CA2644585A1 - Fat-trapping composition comprising an indigestible cationic polysaccharide and an emulsifying agent - Google Patents

Abstract

The present invention relates to a composition for trapping lipids or fats, thereby preventing their degradation and their absorption in the digestive tract. The fat-trapping composition of the invention comprises an edible but indigestible cationic polysaccharide (preferably chitosan) and at least one emulsifying agent (preferably a phosphoglyceride such as lecithin), associating in the stomach and forming in the intestine a matrix for entrapping fat. Further, the present invention relates to methods for treating obesity, for reducing absorption of dietary fat and for treating and/or reducing hypertriglyceridemia, by orally administering the fat-trapping composition of the invention.

Description

FAT-TRAPPING COMPOSITION COMPRISING AN INDIGESTIBLE CATIONIC POLYSACCIIARIDE
AND AN
EMUI,SIFYING AGENT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit on US provisional application 60/743,740 filed March 24, 2006 for the present invention.

TECHNICAL FIELD

[0002] The present invention relates to a composition for trapping fat in the digestive tract, thus preventing its degradation and absorption.

BACKGROUND OF THE INVENTION

[0003] During the past 20 years, obesity among adults has risen significantly.
The number of people whose body mass index, BMI, (and thus body weight) is greater than their suggested BMI is increasing, particularly in developed countries. In the United States, the latest data from the National Center for Health Statistics shows that 30% of adults who are 20 years of age and older, i.e. over 60 million people, are obese. Obese people are at a much higher risk for serious medical conditions such as high blood pressure, heart attack, stroke, diabetes, gallbladder disease, and different types of cancer than people who have a healthy weight. Environmental and behavioral factors are of great influence, as is the consumption of excess calories from high fat foods, and doing little or no daily physical activity over the long run will lead to weight gain.
In weight control programs, it is difficult to control the ingestion of fat, the subsequent digestion and absorption thereof causing weight gain and health problems.

[0004] Medications currently approved for weight loss in the United States fall into two broad categories: i) those that are aimed at decreasing food intake by reducing the appetite or increasing satiety (appetite suppressants) and ii) those that are aimed at decreasing nutrient absorption. A third category, i.e.
medications that increase energy expenditure (such as ephedrine) and other investigational compounds, is not currently approved as a treatment for obesity in the United States.

Appetite-Suppressant Medications [0005] Most appetite suppressants work primarily by increasing the availability of anorexigenic neurotransmitters notably, norepinephrine, serotonin, dopamine, or some combination of these neurotransmitters in the central nervous system.

Noradrenergic drugs [0006] Noradrenergic drugs available in the United States include phentermine, diethylpropion, phendimetrazine, and benzphetamine.
Amphetamines are no longer recommended (and are not approved for use) for weight loss because of the potential for their abuse. All of the above medications are approved by the Food and Drug Administration (FDA) for use lasting a few weeks only (generally presumed to be 12 weeks or less) for the treatment of obesity. These drugs used in combination may be just as effective as either drug alone, with the added advantages of the need for lower doses of each agent and perhaps fewer side effects. Although the combination has not been approved by the FDA, in 1996 the total number of prescriptions in the United States for fenfluramine and phentermine exceeded 18 million.

[0007] Side effects of noradrenergic medications include insomnia, dry mouth, constipation, euphoria, palpitations, and hypertension. The only over-the-counter appetite-suppressant medication approved for the treatment of obesity, phenylpropanolamine, was recently withdrawn from the market due to concern about an association with hemorrhagic stroke in women.

Serotonergic Agents [0008] Serotonergic agents act by increasing the release of serotonin, inhibiting its reuptake, or both such as Fenfluramine (Pondimin) and dexfenfluramine (Redux). These drugs were withdrawn from the market in the United States in 1997 due to their association with valvular heart disease and pulmonary hypertension. Their efficacy in controlled studies appeared similar to that of the noradrenergic agents.

[0009] Another inhibitor of both norepiphedrine et serotonin reuptake approved by the FDA for weight loss is Sibutramine (Meridia) which, unlike fenfluramine and dexfenfluramine, has not been implicated in the development of valvular heart disease. However, adverse reactions such as hypertension, dry mouth, headache, insomnia, and constipation were reported.

Nutrient Absorption reduced Medications [0010] The only FDA-approved medication for obesity that reduces nutrient absorption is OrlistatTM which acts as a gastro-intestinal lipase inhibitor preventing hydrolysis of fat (triglycerides) into absorbable free fatty acids and monoacylglycerols.

[0011] OrlistatTM might be viewed as an analog of a diuretic. The loss of calories as undigested triglycerides would be similar to the loss of sodium with diuretics. The centrally active noradrenergic and serotonergic drugs approved by the FDA for treatment of obesity may be analogous to the earlier drugs used to treat hypertension. Orlistat, found under the commercial name Xenical belongs to a new class of anti-obesity drugs. It prevents the lipolysis of dietary triglycerides (TG), and thus reduces the subsequent intestinal absorption of fat.
Human pancreatic lipase (HPL) has been the main target in the development of Orlistat. The inhibition of human gastric lipase (HGL) by Orlistat has also been investigated in vitro but studies have not yet been carried out by way of test meals. In most clinical studies, the effects of Orlistat have been estimated indirectly from the fecal fat excretion levels, but the inhibition exerted on digestive lipases and the levels of lipolysis have not been measured simultaneously in vivo. Adverse effects of Orlistat include flatulence with discharge, fecal urgency, fecal incontinence, steatorrhea, oily spotting, and increased frequency of defecation. These side effects are usually mild to moderate, and generally decrease in frequency with ongoing treatment. Orlistat also decreases absorption of fat-soluble vitamins, primarily vitamin D, an effect that can be counteracted by daily administration of a multivitamin at least two hours before or after a dose of Orlistat.

