SPECIFIC DELIVERY OF NITRIC OXIDE

IN PHARMACEUTICAL USE

TECHNICAL FIELD

The present invention generally relates to nitric oxide releasing pharmaceutical compounds. More particularly, the present invention relates to pharmaceutical compositions that release nitric oxide under physiological conditions. Specifically, the present invention relates to pharmaceutical compounds that are biodegradable, lipophilic, insoluble amine esters that have been reacted with nitric oxide. The present invention also relates to a method for the synthesis of such amine esters, as well as the use of such compositions in pharmaceutical applications.

BACKGROUND OF THE INVENTION

Recent research has discovered the ubiquitous synthesis and use of nitric oxide (NO) throughout the biological systems of animals. For example,

NO has been found to play a role in blood pressure regulation, blood clotting, neurotransmission, smooth muscle relaxation, and immune systems. For example, within the immune system, NO is believed both to inhibit key metabolic pathways, thereby inhibiting tumor growth, and to serve as an outright toxin that can be used to kill cells.

Furthermore, NO has been found to be a potent vasodilator within the bronchial circulation system of the lungs and is believed to play an important role in regulating pulmonary circulation. NO is also believed to relax the muscles within lung airways, thereby regulating breathing.

It is thus believed that the insufficient production of NO within various biological functions results in deleterious effects as manifested in various immune deficiencies, asthma, bacterial infections, impotence, and high blood pressure, to name a few. From a pharmacological standpoint, the delivery of NO to the body may serve as a remedy for ailments caused by the insufficient production of NO within the body.

Nitric oxide, however, as it is used within the enumerable biological functions of animals, is highly controlled and regulated because excess amounts of NO can be hazardous to living animals. For example, the introduction of NO into the blood stream can cause the irreversible lowering of blood pressure, ultimately leading to death. Thus, the introduction of NO into the body is not the simple solution to the effects caused by insufficient NO production within the body.

There are known pharmaceutical compositions capable of delivering NO. Namely, Keeffer ef al, U.S. Patent No. 5,039,705, teaches pharmaceutical compositions of the formula

wherein R, and R ₂ are independently chosen from straight chain and branched chain alkyl groups of 1 to 12 carbon atoms or benzyl, with the proviso that no branch occur on the alpha carbon of the alkyl groups, or R ₁ and R ₂ together with the nitrogen atom they are bonded to form a pyrrol idino, piperidino, piperazino or morpholino ring, M ⁺ is a pharmaceutically acceptable cation, wherein x is the valence of the cation. Because this particular compound is a salt, the preferred method of administering this compound to animals is through injection into the bloodstream. It is also noteworthy that this particular compound is highly soluble in biological fluids thereby quickly releasing the NO which is loaded to the molecule.

Also, Keeffer ef al, U.S. Patent No. 5,366,997, teaches a similar pharmaceutical composition of the formula

R1 R2— N-N— »-0

N-OFfe

wherein R, and R ₂ are independently chosen from C-. ₁₂ straight chain alkyl, C,. ₁₂ alkoxy or acyloxy substituted straight chain alkyl, C ₂ . ₁₂ hydroxy or halo substituted straight chain alkyl, C ₃ . ₁₂ branched chain alkyl, C ₃ . ₁₂ hydroxy, halo, alkoxy, or acyloxy substituted branched chain alkyl, C ₃ . ₁₂ straight olefinic and C ₃ . ₁₂ branched chain olefinic which are unsubstituted or substituted with hydroxy, alkoxy, acyloxy, halo or benzyl. R, and R ₂ can also comprise various heterocyclic ring molecules as described therein.

It should be appreciated that the molecules as taught by Keeffer ef al are soluble within body fluids. Chemistry dictates as much, as do the teachings of Keeffer ef al as it is recommended to administer these drugs intravenously. It should further be appreciated that upon the intravenous introduction of these chemicals to a living animal, NO will be introduced throughout the body as the soluble compound disseminates throughout the body. As discussed above, unwarranted or overexposure of NO can have many harmful effects on living animals.

Thus, there is a need for a pharmaceutical composition capable of the site specific delivery of NO within living animals.

SUMMARY OF THE INVENTION It is, therefore, a primary object of the present invention to provide a pharmaceutical composition of matter that releases nitric oxide under physiological conditions.

It is another object of the present invention to provide a pharmaceutical composition of matter that releases nitric oxide to the specific area within the body where it is introduced without disseminating uncontrollably throughout the body.

It is yet another object of the present invention to provide a pharmaceutical composition of matter that releases nitric oxide, and following the release of nitric oxide preferably biodegrades into naturally occurring compounds.

