Method for reducing heavy metals and composition for reducing heavy metals

Abstract

The present invention provides a method and the like with which it is possible to reduce heavy metals in a sample.　A method for reducing heavy metals according to the present disclosure includes a reduction step in which cellulose is used to reduce heavy metals in a sample.

Description

Method for reducing heavy metals and composition for reducing heavy metals

[0001] The present disclosure relates to methods and compositions for reducing heavy metals.

[0002] Biological samples such as salmon nasal cartilage contain components such as proteoglycans and collagen. Furthermore, marine biological samples such as salmon nasal cartilage accumulate large amounts of heavy metals such as arsenic due to bioaccumulation through the food chain. Therefore, when extracting these components from the biological sample, the heavy metals are extracted along with the components. Heavy metals cause adverse effects when ingested in excess, so it is necessary to remove them from the biological sample (Non-Patent Document 1).

[0003] Harada, Takanori. “Health Effects and Toxicity Assessment of Heavy Metals.” Foods & Food Ingredients Journal of Japan: FFI Journal 224.3 (2019): 242-248.

[0004] Therefore, an object of the present disclosure is to provide, for example, a method for reducing heavy metals from a sample.

[0005] To achieve the above object, the method for reducing heavy metals of the present disclosure includes a reduction step of reducing heavy metals from a sample using cellulose.

[0006] The compositions of the present disclosure for use in reducing heavy metals in a sample include cellulose.

[0007] According to the present disclosure, for example, a method for reducing heavy metals from a sample can be provided.

[0008] FIG. 1 shows the main disaccharide structures of each chondroitin sulfate.

[0009] <Definition> In this specification, the term "heavy metal" refers to a metal that may be harmful to health if ingested into the body, that is, a metal that is harmful.

[0010] As used herein, "cellulose" refers to a type of insoluble dietary fiber in which D-glucopyranose units are linked via β-1,4-glycosidic bonds. Examples of cellulose include crystalline cellulose and amorphous cellulose.

[0011] As used herein, "proteoglycan" refers to a molecule (glycoprotein) in which a protein (core protein) and a glycosaminoglycan (GAG, also called a "polysaccharide" or "sugar chain") are covalently bonded. Proteoglycans exist as extracellular matrices in, for example, skin, organs, and cartilage. Glycosaminoglycans are generally known as sugar chains with long chain structures that do not have branched structures. Examples of proteoglycans include aggrecan, versican, decorin, testican, brevican, biglycan, serglycin, syndecan, perlecan, dystroglycan, agrin, claustrin, glypican, lumican, keratocan, and neurocan. The proteoglycans can be classified into, for example, chondroitin sulfate proteoglycans, dermatan sulfate proteoglycans, heparan sulfate proteoglycans, and keratan sulfate proteoglycans depending on the type of GAG bound to the protein.

[0012] Examples of the GAG ​​include chondroitin, chondroitin sulfate, dermatan sulfate (chondroitin sulfate B), heparan sulfate, heparin, and keratan sulfate. Examples of the chondroitin include an O-type sugar chain whose main disaccharide structure is a disaccharide structure of glucuronic acid and acetylgalactosamine, and an iO-type sugar chain whose main structure is a disaccharide structure of iduronic acid and acetylgalactosamine (hereinafter also referred to as "chondroitin sulfate O" and "chondroitin sulfate iO," respectively). The chondroitin sulfate has a structure in which a sulfate group is added to a sugar chain in which the disaccharide structure of glucuronic acid and acetylgalactosamine is repeated. Examples of the chondroitin sulfate include chondroitin sulfate A (type A), whose main disaccharide structure is a disaccharide structure of glucuronic acid and acetylgalactosamine 4-sulfate; chondroitin sulfate iA (type iA), whose main disaccharide structure is a disaccharide structure of iduronic acid and acetylgalactosamine 4-sulfate; chondroitin sulfate C (type C), whose main disaccharide structure is a disaccharide structure of glucuronic acid and acetylgalactosamine 6-sulfate; and chondroitin sulfate iC (type iC), whose main disaccharide structure is a disaccharide structure of iduronic acid and acetylgalactosamine 6-sulfate. Each chondroitin sulfate has, for example, the disaccharide structure shown in Figure 1 as its main disaccharide structure. Note that in Figure 1, the sulfate group (sulfo group) is bonded to a hydrogen atom, but the present disclosure is not limited thereto. For example, the sulfate group of the GAG ​​may be ionized by elimination of the hydrogen atom, or may form a salt.

