Natural azadirachtin composition

Details Natural azadirachtin composition Natural azadirachtin composition

2001-03-16

2004-05-11

Witz, Jean C. (Department: 1651)

Drug, bio-affecting and body treating compositions

Plant material or plant extract of undetermined constitution...

Containing or obtained from azadirechta

C424S756000

Reexamination Certificate

active

06733802

ABSTRACT:

BACKGROUND OF THE INVENTION
Many insecticidal formulations are available, some containing naturally occurring insecticidal active agents, or derivatives thereof, such as azadirachtin.
However, those formulations invariably contain synthetic active agents, synthetic inert ingredients and/or long-lived or toxic organic solvents. Also, many of the extraction methods to obtain a naturally occurring insecticidal agent rely on such synthetic reagents. Hence, solvent residues and residual amounts of those synthetic solvents and reagents remain in the extract.
All of those synthetic reagents contribute to the overall toxicity of the formulation. Many of the formulation ingredients have a detrimental environmental effect.
SUMMARY OF THE INVENTION
An object of the instant invention is to provide an insecticidal formulation made solely of naturally occurring, plant-derived, biodegradable ingredients.
Another object is to provide a formulation of high azadirachtin content, free from aflatoxins and synthetic solvents, surfactants, stabilizers and the like commonly used in pesticidal formulations.
Those and other objects have been attained in the discovery and development of naturally occurring reagents for use in an azadirachtin insecticidal formulation, wherein the components generally are plant-derived and are biodegradable, and are prepared in a manner wherein the amount of synthetic reagents found in the final formulation can be essentially zero.
DETAILED DESCRIPTION OF INVENTION
As used herein, “natural”, is meant to indicate that a compound is found in nature. Generally, that natural compound is “plant-derived”, that is, obtained from a plant, and is biodegradable. That is to distinguish a reagent of interest from one which is made synthetic, that is, a compound which is man-made, or one with a negative environmental effect. The instant reagents and compositions of interest generally are devoid of such synthetic reagents, as determined using known diagnostic assays or bioassays, such that a synthetic is present at levels below the normal level of detection for the method used or the level of synthetic is not statistically different from the determined background level.
The insecticidal active agent of interest is a naturally occurring compound such as azadirachtin. Preferably, the extracted azadirachtin is in solid form. The purity of the solid azadirachtin can vary but compositions of high purity are desirable. The final formulation of interest can be a product having about 15% azadirachtin, possibly about 10%, about 5% or even about 2% or 1% active agent. (Unless indicated otherwise, percentages are provided in terms of a w/w relationship, generally in terms of the final composition.) Formulations having as little as about 0.2% active agent are effective. The concentration of the active agent will depend on whether the product is a concentrate for dilution by the end user or is a formulation ready for application without any further manipulation.
Methods for obtaining a solid azadirachtin composition are known and the artisan is directed to, for example Shroeder & Nakanishi, J. Nat. Prod. 50:241-284, 1987; “Neem-A Tree for Solving Global Problems” National Academy Press, Washington, D.C., 1992; U.S. Pat. No. 5,001,146; and U.S. Pat. No. 4,946,681.
A suitable process for extracting azadirachtin is one in which the product contains about 10%-25% azadirachtin, which can be purified further to a level of 40% or greater. The product containing 10%-25% azadirachtin can be identified as, “technical”, azadirachtin.
Another feature of the instant invention is a process for obtaining a surface active agent from certain plants. That surface active agent can be identified under a variety of different names, such as emulsifier, surfactant or detergent. The basic principle behind the plant-derived surface active agent of interest is that said agent reduces surface tension when dissolved in an aqueous medium or which reduces interfacial tension between two liquids or between a liquid and a solid. Emulsifiers, detergents and surfactants are operate on that same basic chemical mechanism, the nomenclature varies chiefly in the nature of the surfaces involved. Another acceptable term is a colloid.
For example, saponins, a plant glycoside which on shaking with water forms colloidal solutions giving soapy lathers, and sapogenins are suitable plant-derived surface active agents which are useable in the practice of the instant invention. The saponins commonly are grouped into two categories, the triterpenoid and the steroid saponins. Either can be used in the practice of the instant invention.
The plant parts, and particularly the fruit of a plant of the genus of Saponaria, Quillaja, Chlorogalum and Sapindus, commonly known as soapnut, can be used to obtain suitable surface active agents.
Also, known compounds with an emulsifying activity, such as lecithin, and other amphipathic compounds can be used in the practice of the instant invention. A suitable source of lecithin is soy beans.
Surface active agents not of plant origin can be used in the practice of the instant invention. A number of suitable surface active agents which are commercially available can be used. For example, those compounds known as Tritons (various polyoxyethylene ethers), Tweens (various polyoxyethylenesorbitans), Brij's (various polyoxyethylene ethers) and Spans (various sorbitan esters) can find use in the instant invention. Those surface active agents do not have a negative environmental impact at the levels used in the instant invention.
At least about 10% of the final formulation comprises a surface active agent, however, that amount can be increased depending on the product, whether a concentrate or an end use product. Thus, the concentration of surface active agent can approach about 50% by weight of the final product. A preferred amount in a concentrate is about 25% to about 20% to about 15%. Either a single species of surface active agent or a plurality of surface active agents can be used so long as the aggregate amounts abide by the amounts recited hereinabove.
Some of the surface active agents of interest for use in the instant invention are the saponins and sapogenins of various plants. They can be obtained from, for example, the fruit of, for example, Sapindus trifoliatus. Dried fruits of Sapindus trifoliatus are decorticated and the seed removed. The rind is pulverized to yield a coarse powder. The coarse powder is extracted with a lower alcohol, such as methanol, ethanol, isopropyl alcohol and the like, preferably the alcohol is a C1-C5 monohydroxylated alcohol. Isopropyl alcohol is a preferred alcohol. A ratio of about 1:2.5 by weight of coarse powder to alcohol is maintained.
The mixture is agitated and maintained at temperature of about 70-75° C. over a period of about 4 hours to extract the surface active agents. The mixture is cooled to ambient temperature and the solids and liquids are separated by filtration or any other known means. The liquid phase is collected and concentrated by evaporation or more quickly under vacuum to provide a soapnut concentrate. The resultant concentrate is dried, for example, in a vacuum shelf drier at about 60° C. for about 4 hours. The product obtained is pulverized and stored in air tight containers since it can be hygroscopic and can tend to cake.
The formulation of interest optionally can contain antioxidants. Suitable antioxidants are for example, vitamin C, tocopherols, grape seed oil and so on. A preferred antioxidant is plant-derived. A suitable source of an antioxidant is a plant of the genus Zingiber, such as Zingiber officinale, or a plant of the genus Curcuma, such as, Curcuma longa.
Generally, when used, about 20% of the formulation comprises an antioxidant, but lower amounts, such as about 5%, about 3% and as low as about 0.5% can be used. A suitable amount is about 10%. Moreover, a plurality of antioxidants can be used, so long as the aggregate amounts of antioxidants are as provided hereinabove.
An extract of Curcuma longa and Zingiber officinale can be made

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