It is yet a further object of the present invention to provide a pharmaceutical composition of matter that releases nitric oxide whereby the rate of release is preferably slowed to provide extended nitric oxide dosage.

At least one of the foregoing objects of the present invention, together with the advantages thereof over existing pharmaceutical compositions which shall become apparent from the specification that follows, are accomplished by the invention as hereinafter described and claimed. In general, the present invention provides a pharmaceutical composition of matter that releases nitric oxide when introduced to physiological mediums comprising: a NONOate, wherein the NONOate is insoluble in physiological mediums.

The present invention also provides a method of synthesizing a NONOate comprising the steps of: reacting an acyl chloride with an alcohol to form an acrylate; reacting the acrylate with an amine having at least one terminal amine group to form an amine ester derivative; and reacting the amine ester derivative with nitric oxide to form a NONOate.

The present invention further provides a method of providing nitric oxide to a specific area of the body comprising the step of delivering a composition of matter to a specific area of the body, the composition of matter comprising a NONOate, wherein the NONOate is insoluble in physiological mediums.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is the mechanism believed to represent NONOate formation by the step wise addition of nitric oxide;

FIG. 2 is the mechanism believed to represent the spontaneous release of nitric oxide from a lipophilic NONOate followed by the spontaneous decomposition of the polyamine ester; FIG. 3 is a release profile for Cholesterylputreanine-NONOate in

PBS, 1 % Survanta, 5% Survanta and 10% Survanta;

FIG. 4 is a release profile for Cholesterylputreanine-NONOate in PBS, 5% Tween 20, and 10% Tween 20;

FIG. 5 is a release profile for Cholesterylputreanine-NONOate in PBS with 10% Tween 80 at pH 2.O.;

FIG. 6 is a release profile for Cholesterylputreanine-NONOate in THF pH at 1.0;

FIG. 7 is a release profile for Dicholesterylspermate-NONOate in PBS;

FIG. 8 is a release profile for Hexadecanylputreanine-NONOate in PBS, 5% Tween 20, and 10% Tween 20; FIG. 9 is a release profile for Dihexadecanylspermate-NONOate in

THF at pH 1.0; and,

FIG. 10 is a release profile for Dihexadecanylspermate-NONOate in PBS and 1 % Survanta.

PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION

The present invention is directed to a composition of matter that includes molecules that are nitric oxide (NO) donors; that is, molecules that release NO. Specifically, these molecules are amines that have been reacted with NO produce a molecule of the general formula (I)

wherein R ₁ and R ₂ are organic radicals, including nitrogen containing organic radicals. It should be appreciated that the molecule of formula (I) is an anion that is typically electronically balanced with a pharmaceutically acceptable cation to produce a stable compound or salt. Such salts are similar to those disclosed in U.S. Patent No. 5,039,705, which is incorporated herein by reference. Pharmaceutically acceptable cations refer to non-toxic cations, which are well known to those of skill in the art.

For purposes of this disclosure, those amine molecules that have been reacted with NO will be referred to as having NO loaded thereto. Heretofore in the art, those amine molecules having NO loaded thereto, as generally represented by formula (I), as well as the general NONOate formulas hereinafter described, have been referred to as 1-Substituted Diazen-1-ium -1,

2-Diolates, or NONOates. Thus, the NO donor molecules of the present invention are NONOates.

Previously known NONOates, however, are soluble in physiological mediums, and thus disseminate throughout the body once introduced therein. The NONOates of the present invention, however, are insoluble in physiological mediums. Thus, upon introduction into the body, the molecules will not rapidly be distributed throughout the body allowing for the site specific delivery of NO. For purposes of this disclosure, physiological mediums will refer to those environments found within the bodies of animals, particularly humans. Thus, physiological mediums will include aqueous mediums.

It has been found that the characteristic of insolubility derives from the chemical nature of the NONOate, and more particularly from the size and/or substituents of one or both of the organic radical groups R ₁ or R ₂ as represented in formula (I). The size of the organic radical group refers to the number of carbon atoms therein. Obviously, where R, or R ₂ is hydrogen, the complementary organic radical group should be sufficiently large to compensate for the lack of carbon atoms and render the molecule insoluble. Thus, the organic radical groups R ₁ and/or R ₂ should be sufficiently large to render the molecule represented by formula (I) insoluble. One of ordinary skill in the art, without undue experimentation, should be able to readily determine the necessary size of each organic radical group that will ultimately render the molecule insoluble. Although it should be appreciated that the size of each organic radical group can fluctuate based on the size of the other organic radical groups within the NONOate, the NONOate, as represented in formula (I), is typically rendered insoluble with a total of 8 carbon atoms, preferably with more than 10 total carbon atoms and most preferably with more than 12 total carbon atoms. Further, each organic radical group typically contains more than 2 carbon atoms and less than 20 carbon atoms, except in the case where a steroid radical is employed. For purposes of this disclosure, steroids can include any polycyclic compound having a fused reduced 17-carbon atom ring system, such as cyclopentanoperhydrophenanthrene.

