Biocidal chitosan derivatives

Details Biocidal chitosan derivatives Biocidal chitosan derivatives

1998-09-16

2001-10-23

Levy, Neil S. (Department: 1616)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Carbohydrate doai

C424S400000, C424S401000, C424S405000, C424S406000, C424S407000, C424S409000, C424S078020, C424S078070, C424S484000, C424S486000, C424S487000

Reexamination Certificate

active

06306835

ABSTRACT:

This invention pertains to antimicrobial compounds and their methods of use, particularly to certain antimicrobial compounds derived from chitosan.
Preservation of a product is the retardation or prevention of its deterioration from the time of manufacture until the consunmer completely uses all of the product in its container. Many components used in cosmetic products, such as fats, oils, and surfactants, are susceptible to degradation by microorganisms. A product may harbor a growing bacterial or flingal population without outward visible signs. A contaminated product may lose effectiveness and can cause infection, particularly if placed in contact with broken or damaged skin. Preservatives are commonly added to personal care products to inhibit the growth of bacteria or fungi, to increase shelf life, and to protect the consumer from infection. Preservatives typically inhibit or prevent microbial growth by depleting water or nutrient sources, or by disrupting cell membranes.
In many applications, it is highly desirable that the preservatives should not only protect the product until its packaging is first opened by the consumer, but also that the preservatives should prevent or reduce the growth of contaminating microorganisms introduced to the product when used by the consumer. A typical goal is that products with preservative agents should self-sterilize within 24 hours of contamination resulting from normal conditions of use. Products containing less than 15% alcohol, and having a pH range between about 3 and about 11, are particularly prone to microbial spoilage.
The most commonly used preservatives in cosmetic formulations are listed in Table 1. Methylparaben (Methyl-4-hydroxybenzoate) is the most frequently used cosmetic preservative. It is common to use mixtures of preservatives that are effective against different microorganisms, or that interact synergistically with one another. Quaternary ammonium compounds, or “quats,” have been tested for irritation and sensitization properties; at concentrations below 0.1%, most quats appear to cause little or no irritation. However, most of the quats listed as preservatives have only been “monographed” by the United States Food and Drug Administration for use as conditioning agents in hair or skin products, because they are not sufficiently active to be considered primary antimicrobial additives.
TABLE 1
Commonly Used Preservatives in Cosmetics
ACIDS
PARABENS
p-Hydroxybenzoic acid
Methyl p-hydroxybenzoate
Benzoic acid
Ethyl p-hydroxybenzoate
Sorbic acid
Propyl p-hydroxybenzoate
Dehydroacetic acid
Butyl p-hydroxybenzoate
Formic acid
Benzyl p-hydroxybenzoate
Salicylic acid
ANILIDES
Boric acid
Tetrachlorosalicylanilide
Vanillic acid
Trichlorocarbanilide
o,p-Chlorobenzoic acid
Trichlorsalicylanilide
Propionic acid
PHENOLS
Sulfurous acid
Phenol
Trichlorophenylacetic acid
Cresol
METAL-CONTAINING
Chlorothymol
Sodium ethyl
Methylchlorothymol
mercurithiosalicylate
Chlorobutanol
Phenyl mercury acetate
o-Phenylphenol
Phenyl mercury borate
Parachlormetacresol
Phenyl mercury nitrate
Parachlormetaxylenol
QUATS
&bgr;-Phenoxyethylalcohol
Benzethonium chloride
Dichlorophene
Benzalkonium chloride
Hexachlorophene
Cetyltrimethyl ammonium
Vanillin
bromide
Ethyl vanillin
Cetyl pyridinium chloride
2-Bromo-2-nitro-1,3-propanediol
Tetramethylthiorandisulfide
&bgr;-Phenoxypropylalcohol
Imidazolidinyl urea
Monomethylol dimethyl
Dimethyldidodeceyl
hydantoin
ammonium chloride
Chitin, poly &bgr;-(1→4)-2-acetamido-2-deoxy-D-glucopyranose, is a major constituent of arthropod exoskeletons. Chitin is the second most abundant biopolymer in nature. Chitin is extracted commercially from the exoskeletons or shells of crustaceans such as shrimp, crab, and crawfish by demineralizing crushed shells and extracting proteins and polypeptides. Chitosan, poly &bgr;-(1→4)-2-amino-2-deoxy-D-glucopyranose, is a natural biopolymer that may be obtained by alkaline deacetylation of chitin.