[0012] Other drugs could also be included hereafter such as statins (PravacholT"', LipitorTM, CrestorT"", etc.) used for lowering cholesterol levels.
The main activity of statins consists of inhibiting the enzyme HMG-CoA
reductase, which is the rate-limiting enzyme of the mevalonate pathway of cholesterol synthesis. Certain adverse effects were observed in some patients on statin therapy such as myalgias, muscle cramps or, far less-frequently, gastro-intestinal or other symptoms.

[0013] Recently, Pfizer has reported the failure of its cholesterol drug TorcetrapibT'", an inhibitor of Cholesteryl Ester Transfer Protein and HDL
cholesterol enhancer. Many explanations for its failure were brought forward, but the most interesting one suggested that it could be due to: i) the increase in HDL which might be less important than it seemed; ii) the side effects (i.e.
high blood pressure) which might be worse than expected, causing heart attacks;
iii) the HDL increase did not prevent heart attacks as it should have done. Then, the question Is good cholesterol always good? can be asked. Generally, the science of HDL, which may have previously appeared simple, is looking increasingly complicated.

[0014] There are many drugs on the market for the treatment of obesity which are not approved by the FDA and several have been proven to be dangerous. Historically, when dinitrophenol was first used in 1933, it resulted in neuropathy and cataracts, which led to its discontinuation.

[0015] The introduction of amphetamine in 1937 was followed by reports of addiction, a problem that has plagued all of the chemicals that are structurally similar to amphetamine, whether they are addictive or not. The use of pills containing amphetamine, digitalis, and diuretics led to several deaths in 1967, and prompted the U.S. Senate to hold hearings. In 1971, aminorex, or aminoxaphen, a new appetite suppressant, was taken off the market in Europe shortly after marketing due to an outbreak of pulmonary hypertension linked to this drug. A few years later, in 1978, seventeen deaths were reported with the use of low-calorie diets containing collagen as the principal source of protein.
The final problem has been valvular heart disease associated with the combined use of fenfluramine and phentermine.

[0016] Because of these adverse effects, there is more and more development of weight loss formulations with special attention given to natural products (free medical condition).

Herbal preparations [0017] Unlike medications, dietary supplements and herbal preparations are not prospectively reviewed for safety or efficacy by the FDA, who takes action only if a dietary supplement is shown to present a significant or unreasonable risk . Producers of a dietary supplement cannot claim that it treats a disease (including obesity), but may claim that it reduces the risk of a disease in a population.

[0018] Various dietary supplements and herbal preparations have been marketed to reduce obesity. These products have been suggested to accomplish this by decreasing energy intake and energy absorption, and/or increasing metabolic rate. From the appetite suppressants to the fat blockers, carbohydrate stoppers and fat burners, the local market is flooded with weight loss "magic capsules", both imported and locally produced. On some level, these products yield results, but chronic dieters are putting themselves at risk for health hazards and even death.

[0019] A few years after their introduction on the market, fat burners (thermogenics) continue to be all the rage, boasting a following of over 15 million men and women around the world. These fat burners include:
Xenadrine, Hydroxycut, Diet Fuel, etc., all of which are available over the counter at pharmacies.

[0020] Xenadrine is a thermogenic formula containing various important ingredients such as ephedrine, caffeine, aspirin (E/C/A) and synephrine.
Greenway (Greenway, F.L. 2001. Obes. Rev., 2, 199-211) reported that ephedrine can reduce body weight. This component is the primary active constituent of the botanical Ephedra sinica (or ma-huang, an evergreen shrub native to central Asia), which has been studied alone and in combination with caffeine. Results showed that the combination of ephedrine and caffeine is effective for reducing body weight and appears to outweigh the risks. The intake of these supplements, however, is associated with an increase in the odds of psychiatric, autonomic, or gastro-intestinal symptoms and heart palpitations.
Because of safety concerns, the FDA is now taking several regulatory actions with regard to ephedra and ephedrine-containing supplements. For Synephrine (Citrus aurantium), an alkaloid specific to the alpha1 adrenergic receptor stimulates the transport of the leptine through the encephalic barrier, thus resulting in a decrease in hunger. This combination of herbal derivatives has been investigated in certain studies and has been found to increase the rate of weight loss in subjects who have been administered the combination. While some evidence is promising, larger and more rigorous clinical trials are necessary to draw adequate conclusions regarding the safety and efficacy of synephrine alkaloids in promoting weight loss.

[0021] Hydroxycut is also a thermogenic weight loss supplement which possesses a similar formulation of Xenadrine composed of hydroxycitric acid, L-Carnitine, green tea extract, ephedrine, guaranine (caffeine extracted from guarana) and willow bark (herbal extracted from aspirin). These ingredients create a cause and effect resulting in appetite suppression and fat burning.

[0022] With respect to the Diet Fuel, it is a formulation which includes milk protein-based products (such as whey protein concentrate, whey protein isolate, calcium caseinate, egg albumen, and soy protein isolate), maltodextrin, fructo-oligosaccharides, fructose and mineral mixture of chromium, boron, selenium, etc.