It is also preferred that the NONOates of the present invention biodegrade following the release of NO, as will hereinafter be described. Even

more preferably, the NONOates of the present invention should biodegrade into substances that are naturally produced or naturally found within the biological systems of animals. For example, the presence of an ester of a carboxylic acid in one or both of the R- or R ₂ groups of formula (I) will allow the molecule to biodegrade upon hydrolysis yielding a carboxylic acid and an alcohol. A NONOate having an ester of a carboxylic acid according to the present invention is represented by the formula (II)

wherein R ₃ and R ₄ are organic radical groups and R ₂ is hydrogen or an organic radical. These organic radical groups can include nitrogen containing organic radicals. As with the NONOate represented by formula (I), the NONOate represented by formula (II) should contain a combination of organic radical groups that are large enough to render the molecule insoluble. As with the NONOate of Formula (I), one of skill in the art, without undue experimentation, should be able to determine the size of each organic radical group necessary to render the NONOate insoluble. Typically, a molecule as represented by formula (II) is rendered insoluble with 12 total carbon atoms, and more preferably with 14 carbon atoms. Preferably, this is achieved when R ₄ contains between 2 and 3 carbon atoms and R ₂ and R ₃ contain between 2 and 20 carbon atoms or steroid radicals.

Like the molecule represented by formula (I), the NONOate of formula (II) is anionic and thus should be associated with a pharmaceutically acceptable cation to create an electronically stable molecule or salt. It should be appreciated that a pharmaceutically acceptable cation can include a protonated amine or polyamine molecule, including amines similar to the amine to which the NO is loaded to form the NONOate of formulas (I) and (II). The salt resulting from the relationship between the pharmaceutically acceptable cation and the anion of the present invention is also referred to as

an intermolecular salt. These intermolecular salts can comprise the pharmaceutical composition of matter of the present invention.

In another preferred embodiment of the present invention, the molecules that form the composition of the present invention are polyamines that contain at least two amine groups that have been reacted with NO to produce a molecule of the general formula (III)

wherein R ₅ and R ₆ are organic radicals, and R ₇ is hydrogen or an organic radical. The organic radical groups R ₅ and R ₇ can include nitrogen containing organic radical groups. The size and/or substituents of the organic radical groups of formula (III) should be large enough to render the molecule insoluble. Particularly, the size of at least one of the organic radical groups R ₅ , R ₆ or R ₇ should be sufficiently large so as to render the molecule insoluble in physiological mediums. Typically, this includes a total of at least 12 carbon atoms, preferably at least a total of 14 carbon atoms and more preferably at least a total of 16 carbon atoms. Preferably R, ₀ contains between 2 and 6 carbon atoms and R ₅ and R ₇ contain between 1 and 20 carbon atoms, and may include more where a steroid radical is employed.

It should be appreciated that the preferred molecules of the present invention represented by formula (III) are zwitterions, which are molecules whose net charge is zero. Therefore, whereas monoamines are typically associated with a pharmaceutically acceptable cation to form a salt, the zwitterion is typically not associated with another molecule in a similar relationship. Nonetheless, while the preferred molecular structure for the polyamine NONOates of the present invention is that of a zwitterion, it is noted that polyamine NONOates can form intermolecular salts with cations

including protonated polyamines similar to the polyamine to which NO is loaded to form the NONOate. Thus, while it is preferred that the pharmaceutical composition of matter of the present invention include polyamine zwitterion NONOates, it can also include polyamine intermolecular salt NONOates. It should be appreciated that a more efficient delivery of NO can be achieved with the zwitterion NONOate. Zwitterion NONOates deliver twice the NO inasmuch as intermolecular salts require two polyamine molecules to deliver two NO molecules and zwitterions only require one polyamine molecule to deliver two NO molecules. Without wishing to be bound to any particular theory, the formation of a zwitterion NONOate is represented in Fig. 1. It is further believed that nitric oxide is released from the NO donor molecules the present invention according to the mechanism as generally represented in Fig. 2. It should therefore be appreciated that the present invention embodies the lipophilic, insoluble, biodegradable NO donor molecules as hereinafter described, as well as the lipophilic, insoluble biodegradable amines and polyamines to which NO is loaded to yield the NO donor molecules as hereinafter described.