Among the characteristics of chitosan that may be varied as needed for a particular application are the degree of deacetylation (compared to chitin) and the molecular weight. The viscosity of solutions containing chitosan is affected by the degree of deacetylation, molecular weight, concentration, ionic strength, pH and temperature. Generally, increases in temperature cause decreases in the viscosity of the solution. The effect of pH on viscosity depends on the particular acid used. Native chitosan is soluble in organic acids when the pH is less than 6, and is insoluble in water, alkali, or organic solvents. However, water soluble salts of chitosan may be formed by neutralization with acids such as hydrochloric acid, acetic acid, lactic acid, or formic acid. Chitosan has been used in water treatment, paper manufacturing, agriculture, food processing, cosmetics, biotechnology, and medicine.
A quaternary nitrogen functional group is a part of many biologically active compounds. Some quaternary ammonium compounds exhibit antimicrobial activity. The antimicrobial action is believed to result when the compounds are adsorbed onto the bacterial cell surface, increasing the permeability of the lipid cell membrane, and causing death through the loss of essential cell materials.
Quaternary ammonium compounds have been used in water treatment, in liquid laundry detergents as sanitizers, in preoperative treatment of surgical patients, and in disinfection of surgical instruments. In the cosmetics and pharmaceutical industries, they have been used as preservatives in consumer products. They are used as disinfectants of food contact surfaces, and are incorporated into latex paints as fungistats.
Some quaternary ammonium polymers have been reported to have antimicrobial activity. These polymers have been used in areas including water treatment, health care and hygienic applications, coatings, textiles, disinfection of air and other gases, and as preservatives. Quaternary polymers are generally more active than their corresponding monomers particularly against gram-positive bacteria. This effect is believed to be due to adsorption of the polymers onto the bacterial cell surface and membrane, with subsequent disruption of membrane integrity. Antimicrobial activity generally increases as the content of the quaternary ammonium moiety increases.
The mechanism of action for quaternary polymers has not been extensively studied. It is probable that “polyquats” interact with bacteria in a similar manner as do the non-polymeric quats: adsorption onto the bacterial cell surface, diffusion through the cell wall, and binding to the cytoplasmic membrane. Adsorption onto the bacterial surface interferes with permeability and transport across the cell membrane. This interference disrupts the cytoplasmic membrane and causes leakage of potassium ions and other low molecular weight cytoplasmic components. Leakage of macrocomponents of the cell and precipitation of cell components occur, and the microorganism dies.
Some quaternary ammonium polymers such as polyquaternium 18 and polyquaternium 27, previously used in cosmetic formulations as conditioners and thickeners, may exhibit some bacteriostatic properties. However, they have only been monographed by the United States Food and Drug Administration for use as conditioning agents in hair and skin care products, because they are not sufficiently active to be considered primary antimicrobial additives. A separate antimicrobial agent has typically been added to such products to achieve good storage stability. Quaternary ammonium polymers have previously been considered bacteriostatic, not bactericidal, because they require long contact times to actually kill microorganisms, and generally do not have broad spectrum activity.
G. Lang et al., “Quaternary hydroxyalkyl chitosan cosmetic for hair and skin,”
Cliem. Abstr
. 106:38223v, German Patent 3,513,277 (1986) (English translation of abstract provided) discloses certain quaternary ammonium chitosan derivatives said to have better compatibility with surfactants and better solubility as compared to chitosan when used in ha

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