[0013] The present disclosure will be described below using examples, but the present disclosure is not limited to the following examples and can be implemented with any modifications. Furthermore, the descriptions in this disclosure and each embodiment can be mutually incorporated unless otherwise specified. In this specification, when the expression "~" is used, it is used to mean including the numerical or physical values ​​before and after it. In addition, in this specification, the expression "A and / or B" includes "A only," "B only," and "both A and B."

[0014] <Method for reducing heavy metals> In one aspect, the present disclosure provides a method for reducing heavy metals in a sample. The reduction method of the present disclosure includes a reduction step of reducing heavy metals from a sample using cellulose. According to the reduction method of the present disclosure, heavy metals can be reduced from a sample.

[0015] As a result of extensive research, the present inventors have discovered that heavy metals can be reduced from samples containing heavy metals by using cellulose, and have established the present disclosure. The reduction of heavy metals is presumed to be due to the adsorption of heavy metal ions to the cellulose. However, this presumption does not limit the present disclosure in any way. Therefore, according to the present disclosure, it is possible to reduce heavy metals contained in a sample.

[0016] Examples of the cellulose include crystalline cellulose and amorphous cellulose. The cellulose may be, for example, powdered cellulose pulverized into a powder form. The powdered cellulose contains, for example, a crystalline portion and an amorphous portion of cellulose. The powdered cellulose can be prepared, for example, by mechanically crushing cellulose fibers in a dry or wet manner, or by acid hydrolysis. The powdered cellulose can be prepared, for example, by subjecting cellulose fibers to mechanical crushing in a dry or wet manner, or by acid hydrolysis. Examples of the powdered cellulose include cellulose fibers (KC Floc W-50(S), KC Floc W-50, KC Floc W-100, KC Floc W-100G, KC Floc W-200, KC Floc W-200G, KC Floc W-250, KC Floc W-300G, KC Floc W-400G, NP Fiber W-100F, NP Fiber W-300F, NP Commercially available products such as Fiber W-10MG2, NP Fiber W-06MG, KC Flock W-50GK, and KC Flock W-100GK (manufactured by Nippon Paper Industries Co., Ltd.), VITACEL-L10, VITACEL-L20, VITACEL-L600-30, VITACEL-L90, ARBOCEL-BMW40, and VITACEL-L500 (manufactured by Rettenmeyer) may also be used. As the crystalline cellulose, commercially available products such as Compressel (Fushimi Pharmaceutical Co., Ltd.) may also be used.

[0017] The heavy metals refer to metals with a specific gravity of 4 or more, and examples thereof include arsenic, mercury, lead, cadmium, chromium, selenium, and tin.

[0018] The sample may be, for example, a biological sample isolated from a subject, such as a sample derived from an animal tissue containing proteoglycan and / or collagen.

[0019] The proteoglycan is not particularly limited, and is preferably aggrecan, for example.

[0020] The proteoglycan may be, for example, an animal proteoglycan. The animal is not particularly limited, and examples thereof include mammals (mammals) such as pigs, cows, and whales; birds (birds) such as chickens; fish such as flatfish (e.g., sole), salmonids (e.g., chum salmon, Atlantic salmon), rays (including, for example, skimmer); and mollusks (e.g., squid). The animal is preferably salmon, pig, bird, flatfish, squid, whale, shark, ray, etc.

[0021] Examples of the collagen include type I, type II, type III, type V, and type XI collagen. Examples of the collagen include collagen derived from the animals.