It is further preferred that the polyamine NONOates of the present invention biodegrade and preferably degrade into substances that are naturally produced or naturally found within the biological systems of animals. The biodegradability of the NONOates of the present invention preferably results from the presence of an ester linkage within one or both of the organic radical groups defined as R ₅ or R ₇ in formula (III). More preferably, one or both organic radical groups defined by R ₅ or R ₇ contain an ester of a carboxylic acid, which when hydrolyzed yields a carboxylic acid and an alcohol.

Thus, in this preferred embodiment where the polyamine NONOate contains an ester of a carboxylic acid, the preferred molecule of the present invention is defined according to the general formula (IV)

wherein R ₆ , R ₈ and R ₉ are organic radicals, and R ₇ is hydrogen or an organic radical. The R ₂ and R ₄ organic radicals preferably include aliphatics, and R ₇ and R ₈ can include nitrogen containing organic radicals. The nitrogen containing organic radicals of R ₇ or R _g preferably contain less than 20 carbon atoms. For example, R ₇ can include a spermidine radical.

As with the molecules of the present that are explained hereinabove, the number of carbon atoms within at least one of the organic radical groups should be large enough to render the molecule represented by the formula (III) insoluble in physiological mediums. It should be appreciated that the necessary size of any given organic radical group is a function of the size of the other radical groups because the overall size of the molecule is typically determinative of the solubility of the molecule. Again, one of skill in the art should readily be able to determine the necessary size of each organic radical to render the molecule insoluble without undue experimentation.

Accordingly, with the goal of rendering the molecule defined by formula (IV) water insoluble, the following is preferred: R ₆ is an organic radical having at least 2 carbon atoms; R ₇ is hydrogen or an organic radical having at least one carbon atom; R ₉ is an organic radical having at least 1 carbon atoms; and R ₈ is an organic radical having at least 9 carbon atoms. More preferably,

R ₆ includes between 2 and 6 carbon atoms, R ₇ is hydrogen or an organic radical having between 1 and 6 carbon atoms; R ₉ is an organic radical having between

1 and 3 carbon atoms; and R ₈ is an organic radical having between 9 and 20 carbon atoms or a steroid radical.

In yet another preferred embodiment, the R ₇ organic radical group of formula (IV) includes an ester of a carboxylic acid. When this is the case, the molecule of the present invention is defined according to the general formula (V)

wherein R ₆ , R ₉ and R ₁₀ are organic radicals and R ₈ and R are hydrogen or organic radicals.. The R ₆ , R ₉ , and R ₁₀ organic radicals preferably include aliphatics and the R ₈ and R organic radical groups can include nitrogen containing organic radicals.

At least one of the organic radicals R ₆ , R ₄ , R ₈ , R ₁₀ and R should be of sufficient size so as to render the molecule insoluble in physiological mediums. Again, it should be appreciated that the given size of any one organic radical group will be a function of the size and/or chemical makeup of the other organic radical groups. It is, however, preferred that the organic radical R ₆ contain at least 2 carbon atoms, and more preferably contain between 2 and 6 carbon atoms; the organic radicals R ₉ and R ₁₀ , which can be the same or different, contain at least one carbon atom, and more preferably contain between 1 and 2 carbon atoms; the organic radicals R ₈ and R„, which can be the same or different, contain at least 2 carbon atoms, and more preferably contain between 2 and 20 carbon atoms, or contain steroid radicals.

As previously stated, it is preferred that the NO donor molecules of the present invention hydrolyze and yield a carboxylic acid and an alcohol. Accordingly, the carboxylic acid will preferably contain a polyamine functionality, and the alcohol, for example, will be that which is derived from the R ₈ or R organic radical groups when the molecule of formula (V) is

hydrolyzed. Because the NO donor molecules of the present invention are for pharmaceutical use, the resulting carboxylic acids and alcohols preferably should not be hazardous to the health of animals. In a preferred embodiment of the present invention, hydrolysis of the NO donor molecule will yield a naturally occurring polyamine carboxylic acid and a naturally occurring alcohol. The term "naturally occurring" refers to those polyamine carboxylic acids and alcohols that are naturally present within the biological systems of animals.