[0023] Several polysaccharides have also been used as a fat trapper or fat blocker such as chitosan, glucomannan, guar gum, etc. Several authors (U.S.
Patent No. 4,223,023; Nagyvary, J.J., et al., 1979. Nutr. Rep. Int., 20, 677-684;
Nauss, J.L., et al., 1983. Lipids, 18, 714-719; Vahouny, G.V., et al., 1983, Am.
J. Clin. Nutr., 38, 278-284) reported that chitosan could be used as a fat trapper to reduce fat absorption. However, according to Pittler and Ernst (Pittler, M.H., Edzard Ernst, E. 2004. Am. J. Clin. Nutr., 79, 529-536), it has been shown that the effectiveness of chitosan for body weight reduction has not been established beyond a reasonable doubt. Overall, the evidence available in the literature indicates that there is considerable doubt that chitosan is effective in reducing body weight in humans. Adverse effects most frequently included gastro-intestinal symptoms such as constipation and flatulence.

[0024] Doi (Doi, K. 1995. Eur. J. Clin. Nutr., 49, 190-197) reported that the glucomannan can cause weight loss. The active ingredient is derived from konjac root (from Amorphophallus konjac). Its chemical structure is similar to that of galactomannan from guar gum and comprises a polysaccharide chain of glucose and mannose. The report suggests significantly greater weight loss in the treatment group than in the placebo group. There were no adverse effects in the treatment group. Independent replication of this trial is warranted (Pittler and Ernst, 2004, supra).

[0025] A dietary fiber, guar gum, derived from the Indian cluster bean (Cyamopsis tetragonolobus) was assessed as an effective agent in lowering body weight. However, Pittler and Ernst (Pittler MH, Ernst E. 2001. Am. J.
Med., 110, 724-730) showed that guar gum is not effective in reducing body weight, and adverse effects relate to the gastro-intestinal system.

[0026] Andersen and Fogh (Andersen T, Fogh J. 2001. J. Hum. Nutr. Dietet., 14, 243-250) reported that Yerba mate (Ilex paraguariensis), an evergreen tree of South America, also possesses weight loss properties. In a combination preparation also containing guarana (Paullinia cupana) and damiana (Turnera diffusa), it has been shown that this could potentially be effective in lowering body weight. Adverse effects have not been reported.

[0027] Yohimbe (Pausinystalia yohimbe) is a tall evergreen tree that is native to Central Africa. Yohimbine, an a-2 receptor antagonist, is the main active constituent of the ground bark of P. yohimbe. Most clinical studies relate to the effects of this isolated constituent of yohimbe bark. At present, therefore, it is unclear whether Yohimbine is effective in reducing body weight, and few adverse effects have been reported.

[0028] Other products were also known as reducers of body weight, such as Plantago psyllium (derived from the husks of ripe seeds from Plantago ovata), Hydroxy-methylbutyrate, pyruvate (generated in the body via glycolysis), etc.
However, according to Pittler and Ernst (2001, supra), no study of these substances has reported significantly greater effects on weight reduction.

[0029] As the pharmaceutical treatment of obesity involves the more or less successful use of appetite suppressants, these drugs tend to cause dependence and unpleasant side effects. Furthermore, these drugs do not alter unfavorable eating habits and lifestyles, and they are not approved for long-term use.

[0030] From the above, it is clear that there is still a great need for a weight loss composition that is edible, non toxic and has the possibility of long-term consumption.

BRIEF SUMMARY OF THE INVENTION

[0031] One aim of the present invention is to provide a composition for trapping lipids and excretion of lipids (one of the major causes of obesity), by preventing their degradation and absorption, resulting in excretion of same.

[0032] In accordance with the present invention there is provided a fat-trapping composition comprising:

i) an indigestible cationic polysaccharide; and ii) at least one anionic emulsifying agent, said cationic polysaccharide and said anionic emulsifying agent associating electrostatically in the stomach to form a matrix once in the intestinal tract, said polysaccharide in the presence of fat forming a complex with said fat, said emulsifying agent stabilizing said complex, preventing said fat to be released from the matrix.

[0033] Still in accordance with the present invention, there is also provided a method for treating obesity in a mammal, preferably a human, comprising the step of orally administering to the mammal an effective amount of a fat-trapping composition as defined herein.

[0034] Further in accordance with the present invention, there is provided a method for reducing absorption of dietary fat in a mammal, preferably a human, comprising the step of orally administering to the mammal a therapeutic amount of a fat-trapping composition as defined herein.

[0035] There is also provided in accordance with the present invention a method for treating and/or reducing hypertriglyceridemia in a mammal, preferably a human, comprising the step of orally administering to the mammal a therapeutic amount of a fat-trapping composition as defined herein.

[0036] A variety of polymers can be employed in the invention described herein. Preferred polymers are cationic polysaccharides. Furthermore, the polysaccharides must not be degraded or digested in the intestinal tract.

[0037] The present invention also relates to a method for treating obesity, a method for reducing the absorption of dietary fat, and a method for treating hypertriglyceridemia in a patient with the composition of the present invention.
The composition of the present invention can also be used for the manufacture of a medicament for the treatment of the above-mentioned conditions. The methods comprise the step of orally administering to a mammal, such as a human, a therapeutically effective amount of the fat-trapping composition described herein. The administration of the composition of the present invention prevents adsorption of fat from the body.

[0038] For the purpose of the present invention the following terms are defined below.

