terms have been used synonymously.

I thank all the RG members who have shared their views for the benefit of young researchers.

Best wishes and good luck.

Extraction is gettling solvent (using polar and non-polar agents) of the test material containing all possible compounds, while isplation, is the sseperation of the components of the compound to its isolated pure phytochemical

Removal of pigments or oil as a whole from a plant matrix is an extraction process...

But inside the pigments there are bioactives compounds by the time you are targeting a particular bioactive compound inside a pool of other compounds you are performing isolation.. .Take for example there are many oleoresins inside the spice oil of red peppee pepper....The process of leaching out the spice oil is called extraction but if you now have a target sample you are interested take for example if your target sample is capsaicin the process of removing capsaicin alone is called isolation.... That is why you will always need a standard in identifying your target sample either by using HPLC or GCFID....

I stand to be corrected...

Thanks

Dear Bala

Thanks for your response and participation.

 Dear Olalere

Thanks for your detailed answer.

Extraction is the process in which we may get essential components with non essential components but isolation is the process in which we may get essential and specific component.......up yo my knowledge.

If you want to get the components of a plant you need to extract them either if they are liquid,or solid, or  use hydrodestillation, solvents, Independence if they are coloured or not; in any case you are extracting. Isolation if the process to separate one o more from the mixture of the extracts

Thanks for your informative response.

Thanks Nana for your participation in the discussion and a new twist to the responses.

Thanks for your participation Dr. Adam.

My opinion reinforces others answers presented.

The extraction procedure seeks the removal of substances from a particular source, plant for example, using the most varied means and methods.

Moreover isolation takes place by means and methods that seek to separate one or more substances or class of substances from mixture obtained by extraction.