Accordingly, the NO donor molecules of the present invention can hydrolyze into polyamine-carboxylic acids having the general formula (VI)

wherein R ₁₂ and R ₁₃ are organic radicals and R ₁₄ is hydrogen or an organic radical. Preferably, R ₁₂ contains at least carbon atom, and more preferably contains between 1 and 3 carbon atoms; R ₁₃ contains at least 2 carbon atoms, and more preferably contains between 2 and 6 carbon atoms; and R ₁₄ is hydrogen or an organic radical having more than one carbon atom and more preferably between 1 and 6 carbon atoms. For example, the NO donor molecules of the present invention will hydrolyze into the naturally occurring polyamine-carboxylic acids of putreanine or isoputreanine. R ₁₂ and R ₁₃ are preferably aliphatic organic radicals, and R ₁₄ can include nitrogen containing organic radicals.

Further, the NO donor molecules of the present invention can hydrolyze into polyamine-dicarboxylic acids having the general formula (VII)

wherein R ₁₂ , R ₁₃ , and R ₁₅ are organic radicals, typically including aliphatic organic radicals. Preferably, R ₁₂ and R ₁₅ , which can be the same or different, contain at least one carbon atom, and more preferably include between 1 and 3 carbon atoms; R ₁₃ contains at least 2 carbon atoms, and more preferably contains between 2 and 6 carbon atoms. For example, the NO donor molecule of the present invention will hydrolyze into the naturally occurring polyamine- dicarboxylic acid spermic acid.

The alcohols resulting from the hydrolysis of the molecules of the present invention can be any alcohol and is preferably those which are naturally found within the body. Preferred are aliphatic alcohols having from 2 to 20 carbon atoms, as well as sterol alcohols such as cholesterol.

For example, in one embodiment of the present invention, hydrolysis of an NO donor molecule of the present invention will yield the naturally occurring products of putreanine and cholesterol. This NO donor molecule is defined according to the general formula (VIII)

In another embodiment of the present invention, the NO donor molecule of the present invention will hydrolyze into ethanol and spermic acid. This NO donor molecule is defined according to the general formula (IX)

Other examples of molecules according to the present invention that are capable of being reacted with NO to produce NO donor zwitterion molecules according to the present invention are represented in the subsequent discussion of Examples. As previously mentioned, the molecules of the present invention are

NO donors, also referred to as NONOates. These NONOates release NO in aqueous environments at physiological pH. It has been observed that the release of NO from the NO donor molecules of the present invention is a function of both pH and solubility. Furthermore, it has been observed that the release of NO from the NO donor molecules of the present invention is a function of the terminal organic radical groups such as represented by R ₈ and R„ in the general formula (V). Without wishing to be bound to any particular theory, it is believed that certain terminal organic radical groups such as the R ₈ or R„ substituents shield the NONOate from solvent, thus allowing for a more sustained acid catalyzed release of NO. In other words, because the release of NO is a function of pH, i.e. NO release increases with acidity, it should be appreciated that the lipophilicity of the NO donor molecules of the present invention serve to regulate the NO release by maintaining the molecule in a non-aqueous environment, which is typically an environment where there is minimal contact with protons. With this understanding, the molecules of the present invention can be tailored to release NO at various rates depending on the lipophilicity of the molecule. It should further be appreciated that the lipophilicity and insolubility of the molecules of the present invention control the rate or degree that the NONOate molecules will disseminate throughout the body, thereby allowing for the site specific delivery of NO.

The present invention also embodies the synthesis of lipophilic, biodegradable amine molecules capable of being reacted with nitric oxide to form the NO donor molecules, or NONOates, as described in the foregoing discussion. Particularly, this method entails synthesizing the preferred NONOates of the present invention that include ester linkages, and more specifically the esters of carboxylic acids. Generally, this method comprises the reaction of an acyl chloride with an alcohol to form an ester of a carboxylic acid, or more specifically an acrylate. This acrylate is then reacted with a polyamine having at least one terminal primary amine group. The resulting polyamine ester derivative can be reacted with nitric oxide to form the zwitterion of the present invention. Accordingly, the molecules to which NO is loaded to form the NONOate molecules of the present invention will be referred to as polyamine ester derivatives. A more detailed discussion of the method of synthesis of the NO donor molecules of the present invention is found within the Examples of the present disclosure.

The present invention also embodies a method of delivering the NO donor molecules, or NONOates, of the present invention to specific areas within the body. It should be appreciated that a variety of delivery methods and/or systems can be employed to deliver NO to a specific area of the body, and such methods and/or systems are often dictated by the exact location within the body where NO is needed. For example, one such method can comprise placing the NO donor molecule of the present invention in an aqueous solution. Preferably, a surfactant is employed to form a suspension. The method would further comprise introducing this aqueous suspension into the lungs, such as through an inhaler, for the site specific delivery of NO to the bronchial airways. In this application, the use of the pharmaceutical lung surfactant Survanta ^® , available from Ross of Abbott Laboratories, Columbus, Ohio, would be preferred. It should be appreciated that the NO donor molecules will remain in the lungs inasmuch as the molecules are insoluble and will not enter the blood stream.