[0039] As disclosed herein, in a preferred embodiment, the fat-binding composition is administered in combination with other dietary supplements or dietary fibers, as described herein. The term "in combination" in this context includes both simultaneous and sequential administration, but preferably a sequential application where the composition is administered first. The fat-binding polymer and lipase inhibitor, when used in combination, can be employed together in the same dosage form or, as disclosed herein, preferably in separate dosage forms taken at the same time or within a certain period of time, wherein both the fat-binding composition and the dietary supplements or the dietary fibers are present in a therapeutically effective amount.

[0040] "Fat-trapping composition" or "Fat-trapping formulation", as these terms are used interchangeably herein, relates to a formulation or a composition which absorbs, binds or otherwise associates with fat thereby preventing fat digestion, hydrolysis, or absorption in the gastro-intestinal tract.

[0041] "Fats", as that term is used herein, are solids or liquid oils generally consisting of glycerol esters of fatty acids. Sources of fats include both animal and vegetable fats, for example, triglyceride esters of saturated and/or unsaturated fatty acids, free fatty acids, diglycerides, monoglycerides, phospholipids and cholesterol esters are fats, as defined herein.

[0042] As used herein, the terms "therapeutically effective amount" and "therapeutic amount" are synonymous. The terms refer to an amount which is sufficient to treat obesity, reduce the absorption of fat or treat hypertriglyceridemia. The dosage of the fat-trapper formulation to be administered to a patient will vary depending among other things on the weight of the patient, age, sex and the general health of the patient. The dosage can be determined with regard to established medical practice. The amount of fat-trapper formulation administered can be in the range of from about 0.1 g to about 30 g a day.

[0043] The fat-trapper formulation of the invention can be formulated using conventional inert pharmaceutical adjuvant materials into dosage forms which are suitable for oral administration. The oral dosage forms include tablets, capsules, suspension, solutions, and the like. The identity of the inert adjuvant materials which can be used in formulating the fat-trapper formulation of the invention will be immediately apparent to persons skilled in the art.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWING

[0044] Fig. 1 illustrates FTIR spectra of lecithin, chitosan and lecithin/chitosan complex.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0045] In accordance with the present invention, the composition aims to trap and promote the excretion of lipids such as triglycerides, fatty acids and bile acids, as well as cholesterol and other sterols. The composition consists of mixing a polysaccharide to be used as a matrix (i.e. chitosan) with an emulsifying agent entrapped therein and used as enhancer (i.e. lecithin) which present a high affinity to the various fatty matters thus increasing the lipid binding capacity of the composition. In addition, the matrix and the emulsifying agent, in the presence of a suitable gelling agent (i.e. hydroxyl citric acid sodium salt and/or xanthan gum), are able to form a stable complex which prevents the fat release from the matrix and promotes their excretion. Other dietary fibers, dietary supplements (i.e. hoodia extract) and/or additives (flavoring agent, masking agent, preservative agents, etc.) could also be added to the formulation.

[0046] Approximately 90% of the ingested food fats consists of neutral fats, known as triglycerides. The remaining 10% is made of up cholesterol, cholesterol esters, and phospholipids. It is of interest to note that about 95% of fats present in food are normally absorbed in the small intestine. To this end, the triglycerides are first broken down into free fatty acids and monoglycerides by fat-splitting lipases produced in the pancreas. The resulting monoglycerides and fatty acids combine with bile salts to form smaller, nanometersized fat droplets that permit close contact with the epithelial cells of the small intestine, thus initiating fat absorption. The approach in the present invention consists of preventing this absorption phenomenon by trapping the fat in a matrix and preventing its absorption, thus causing its excretion. For this purpose, the composition also referred to as a fat trapper in this invention includes:

= a cationic polysaccharide (i.e. chitosan) used as a matrix;
= an emulsifying agent (i.e. lecithin) used as an enhancer which can increase the fat binding capacity of chitosan in the gastric medium and also play a role in stabilizing the chitosan/fat complex during intestinal transit; and = optional additives such as dietary fibers (i.e. xanthane gum, fructose-oligosaccharide, inuline, etc.) or dietary supplements (hydroxycitric acid sodium salt or HCA extracted from Garcinia cambogia, phaseolamine extracted from white kidney bean, Phaseolus vulgaris and hoodia extracted from Hoodia gordonii, etc.).

Matrix [0047] In the present invention, the matrix is generally selected from cationic (positively charged) polysaccharides such as chitosan or other aminopolysaccharides. Chitosan is a deacetylated form of chitin, an aminopolysaccharide found in the shell of the crustacean (shrimp or crab) or the exoskeleton of the arthropod and certain fungi. Chitosan is indigestible by mammalian digestive enzymes.

[0048] Many studies have shown that chitosan possesses a clinical hypocholesterolemic effect mediated by changes in cholesterol absorption and bile acids (Gallaher, C.M., Munion, J., Hesslink Jr, R., Wise, J., Gallaher, D.D.
2000. J. Nutr., 130, 2753-2759; LeHoux, J.G. and Grondin, F. 1993.
Endocrinology, 132, 1078-1084). However, these reports remain uncertain, as no significant results have been evidenced (Mhurchu et al. 2004. Int. J. Obes.
Relat. Metab. Disord. 28, 1149-1156; Gades, M., and Stern, J.S. 2005. J. Am.
Diet. Assoc., 105, 72-77). It is of interest to mention that the chitosan tested by these authors possesses a molecular weight of about 130 kDa and a DDA of about 75%. Mechanically, for this supplement to be effective as stated, the following must be true: i) chitosan can bind some amounts of fats; and ii) the amount of fat binding and excretions can be significant and lead to weight loss.

