The patent's assignee for patent number 8722116 is
News editors obtained the following quote from the background information supplied by the inventors: "Consumer products and environmental mandates have created a large demand for natural biocides. There are a number of commercial extracts made of plants, notably essential oils, that provide antimicrobial activity. However, all current natural antimicrobials are limited by some combination of low potency, high cost, toxicity, taste, odor and color of the extracted compounds at their minimum effective concentrations. Synergistic combinations of essential oils have met with some success, but their performance still pales compared to common synthetic biocides. The pharmakinetics of all current commercial antimicrobials is still based on dilution of individual molecules.
"Plants have various mechanisms for delivering localized and concentrated immune responses against pathogens. Plants cannot rely on general diffusion of antimicrobial compounds throughout their tissues. Effective protective concentrations would be systemically toxic. When plants are exposed to external stress, an almost universal defense mechanism is the local expression of reactive oxygen species (ROS) that initiate compounds rapid formation of physical barriers as well as mounting direct attack against the invading pathogen. These ROS include hydrogen peroxide (H.sub.2O.sub.2), superoxide (O.sub.2.sup.-), singlet oxygen (.sup.1O.sub.2*), and hydroxyl radical (.OH).
"These radicals damage the cell walls of pathogens on contact or create a hyperoxygenated environment that the cell cannot tolerate. They also can initiate reactions of alkaloids, terpenes, phenolics, peptides or other astringent compounds, to aggressively bind and immobilize amino acids of the plant and pathogens.
"The cell walls of bacteria and fungi are protected by peroxidase, catalase, and other enzymes that scavenge ROS. Therefore, an effective oxidative attack on a pathogen requires providing a sufficient concentration of ROS molecules to overwhelm the pathogen's defenses.
"The cell walls and membranes of eukaryotic organisms are populated with peroxisomes. Subcellular organelles, which are rich in enzymatic proteins, carry out a wide range of functions including .beta.-oxidation of fatty acids, glyoxylate metabolism, and metabolism of reactive oxygen species. H.sub.2O.sub.2 producing enzymes NAD(P)H oxidase, oxalate oxidase, and glucose oxidase, are found on the peroxisomal membrane. Peroxisomes contain antioxidant molecules, such as ascorbate and glutathione, the cell's principal H.sub.2O.sub.2 degrading enzyme-catalase, and a battery of antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, dihydro- and monohydroascorbate reductase, glutathione reductase. These tightly regulate the amount of H.sub.2O.sub.2 accumulation in healthy plant tissue. Changes in activities of these enzymes are correlated with many situations in which plants experience stress. Accordingly, peroxisomes have been suggested to play important roles in defense against abiotic and biotic stress in plants. Mitochondria and chloroplasts also use H.sub.2O.sub.2 as a transduction medium. Superoxides are also converted in the organelle matrix.
"Reactive oxygen species (ROS) can destroy invading microorganisms by denaturing proteins, damaging nucleic acids and causing lipid peroxidation, which breaks down lipids in cell membranes. Both plant cells and pathogens are protected, at least in part, from ROS by enzymatic and non-enzymatic defense mechanisms.
"Defense against its endogenous ROS as well as a pathogen ROS attack is believed to be provided by the scavenging properties of antioxidant molecules found in the organelles and the cell membranes. Superoxide dismutases (SODs) catalyze the reduction of superoxide to hydrogen peroxide. Hydrogen peroxide is then decomposed to H.sub.2O by the action of catalases and peroxidases. A certain concentration of H.sub.2O.sub.2 also diffuses into the intracellular matrix and is released by lysis or mechanical rupture of cells. Cell disruption causes H.sub.2O.sub.2 to come in contact with separately compartmentalized polymers and initiates rapid cross-linking of cellular proteins to form a protective barrier at localized stress sites. The in-vivo anti-bacterial efficacy of antibiotics encapsulated in synthetic liposomes was demonstrated to be four times more effective than the free systemic application (
"Hydrogen peroxide is a common and effective broad spectrum disinfectant, which is notable for its ideal environmental profile (H.sub.2O.sub.2 decomposes into water and oxygen) and low toxicity. It is an ubiquitous multifunctional factor in both plant and animal immune and metabolic processes. Hydrogen peroxide is generally regarded as safe (GRAS) by the
"The ability to withstand oxidative attack is generally, a function of the organism size. Most pathogens are small and more susceptible to ROS damage than plant and animal cells. Once the pathogen is depleted of ROS degrading molecules, further oxidation can damage the cell membrane, causing cell death. This is a completely different mechanism than the blocking of metabolic transduction sites and other highly specific molecular interactions of antibiotics that are becoming alarmingly less effective as bacteria adapt and become resistant.
