GB2352397A - Extraction of materials from plants - Google Patents

Abstract

Materials, particularly bio-active materials having insecticidal, bactericidal and/or insect repellent properties, are extracted from plants, eg of the <I>Chrysanthemum</I> family, by solvent extraction using plant-derived solvents, eg. terpenes and plant oils.

Description

2352397 Title: Extraction of Materials from Plant

Field of the Invention

This invention concerns the extraction of materials from plants, particularly bio-active materials, that is materials having insecticidal, bactericidal and/or insect repellent properties.

BackaQund to the Inventio It is known to- extract bio-active material known as pyrethruni from flowers of the plant Chrysanthemum cinerariaefolium. Pyrethrum is a mixture of substances that acts as a powerful but non-persistent contact insecticide with rapid "knowndown" effect, while being non-toxic to mammals.

The normal methods of extraction of pyrethruni are complex, multi-step processes that involve heating of organic solvents derived from petroleum, and require several stages of concentration, selective separation and refinement which are carried o ut in expensive equipment. A typical pyrethrum, extraction process involves the following steps:- 1. Flowers are gathered at full bloom 2. Flowers are dried, usually in the open air.

3, Dried flowers are transported to a central processing facility. 4. Dried flowers are ground to fine powder.

5. Ground flowers are extracted using hexane solvent at elevated temperature. 6. Hexane solvent is distilled off leaving a dark tarry oleoresin.

7. Oleoresin is refined by ftirther selective solvent extraction performed at elevated temperature to provide a light coloured liquid.

8. Refined extract is diluted using mineral oil to form a 25% (by weight) solution ready for sale and use.

2 The process produces approximately 3% by weight pure pyrethrum extract from dry flowers.

The present invention is based on a novel method of extracting materials from plants.

Summary of the Invention

In one aspect the invention provides a method of extracting materials from plants, comprising mixing plant matter with one or more solvents derivable from plants, resulting in extraction into the solvent or solvents of material from the plant matter.

The plant matter conveniently comprises flowers or flower heads (without petals), which may be in fresh- or dried condition.

The plant matter may be reduced to smaller pieces for processing, eg by cutting, shredding or grinding.

The solvent or solvent mixture conveniently comprises one or more terpenes (including sesquiterpenes, diterpenes and higher polymers and various oxygen-containing compounds from terpenes, such as alcohols, eg terpineol, ketones and carnphors) and plant oils eg rosemary oil and lavender oil. Currently preferred plant solvents include the terpenes terpineol, D-limonene, (x-pinene, P-pinene and mixtures thereof, eg a mixture of equal parts by weight of terpineol and D-limonene.

The mixture is preferably agitated or stirred, desirably in a way that reduces the size of pieces of the plant matter to expose a greater surface area of plant matter to the solvent and increase the speed of the extraction process. This is conveniently achieved using a mechanical macerating mixer. Extraction starts to occur relatively rapidly (within a few minutes) even at ambient temperature (about 20'Q and occurs more rapidly with heating, and is typically complete within about 10 minutes even at ambient temperature. Heating, however, is not currently favoured as this may cause evaporation of one or more bio-active ingredients of the material, reducing efficacy of the product.

3 After extraction, the residual solid plant matter is preferably removed, eg by filtration, leaving solvent having dissolved therein extracted plant material.

The solvent may be-removed or reduced in amount, eg by evaporation or distillation.

The method is applicable to a range of plants, particularly those containing extractable bioactive materials having insecticidal, bactericidal and/or insect repellent properties. In particular the method is applicable to plants of the Chrysanthemum family, especially Chrysanthemum cinerariaefolium (for extraction of pyrethrurn as discussed above), marigold plants and also Leucanthemum vulgare (commonly known as the Oxeye daisy) (for extraction of a novel bio-active material as described in a co-pending patent application filed on the s ame dae as the present application under the reference C I 313.00/P).

The materials extracted by the method of the invention can find use as bio-active materials, particularly as insecticides, bactericides and/or insect repellents.

In a further aspect the invention thus covers material extracted by the method of the invention.

The extracted material can be used as an ingredient of a composition, particularly a composition having insecticidal, bactericidal and/or insect repellent properties.

