How to maintain the weak alkalinity of disinfectants for a long period of time

Abstract

To provide a bactericidal agent that sterilizes Escherichia coli or the like.SOLUTION: A bactericidal agent comprises water, the bactericidal agent containing a citrus seed extract and a weak alkalinity long-term maintenance agent that maintains a weak alkaline state for a predetermined period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for maintaining a disinfectant in a weak alkaline state for a long period of time. [Background technology]

[0002] Various virus inactivators have been used to prevent infectious gastroenteritis and food poisoning caused by norovirus, for example. For example, as disclosed in Patent Document 1, an anti-norovirus composition containing grapefruit seed extract and alkaline electrolyzed water and having an overall pH of 11.5 to 14 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5388325 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have discovered that by incorporating a citrus seed extract into a weakly alkaline solution having a pH of a predetermined level or higher, a virus inactivator that is sufficiently effective against norovirus can be obtained, even if it is non-alcoholic.

[0005] To make the virus inactivating agent weakly alkaline with a pH of 8 or higher, a method using alkaline electrolyzed water as described in Patent Document 1 is considered. Since alkaline electrolyzed water is obtained by electrolyzing an aqueous NaCl solution, it is essentially an aqueous NaOH solution, which is a strong base solution. For this reason, if the anti-norovirus composition described in Patent Document 1 is stored for a long period of time, carbon dioxide in the air will dissolve into the composition and become H + The inflow of OH ions - Ions decrease, and the pH tends to shift to the acidic side.

[0006] If the pH of the aqueous solution is in the strong alkaline region, the aqueous solution will- Because it contains a lot of ions, even if a small amount of carbon dioxide dissolves in the solution, it is thought that the pH of the solution will not change significantly. However, in the weak alkaline region, - Because the ion concentration is low, when the pH is adjusted to a weak alkaline with alkaline electrolytic water, OH is dissolved by carbon dioxide. - There is a risk that the pH will fluctuate significantly when ions are reduced. For this reason, weakly alkaline virus inactivators using alkaline electrolyzed water have low stability over time, and it may be difficult to maintain the desired performance over a long period of time.

[0007] A common method for stabilizing the pH of an aqueous solution is to use a buffer solution; however, it is not always easy to find an optimal buffer solution for a virus inactivating agent, and there is a demand for a virus inactivating agent that stabilizes the pH in a simpler manner.

[0008] The present invention has been made in view of the above points, and its object is to , simple To provide a virus inactivator which can maintain a weak alkalinity for a long period of time by a convenient method and has high efficacy especially against non-enveloped viruses such as norovirus. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a disinfectant containing water, which contains a citrus seed extract and a weakly alkaline long-term maintaining agent that makes the disinfectant weakly alkaline and maintains the weakly alkaline state for a predetermined period of time.

[0010] Alternatively, the composition may contain at least a citrus seed extract, a pH adjuster consisting of a salt of a strong alkali and a weak acid, and water.

[0011] With this configuration, not only is the citrus seed extract highly effective at disinfecting, but the synergistic action of the citrus seed extract and the alkali from the salt of a strong alkali and a weak acid also results in high virus removal efficacy against norovirus and the like.

[0012] Here, the pH of a salt is determined by the combination of the acid and base that make up the salt. For example, when a salt of a strong acid (hydrochloric acid) and a strong base (sodium hydroxide) such as sodium chloride is dissolved in water, sodium ions (Na + ) and chloride ions (Cl - ) and no further reaction occurs.

[0013] On the other hand, a salt of a weak acid (acetic acid) and a strong base (sodium hydroxide), such as sodium acetate, will first ionize almost completely in water, forming acetate ions (CH3CO0 - ) and sodium ions (Na + ) At this time, the sodium ions are almost completely ionized in water and do not behave as either an acid or a base. On the other hand, there is an equilibrium between acetate ions and acetic acid in water, as shown in Equation 1 below, and acetate ions behave as a base.

[0014] CH3COO - +H2O←→CH3COOH+OH - formula 1

[0015] Because of this equilibrium that produces hydroxide ions in an aqueous solution, salts of weak acids and strong bases become basic when dissolved in water, and the pH then settles at a constant value according to the equilibrium constant.

[0016] Due to the existence of this equilibrium, the pH of an aqueous solution of a salt of a weak acid and a strong base is relatively resistant to dropping when an external source of acid, such as carbon dioxide, is introduced into the solution, compared to an aqueous solution of a strong base (such as sodium hydroxide) of the same pH.

