Take a look at this document: Green extraction processes for bioactive phytochemicals: supercritical CO2 extraction and microwave-assisted extraction

have you looked at the accelerated solvent extraction (ASE), it is the Dionex product use high temperature and pressure. You can change the mixture of solvent on the fly like HPLC. Google it for more info.

Ionic liquids also known by the names liquid electrolytes, ionic melts, ionic fluids, fused salts, liquid salts, ionic glasses and designer solvents are salts in liquid state either at room temperature or at low temperatures and are miscible with water and other organic solvents. Ammonium, choline, imidazolium, pyridinium, phosphonium, pyrrolidinium, pyrazolium, sulfonium based and other ionic liquids are available in the market. They are hailed as environmental-friendly, green solvents. May be you can try some of them.

I would recommend Supercritical fluid extraction. Maybe expensive to start up however pure extracts are obtained, free of solvents .

If you want to investigate the folk phytotherapy, it is more reasonable to reproduce the preparation the people use as remedy, applying well-defined experimental techniques, like pharmacopoeial methods. This is meaningful since the active substances must be present in the preparation the people use. Once the active substance is isolated and chemically and pharmacologically characterized, you can search a better way to get it using any other type of extraction. This approach serves to save time, material and efforts to find the active substance, besides to be useful to validate the folk phytotherapy and, in case of development of a phytomedicine, it seems to be a very clever strategy; biomonitored medicinal plants phytochemical investigation.

It depends on the compound type you are trying to extract. which type of natural compounds you are trying to extract?

Take a look at this document: Green extraction processes for bioactive phytochemicals: supercritical CO2 extraction and microwave-assisted extraction

I agree, microwave extraction is a very useful technique. See paper via attached link

http://www.ncbi.nlm.nih.gov/pubmed/22367895

Microwave extraction, SFE (supercritical fluid extraction) and ultra sonication extraction are the other types of extractions used recently 

Microwave extraction

supercritical fluid extration

sonication

microwave

soxhlet

dionex ASE 

Of coursesuper-critical CO2 and micro-wave assisted extractions are modern enough. However, new methods may not necessarily be economic, efficient or more effective. For medicinal compounds from plants traditional extraction methods used by indigenous people should be strictly adopted as outlined in the pharmacopoeia. The other extraction methods including modern ones may release toxins from the plant instead of drugs. Further the traditional methods control the dosage of the drug extracted and thus takes of safety issues as well. It may also be responsible for formation of useful artifacts which act as drugs

Phyto-constituents are not uniformly distributed in plants. They are widely distributed with complex structures and varied solubility differences. In addition, these compounds have significantly varied stabilities. Extraction and isolation processes are therefore complicated. It is therefore difficult to suggest a simple single standardize procedure or method. The procedure to be adopted must depend on the particular functional group of interest. Modern methods such as Super-critical CO2 and micro-wave assisted extraction are useful and may help but these methods are sometimes not available in laboratories that have financial and economic difficulties. I therefore suggest the adoption of the existing classical method of extraction ie solvent-solvent extraction in which solvent are used in increasing polarity order. Sometimes, the compound can be isolated with methanol first and the dried extract re-dissolved in distilled water then successively extracted with solvents of different polarities.

It is interesting to know about so many techniques. But, which of these are factually "recent". Most of these techniques have been there for quite sometime. Am I wrong?

Indeed Mr. R. Rao, some techniques are developed to solve very specific problems; however, the extraction using pharmacopeic and classical methods is still very useful!

Dear Danladi

Pl. check whether any of the attached publications are useful to you.

Best wishes.

Dear Danladi,

The extraction method highly depends on the nature and final use of your compounds, please take a look on the review in the link to have an overview of the new and environmentally friendly methods used for the extraction of natural bioactive compounds.

Best regards,

http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12005/abstract

Hi, ultrasonication, microwave and supercrtical fluid extraction.

I believe it is not a question of recent or "classical" method but what is your aim. SFE has been there for some time but may be limited due to availability of equipments.

If you are trying to extract novel compounds, your method might differ than if you are trying to isolate previously known compounds or to obtain active fractions that have been studied earlier.

If you are trying to obtain novel compounds, would suggest using simple extraction technique such as maceration but then study the fraction obtained using columns other than silica gel (the often preferred column).

Another point might be whether you are trying to obtain extracts for research purposes or for increase the extraction scale for commercial purposes, etc.

I agree, with Dr. Saravanan Dharmaraj's answer.

Best regards,