Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Conjugate or complex
Reexamination Certificate
1998-08-27
2001-02-27
Tate, Christopher (Department: 1651)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Conjugate or complex
C424S405000, C514S453000
Reexamination Certificate
active
06193974
ABSTRACT:
BACKGROUND OF THE RELATED ART
Several power and effective synthetic insecticides have been used to protect food and fiber crops with varied success for many years now. More recently, there has been a great deal of controversy about the effect of these on the environment and some of the insecticides which have been in extensive use have been banned. It is likely that other insecticides could be banned but which are still in use are considered to be potentially harmful to the environment but are required to be used for lack of other alternatives.
As a result, a search has been going on for “botanical pesticides” which are environmentally friendly. These are compositions which would deter insects or other pests but would have no or minimal harmful effect on the environment, particularly to humans who sometimes are at the end of the food chain and may thus suffer bio-accumulation.
Presently an agent known to protect crops from pests is Azadirachtin which is a natural product found in the seeds of the neem tree (
Azadirachtin indica
A. Juss). This has gained a lot of importance all over the world as the most environmentally safe pesticide. The neem tree is found in great abundance in India and also is distributed in other countries like Pakistan, Bangladesh, Burma, Thailand and Malaysia and is also found in Africa.
Several Azadirachtin isomers, derivatives and related compounds have been studied. From such studies it is evident that Azadirachtin A is the most important compound which has the desired insecticidal property. Azadirachtin A has been extracted from neem seeds and is found to have an anti-feedant property (which deters insects from feeding on plants) and growth regulation potency against such pests. It is readily applied by coating seeds or by applying a spray to the crops themselves.
Various methods of extracting Azadirachtin or such similar principles have been described in Indian patents 153415, 172150, 173327, 173328, 173449, 173989, 173996, 173997 and 173998 and U.S. Pat. Nos. 4,556,562, 5,391,779, 5,372,817, 5,352,677, 5,298,251, 5,281,618, 5,229,007 and 5,124,349. Azadirachtin is a known agent, but stable Azadirachtin A has not been purified to a higher content through a process which enriches the content to about 60-75% of the total Azadirachtin content without the use of laborious columns. The commercial uses of Azadirachtin A have been based on its stability and purification and nowhere in the above patents is a process for purifying and enriching Azadirachtin A described.
U.S. Pat. No. 5,736,145, upon which the present application relies for its teaching of a successful method of extracting Azadirachtin A from neem seeds is incorporated herein by reference.
SUMMARY OF THE INVENTION
It is therefore a principal object of this invention to prepare Azadirachtin A rich extract from total Azadirachtin, with emphasis on a stable and purified form.
To achieve the objective, this invention provides a process of preparing storage stable aqueous Azadirachtin containing Azadirachtin A predominant pesticidal composition, which comprises the steps of:
diluting 50,000-100,000 ppm Azadirachtin with 25,000 to 50,000 Azadirachtin A weight/volume with ethanol water solvent in a ratio 100-70:0-30 volume/volume to 2000-40000 ppm Azadirachtin containing 1000-20000 ppm of Azadirachtin A weight/volume;
emulsifying the diluted Azadirachtin with non-ionic and non-toxic emulsifying agents as herein described in an amount ranging from 0.2 to 30% and neem oil 20-50% volume/volume;
adjusting the pH of emulsified diluted Azadirachtin to 3.5 to 6.0 by adding alkali solution; and
adding 1-2.5% of a sunscreen comprising one of p.aminobenzoic acid or its esters and 1-10% oleic acid volume/volume, to create a micro-emulsion for stabilizing the composition with a good bio-efficacy.
Preferred non-ionic and non-toxic emulsifying agents used in the process are sorbitan esters, ethoxylated and propoxylated mono or diglycerides, acetylated mono or diglycerides, lactylated mono, or diglycerides citric acid esters of mono or diglycerides, sugar esters, polysorbates and polyglycerol esters. A preferred emulsifier is polyoxyethylene sorbitan monolaurate which is sold under the name “Tween 20 (R)”
The alkali solution preferably used in the process is NH
4
OH, and the emulsifying agent preferably used is 15-25% volume/volume of the composition.
An oleic acid, preferably 1% volume/volume of the composition, is added to create a micro-emulsion for stability with a good bio-efficacy.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The step of forming neem kernels pellets involves decortication of the seed either manually or using a decorticator, i.e., a known mechanism for shelling nuts.
The extraction of 80% enriched Azadirachtin A without oozing oil is carried out using acetone and water solvent (hereinafter referred to as the “extracting agent”) in the ratio 90; 10 at 80° C. by involving multiple passes of the acetone and water solvent through the neem kernels.
This involves, for example, passing a batch of the extracting agent through the kernels and recovering it and then passing another batch of the extracting agent through the kernels again, and continuing this process until a total of 3 to 5 passes occur. The extract is filtered using an ordinary filter paper to remove clay, sand and some scum. The extract is then washed several times with dichloromethane. The dichloromethane extract is pooled, and moisture removed therefrom with anhydrous sodium sulphate. Dichloromethane is removed, distilled and recovered. Azadirachtin enriched in Azadirachtin A is stuck on the walls of the container and is scraped and collected. Dichloremethane is used in the process as it is an environmentally friendly solvent.
The process requires diluting of 50,000-100,000 ppm Azadirachtin with 25,000 to 50,000 Azadirachtin A weight/volume. The step of diluting to form an emulsion comprises adding dilutent, preferably ethanol:water in the range 100-70:0-30, and an emulsifying agent along with oleic acid volume/volume comprising from about 2,000 to about 40,000 ppm Azadirachtin comprising 1,000-20,000 ppm of Azadirachtin A weight/volume usually from about 20% to about 25% neem oil. Ethanol:water is preferably in the ratio 70:30 volume/volume.
It is highly preferred to include an emulsifying agent in the composition so that the Azadirachtin and neem oil and any other ingredients are kept uniformly distributed in the composition. The percentage of the composition which is the emulsifier normally depends on the emulsifier which is used and the emulsifying agent that is the active ingredient is used in an amount ranging from about 0.2% to about 25% volume/volume.
Preferred emulsifying agents are those normally utilized in foods, and include sorbitan esters, ethoxylated and propoxylated mono or diglycerides, acetylated mono. or diglycerides, lactylated mono. or diglycerides citric acid esters of mono. or diglyerides, sugar esters, polysorbates and polyglycerol esters. The preferred emulsifier is polyoxyethylene sorbitan monolaurate which is solid under the name “Tween 20 (R)”.
It is preferred to include oleic acid at a level for example of about 1-10% volume/volume to aid microemulsion preparation and about 1% volume/volume of a sunscreen like P. Amino benzoic acid.
The instant invention will now be described with reference to the following examples:
REFERENCES:
patent: H1541 (1996-06-01), Holla
patent: 4556562 (1985-12-01), Larson
patent: 4943434 (1990-07-01), Lidert
patent: 4946681 (1990-08-01), Walter
patent: 5001146 (1991-03-01), Carter et al.
patent: 5110591 (1992-05-01), Williams
patent: 5229007 (1993-07-01), Ellenberger et al.
patent: 5397571 (1995-03-01), Roland et al.
patent: 5420318 (1995-05-01), Lidert et al.
patent: 173327 (1994-02-01), None
Dalmia Center for Research and Development
Jain Mishrilal
Jones Jain, L.L.P.
Nirmel Chittaranjan N.
Tate Christopher
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