Another aspect of the invention thus provides a composition comprising material extracted by the method of the invention.

In a simple case, the composition may comprise extracted plant material in the solvent or solvents used for the extraction process, as discussed above. As the solvent is plant-derived, the composition may be fully plant-derived. The solvent or solvents may be used as a carrier for the bio-active material be when formulated into a product and may be selected having regard to the intended use of the compositio. n, to impart desired properties to the composition such as odour, evaporation rate and other physical and chemical properties. Such a composition may be used as it is as an insecticide, bactericide and/or insect repellent.

4 The composition need not include solvent used for extraction purposes. Such solvent may be removed, eg by evaporation or distillation.

The composition may include optional additional ingredients selected having regard to the intended use of the composition. For example, a composition intended for use as an insecticidal or insect repellent cream, lotion, ointment, spray etc may include a base or vehicle known to those skilled in the art for such purposes.

The method of the invention can be performed simply without the need for complex, costly equipment, and can be performed rapidly and efficiently at ambient temperature (about 20'C). This thus provides benefits and advantages compared with the conventional method for extracting pyrethrum, as discussed above, which are complex, multi-step processes involving several high temperature steps.

The invention will be further described, by way of illustration, in the following Examples.

In the Examples, all percentages are by weight unless otherwise stated.

Exa=le I Material was extracted from the plant Leucanthemum vulgare in the following way.

Flowers of the plant Leucanthemum vulgare were gathered at full bloom or harvested at petal drop and dried in conventional manner. The dried flowers were mixed with terpineol (20 grains of dried flowers to 100 grams of terpineol) and the mixture ground at ambient temperature (about 20'Q in a high speed mechanical macerating, mixer with cutting head in the form of a Silverson laboratory mixer (Silverson is a Trade Mark), which acts to cut'the dried flowers into small fragments and mix them intimately with the terpineol. Within a few minutes the colour of the terpineol starts to change, becoming yellow, as a result of solvent extraction of material from the flowers. Mixing is continued until no further colour change in the terpineol is observed, ie the terpineol acquires a maximum density of yellow colour, indicating maximum extraction. This occurs after about 10 minutes. The mixer is switched off, and the resulting mixture is filtered in conventional manner to remove ground flower residue, leaving a yellow liquid comprising terpineol with dissolved material extracted from Leucanthemum vulgare.

The separated ground flower residue is rinsed with a fresh batch of terpineol to remove remaining material from the residue, and this batch of terpineol is used for extraction of the next batch of flowers.

The yellow liquid produced by treatment of the first batch of flowers as described above has bio-active properties and may be used in this form, without further treatment, on its own or as an ingredient in a composition, eg an insecticidal cream, where it will exhibit bio-active properties as described above. Alternatively, the yellow liquid may be treated to remove some or all of the terpineol, eg by heat treatment or distillation, to produce a more concentrated product. This product can again be used on its own or as an ingredient in a composition.

The process produces pure extracted bio-active material from dry flowers in an amount of about 5% by weight of the flowers.

Ex=ple 2 Material produced as described in Example 1, in the form of the yellow liquid of maximum density of yellow colour, was tested for insecticidal properties. About I grams of the liquid was placed on filter paper and allowed to age for several hours. The filter paper was then placed in a container with live flies. All of the flies died within about 4 minutes. By way of comparison, terpineol alone used in the same way under the same conditions did not kill flies.

6 Example 3

Material was produced as described in Example 1, but using D-limonene or a mixture of equal parts by weight of D-limonene and terpineol in place of terpineol. The extracted material, in the form of the yellow liquid of maximum density of yellow colour, was used as an ingredient in an insect repellent product intended for use on the skin as protection against mosquitoes and other flying insects. The insect repellent product formulation was as follow:- Extract 3.0 grams Water 47.0 grams Com Oil 47.0 grams Alginate (seaweed extract) 2.0 grams Non-ionic surfactant 1.0 grains Exmple 4 Material was produced as described in Example 1, but using D-limonene in place of terpineol. The extracted material, in the form of the yellow liquid of maximum density of yellow colour, was concentrated by evaporation of the D-limonene until no solvent remains. The vapour produced from the remaining extracted material (which is in the form of an essential oil) has bactericidal properties, eg against methicillin resistant Sta hylococcus aureus, Burkholderia cepacia and Escherichia coli. Tests were carried out in a Petri dish at an appropriate temperature for bacterial culture (about 37'C).