In this context, many factors should be revised, such as for example, the fat binding capacity of chitosan to fats in the stomach, interferes with the complex chitosan/fat due to the presence of other substances (i.e. bile acids) and changes of environment (pH value, viscosity, etc.) during intestinal transit.

[0049] To come up with an explanation, analysis in the inventors' laboratory indicated several important aspects which could explain this controversy.
Anterior studies demonstrated that chitosan can bind with lipids via electrostatic interactions. However, the binding capacity of the lipids depends on the following factors:

= The molecular weight (Mw);
= The viscosity;
= The deacetylation degree (DDA);
= The mucoadhesive properties.
Molecular weight (Mw) [0050] The molecular weight of chitosan essentially plays an important role in the binding capacity of the lipids. To evidence this parameter, an experiment was carried out dispersing an amount of 1.0 g of chitosan (purchased from Marinard Biotech, Riviere-au-Renard, QC, Canada) at various molecular weights (75-1500 kDa, DDA 85%) in 94.0 g of simulated gastric fluid (pH 1.2 according to USP method 27) at 37 C. Thereafter, an amount of 5.0 g of triolein was added under agitation in order to maintain conditions imitating those in the human stomach. After 1 h, the shaker was stopped and the quantity of separated triolein was determined.

[0051] Results showed that chitosan having Mw inferior to 600 kDa presents greater quantities of separated triolein (about 95%) after a few minutes, i.e., the fat binding capacity of chitosan with low Mw was very weak. Contrarily, no important separation of triolein (approximately 10%) for chitosan with Mw superior to 600 kDa was observed.

Viscosity [0052] Certain studies reported that the fat trapping effect of chitosan observed in vitro is possibly due to the high viscosity of chitosan induced in the simulated gastric fluid. In in vivo, Deuchi et al. (Deuchi, K., Kanauchi, 0., Imasato, Y., Kobayashi, E. 1995. Biosci. Biotechnol. Biochem., 59, 781-785) reported that an increase of the viscosity or DDA of chitosan resulted in a pronounced effect on the apparent digestibility of fats. To evidence this phenomenon, a similar test was carried out as described above, i.e. mixing chitosan and triolein in 1000 mL of simulated gastric fluid (instead 100 mL).
The use of a great quantity of simulated gastric fluid results in avoiding the viscosity effect which can influence interactions of chitosan with fats (triolein).
Practically, an amount of 1.0 to 3.0 g of chitosan (Mw ~ 400 kDa and 800 kDa, DAD ;Z~ 85%) was dispersed in 990 mL of simulated gastric fluid at 37 C. Then, 5.0 g of triolein was added and the separated triolein was determined after 1 h shaking.

[0053] Results showed that there is no significant difference between the quantity of separated triolein (approximately 90%) from chitosan regardless of its Mw and its concentration. In this case, these results confirmed that the high viscosity of chitosan can influence final results, particularly for tests in vitro.

[0054] In comparing the results obtained above and those obtained in 100 mL of simulated gastric fluid, a significant different was noted. Based on this data, the high viscosity of chitosan induced by the fat trapping effect can constitute a valid argument to explain the discordance between the two tests in vitro and in vivo and the reason for the doubt with the majority of tests previously carried out.

Degree of deacetylation (DDA) [0055] This parameter also appears as important as Mw. In a similar experiment described previously, chitosan (Mw approximately 800 kDa) with various DDA from about 80 to 97%, was dispersed in 1 L of simulated gastric fluid and incubated in the presence of 5.0 g of triolein.

[0056] The results indicated that chitosan with low DDA possesses a large capacity to bind to triolein, suggesting that interactions of chitosan and lipids were not only electrostatic, but also hydrophobic in nature. However, the difference is minimal, about 8%.

[0057] Additionally, it is of interest to mention that it is not in the gastric medium in which DDA affects lipids interactions, but rather in the medium of the intestinal tract where bile acids and its salts are present. Indeed, the task of the bile acids in the digestive tract is to emulsify lipids and provide a broad digestive surface for the action of the pancreatic lipase. However, when a complex of chitosan and lipid is formed and arrives in the intestinal tract (pH 7.0-7.2), the latter could be altered by the presence of bile acids (or its salts) and lead to the release of fat. It is evidenced that this phenomenon could be due to the competition of ionic interactions between lipids and bile salts to chitosan.
In this case, chitosan with the highest DDA presents more affinity with bile acids than that having a low DDA.

[0058] To evidence this interference phenomenon caused by the bile acids, an investigation was carried out to determine the amount of bile acids which can interact with the complex chitosan/lipid. Indeed, simulated gastric fluid suspensions containing 0.5% of chitosan (Mw 400 and 800 kDa) at various DDA (82-97%) and 5.0% of triolein were incubated at 37 C under agitation as previously described. After 2 h incubation, the pH value of solution was adjusted to about 7.0 (corresponding to the pH of the intestinal juice) always while shaking (300 rpm) at the same temperature. Then, a suitable volume of bile salts was added in order to obtain a final concentration of bile acids in the solution of about 5.0% and the mixture was maintained in incubation for a period of 3 h. Finally, an aliquot of 3.0 mL of solution was taken and centrifuged (15000 g) for 5 minutes and the determination of bile acids was carried out spectrophotometrically in UV. Results showed that chitosan possessing a high DDA retained considerable quantities of bile acids and presented important quantities of separated triolein.

[0059] Generally, chitosan possessing a low (400 kDa) or high (800 kDa) Mw with any DDA shows a complete destabilization of complex chitosan/triolein in the presence of bile acids. For chitosan possessing a high Mw with low DDA, the destabilization of complex chitosan/triolein by bile acids was approximately 80%.