In another example, a method of delivering NO to desired body tissues and organs can comprise the direct application of the NO donor molecules dissolved or suspended in a solvent or liquid. More specifically, a

common procedure in the repair of arteries includes grafting a synthetic tube to an artery to replace damaged tissue. It would be desirable to deliver NO to the area of fusion between the synthetic tube and the artery. Accordingly, an aqueous mixture or suspension of the NO donor molecules of the present invention could be employed and painted directly on the synthetic artery prior to grafting. Alternatively, the tube could be dipped in a mixture containing the NO donor molecules of the present invention. The mixture could employ solvents such as THF or ether, and such solvents would be evaporated prior to placing the tube within the body. Still another example would entail topically delivering the NO molecules of the present invention. This would entail placing the NO donor molecules of the present invention in aqueous dispersion employing an appropriate level of surfactant. The mixture could then be applied topically via a spray, as a constituent within a topical cream, or as part of a pre-medicated bandage.

Yet another example entails placing the NO donor molecules of the present invention is a tablet for oral intake. Such a delivery system would target the stomach and aid in the healing of such ailments as stomach ulcers. The bile salts encountered within the stomach would emulsify the tablet and bring the NO donor molecules of the present invention in contact with the acidic conditions within the stomach which would initiate and fully exhaust the NO release within the stomach.

In order to demonstrate a practice of the invention, NONOates as described hereinafter were prepared according to the concepts of the present invention. The examples disclosed herein should not be viewed as limiting the scope of the invention, the claims being determinative of the scope of the invention.

EXAMPLES Synthesis of Cholesterylacrylate

Cholesterylacrylate was synthesized by dissolving 10 g of cholesterol in 50 ml of benzene. A 1.2 molar excess of acryloylchloride was added to the mixture and refluxed at 80 °C for 24 hours with stirring. The reaction mixture

was allowed to cure to room temperature and the solvent removed by roto- evaporation in a room temperature water bath. The product was recrystallized twice using an ether/ethanol mixed solvent. The white solid product was isolated by vacuum filtration and dried in a room temperature vacuum oven for 18 hours. Cholesterylacrylate is represented by formula (X):

Synthesis of Hexadecanylacrylate Hexadecanylacrylate was prepared by dissolving 10 g of hexadecanol in 50 ml of benzene. A 1.2 molar excess of acryloylchloride was added to the mixture and refluxed at 80 °C for 24 hours with stirring. The reaction mixture was allowed to cool to room temperature and the solvent was removed by roto- evaporation and room temperature water bath. The product was redissolved and 100 ml of diethyl ether and extracted five times with an equal volume of 10% NaHC0 ₃ in a separatory funnel. The ether fraction was isolated and the solvent was removed by roto-evaporation at room temperature followed by vacuum drying in a room temperature oven. Hexadecanylacrylate is represented by the formula (XI):

H O I II H- C ^C _/ CH ₂ — (CH ₂ )i4— CH3 (XI)

Synthesis of Cholesterylputreanine Cholesterylputreanine (CP) was prepared by dissolving 2.0 g of cholesterylacrylate in 100 ml of THF which was then added dropwise to a five molar excess (2 g) of 1,4-diaminobutane in 50 ml of THF over an 18 hour period using an addition funnel with constant stirring by a magnetic stirrer. The reaction was stirred at room temperature for an additional four hours at which time the completion of the reaction was confirmed by H NMR. The cholesterylputreanine was separated from the diaminobutane by extraction into cold hexane, crystallized diaminobutane was separated by gravity filtration. The hexane was removed by roto-evaporation and vacuum oven dried at room temperature overnight. Cholesterylputreanine is represented by the formula (XII):

Synthesis of Dicholesterylspermate

Dicholesterylspermate (DiCS) was prepared by dissolving 2 g of cholesterylacrylate and 50 ml of THF which was added to a .05 molar amount of diaminobutane and 50 ml of THF over an 18 hour period using an addition funnel with constant stirring by a magnetic stirrer. The solvent was removed by roto-evaporation yielding a white precipitate. The solid was then dissolved in hexane and transferred to a separatory funnel. Residual diaminobutane was removed by extraction into acetonitrile which was performed in a total of three minutes. The hexane portion was subjected to roto-evaporation by subsequent

drying in a vacuum oven at room temperature overnight. Dicholesterylspermate is represented by the formula (XIII):

