WO2000004781A1

WO2000004781A1 - Anti-mollusc compositions

Info

Publication number: WO2000004781A1
Application number: PCT/GB1999/000902
Authority: WO
Inventors: John Anthony Lowe
Original assignee: Gilbertson & Page Limited
Priority date: 1998-07-24
Filing date: 1999-03-22
Publication date: 2000-02-03
Also published as: GB2339693A; GB9916659D0; GB2339693B; GB9816252D0; GB2339693A8

Abstract

A mixture of saponins from two plant species, Yucca shidegra and Quillaja saponaria, shows significant synergy in anti-mollusc properties.

Description

ANTI-MOLLUSC COMPOSITIONS

The present invention relates to anti-mollusc compositions comprising mixtures of saponins.

Saponins are glycosides that occur in many plants such as soapbar , soapwort or sarasparilla. It is known that saponins derived from certain plants, such as species of Yucca and Quillaja, exhibit molluscicidal activity to terrestrial and aquatic molluscs (see, for example, US 5,290,557 and 5,698, 191 and GB 1277417).

We have now found that, very surprisingly, mixtures of saponin-containing liquid plant extracts from two particular species of plants exhibit significant synergy in anti-mollusc properties, so that the mixtures are far more effective than equivalent amounts of the plant extracts alone.

According to one aspect of the present invention, there is provided an anti-mollusc synergistic mixture of saponins derived from two different plant species, one plant species being Yucca shidegra, and the other plant species being Quillaja saponaria.

The invention also includes an anti-mollusc composition which comprises a mixture of the invention and a carrier therefor. In one particular embodiment, the invention provides an anti- mollusc composition which comprises an aqueous solution of at least two saponin-containing liquid plant extracts derived from Yucca shidegra and from Quillaja saponarla, each extract containing approximately 50% solids, and being present in an amount of from 0.1 to 10% v/v of the composition.

Mixtures and compositions of the present invention are particularly effective as molluscicides, mollusc repellants or as mollusc barriers. One advantageous property of the mixtures of the present invention is their natural "stickiness", which may contribute, at least in part, for their molluscicidal, mollusc repellant or mollusc barrier properties.

The mixtures of the invention comprise one or more saponins from each of the two species. The saponins can be pure but most preferably we use the crude or cleaned liquid extracts from the plants. Each extract will normally contain many saponins. Preferably, the crude plant extract is obtained by mechanical pressing of the plant flesh and concentrating the extract by evaporation of excess water, if necessary. A substantially pure saponin may be obtained from a crude plant derived extract by dialysis and/or dia-filtration, for example. It has been found that these processes may eliminate almost all of the extraneous material from the crude extract such as cellular debris, tannins and free sugars.

Synthetic saponins can also be used if they are identical to the naturally occurring compounds in the two plant species.

Plants of the genus Quillaja (family name Rosacea) are indigenous to Chile and Peru and are cultivated in the Indian subcontinent and elsewhere. The dried inner part of the bark of the Quillaja saponaria tree contains the colourless, amorphous saponin glycosides quillaic acid and quillaia-sapotoxin which have utility in the present invention.

Saponins extracted from the Yucca shidegra plant for use in the present invention include both steroidal and non-steroidal compounds. One commercially available source of Yucca shidegra extract is Foamation 50 (Desert King International, Chula Vista, San Diego, California) a Yucca shidegra extract having a 50% dissolved solids. A typical contents analysis for Foamation 50 is given in Example 1 herein.

Mixtures of the invention can take the form of a saponin liquid concentrate, or a solid such as a powder for example. Each saponin component of the mixture may be in a solid or liquid form. The mixture need not be substantially pure but may be in the form of a mixture of crude plant extracts. The crude plant extract mixture may be a solid such as a powder, a liquid, or a liquid suspension of a solid in which the liquid fraction of the mixture is one saponin component of the mixture and the solid is a second saponin component of the mixture.

The mixtures of the present invention may include solid, powdered or liquid Quillaja saponarla extract. We presently prefer to use the liquid extract. A liquid extract may be obtained from Desert King International, Chula Vista, San Diego, California. This has a similar solids content to Foamation 50 described above i.e. about 50% dissolved solids extract. A substantially pure saponin solution is also available from Desert King International marketed under the name Quillaia Ultra. This is a dialysed and dia- filtrated crude extract and has about 50% saponin solids, but lacks the tannins, sugars etc. found in the crude extract. Both extracts will be referred to herein as Quillaia 50, unless specifically designated "Ultra".