Mucoadhesive properties [0060] Results of numerous tests have shown that chitosan possesses mucoadhesive properties owing to the molecular attractive forces formed by electrostatic interactions between positively-charged chitosan and negatively-charged mucosal surfaces (Lehr, C.M. et al., 1992. Int. J. Pharm., 78, 43-48;
Kas, H.S. 1997. J. Microencapsul. 14, 689-711). Additionally, these properties are more pronounced in the case of chitosan possessing high Mw and high DDA.

[0061] In any case, the important feature is that these bioadhesive properties of the mucosa intestine could constitute a main factor in destabilizing the complex chitosan fats, as well as the bile acids. In addition, this phenomenon can increase the intestinal transit time which could cause adverse effects, such as flatulence or constipation, in certain people.

Emulsifying agent [0062] As described above, the destabilization of,the complex chitosan/fat could be due to several factors, mainly the bile acids under intestinal conditions.
Great attention has been directed to address these destabilization problems of the chitosan and lipids. In accordance with the present invention, the addition of an emulsifying agent (preferably a natural emulsifying agent such as a phosphoglyceride) to the chitosan can improve the stability of the complex chitosan/fat.

[0063] In this context, it is preferable to use emulsifying agents which possess negative charges, such as phosphatidylinositol, phosphatidic acids or zwitterion molecules or phosphoglycerides (phosphatidylcholine, phosphatidylethanolamine, phosphatidyl-serine, etc.). The reason for the use of emulsifying agents possessing a negative charge in this embodiment consists in creating ionic interactions with chitosan (i.e. a positively charged polysaccharide) in order to generate a stable and resistant matrix under gastro-intestinal conditions.

[0064] In the present invention, lecithin is preferably used, because it is non-toxic, commercially available at low cost and approved by the Food and Drug Administration (FDA) for human consumption. Lecithin is a mixture consisting mainly of phospholipids (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, etc.), glycolipids and triglycerides. Lecithin may be isolated from soy beans, sun flower or egg yolk, etc.

Evaluation of the fat binding capacity of chitosan/lecithin based matrix [0065] To investigate the fat binding capacity of the chitosan/lecithin based matrix, a similar experiment as detailed above to test viscosity was carried out.
Indeed, an amount of 0.5 g of chitosan (Mw z:~ 400 kDa and 800 kDa, DDA 80-97%) was dispersed in 990.0 mL of simulated gastric fluid at 37 C while gently stirring. After complete dissolution of the chitosan, various quantities of lecithin (1-5.0%) were slowly introduced in the suspension, always while stirring.
Then, an amount of 5.0 to 10.0 g of triolein was added and the separated triolein was determined after 1 h shaking. Surprisingly, no separated triolein was noted for all the tested chitosan regardless of its Mw and DDA, whereas the sample without lecithin showed complete separation of the triolein after a few minutes.
Moreover, the complex chitosan/lecithin (ratio 1:5 respectively) could entrap more lipids, up to 20 times its weight.

Stability of matrix in presence of bile acids [0066] To investigate the stability of the chitosan/lecithin matrix, the previous experiment was reproduced with the exception this time that the pH of the solution was adjusted to 7.0 and various quantities (1.0-5.0%) of bile acids were added under mild stirring at 37 C. No destabilization of the complex triolein/matrix was observed in any of the samples containing the chitosan/lecithin, whereas the triolein in the chitosan matrix without lecithin was uniformly dispersed. In the latter case, it was probably due to the micelles formation resulting from the association of separated triolein and bile acids in the simulated intestinal medium.

Stability of matrix in simulated intestinal fluid [0067] For this test, similar preparation was carried out as described above in 1000 mL of simulated gastric fluid. The mixture was incubated during 2 h at 37 C. Thereafter, the complex matrix/triolein was separated and introduced in 1000 mL of simulated intestinal fluid (pH 7.2, USP method 27) while shaking for a period of 3 h. Results showed that there was no significant change before and after incubation in the complex matrix/fat. In addition, no release of triolein in the simulated intestinal fluid was observed.

[0068] The addition of an emulsifying agent provides a number of advantages selected from:

- promoting the interactions of chitosan with fatty matters;
- enhancing the affinity of chitosan with respect to fat and consequently increasing the fat binding capacity of chitosan;
- improving the stability of the complex chitosan/fat in gastro-intestinal media and thus preventing the release of trapped fats;
- preventing interferences of the bile acids and mucoadhesion phenomenon;
- decreasing the influence of DDA;
- refining the size of the complex chitosan/fat which diminishes the viscosity in intestinal medium and favors the excretion of fats;
- limiting the attack of lipases and decreasing the digestion of fats.

[0069] The emulsifying agent used in combination with chitosan is necessary to enhance the affinity of the matrix with fats and the stabilization of the matrix during gastro-intestinal transit. It is worth noting that preferably chitosan with Mw 100-1000 kDa and DDA 75-99% is used. The daily quantities could be varied 0.1 to 5.0 g/day and the emulsifying agent quantities could be from about 0.25 to 10.0 g/ day.

Additives [0070] Several polysaccharides such as xanthan gum can be used as dietary supplements to assist in reducing body weight. Moreover, none of these supplements has yet shown promising results. In accordance with the present invention, these dietary supplements or fibers are used to improve the resistance of the matrix and/or to avoid the possible side effects of chitosan (i.e.
constipation). To this end, these dietary supplements or fibers are preferably administered subsequently to the composition of the present invention, and more preferably after a meal.