[0022] The animal tissue is, for example, a tissue containing proteoglycan and / or collagen, and examples thereof include epithelial tissue such as skin, cartilaginous tissue such as cartilage, digestive organs, circulatory organs, respiratory organs, and placenta, etc. Specific examples of the animal tissue include cartilage, fins, digestive organs, circulatory organs, respiratory organs, and ears.

[0023] Examples of the sugar chain of the proteoglycan include chondroitin, chondroitin sulfate, dermatan sulfate (chondroitin sulfate B), heparan sulfate, heparin, and keratan sulfate. The sugar chain is preferably chondroitin sulfate.

[0024] The reduction method of the present disclosure may include an extraction step of extracting a sample containing proteoglycans and / or collagen derived from animal tissue using a solvent prior to the reduction step. The extraction step can be carried out, for example, by contacting the animal tissue with a solvent. Examples of the solvent include water, acidic aqueous solutions such as guanidine hydrochloride aqueous solution and acetic acid aqueous solution, urea aqueous solution, and magnesium chloride aqueous solution. For example, Japanese Patent Application Laid-Open No. 2020-127397 can be referenced for the method of extracting proteoglycans from animal tissue. For example, International Publication No. WO 2023 / 013301 can be referenced for the method of extracting collagen from animal tissue.

[0025] In the reduction method of the present disclosure, as described above, the heavy metals are reduced from the sample using the cellulose in the reduction step. Specifically, the reduction step can be carried out, for example, by contacting the cellulose with the sample. As a result, the heavy metals contained in the sample are supported by the cellulose. The contact between the cellulose and the sample can be carried out appropriately depending on the state of the cellulose and the sample. The cellulose and the sample to be contacted may be, for example, solid or liquid. When the cellulose and the sample are solid, the cellulose and the sample are preferably dispersed in a solvent before contact. When one of the cellulose and the sample is solid and the other is liquid, the contact can be carried out, for example, by a known solid-liquid contact method. Specifically, the contact can be carried out by mixing or blending (hereinafter collectively referred to as "blending") the cellulose and the sample. When the cellulose and the sample are solid, the contact can be carried out, for example, by adding the cellulose and the sample to a solvent. Examples of the solvent include water and an aqueous solution of acetic acid.

[0026] The amount of cellulose added in the reduction step is not particularly limited as long as it is an amount that can reduce heavy metals from the sample. Specifically, in the reduction step, the cellulose is preferably used in an amount of, for example, 10 to 50 mass %, or 12 to 40 mass %, relative to the mass of the sample.

[0027] The contact conditions (temperature, time, etc.) in the reduction step may be within a range in which the cellulose can reduce the heavy metals in the sample. The contact temperature may be, for example, a temperature at which the mixture of the cellulose and the sample does not freeze, such as 1 to 30°C or 5 to 25°C. The contact time may be, for example, a time at which the cellulose can be dispersed in the mixture, such as 10 minutes or more, or 30 minutes or more.

[0028] In the reduction step, for example, further mixing may be performed after the contacting step. The mixing may be performed using a stirring device such as a vortex mixer, by inversion mixing, or by ultrasonic treatment.

[0029] Next, in the reduction step, a liquid fraction is recovered from the mixture of the cellulose and the sample, thereby recovering a solution containing the sample with reduced heavy metals. The recovery can be performed, for example, by filtration or the like. As a result, in the reduction step, the cellulose and the sample can be separated while the heavy metals are supported on the cellulose, and the heavy metals contained in the sample can be reduced.

[0030] The reduction method of the present disclosure may measure the concentration of heavy metals contained in the recovered sample after the reduction step. The concentration of heavy metals may also be referred to as the concentration of heavy metals contained in the solid content of the sample contacted with the cellulose. The solid content can be obtained, for example, by freeze-drying the recovered sample. The concentration of the heavy metals can be measured by Heavy Metal Test Method 2 described in the 9th Edition of the Japanese Standards of Food Additives. When the heavy metal is arsenic, the concentration of the heavy metal can be measured by Arsenic Test Method 3 described in the 9th Edition of the Japanese Standards of Food Additives.