"The tissue of many succulents has a long history of use in traditional medicine as antimicrobial wound dressings and for other medicinal purposes. Aloes are widely cultivated and processed for a variety of purposes. Several species of cacti are less widely commercialized but equally valued in traditional medicine and as a food source. Plants evolved in harsher environments, such as the dessert succulents, tend to have enhanced capacity to produce hydrogen peroxide in response to biotic and abiotic stresses. Cleanly sliced fresh pieces of cacti and aloe plants are traditionally effective against infection largely due to the H.sub.2O.sub.2 expression in the plant tissues in response to its injury. Commercially processed aloe gels generally lose their antimicrobial activity.
"U.S. Patent Application No. 2002/0034553 teaches a composition of Aloe vera gel, Irish moss and approximately 3% hydrogen peroxide where the aloe vera primarily forms a gel holding the ingredients together in an ointment or lotion which may be applied directly to a cleansed infected or irritated skin tissue area. The application relies on a conventional bulk concentration (1.5%) of H.sub.2O.sub.2 to provide an oxygen-rich environment, and it makes no specific teaching regarding functional interactions of H.sub.2O.sub.2 and the enzymatic or other cellular chemistries of the plant fractions.
"U.S. Pat. No. 6,436,342 teaches an antimicrobial surface sanitizing composition of hydrogen peroxide, plant derived essential oil, and thickener. However, it does not teach interaction between components.
"U.S. Pat. Nos. 5,389,369 and 5,756,090 teach haloperoxidase-based systems for killing microorganisms by contacting the microorganisms, in the presence of a peroxide and chloride or bromide, with a haloperoxidase and an antimicrobial activity enhancing .alpha.-amino acid. Although highly effective antimicrobials, the systems cannot generally be considered natural products and the components must be separately stored or packaged in anaerobic containers to prevent haloperoxidase/peroxide interaction and depletion prior to dispensing for use.
"U.S. Pat. No. 5,389,369 teaches an improved haloperoxidase-based system for killing bacteria, yeast or sporular microorganisms by contacting the microorganisms, in the presence of a peroxide and chloride or bromide, with a haloperoxidase and an antimicrobial activity enhancing .alpha.-amino acid. Although the compositions and methods of U.S. Pat. No. 5,389,369 have been found to be highly effective antimicrobials, the components must be separately stored and maintained in order to prevent haloperoxidase/peroxide interaction and depletion prior to dispensing for use.
"The above references describe the application of various oxidative antimicrobials in a free liquid dispersion. Ability of a solution of free soluble biocidal compounds to effectively kill pathogens is determined by the probability of individual molecular interactions with the pathogen. This ability rapidly diminishes with volumetric dilution and consumption of the active solute.
"For this reason, application of diffuse free active chemicals in solution is grossly inefficient at killing bacteria and fungi, yet this is predominantly how antimicrobials are formulated into commercial products for topical therapeutics, personal care products, commercial and industrial sanitizers, and sanitation or preservation of food and water. This method demands extraction processes that highly concentrate active chemicals. To obtain adequate microbial suppression, product formulations commonly require higher concentrations of these chemicals that would be toxic to the tissues of plants of origin. There are some examples of encapsulation of essential oils for stabilization of fragrance, and commercially available synthetic liposomes for targeted intravenous drug delivery, but there are no commercial examples of ex-vivo generation of unencapsulated plant material complexes for improved antimicrobial efficiency.
"FIG. 1 illustrates a traditional biocidal solution 100. The working principle of traditional biocidal solution is based on free liquid dispersion. The effectiveness of the biocidal compounds solution is determined by the probability of individual molecule that encounters with the pathogen. The target 102 is within the solution 100 which contains free liquid dispersed hydrogen peroxide 104.
"Therefore, there exists a need for compositions and methods of preparing microscale antimicrobial complexes or aggregates of stable active chemistries that provide an efficient means of concentrating the assault on pathogenic organisms. Ideally, such antimicrobial complexes should be fast acting with minimal host toxicity and with maximal germicidal action. The compositions should be naturally derived, easy to deliver or formulate, and should not cause damage to host tissue or common surfaces on contact. Depending upon the strength of composition and the time interval of exposure, the compositions should produce antisepsis, disinfection, or sterilization at lower molar concentrations than typical free active chemicals in solution. Such compositions will have utility as an efficient means of controlling microbial population for anti-infection, sterilization, deodorization, sanitation, environmental remediation, preservation of topical products, and safety and preservation of food and water."
As a supplement to the background information on this patent, NewsRx correspondents also obtained the inventors' summary information for this patent: "The present invention describes compositions, applications, application methods and methods of producing a biocidal substance with a substrate of biologically reactive material. In some embodiments, the biocidal substance includes plant-tissue aggregates, extracted polymers, or combinations thereof. In some embodiments, the biocidal substance with a substrate of biologically reactive material creates high localized density of bioactive sites for improving microbicidal efficiency and astringent effect.