[0071] These dietary fibers can, for example, be anionic polysaccharides (e.g. pectin, xanthan gum, alginate, carrageenan, etc. or any combination thereof) which could gel with the complex chitosan/fat and promote its excretion. Uncharged compounds, such as inuline, guar gum or FOS (fructo-oligosaccharide), etc., can also be included in the formulation. The advantage in using these natural molecules is that they are non-toxic (edible) and readily available at low cost.

[0072] Other dietary supplements can also be added to the formulation.
These other dietary supplements can be, for example, HCA sodium salt extract (from Garcinia cambogia), phaseolamine extract (from white kidney bean Phaseolus vulgaris which contains an alpha-amylase inhibitor), hoodia extract (from Hoodia gordonii which is responsible for its appetite-suppressant effect), corosolic acid extract (from banana leaves), fructo-oligosaccharide (FOS), inuline, guaranine, theobromine, theophyllin, tannic acid, forskolin (Coleus forskolii), rosalin (Rhodiola rosea), polyphenols (primrose oil, green tea, pomegranate, etc.), phytosterols (tribulus, maca, acai, etc.), xanthones (mangostino), 5-hydroxytryptophane (from Griffonia simplicifolia), boswellic acid (Boswellia serrata), etc.

[0073] The composition of the present invention can also be formulated into a liquefied form such as a syrup or juice mixture. In such cases, flavoring and/or savoring agents and preservative agents can also added to the formulation.

[0074] It is worth noting that these additive compounds could be used alone or in combination. The composition of the present invention is preferably administered after a meal. With regard to the quantity of additive compounds, it varies from one compound to another. For example, the quantity of HCA used after a meal can be varied from about 0.1 g to 5 g/ day, whereas pectins could reach up to 10 g/ day. One skilled in the art will know the amount of any desired additive compounds to be used.

Action of composition lipids binder [0075] Taken approximately 20-30 minutes before meals, chitosan disperses in gastric fluid (pH 1.2-2.5) and associates with the emulsifying agent (such as lecithin) via ionic interaction between the amino group of chitosan and the phosphate group of phospholipids. This interaction was evidenced in Fig. 1 by FTIR analysis using a Spectrum 100 (Perkin-Elmer Instruments, FT-IR
spectrometer Norwalk, USA) equipped with a Universal Attenuated Total Reflectance (UATR) device recording in the spectral region of 1800-600 cm-1 with 256 scans at 4 cm-1 resolution. All spectra were normalized over the range using the Spectrum software version 3.02. In fact, the band of chitosan spectrum at 1512 cm-1 assigned to the NH2 scissoring vibration of the primary amino group was not (or weakly) present in the chitosan/lecithin spectrum.
This event was due to the formation in acidic medium of a chitosan ionized form and to the ionic interaction of the amino groups of chitosan with the phosphate groups of phospholipids in lecithin. Furthermore, the absorption band of phosphate groups was shifted from 1236 cm-1 in the lecithin to 1230 cm-1 in the chitosan/lecithin mixture which indicates the ionic interaction has taken place.

[0076] Indeed, the chitosan/lecithin association attracts fat droplets and forms particles in the stomach before they are exposed to the action of the bile acids and the pancreatic enzymes in the intestine. When these particles reach the intestinal tract (pH - 7.0), they became more and more stable due to the pH

change causing chitosan gelation, forming a matrix. This phenomenon is interesting because it promotes the formation of a stable barrier which separates the fat from the bile acids and the lipases.

[0077] Although the chitosan/lecithin association presents a notable stability, the addition of a gelling agent (i.e. HCA, pectin, xanthan gum or a combination thereof) can further improve the resistance of the chitosan matrix in the intestinal medium. Additionally, the matrix surroundings can limit the access of lipases to fats and/or restrict the migration of fats from the matrix to the outside environment. This phenomenon prevents the lipolysis and the micelles formation of fat with the bile acids which can contact the epithelial cells of the intestine from where the absorption would normally take place. Moreover, the chitosan, a cationic polymer, is susceptible to interact with the lipases by ionic interactions, and possibly leads to a certain decrease in the lipolysis activity.
Finally, the undigested matrix of chitosan/fat complex travels through the intestine and is then excreted.

EXAMPLES

[0078] In accordance with the present invention, the composition of the present invention can be formulated into various forms, such as tablets, capsules, suspension, solution, powder or used as a supplement in food. The daily doses could be varied from 0.1 to 30 g of matrix/day and at least as many additives. Chitosan with Mw <1000 kDa with DDA >75 % is preferably used. To obtain better results, it is recommended to consume the matrix composition approximately 20-30 minutes before a meal and the other diet supplement separately at the end of a meal.

EXAMPLE I
Preparation of fat trapper formulation with commercial lecithin Preparation of chitosan/lecithin powder (matrix) [0079] In general, chitosan and lecithin are commercially available in powder form and in this case, chitosan (approximately 150 kDa and DDA, 90 %) and lecithin are simply mixed together in a proportion of 1:5 respectively to obtain a homogeneous mixture.

Preparation of HCA/xanthan gum mixture (additive) [0080] To the matrix preparation described above, HCA and xanthan gum can be further added in a ratio of HCA/xanthan gum of 3:1.

[0081] The resulting powder mixture can be used as an additive in juices or food. For making the tablet, the resulting powder could be compressed directly.
With regard to the capsule, the latter is carried out by a powder filling machine.