[0031] The concentration of heavy metals after the reduction step is, for example, 1.5 μg / g or less, 0.5 μg / g or less. The concentration of heavy metals is, for example, preferably 0 μg / g, but in reality, it is greater than 0 μg / g (about the detection limit) or 0.01 μg / g or more. The concentration of heavy metals is, for example, greater than 0 μg / g and 1.5 μg / g or less, 0.01 μg / g to 1.0 μg / g or less, or 0.01 μg / g to 0.5 μg / g.

[0032] In the reduction method of the present disclosure, after the reduction step, the solution containing the sample in which the heavy metals have been reduced may be further subjected to solid-liquid separation using a separation membrane, filter, or the like having an appropriate molecular weight cutoff.

[0033] The reduction method of the present disclosure may include, after the reduction step, a solidification step of solidifying the solution containing the sample whose heavy metals have been reduced. The solidification step can be carried out, for example, by a known method capable of solidifying the sample from the solution containing the sample whose heavy metals have been reduced, specifically by a drying process such as freeze-drying or spray-drying.

[0034] <Composition for reducing heavy metals> In another aspect, the present disclosure provides a composition for use in reducing heavy metals in a sample. The composition of the present disclosure includes cellulose. For example, the description of the method for reducing heavy metals of the present disclosure can be used for the composition of the present disclosure.

[0035] The composition of the present disclosure may be used in the method of reducing heavy metals of the present disclosure.

[0036] Next, examples of the present disclosure will be described. However, the present disclosure is not limited to the following examples. Commercially available reagents were used according to their protocols unless otherwise specified. Note that "mol / l" may also be abbreviated as "M."

[0037] Example 1 Heavy metals could be reduced from a sample by the method for reducing heavy metals of the present disclosure.

[0038] (1) Investigation of Heavy Metal Removal from Samples: Salmon nasal cartilage extract was extracted from salmon nasal cartilage by conventional methods, and two containers containing the resulting extract were prepared. The amounts of heavy metals and arsenic contained in 100 g of salmon nasal cartilage or bone are shown in Table 1 below. The method for measuring the amounts of heavy metals and arsenic is described below. 23 g of diatomaceous earth (Radiolite #1500, Showa Chemical Industry Co., Ltd.) was added to one container, and 23 g of powdered cellulose (KC Flock (registered trademark) W-300G, Nippon Paper Industries Co., Ltd.) was added to the other container. After the addition, a filtration aid was applied to each container. After the filtration aid, the filtrates were dried in a freeze dryer to obtain powders. The recovered amounts of the powders were 1.9 g (diatomaceous earth) and 2.1 g (powdered cellulose), respectively. Next, the amounts of heavy metals and arsenic contained in these powders were measured, and the amount of heavy metals or arsenic per 1 g of sample after freeze-drying was calculated. The measurements were performed using Heavy Metal Test Method No. 2 and Arsenic Test Method No. 3 described in the 9th Edition of the Japanese Standards for Food Additives (see https: / / www.mhlw.go.jp / content / 11130500 / 000641289.pdf).The results are shown in Table 2 below.

[0039]

[0040]

[0041] In Table 2, "ND" means not detected, and "Good" means that the detected amount was 1.5 μg / g or less. As shown in Table 2, when powdered cellulose was used, the heavy metals and arsenic contained in salmon nasal cartilage could be reduced more than when diatomaceous earth was used.

[0042] (2) Study of powdered cellulose capable of reducing heavy metals From Example 1(1), it was found that powdered cellulose can reduce heavy metals and arsenic from samples. Therefore, the amount of powdered cellulose capable of reducing heavy metals and arsenic from samples was studied. Specifically, the same method as in Example 1(1) was used with the combinations of samples and powdered cellulose shown in Table 3 below.

[0043]

[0044] As shown in Table 3 above, when the powdered cellulose was 1% by mass relative to the mass of cartilage, no reduction in heavy metals was observed, but when the powdered cellulose was 12% by mass or more relative to the mass of cartilage, a reduction in heavy metals was observed.

