Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
2001-12-10
2004-03-09
Metzmaier, Daniel S. (Department: 1712)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C516S076000, C424S761000, C514S453000, C514S938000, C106S504000
Reexamination Certificate
active
06703034
ABSTRACT:
BACKGROUND OF THE INVENTION
The Indian Neem Tree (
Azadirachta indica
A. Juss) has been recognized as a promising source of a plurality of biologically active chemicals, finding applications in diverse areas of utility to mankind. Neem Oil is obtained mainly from its seeds and may be obtained by press or solvent extraction from Neem seeds/kernels. Neem Oil consists primarily of fatty acids and meliacins. The latter, in particular, have been established to be bio-active. The principal meliacin, azadirachtin-A, has been reported to be present in different oils ranging from non-detectable to about 2500 parts by weight per million parts of the oil.
Neem Tree derivatives are used widely in agriculture, consumer products, human and veterinary medicine, insecticides as well as other areas. Derivatives from the Neem Tree have been shown to rejuvenate, detoxify and purify the skin of humans. For example, Neem Oil derived from Neem leaf and Neem bark have been reported to be effective for treatment of cuts, bruises, skin disorders and acne, and as a cosmetic to remove skin blemishes. Neem Oil also has a large number of medical applications and is reportedly effective for treating psoriasis. It has been shown to be antimalarial, antitubercular, antiviral, antiallergic antigingvitic, antiperiodonitic antiseptic, antimicrobial and antihyperglycemic. Neem Oil has been shown to be an effective analgesic, especially for earaches and headaches. It is also effective in controlling diabetes. Neem leaf is regarded as a traditional herb for treating diabetes and has been specifically proven to be effective in preventing and treating diabetes.
Neem Oil has been reported to be an effective insecticide. Entomologists have isolated approximately 390 different insect species that are controlled by the bio-activity of chemicals described from the Neem Tree. Several of these insect species are resistant to chemical pesticides or are inherently difficult to control. However, as the chemical composition of the meliacins of Neem Oil are extremely complex, thus far there are no recorded cases of insect pests having developed a resistance to Neem Oil.
When ingested by insects, Neem Oil creates hormonal disruptions which prevent the insect from feeding, breeding or metamorphosing. As a pesticide, the United States EPA has exempted Neem Oil from the requirement of tolerance (Federal Register: Dec. 13, 1995, Volume 60, number 239).
The main active ingredient of Neem Oil, azadirachtin, exhibits antifeedant, insect repellent and insect sterilization properties. It is potent at quantities as low as 1 ppm which can repel certain insects. Neem Oil interferes with ecdysone, the key insect molting hormone and prevents insect larvae and pupae from completing the molting process.
Insects treated with azadirachtin during the larval and pupal stages, which comprise approximately 60-70% of their lives, generally die within 3-14 days. Unlike chemical insecticides em Oil works on the insect's hormonal system, not on the digestive or nervous system. Accordingly, Neem Oil does not lead to development of resistance in future insect generations and is recognized as an effective insect antifeedant and repellent. But better results can be obtained by using all meliacins together. A kind of synergistic effect is obtained whereby one component strengthens and increases the working of another.
Neem Oil has also been shown to be a useful lubricant and fuel additive. For consumer applications, Neem Oil is used in various toiletry preparations such as soaps, shampoos, dental and mouth hygiene items, cosmetics, and other personal care products.
Neem Oil can be dispensed directly or incorporated into various products. Neem Oil is generally used either in a solution, in an organic solvent or in various forms of dispersions, such as emulsions, suspensions, etc. The direct use of Neem Oil poses problems of non-uniform distribution. The use of organic solvents, besides being costly, can introduce fire and the toxicity hazards. Moreover, currently used dispersions are usually unstable. For example, a typical Neem Oil emulsion may have an average particle diameter in the range of 0.2 to 50 micrometers (&mgr;m). These emulsions quickly separate into the Neem Oil and the aqueous phases upon standing, often in periods measured in hours.
Thus, a need exists for alternative methods of dispensing oils such as Neem Oil for various applications such as soaps, shampoos, cosmetics and other personal care products, medical and public health products, pesticidal sprays and fertilizer coats.
The development of microemulsion technology has enabled formation of improved dispersions for some materials. Microemulsions are thermodynamically stable dispersions of one liquid phase into another, stabilized by an interfacial film of surfactant. This dispersion may be either oil-in-water or water-in-oil. Microemulsions are typically clear solutions, as the droplet diameter is approximately 100 nanometers or less. The interfacial tension between the two phases is extremely low.
Emulsions (or macroemulsions) are in contrast unstable. The suspended droplets will eventually agglomerate and the dispersed phase will phase separate. Emulsion droplet sizes are much larger, typically one micron or more, resulting in a cloudy or milky dispersion. The nature of an emulsion may depend on the order of mixing of the ingredients and the amount of energy put into the mixing process. The final microemulsion state will not depend on order of mixing, and energy input only determines the time it will take to reach the equilibrium state. There have been limited efforts to develop Neem Oil dispersions, including microemulsions. For example, U.S. Pat. No. 5,110,591, to Williams, discloses a concentrated water-in-oil Neem Oil microemulsion containing a pesticidally effective amount of azadirachtin formed as a concentrated emulsion. Upon dilution with water, the concentrate forms storage stable oil-in-water emulsions. In U.S. Pat. No. 5,792,465 to Hagerty, microemulsions containing insecticides or other insect control agents including Neem Oil, and methods for their use are disclosed. The disclosed microemulsions have above 20% hydrocarbon, and use less than about 7.5% emulsifier, weight by weight of the final product. The microemulsions can be delivered in aerosol form using a hydrocarbon propellant. Although both of the above patents describe oil dispersions, each employ a complex surfactant system and/or alcohols as a co-surfactant and are accordingly complex and expensive to prepare as well as potentially harmful to the environment.
It is desired to develop a Neem Oil microemulsion which is co-surfactant and alcohol free. In addition, it would be desirable to develop a Neem Oil microemulsion that is simpler, safer and more environment friendly.
SUMMARY OF THE INVENTION
A method of forming an oil in water microemulsion includes the steps of providing at least one non-ionic ethoxylated surfactant, providing an oil and mixing the surfactant and the oil to form a microemulsion. The surfactant can be a single surfactant. The oil in the microemulsion can vary from 0.001 to 5%, weight by weight of the final product (w/wf). The oil droplet size can range from approximately 5 nm to 80 nm. The microemulsion may be used for a variety of applications, such as cosmetics, toiletries, paints, varnishes, agrochemicals, medicines and pesticides.
The surfactant can be selected from the group of alkyl phenol ethoxylates, where the alkyl group contains 8 to 12 carbons and the ethoxylate contains an average of 4 to 12 ethoxylate groups. The surfactant can be a nonyl phenol ethoxylate.
The surfactant can be a mixed surfactant. In one embodiment, the surfactant includes nonyl phenol ethoxylate and an ionic surfactant. In this embodiment, the ionic surfactant can be alkyl benzene sulfonate and the surfactants comprise 0.003 to 25% w/wf. The surfactant to oil ratio in this embodiment is preferably at least 3:1. The mixed surfactant can also include at least one alkyl alcohol having 1 to 7 carbons.
The oil
Parmar Balraj S.
Shah Dinesh O.
Varshney Manoj
Akerman & Senterfitt
Metzmaier Daniel S.
University of Florida
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