A presently preferred composition according to the invention is an aqueous solution comprising from 0.1 to 25% v/v Foamation 50 and from 0.1 to 10% v/v of the Quillaia 50. Most preferably the composition is an aqueous solution comprising 10% v/v Foamation 50 and 5% v/v of the Quillaia 50.

An indication of the synergistic effect of the mixture of the present invention is that 2% Foamation 50 plus 2% liquid Quillaia 50 is a significantly better mollusc barrier than 4-10% Foamation 50 alone.

The active ingredient saponins in the compositions for use in the present invention are preferably present in the range about 1 x 10^"6 % to about 20% by weight, more preferably about 0.1% or about 10% by weight, and most preferably about 5% to about 7% by weight. The lower saponin concentrations in the compositions are effective as mollusc repellants, whereas the higher concentrations show molluscicidal activity. Molluscicidal activity has been observed at saponin concentrations of about 0.1%o by weight, whereas mollusc repellant properties are realised with saponin concentrations of about 5 x 10 ³ weight %. In Foamation 50 and Quillaia 50 each have saponin contents typically in the range 5-12%. The concentration can be adjusted to suit the requirements of the mixture.

The compositions of the invention can be in liquid or dry form. For liquid compositions, the mixture component may also be a liquid. At its simplest the liquid composition can be an aqueous solution of the mixture i.e. the carrier is water. Alternatively, if the mixture component is a solid, such as a powder, the powder can be dispersed in an oil-based liquid carrier phase. The oily powder suspensions may be in a mineral or vegetable oil carrier, for example.

Liquid compositions may include a further component to prevent the composition from washing off a plant coated therewith. For aqueous compositions this component may be a gum or gum-like material. For the oily powder suspension of dry mixture formulations, the oil-based carrier may be chosen to impart the wash-resistant property to the composition.

Further components may include dispersants, preservatives such as antioxidants and anti-foaming agents.

When the composition is a solid formulation, the carrier may be a clay, for example. The solid composition can be compacted into pellets or left as a powder for depositing around plants as a repellant or as a barrier. Dry compositions may also include dispersants, preservatives and other additives.

Depending on the formulation of the composition of the present invention, and in particular the carrier used, the mode of dispensing the composition may be chosen accordingly. We presently prefer to dispense the mixture of the present invention via an aerosol, and to this end the carrier is a compressed gas. Means for dispensing a composition wherein it is a solid pellet, a liquid dispersion or suspension or an aqueous solution or suspension are known to the skilled person.

In order that the invention may be more fully understood reference is made to the following non-limiting Examples and to the accompanying drawings in which:

Figure 1 is a graph showing the results of a study of Yucca shidegra extract Foamation 50 as a mollusc anti-feedant;

Figure 2 is a graph showing the results of a further study of Yucca shidegra extract Foamation 50 as a mollusc anti-feedant;

Figure 3 is a graph showing a comparison of the mollusc deterrent action of Yucca shidegra extract Foamation 50 with mixtures of Foamation 50 and pepper oleoresin; and

Figure 4 is a graph demonstrating the synergistic effect of mixing Yucca shidegra extract Foamation 50 and Quillaia 50.

Example 1

An analysis of a 50% solids crude extract of Yucca shidegra obtained from Desert King International of Chula Vista, California is as follows: Analysis Properties

Moisture 497.5 g.kg ¹ Concentration 47.5±0.5 Brix @ 20°C

Protein 8.0 g.kg ¹ Density L l - l .2 g.kgl-¹

Fat 6.0 g.kg ¹ Colour Foamation grade R 0.7-1.0

Crude Fibre 3.0 g.kg ¹ (Absorbance of a Foamation grade 10% solution at C 0.5-0.7 520 nm) Foamation grade P 0.49 mxa

Ash 25.0 g.kg^"1 pH 3.9±0.2

Carbohydrates 459.5 g.kg^'1 Yeast <1 per ml

Mould <1 per ml

Total Plate Count <1 per ml

Shelf life 1 year @ 5-25°

The above extract has 9-1 1 % Saponins total content. As is known, the exact composition of natural extracts from the plant varies slightly throughout the year and depends on when the plant is harvested.

Example 2 An analysis of 100% powder Yucca shidegra obtained entirely from the stem of the plant and produced by mechanical, not chemical, extraction was as follows:

Analysis Properties

Moisture 60.0 g.kg^'1 Ammonia Binding B₅₀ <6.0

Protein 24.3 g.kg^"1 Unrease Inhibition I₅₀ <6.0

Fat 8.10 g.kg^"1 Saponin content >60 g.kg^"1 (1-butanol soluble method)

Fibre 247.1 g.kg^"1 Particle size 98%<60 mesh

Ash 49.4 g.kg^{" 1} Density 540-550 kg.m^"3

Carbohydrates 61 1 .1 g.kg^{' 1} Shelf Life 2 years kept dry The comments in Example 1 concerning the year-round variation in composition of the Yucca plant flesh apply equally to the dry powder extract.