Example 5

A comparison was made of the insecticidal efficacy of pyrethrum (in the form of a 25% solution in mineral oil) extracted in conventional manner and material extracted from Leucanthemum vulgare by the method of the invention.

The materials tested were as follows:

7 1. 25% pyrethrum solution obtained from The Pyrethrum Board of Kenya.

2. 20% solution of material prepared by the method in accordance with the invention, prepared from dried mature flowers of Leucanthemum vulgare as described in Example 1 by processing a mixture of 20 grams flower to 80 grams terpineol using a Silverson mixer.

3. 20% solution prepared as described in 2. above but using a serrated head stirrer (having a 64mm diameter serrated disc, rotating at 1000 rpm) in place of a Silverson mixer.

Equal volumes (about 0.5 grams) of the above 3 materials were placed in the centre of respective Watman No. 1 filter papers 11 cm. in diameter and allowed to settle for about 1 hour uncovered at ambient temperature (about 20'C). The resulting colours on the filter papers were as-follows:- 1. medium red/brown 2. stronger red/brown 3. very little colour, indicating less effective extraction of active material.

No significant chromatographic separation of any of the samples on the filter papers occurred during this time.

Efficacy tests were carried out by placing a respective inverted glass jar or beaker over each filter paper and placing two live flies of similar type in each container at various different times after the start of the tests. The tests were started about I hour after placing of samples on the filter papers. The effect of the materials on the insects with time was observed, with the time (in minutes) taken for the flies to die or become moribund being noted. Test results for the three different materials, using the same identification numbers as above, were as follows:- 8 Time of day Material I Material 2 Material 3 11 am 7 1) 5 noon 7 2 no effect 2pm 3 3 no effect 4pm 5 5 no effect 2am (next day) 10 12 no effect The following remarks and observations are offered.

1. Sample 2 (prepared in accordance with the invention) showed more effective results compared with- sample I (pyrethrum) at early stages of the tests. At later stages these two samples gave similar results.

2. The early higher efficacy of sample 2 as compared with sample 1 indicates the presence of a more volatile bio-active component in sample 2 as compared with sample 1.

3. Sample 3 gave poor results after 1 hour from start of the tests. This indicates that sample 3 contains mainly terpineol and very little extracted active material. This indicates that the solvent component of samples 2 and 3 is not effective against the flies, and that also it is preferred to use a Silverson mixer for extraction.

4. During the test period the colour of samples I and 2 gradually faded. At the end of the test sample 2 was pale yellow and sample I was a darker yellow/brown.

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Claims (13)

Claims

1. A method of extracting materials ftom. plants, comprising mixing plant matter with one or more solvents derivable from plants, resulting in extraction into the solvnt or solvents of material from the plant matter.

2. A method according to claim 1, wherein the plant matter comprises flowers or flower heads, in fresh or dried condition.

3. A method according to claim I or 2, wherein the plant matter is reduced to smaller pieces for processing.

4. A method according to claim 1, 2 or 3), wherein the solvent comprises one or more terpenes and/or plant oils.

5. A method according to claim 4, wherein the solvent comprises terpineol and/or Dlimonene.

6. A method according to any one of the preceding claims, wherein solvent extraction is carried out at ambient temperature.

7. A method according to any one of the preceding claims, wherein solvent extraction is carried out in a mechanical macerating mixer.

8. A method according to any one of the preceding claims, wherein after extraction residual solid plant matter is removed, leaving solvent having dissolved therein extracted plant material.

9. A method according to claim 8, wherein after removal of residual solid plant matter, solvent is removed or reduced in amount.

10. Material extracted from a plant by the method of any one of the preceding claims.

11. A composition, comprising material according to claim 10.

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12. A composition according to claim 11, further comprising one or more solvents used for extraction of the material.

13. A composition according to claim I I or 12, in the form of an insecticidal, bactericidal or insect repellent composition.