How do I extract quercetin, apigenin, isorhamnetin and thymol?

Dear Flurin,

It seems you want to extract flavonoids.

General procedure

As flavonoids are fat-soluble, you can use an alcohol extraction method for all of them. To do this, place the grated or crushed plants in an alcohol (methanol or ethanol).

You then filter out the insoluble particles and evaporate the alcohol.

As you can see, this requires chemical solvents and, if possible, laboratory equipment.

You would then need to purify the pure substance from the residue left over after evaporating the alcohol. This also requires specialised equipment.

Unanswered questions

I’d be happy to help you further if you tell me what you’re planning to use as the starting material, if you already know.

• Do you have access to a chemistry lab, solvents, a distiller, a chromatograph and similar equipment?
• How pure does the end product need to be, and what do you intend to use it for?

Home remedies

In principle, you can make an alcohol extract at home, and evaporation is also possible, but you cannot purify it at home.

There are other methods for purifying these substances as well; these are technically more complex but yield a higher yield and purity. As the substances are similar but not identical, you could optimise many aspects for the specific extraction if you have the technical capabilities.

Detailed procedure

Recipe for an alcohol extraction that generally extracts these flavonoids from the relevant source material:

Materials

• Plant material?
• Solvent (e.g. ethanol or methanol)
• Mortar and pestle or grinder
• Filtration material (coffee filter or fine sieve)
• Evaporator or water bath (for evaporating the solvent)

Extraction steps

1. Grinding the plant material:

Grind the selected plant material thoroughly using a mortar and pestle or a grinder to increase the surface area.

2. Mixing with the solvent:

Mix the crushed material with the solvent in a ratio of approximately 1:10 (1 part plant material to 10 parts solvent).

Leave the mixture to stand at room temperature for several hours to several days. Sometimes the mixture is also gently heated to speed up the extraction process; however, temperatures should be kept below 60 °C.

3. Filtration:

Filter the mixture through a coffee filter or a fine sieve to separate the solid material from the liquid extract.

4. Evaporation of the solvent:

Use an evaporator or a water bath to carefully remove the solvent and obtain a concentrated flavonoid extract.

Ensure that this is carried out under controlled conditions and that high temperatures are not used.

5. Purification of the extracted substance:

If necessary, further purification steps such as chromatography can be carried out to isolate the pure substance from the crude extract.

Safety instructions

Ensure you work in a well-ventilated area and, where necessary, use appropriate protective equipment (gloves, safety goggles). Handling chemical substances requires caution.

This method serves as a general guide; depending on the starting material, the steps may need to be adapted. If in doubt, consult specialist literature or seek advice from experts.