Example 3

Cabbage leaves coated with a known concentration of Yucca shidegra Foamation 50 were placed in a tank housing 10 snails. The temperature of the tank was regulated to an ambient temperature of about 18-20°C. Observations were made at regular intervals during the day and night and the number of molluscs feeding on the vegetation was recorded at each observation. The experiment was repeated for each of a number of different Foamation 50 concentrations.

The results of two individual sets of experiments are shown graphically in Figures 1 and 2. In each graph, the x-axis represents the % v/v of Foamation 50 diluted with H₂0 sprayed onto the cabbage leaves in the experiment. The y-axis represents the number of feeds per tank per 25 observations of snails feeding on Foamation 50 coated cabbage leaves. A control was run in parallel to each set of experiments in which the cabbage leaves were each sprayed with water only.

Example 4

Example 3 was repeated, but in one set of experiments the Foamation 50 solutions included 100 mg/1 pepper oleoresin. The results are shown in Figure 3. In the plot the slope ratio assay indicates no difference in effect between the mollusc anti-feedant properties of a Foamation 50 solution above, or additionally including 100 mg/1 pepper oleoresin.

Thus, the addition of the pepper oleoresin did not significantly improve the effectiveness of the Yucca as a mollusc anti-feedant. Thus it is a property of the Yucca rather than an unpleasant smell/ irritant effect of the pepper oleoresin that stops the snails from feeding on the plant. Example 5 A series of experiments was carried out to show the synergism of the mixtures of the present invention. Similarly to Example 3, the experiments were carried out in a tank in which were placed ten snails and cabbage leaves as a feed source. Instead of coating the leaves with the mixtures described below, the mixtures were applied to the surfaces between the feed source and the snails. The mean number of barrier crossings by snails in the period between observations was recorded for each mixture and the results are plotted against the % (v/v) of the following saponin containing ingredients, the balance being H₂0. (i) Foamation 50; (ii) Quillaia 50; (iii) Quillaia Ultra 50;

(iv) 1% aqueous solution of each of Foamation 50 and Quillaia 50; (v) 2% aqueous solution of each of Foamation 50 and Quillaia 50; and (vi) 5% aqueous solution of each of Foamation 50 and Quillaia 50. The results are shown graphically in Figure 4. The data could be fitted to a curvilinear equation as in Figures 1 and 2. However, the straight-line technique has been used to determine the relative effectiveness of each treatment for comparative purposes. This technique is known as a slope-ratio-assay and is well recognised in the literature as a valid statistical method for the comparison of dose/response data (Finney, D.J. (1978) Statistical Method in Biological Assay. Third Edition, Charles Griffen & Co. Ltd., London UK).

From the graph it will be seen that each composition is an effective barrier (P<0.05) with the exception of the Quillaia 50. All the mixtures of Foamation 50 and Quillaia 50 or Quillaia Ultra 50 are better barriers than the theoretical additive effect of Foamation 50 and Quillaia 50 (P<0.003). A 1 % or 2% solution of Foamation 50 alone or the theoretical additive effect of a Foamation 50/Quillaia 50 mixture.

Foamation 50 is an effective anti-feedant and barrier for slugs and snails as a plant protective agent. Further, a Foamation 50/Quillaia 50 blend is a more effective barrier at lower rates of application than would be expected from adding the two together. A synergistic effect of Quillaia 50 on Foamation 50 as a barrier is demonstrated.

Claims

CLAIMS:

1. An anti-mollusc synergistic mixture of saponins derived from two different plant species, one plant species being Yucca shidegra, and the other plant species being Quillaja saponaria.

2. A mixture according to claim 1 , wherein the mixture comprises plant extracts from pressing the flesh of plants from the two species.

3. A mixture according to claim 2, wherein the plant extract is a liquid and includes approximately 50%) solids.

4. An anti-mollusc composition which comprises a saponin mixture according to any preceding claim, and a carrier therefor.

5. A composition according to claim 4, wherein the carrier is water, a mineral oil, a vegetable oil, a clay or a compressed gas.

6. A composition according to claim 4 or 5, further including a gum or gum-like component, a dispersant, a preservative, and anti-foaming agent or a mixture of any two or more thereof.

7. An anti-mollusc composition which comprises an aqueous solution of at least two saponin-containing liquid plant extracts derived from Yucca shidegra and from Quillaja saponaria, each extract containing approximately 50% solids, and being present in an amount of from 0.1 to