Synthesis of Hexadecanylputreanine Hexadecanylputreanine (HP) was prepared by dissolving 2.0 g of hexadecanylacrylate in 100 ml of THF which was then added dropwise to a 4 molar excess of 1,4-diaminobutane and 50 ml of THF over an 18 hour period using an addition funnel with constant stirring by a magnetic stirrer. The reaction was stirred at room temperature for an additional four hours at which time the completion of the reaction was confirmed by NMR. The solvent was removed as described in Example 4 and the white solid product was washed with small amounts of acetonitrile. The product was then dissolved in hexane and added to a separatory funnel and extracted five times with acetonitrile as described in Example 4. The product was then isolated and characterized as described in Example 4. Hexadecanyputreanine is represented by the formula (XIV):

Synthesis of Dihexadecanylspermate Dihexadecanylspermate (DiHS) was prepared by dissolving 2.0 g of hexadecanylacrylate in THF and proceeding as described in Exhibit 4. Dihexadecanylspermate is represented by the formula (XV):

Nitric Oxide Modification of the Molecules Synthesized in Examples

The polyamine ester derivatives synthesized above, including CP, DiCS, HP and DiHS, were modified with nitric oxide to form the following NONOates: Cholesterylputreanine-NONOate (CPNO); Dicholesterylspermate- NONOate (DiCSNO); Hexadecanylputreanine-NONOate (HPNO); Dihexadecanylspermate (DiHSNO); respectively. About .2 to about .5 grams of each of the polyamine ester derivatives synthesized above were dissolved in 80 ml of THF in a high pressure bottle equipped with a magnetic stir bar. The stirred mixture was purged with nitrogen gas and then purged with NO gas. The mixture was then brought to 70 psi of NO and left to react for 24 hours under continuous stirring. The reaction was purged with nitrogen gas and an aliquot was removed for U.V. analysis. The reaction was repeated until a maximum U.V. absorbance was achieved, which is indicative of complete NO loading to the polyamine ester derivative molecules. The NO gas was released, and the mixture was purged and flushed with nitrogen. The solvent was removed by roto-evaporation at room temperature followed by four hours in a vacuum oven set at room temperature. The sample containers were flushed with nitrogen gas and stored at -20 °C in a desiccator.

Nitric Oxide Release Profiles Using a Monitor Labs Model 8440 Nitric Oxide Analyzer, interfaced with an HP 3396 A Chromatography Integrator, the nitric oxide release from the above synthesized NONOates was measured. The analyzer was connected to a release chamber consisting of an impinger bottle that had a one-way

Teflon® stop cock valve attached in order to prevent the escape of any generated nitric oxide. Teflon® flow meters were inserted at the beginning of the circuit just before entry into the analyzer, and a helium tank with regulator was connected to the first flow meter. The release profile was performed by adding about 3 to about 8 mg of the NO donor molecules prepared above to 25 ml of phosphate-buffered saline (PBS) (pH 7.4) in an impinger bottle that was subjected to continuous stirring. Varying amounts of the lung surfactant Survanta was added to certain samples, as were the surfactants Tween ^® 20 and Tween ^® 80. Tween ^® is available from Fisher Scientific Company, Fair Lawn, New Jersey. Still in other examples, the NONOates were simply dissolved in THF. Although the NONOates are insoluble in aqueous solution, sonication pulverized the compound adequately to produce fine particles that increased the surface area of the compound allowing a suspension to form. Once the impinger bottle was assembled, it was held in a water sonicator bath and sonicated until the insoluble sample was pulverized into fine particles or an emulsion. The amount of liberated NO was determined by the daily or timely flushing of helium through the solution and into the analyzer. Typically, measurements were taken every 2-4 hours during the first 18 hours and then every 12 hours thereafter. Eventually, readings only needed to be taken every 24 hours as the end of the release profile was approached. Helium gas was flushed through the system at 12 psig and the first flow meter was set to 150 ml/min. The second flow meter was adjusted to allow maximum flow. The released data was then used to compile the release profiles represented in Figs. 3-10. The release profiles as represented in Figs. 3-10 depict NO release from the NONOates in nmol NO/mg NONOate versus time in hours.

Based on these release profiles, the half-life and % Release for each NONOate prepared above was calculated and is represented in Table I, which represents NO release in PBS at pH 7.4.