"In one embodiment of the invention, the method of forming and the composition of a plant-based biocidal solution includes a bioactive material and a plant-based substance formed from the cellular material of a plant capable of binding to the bioactive material. In some embodiments, the interaction between the plant-based substance and the bioactive material stabilizes the bioactive material. The combination of the plant-based substance and the bioactive material provides a stable source of providing bioactive material. In some embodiments, the bioactive material is a substrate of compounds of reactive oxygen species. Alternatively, in some embodiments, the bioactive material is hydrogen peroxide. The hydrogen peroxide can be generated endogenously or exogenously. The exogenously added hydrogen peroxide can be obtained directly from commercially available sources. In some embodiments, such hydrogen peroxide has a concentration of 1%-90% hydrogen peroxide in water. Alternatively, the hydrogen peroxide has a concentration of 25%-50% hydrogen peroxide in water. The endogenous generation of hydrogen peroxide can be achieved by measured gross cutting or other physical abiotic stressing of a metabolically viable harvested plant structure or controlled wounding of a pre-harvest plant to activate an expression of an increased H.sub.2O.sub.2 acting compound. Alternatively, in some embodiments, the bioactive material is generated by the degradation of added ozone (O.sub.3) by an active dismutase in the complex or solution, or in combination with direct addition of the H.sub.2O.sub.2.
"In some embodiments, the plant-based substance, cellular materials, and plants are obtained naturally or artificially. In some embodiments, the plant-based substance is formed from a cellular fragment, a multivalent polymer, an oligomer, an intact cell, a lignin, a subcellular organelle, a membrane fragment, a soluble protein, a polysaccharide, a phenolic compound, a terpene, an enzyme, and a denatured proteinaceous fragment. In some embodiments, the cellular material comes from a cell of a plant with a hydrogen peroxide acting enzyme on the cell membrane, a membrane bound organelle, or a tissue with the ability to fix and significantly increase the half-life of hydrogen peroxide or other oxygen radical while preserving its bio-reactivity. Most higher plants have some degree of ROS generation and preservation capability in their tissues. In some embodiments, the plant is a species from of the family of Cactaceae, Agavaceae, or Poacea. In some embodiments, the plant is a species with a history of food or medicinal application or Generally Regarded As Safe (GRAS) by the
"In accordance with further embodiments, the bioactive material-degrading enzyme, such as catalase and peroxidase, contained in the cellular material needed to be processed to be at least partially inactivated. This can be accomplished by desiccating, blanching, heating of dried materials, exposing to UV radiation, freeze-thaw cycling, heating or boiling in a solution of water, storing processed or partially processed for natural degradation with time, or exogenously adding of a chemical enzymatic inhibitor.
"In some embodiments, the plant-based biocidal material is a natural product. The plant-based biocidal material is able to be used alone, in combination with other oxidizers, material, or in synergistic interaction with additional exogenous or endogenous plant-derived or synthetic antimicrobals. In some further embodiments, the plant-based biocidal material has an effective concentration sufficiently low to dilute a non-functional or undesirable component or characteristic in solution to a sub-functional or sub-concern level.
"Another embodiment of the invention is the use of the plant-based biocidal material to impair a target. The use of the plant-based biocidal material is achieved by taking the plant-based substance formed from a cellular material of a plant with a bioactive material and applying the plant-based substance with the bioactive material to a target, such as a pathogen. The applying of the plant-based substance with the bioactive material is able to deliver high localized concentration of the bioactive material to the target. Such application can be for a purpose of providing direct biocidal activity or for biocidal preservation of the formulation. Furthermore, such application can also be applied to a beneficial effect to human or animal wound healing, such as exudate control, wound closure, and rapid scab formation attributable to the aggressive bio-oxidative and protein cross linking capacities of H.sub.2O.sub.2 by itself, or in combination with potentiating endogenous and or exogenous co-factors.
"Another embodiment of the invention is the method of using the plant-based biocidal material. The use is achieved by taking a plant-based substance formed from a cellular material of a plant with a bioactive material, forming a microscopic cluster, a complex, or an aggregate from a suspension of the plant-based substance, and applying the microscopic cluster, the complex, or the aggregate to a target, such as a pathogen, thereby impairing the target. In some embodiments, the impairment of a target can be oxidative damage. In other embodiments, applying the microscopic cluster, the complex, or the aggregate to impair a target is for the purpose of stable binding of a dense localized concentration of hydrogen peroxide to enact a nearly simultaneous oxidative attack with sufficient number and rate of reactions to overwhelm oxygen scavenging and enzymatic Reactive Oxygen Species (ROS) defenses of pathogens or a combination of isolation, immobilization and ROS attack."
For additional information on this patent, see: Huang,
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