Example II
Preparation of fat trapper formulation with phosphatidylcholine enriched lecithin Preparation of phosphatidylcholine enriched lecithin [0082] Phosphatidylcholine enriched lecithin may be obtained by fractionation in ethanol. While most other phospholipids do not dissolve well in ethanol, phosphatidylcholine does. Practically, an amount of 100 g of lecithin is dispersed in 1 L of absolute ethanol at 40 C. After 2 h stirring, the supernatant is separated and the ethanol is removed by evaporation at 75-80 C. The remaining residue constitutes the phosphatidylcholine enriched lecithin fraction.
Preparation of phosphatidylcholine enriched lecithin chitosan matrix [0083] An amount of 10 g of chitosan (Mw approximately 400 kDa and DDA
82 %) was dispersed in 1 L of purified water acidified with 0.12 M of acetic acid.
The solution was heated at 50 C and stirred until complete dissolution of the chitosan. Then, an amount of 30 g of phosphatidylcholine enriched lecithin (obtained as described above) was slowly added in the suspension always while stirring at the same temperature. After 1 h mixing, the chitosan/phosphatidylcholine enriched lecithin suspension was cooled down, precipitated in ethanol and filtered. The precipitate was washed, filtered and dried at room temperature (23 1 C). Another method of obtaining the powder of chitosan/phosphatidylcholine enriched lecithin mixture would consist of using a spray-drier, which has the advantages of avoiding the use of solvents, thereby being fast and inexpensive.

Preparation of phosphatidylcholine enriched lecithin chitosan mixture (matrix) [0084] This is a similar preparation to that previously described, but chitosan/phosphatidylcholine enriched lecithin powder was used instead of chitosan/lecithin.

Preparation of pectin/ white kidney bean mixture (additive) [0085] This is a similar preparation to that previously described above, but powders of a pectin/white kidney bean mixture were used instead of HCA/xanthan gum, still in a ratio of 3:1.

Example III
Other fat trapper formulations Matrix formulation Ingredients Unit amount (mg) Chitosan (Mw - 800 kDa and DDA -95%) 250 Glucomannan 50 Phosphatidylinositol enriched lecithin 1200 Additive formulation Ingredients Unit amount (mg) Pyruvate 500 Example IV

Matrix formulation Ingredients Unit amount (mg) Chitosan (Mw - 50 kDa and DDA -90%) 800 Phosphatidylserine enriched lecithin 1200 Additive formulation Ingredients Unit amount (mg) Carrageenan 250 Gelatin 500 Example V
Matrix formulation Ingredients Unit amount (mg) Chitosan (Mw - 75 kDa and DDA -95%) 450 Inuline 50 Phosphatidylcholine enriched lecithin 1500 Additive formulation Ingredients Unit amount (mg) Whey protein 500 [0086] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.

Claims (18)

1 A fat-trapping composition comprising:

i) 5 - 50% of an indigestible cationic polysaccharide having a degree of deacetylation of 75-99% and a molecular weight of less than 1000 kDa; and ii) 50 - 95% of at least one anionic or zwitterionic emulsifying agent selected from the group consisting of phosphoglyceride, phosphatidylinositol, a phosphatidic acid salt, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lecithin in electrostatic association with said cationic polysaccharide.

2. The fat-trapping composition of claim 1, wherein the cationic polymer is an aminopolysaccharide.

3. The fat-trapping composition of claim 1, wherein the cationic polymer is chitosan.

4 The fat-trapping composition of any one of claims 1 to 3, formulated into tablets, capsules, an oral suspension or a powder.

5. A method for treating obesity in a mammal, comprising the step of orally administering to the mammal an effective amount of a fat-trapping composition as defined in any one of claims 1 to 4

6. A method for reducing absorption of dietary fat in a mammal, comprising the step of orally administering to the mammal a therapeutic amount of a fat-trapping composition as defined in any one of claims 1 to 4.

7 A method for treating and/or reducing hypertriglyceridemia in a mammal, comprising the step of orally administering to the mammal a therapeutic amount of a fat-trapping composition as defined in any one of claims 1 to 4.

8. The method of any one of claims 5 to 7, wherein the mammal is a human.

9. The method of any one of claims 5 to 8, wherein the composition is administered before each meal.

10. The method of any one of claims 5 to 9, wherein the composition is administered 20 to 30 minutes before each meal.

11. The method of any one of claims 5 to 10, wherein the amount of the composition administered varies from 0.1 g/day to 30 g/day.

12 The method of claim 10, wherein the amount of the composition administered before each meal varies from 0.03g to 10g.

13. The method of any one of claims 5 to 12, further comprising the administration of at least one dietary supplement or dietary fiber, for improving the resistance of the complex to digestion.

14. The method of claim 13, wherein said dietary supplement or said dietary fiber is administered after the meal.

15. The method of daim 13 or 14, wherein the dietary supplement is selected from the group consisting of xanthan gum, inuline, guar gum, fructo-oligosaccharide (FOS), hydroxycitric acid salts (HCA), phaseolamine extract, hoodia extract, corosolic acid extract, guaranine, theobromine, theophyllin, tannic acid, forskolin, rosalin, polyphenols, phytosterols, xanthones, 5-hydroxytryptophane, and boswellic acid

16. The method of claim 15, wherein the polyphenols are extracted from primrose oil, green tea or pomegranate.

17. The method of any one of claims 13 to 16, wherein the dietary supplements or the dietary fibers are administered in equal or greater amount than the amount of the composition administered.

18. The method of any one of claims 13 to 17, wherein from 0.1 to 10 g of the dietary supplements or the dietary fibers are administered after each meal.