[0045] Although the present disclosure has been described above with reference to embodiments and examples, the present disclosure is not limited to the above embodiments and examples. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0046] The patents, patent applications, and publications cited herein are incorporated by reference into this specification in their entirety as if the contents were specifically set forth herein.

[0047] This application claims priority based on Japanese Patent Application No. 2024-025910, filed February 22, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0048] <Appendix> Some or all of the above embodiments and examples can be described as, but are not limited to, the following appendices. <Heavy Metal Reduction Method> (Appendix 1) A heavy metal reduction method comprising a reduction step of reducing heavy metals from a sample using cellulose. (Appendix 2) The reduction method according to Appendix 1, wherein the heavy metals in the sample are reduced by using 10 to 50% by mass of the cellulose relative to the mass of the sample in the reduction step. (Appendix 3) The heavy metal reduction method according to Appendix 1 or 2, wherein the heavy metals include arsenic. (Appendix 4) The reduction method according to any of Appendixes 1 to 3, wherein the cellulose is powdered cellulose. (Appendix 5) The reduction method according to any of Appendixes 1 to 4, comprising an extraction step of extracting a sample containing proteoglycan and / or collagen derived from animal tissue using a solvent from animal tissue. (Appendix 6) The reduction method according to any of Appendixes 1 to 5, wherein the sample contains proteoglycan and / or collagen derived from animal tissue. (Appendix 7) The method for reducing heavy metals according to Appendices 5 or 6, wherein the animal is selected from the group consisting of salmon, pig, poultry, flounder, squid, whale, shark, and ray. <Compositions for reducing heavy metals> (Appendix 8) A composition for use in reducing heavy metals in a sample, comprising cellulose. (Appendix 9) The composition according to Appendices 8, wherein the heavy metal comprises arsenic. (Appendix 10) The composition according to Appendices 8 or 9, wherein the cellulose is powdered cellulose. (Appendix 11) The composition according to any of Appendices 8 to 10, wherein the sample comprises proteoglycan and / or collagen derived from animal tissue. (Appendix 12) The composition according to Appendices 11, wherein the animal is selected from the group consisting of salmon, pig, poultry, flounder, squid, whale, shark, and ray. (Appendix 13) The composition according to any of Appendices 8 to 12, for use in the method for reducing heavy metals according to any of Appendices 1 to 7.

[0049] As described above, the present disclosure can provide a method for reducing heavy metals from a sample, etc. Therefore, the present disclosure can be said to be extremely useful in the food industry, for example.

Claims

1. A method for reducing heavy metals, comprising a reduction step of reducing heavy metals from a sample using cellulose.

2. The method according to claim 1, wherein the cellulose is used in an amount of 10 to 50% by mass relative to the mass of the sample in the reduction step, thereby reducing the heavy metals in the sample.

3. The method for reducing heavy metals according to claim 1 or 2, wherein the heavy metals include arsenic.

4. A reduction method according to any one of claims 1 to 3, wherein the cellulose is powdered cellulose.

5. A reduction method according to any one of claims 1 to 4, comprising an extraction step of extracting a sample containing proteoglycans and / or collagen derived from the animal tissue using a solvent from the animal tissue.

6. A reduction method according to any one of claims 1 to 5, wherein the sample contains proteoglycans and / or collagen derived from animal tissue.

7. The method of claim 5 or 6, wherein the animal is selected from the group consisting of salmon, pig, chicken, flounder, squid, whale, shark, and ray.

8. A composition for use in reducing heavy metals in a sample, comprising cellulose.

9. The composition of claim 8, wherein the heavy metal comprises arsenic.

10. The composition according to claim 8 or 9, wherein the cellulose is powdered cellulose.

11. The composition of any one of claims 8 to 10, wherein the sample contains proteoglycans and / or collagen derived from animal tissue.

12. The composition of claim 11, wherein the animal is selected from the group consisting of salmon, pig, bird, flounder, squid, whale, shark, and ray.

13. A composition according to any one of claims 8 to 12 for use in a method for reducing heavy metals according to any one of claims 1 to 7.

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