Drug – bio-affecting and body treating compositions – Plant material or plant extract of undetermined constitution... – Containing or obtained from azadirechta
Reexamination Certificate
2000-04-07
2002-01-22
Lankford, Jr., Leon B. (Department: 1651)
Drug, bio-affecting and body treating compositions
Plant material or plant extract of undetermined constitution...
Containing or obtained from azadirechta
C424S776000, C424S405000, C514S453000, C514S023000, C514S053000, C514S054000, C514S057000
Reexamination Certificate
active
06340484
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to compositions containing neem seed extracts such as azadirachtins. The present invention further relates to methods to prepare a stabilized pesticide composition containing neem seed extracts.
Extracts of various parts of the neem tree (
Azadirachta indicia
) such as leaves, bark, seeds, etc. have been long known to have insecticide activity. The seed kernel, in particular, processes the most active limonoids, such as Azadirachtin A and B and structurally related compounds such as C, D, E, F, G, H, I, J, K, and the like, along with nimbin, salannin, azadiradione, and the like. All the natural azadirachtins have reported a very high growth disturbing activity against
Epilachna varivestis
, with LC
50
s in the range of 0.3 to 2.8 ppm (H. Rembold and I. Puhlmann, 1995). More than 100 terpenoid metabolites are reported from the neem seed/fruit of the neem tree. Various methods have been described to extract these active components in the crude or semi crude forms to be used in commercially acceptable vehicles in the form of liquid and solid formulations. The crude neem seed extracts obtained, after removal of lipid components, normally contain about 20-45% by weight of Azadirachtin A and B and have been shown to be potent insect growth regulators and feeding deterrents and are potential active ingredients in commercial pest control formulations. The active molecules, however, of the neem seed extracts are rather large and complex, and having acid and base sensitive functional groups, they tend to be unstable in these vehicles thus posing a major limitation for commercial use of these extracts.
So far azadirachtin has been widely formulated in liquid forms to be applied as an emulsion or solution to agriculture crops. Various organic solvents and other inorganic additives have been used as carriers in order to make a cost effective and efficacious delivery system. The use of such carriers is rather limited, however, since many solvents are deleterious to the stability of azadirachtin. Dureja (1999) has studied the degradation of azadirachtin A in various solvents for 25 days at 29+/−1° C. The results indicated 50% degradation of azadirachtin A in methanol and acetone, 75-80% degradation in methylene chloride, carbon tetrachloride and chloroform, and about 85% degradation in ethanol and water.
Storage-stable azadirachtin formulations and methods of preparing stable azadirachtin compositions have been proposed. U.S. Pat. No. 4,556,562 reports that the stability of azadirachtin in ethanol emulsions increased by diluting the concentration of azadirachtin to between 2000 and 4000 ppm and adjusting the pH to between 3.5 and 6.0. U.S. Pat. No. 4,946,681 (Walter) reports greater stability for azadirachtin in solutions of aprotic solvents containing less than 2-5% of water. U.S. Pat. No. 5,001,146 indicates that azadirachtin stability is improved by adjusting the concentration of the polar aprotic solvent to at least 50% by volume and by decreasing the water content to less than 15% by volume. Moreover, U.S. Pat. No. 5,001,146 further indicates that azadirachtin stability depends upon the type of solvent employed, and that stability requires storage in large quantities of certain enumerated aprotic and alcohol solvents. Murali (U.S. Pat. No. 5,736,145) reports a storage stable aqueous composition containing azadirachtin A and U.S. Pat. No. 5,827,521 indicates a stable azadirachtin formulation containing aliphatic dihydroxylated alcohols of more than 80% by volume and optionally with sunscreens and antioxidants.
U.S. Pat. No. 5,352,697 describes the stability enhancement of azadirachtin in solution by the presence of epoxide, preferably an epoxidized vegetable oil. These methods describe the enhancement of azadirachtin containing extracts in the liquid form prepared from neem seed kernel with organic solvents.
European Patent No. 579,624 describes making an extract of neem seed in solid form with greater stability. The stability of azadirachtin in neem extracts is reported to be improved by removing the lipid impurities from extracts (India Patent Application No. 1855). Walter (U.S. Pat. No. 5,635,193) reports that an azadirachtin containing solid is stable by limiting moisture and volatile polar solvents to less than 1% and 5%, respectively. A formulation containing 0.05% to 2% surfactant and 99% of solid diluent has been claimed as a stable bio-control agent by retention of at least 75% of azadirachtin after 2 weeks of storage at 54° C. Such a formulation may be used as a dust and wettable powder, but the efficacy of azadirachtins in such vehicular formulations is not practically reported.
Another formulation is a solid form of neem seed extract prepared from the kernel of neem seed as per the methods described in U.S. Pat. No. 5,695,763, European Patent No. 579,624, and IN 181,845. The product is quite stable with respect to its active ingredients viz Azadirachtin A, B, nimbin, salannin, and the like.
Though various extracts with stable azadirachtin have been reported, stability of azadirachtin in a formulated state is still a concern. Azadirachtin is highly unstable in various surfactants, organic solvents, and in different combinations of solvents and surfactants in liquid formulations which is a serious limitation for the development of a shelf stable commercial product.
Normal pesticide formulations contain various solvents made mostly from petroleum, and there is a concern that usage of such solvents in specialty pesticide formulations, especially meant for organic farming, veterinary application, and the like, is discouraged. The use of such solvents, even at a lower rate, demands large amounts of surfactants and other additives which makes the cost of the formulations high.
The use of a broader range of ingredients in liquid formulations and the associated problem of instability in such formulations is also a serious concern for the commercial success of azadirachtin containing crop protection agents. Accordingly, there is still a need for a formulation containing simple, safe, and cost effective vehicles which yet provides stable and efficacious products.
As noted above, the pesticidal effect of neem active compounds, such as azadirachtins, is mostly through insect growth regulation, molting inhibition, antifeedant, ovicidal, and other physiological effects and is normally slow compared other synthetic pesticides which result in immediate knockdown. Hence, there is a need to identify ways and methods to enhance the efficacy of neem extracts for their wide spread acceptance as a pesticide.
Accordingly, there is a need to develop environmentally safe pesticide formulations which contain azadirachtin and which are further storage stable, efficacious, and economical.
The aim of the present invention is to develop a delivery system for azadirachtin containing neem seed extracts, free from any organic solvent, and which is completely soluble in water and efficacious at a dosage lower than the normal desired dose of azadirachtin containing neem seed extracts for pest control.
All of the patents and publications mentioned throughout this application are incorporated herein in their entirety.
SUMMARY OF THE INVENTION
A feature of the present invention is to provide a delivery system for neem seed extracts such as azadirachtin and the like, which is preferably free from any organic solvent and completely soluble in water.
Another feature of the present invention is to provide a neem seed extract in solid form which is stable and flowable.
An additional feature of the present invention is to provide a neem seed extract in efficacious solid form which is water soluble and thus is quite easily used to control insect pests.
Additional features and advantages of the present invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized
Damarla Sreenivasa Rao
Gopinathan Mambully Chandrasekaran
Sridhar Srinivasa
Coe Susan D.
E.I.D. Parry (India) Limited
Kilyk & Bowersox P.L.L.C.
Lankford , Jr. Leon B.
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