[0017] When an acid enters an aqueous solution, hydrogen ions (H +) will flow into the aqueous solution. In a typical aqueous solution of a strong base, an increase in hydrogen ions will decrease hydroxide ions, causing a drop in pH. However, in the case of a salt of a weak acid and a strong base, as mentioned above, the consumed hydroxide ions are supplied by the weak acid ions in the solution combining with water due to the existence of equilibrium, and the drop in pH is gradual.

[0018] This pH stability is particularly useful for this drug, whose efficacy is closely linked to pH.

[0019] It is also characterized by being adjusted to a pH of 8 or higher.

[0020] This configuration can enhance efficacy not only against bacteria such as E. coli, but also against non-enveloped viruses that do not have a lipid membrane known as an envelope.

[0021] In addition, the pH adjuster may be configured to generate carbonate ions when ionized.

[0022] In addition, the pH adjuster may be configured to generate bicarbonate ions when ionized.

[0023] In addition, the pH adjuster may be an ampholyte, such as sodium bicarbonate (sodium bicarbonate), and the use of an ampholyte further stabilizes the pH.

[0024] There are also compositions that are adjusted to a pH of 11.0 or less.

[0025] According to this configuration, the virus inactivator does not exhibit strong alkalinity, thereby increasing safety during handling. The virus inactivator may also be adjusted to a pH of 10.5 or less. The virus inactivator may also be adjusted to a pH of 8.5 or more. The virus inactivator may also be adjusted to a pH of 10.0 or more. By adjusting the pH to 8.5 or more or 10.0 or more, high virus removal efficacy can be achieved, for example, even if the contact time with non-enveloped viruses is short.

[0026] Alcohol-free formulations are also available. [Effects of the Invention]

[0027] According to the present invention, a sterilization effect of 99.99% or more can be obtained. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a graph showing the relationship between the concentration of a pH adjuster and pH. [Figure 2] 1 is a graph showing the results of an antiviral test. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0030] A virus inactivator according to an embodiment of the present invention contains at least grapefruit seed extract as a citrus seed extract, a pH adjuster consisting of a salt of a strong alkali and a weak acid, and water. The virus inactivator has a pH adjusted to 8 or higher using the pH adjuster. It can also be described as a virus inactivator in which a pH adjuster is contained in an aqueous solution of grapefruit seed extract. The aqueous solution of grapefruit seed extract is prepared by dissolving grapefruit seed extract in ion-exchanged water. The concentration of grapefruit seed extract in this aqueous solution can be set within a range of 0.1% to 5.0% by mass. The lower limit of the grapefruit seed extract concentration is preferably 0.15% by mass, more preferably 0.2% by mass. The upper limit of the grapefruit seed extract concentration is preferably 3.0% by mass, more preferably 0.8% by mass.

[0031] Grapefruit seed extract is extracted and purified from grapefruit seeds and is generally recognized as a food additive. When grapefruit seed extract is obtained from grapefruit, the seeds are removed from harvested grapefruit, the removed seeds are crushed, and the grapefruit seed extract can be extracted from the crushed product. In this case, the grapefruit seed extract can be extracted from the crushed product in an undried state, or from the crushed product in a freeze-dried state.

[0032] When extracting grapefruit seed extract, a solution such as water or alcohol can be used. Examples of alcohols used as extraction solvents include ethanol. When extracting grapefruit seed extract, the seeds may be heated to, for example, 30°C or higher. Grapefruit seed extract contains fatty acids, flavonoids, and the like. While food-grade grapefruit seed extract is preferred, it does not necessarily have to be food-grade.

[0033] The citrus seed extract may be one other than grapefruit seed extract, and seed extracts extracted in the same manner from the seeds of citrus fruits such as lemon may also be used.

[0034] The pH adjuster can be one that generates carbonate ions upon ionization or one that generates bicarbonate ions upon ionization. Furthermore, amphoteric electrolytes can also be used as the pH adjuster, and amphoteric electrolytes such as sodium bicarbonate (sodium bicarbonate) are preferred for pH stabilization. Examples of pH adjusters that can be used include sodium bicarbonate and sodium carbonate.

[0035] The pH of the virus inactivator can be adjusted by the amount of pH adjuster. In this embodiment, the content of the pH adjuster is set so that the pH of the virus inactivator is 8 or higher. The content of the pH adjuster is preferably set so that the pH of the virus inactivator is 8.5 or higher, and more preferably set so that the pH of the virus inactivator is 10.0 or higher. When determining the content of the pH adjuster, the pH adjuster is added while measuring the pH of the virus inactivator, and the content of the pH adjuster when the desired pH is achieved is determined.