TABLE 1

Compound half-life % Release

CPNO 60 hr 3.4

DiCSNO 23 days 4.9

HPNO 81 hr 23

DiHSNO 7.1 days 7.4

This table is representative of the affect that molecular weight has on the NO release, which for CPNO was about 3.4%, yielding a half-life of about

60 hours, for DiCSNO was about 4.9% yielding a half-life of about 23 days, for HPNO was about 23%, yielding a half-life of about 81 hours, and for DiHSNO was about 7.4% yielding a half-life of about 7.1 days.

The effect that the lung surfactant Survanta has on the release of NO from NONOates of the present invention is represented in Table II where the half-life and % Release of cholesterylputreanine-NONOate (CPNO) and dihexadecanylspermate-NONOate (DiHSNO) are represented.

TABLE II

PBS 1% Survanta 5% & 10% Survanta Compound half-life % Release half-life %Release half-life %Release CPNO 60 hr 3.4 62 hr 7.4 39 hr 1.1

DiHSNO 7.1 days 7.4 8.9 days 11 no data no data

Based on the data represented in TABLE II, it is evident that the percent release increased in 1 % Survanta ^® , while the half-life did not change substantially; the CPNO having a release of about 3.4% in PBS with a half-life

of about 60 hours, and about 7.4% in 1 % Survanta ^® with a half-life of about 62 hours; the DiHSNO having a release of about 7.4 % in PBS with a half-life of about 7.1 days, and about 11% in 1 % Survanta ^® with a half-life of about 8.9 days. When the concentration of Survanta ^® was raised to 5 and 10 percent, the results were similar with decreased percent release and shortened half-life; the CPNO having a release of about 1.1 % with a half-life of about 39 hours. No data was obtained for DiHSNO.

Table III similarly demonstrates the affect that the surfactant Tween 20 has on the NO release of cholesterylputreanine-NONOate (CPNO) and hexadecanylputreanine-NONOate (HPNO) as represented in half-life and % Release.

TABLE III

PBS 5% Tween 10% Tween 20

Compound half-life % Release half-life %Release half-life %Release

CPNO 60 hr 3.4 104 hr 3.6 72 hr 3.7

HPNO 81 hr 9.5 89 hr 7.1 108 hr 2.0

For CPNO, little change was observed in percent release as the surfactant concentration was raised to 10%; the percent release in PBS was about 3.4%, in 5% Tween ^® was about 3.6%, and in 10% Tween ^® was about 3.7%. The half life increased in 5% Tween ^® and decreased in 10% Tween ^® ; in PBS, the half-life of CPNO was about 60 hours, in 5% Tween ^® was about 104 hours, and in 10% Tween ^® was about 72 hours. With HPNO, however, the percent release was about 9.5% in PBS with a half-life of about 81 hours, about 7.1% in 5% Tween ^® with a half-life of about 89 hours, and about 2.0% in 10% Tween ^® with a half-life of about 108 hours.

Finally, the affect that THF at pH 1.0 has on the NO release of cholesterylputreanine-NONOate (CPNO) and dihexadecanylspermate-NONOate (DiHSNO) is presented in terms of half-life and % Release in Table IV.

TABLE IV

Compound in THF pH 1 half-life % Release

CPNO 21 hr 20

DiHSNO 24 hr 17

As is represented in TABLE IV, at a pH of 1, the percent release of CPNO was about 20% with a half-life of about 21 hours, and for DiHSNO was about 17% with a half-life of about 24 hours. It should be understood that the NO donor molecules of the present invention are an improvement over the existing art, as are the methods of synthesizing such NO donor molecules and the methods of delivering such NO donor molecules to specific sites within the body. It should also be appreciated that the NO donor molecules of the present invention can be used in a multitude of pharmaceutical uses wherein the delivery of NO is desired.

Based upon the foregoing disclosure, it should now be apparent that the NO donor molecules, methods of synthesizing NO donor molecules, and methods of employing the NO donor molecules to deliver NO to specific sites within the body as described herein will carry out the objects of the invention set forth hereinabove. It is, therefore, to be understood that any obvious variations fall within the scope of the claimed invention and thus, the selection of specific constituent and substituents can be determined without departing from the spirit of the invention herein disclosed and described. In particular, the NO donor molecules according to the present invention are not necessarily limited to those as set forth in the Examples. Moreover, as noted hereinabove, a variety of acrylyl and polyamine compounds could be employed in the synthesis of the molecules of the present invention but the starting materials which are preferred and which are specifically represented in this specification are chosen based on their ability to generate a product capable of decomposing into natural products. Furthermore, it should also be appreciated that, while preferred, the invention should not be limited to constituents that hydrolyze and yield carboxylic acids and naturally occurring alcohols. Thus, the scope of

the invention shall include all modifications and variations that may fall within the scope of the attached claims.