[0036] The upper limit of the pH of the virus inactivator can be, for example, 11.5, and the content of the pH adjuster is preferably set so that the pH is 11.5 or lower. A pH of 11.0 is more preferable. This prevents the virus inactivator from exhibiting strong alkalinity, thereby increasing safety during handling.

[0037] By using salts of strong alkalis and weak acids as pH adjusters, ,a The pH can be stabilized over time compared to when the pH is adjusted with alkaline electrolyzed water. When a salt of a strong alkali and a weak acid is used, the pH is not stabilized at a constant level like a buffer solution, but the weak acid reacts with OH in water. - Because an equilibrium is created that supplies ions, the pH is less likely to change even when carbon dioxide from the air dissolves.

[0038] That is, when a salt of a strong acid (hydrochloric acid) such as sodium chloride and a strong base (sodium hydroxide) is dissolved in water, sodium ions (Na + ) and chloride ions (Cl - ) and no further reaction occurs, but in the case of a salt of a weak acid (acetic acid) and a strong base (sodium hydroxide), such as sodium acetate, it first ionizes almost completely in water, forming acetate ions (CH3CO0 - ) and sodium ions (Na +) At this time, the sodium ions are almost completely ionized in water and do not function as either an acid or a base. On the other hand, an equilibrium exists between acetate ions and acetic acid in water, as shown in Equation 1 above, and acetate ions behave as a base.

[0039] Because of this equilibrium that produces hydroxide ions in an aqueous solution, salts of weak acids and strong bases become basic when dissolved in water, and the pH then settles at a constant value according to the equilibrium constant.

[0040] Due to the existence of this equilibrium, the pH of an aqueous solution of a salt of a weak acid and a strong base is relatively resistant to a drop when an external source of acid, such as carbon dioxide, flows into the solution, compared to an aqueous solution of a strong base (such as sodium hydroxide) of the same pH.

[0041] When an acid enters an aqueous solution, hydrogen ions (H + ) will flow into the aqueous solution. In a typical aqueous solution of a strong base, an increase in hydrogen ions will decrease hydroxide ions, causing a drop in pH. However, in the case of a salt of a weak acid and a strong base, as mentioned above, the consumed hydroxide ions are supplied by the weak acid ions in the solution combining with water due to the existence of equilibrium, and the drop in pH is gradual.

[0042] There is a limit to the speed at which carbon dioxide in the air dissolves into the virus inactivator, so if the virus inactivator is stored or used in a normal environment, the decrease in pH will be extremely gradual.

[0043] In particular, when adjusting the pH level around 8 using alkaline electrolyzed water, OH - However, with the pH adjuster according to this embodiment, the pH decreases very slowly, making the effect even more pronounced.

[0044] By using a salt that generates carbonate ions or bicarbonate ions upon ionization, i.e., sodium carbonate or sodium bicarbonate, as the pH adjuster, a large amount of carbonate ions or bicarbonate ions will be present in the aqueous solution when ionized in the aqueous solution, making it difficult for carbon dioxide to dissolve and shift the equilibrium in the direction of generating carbonate ions or hydroxide ions. As a result, carbon dioxide is less likely to dissolve and the solution is less susceptible to the effects of carbon dioxide, which is preferable.

[0045] Figure 1 is a graph showing the results of adjusting the pH using sodium bicarbonate as a pH adjuster and adjusting the pH using alkaline electrolyzed water at around pH 8. When sodium bicarbonate is used as a pH adjuster, the pH hardly changes even when the sodium bicarbonate concentration is changed near pH 8, especially near pH 8.3. In other words, the pH stabilizes near pH 8.3 because the concentration range in which the pH is near 8.3 is wide.

[0046] On the other hand, when carbon dioxide dissolves in a sodium hydroxide solution, OH - Once the ions are consumed, the OH ions, as in the case of sodium bicarbonate, - Since there is no supply of ions, the pH fluctuates quickly, making it extremely difficult to adjust the sodium hydroxide solution to such a low concentration.

[0047] Also, since electrolyzed water is made by electrolyzing a NaCl solution, the alkaline side of the electrolyzed water is in the same state as a NaOH solution. Therefore, alkaline electrolyzed water can be considered in terms of NaOH, and the same logic as above applies, making it extremely unstable around pH 8.3.

[0048] The virus inactivator can be stored in a container with a spray lever and sprayed onto various items. Examples of containers with a spray lever include various conventionally used containers, and any container may be used. The virus inactivator can also be sprayed using a spraying device equipped with a hand pump or an electric pump. The virus inactivator can also be used by applying it to an item or by dripping it onto it. The virus inactivator can also be used by directly spraying it onto, for example, cooking utensils such as cutting boards and knives, countertops, tableware, dishcloths, towels, etc. The virus inactivator can also be used by spraying it onto clothing, floors, walls, toilets, sinks, and the interior of a car. The virus inactivator may also be sprayed onto the hands.

[0049] Furthermore, the virus inactivator does not contain alcohol, meaning that the virus inactivator does not have disinfecting or antiviral effects due to alcohol, but rather exerts its disinfecting and antiviral effects through the pH value and grapefruit seed extract.

[0050] (pH stability test) The citrus seed extract contained in the virus inactivating agent according to Example 1 of the present invention is, for example, grapefruit seed extract (grapefruit seed extract). The pH adjuster is sodium bicarbonate at a concentration of 0.21%. The remainder is ion-exchanged water. The initial pH of Example 1 is adjusted to around 8.3. Furthermore, Comparative Example 1 is prepared using alkaline electrolyzed water as a pH adjuster, and the initial pH of this comparative example is set to 10.0.

[0051] The pH stability test method is shown below. 1. Place each sample in a glass vial. 2. Store the glass vial containing the sample in a 60°C incubator. 3. Remove the glass vials from the thermostatic chamber at regular intervals to measure the pH and check the appearance. The reason for using a 60°C constant temperature chamber is to obtain so-called accelerated test results.

[0052] In the case of Example 1 of the present invention, the pH after three weeks was about 8.0, with almost no difference from the initial pH. On the other hand, in the case of Comparative Example 1, which used alkaline electrolyzed water, the pH after one week was about 9.3, and after three weeks was about 8.2, with an extremely large decrease from the initial pH. From the above, it can be seen that the virus inactivating agent according to this embodiment has high stability over time.

[0053] (Antiviral test) Next, we will explain the virus infectivity titer measurement test before and after treatment with a virus inactivating agent. This test uses feline calicivirus, which is used as a surrogate for norovirus, which has a similar structure. This is because norovirus is difficult to culture, and a simple method for evaluating the infectivity titer has not yet been established. In other words, it is generally believed that an agent that shows sufficient antiviral activity in a test using feline calicivirus will also show sufficient antiviral activity against norovirus.

[0054] To perform a virus infectivity titer measurement test, cells are first cultured in a monolayer in a cell culture microplate (96 wells) using cell growth medium. The cells are CRFK cells. A diluted virus suspension containing feline calicivirus (FCV) is then inoculated into this monolayer culture. The virus is then allowed to adsorb to the cells for 1 hour in a carbon dioxide incubator (CO2 concentration: 5%) at 37°C ± 1°C. The virus inoculum is then removed, and cell maintenance medium is added for 4 to 7 days of culture. Cell viability is then confirmed by amido black staining, and the 50% tissue culture infectivity titer (TCID50 / ml) is calculated using the Reed-Muench method. The lower this value, the lower the infectivity.

[0055] In general, non-enveloped viruses such as feline calicivirus are more resistant to various disinfectants and antibacterial agents than enveloped viruses such as influenza virus. Therefore, agents that are effective against non-enveloped viruses are likely to be effective against enveloped viruses in a shorter time.

[0056] The test agents are as shown in Table 1. The remainder is ion-exchanged water.

[0057] [Table 1]

[0058] The results of the virus infectivity measurement test are shown in Figure 2. In the graph, "30 seconds" indicates that the contact time between the test agent and the virus was 30 seconds, and "120 seconds" indicates that the contact time between the test agent and the virus was 120 seconds. "30 seconds" can be called a short-contact test, and "120 seconds" can be called a long-contact test. The values ​​on the graph are the log value of the infectivity titer TCID50 / ml (logTCID50 / ml). Sterilized water was used as a control. The lower the logTCID50 / ml of the test agent compared to the control, the higher the antiviral activity.

[0059] As shown in Figure 2, Comparative Example 2 (pH 7.0) showed a decrease in log TCID50 / ml from the control of 0.5 or less at both "30 seconds" and "120 seconds." On the other hand, Example 2 (pH 8.0) showed a significantly large decrease in log TCID50 / ml from the control of 2.5 at "120 seconds." Example 2 was prepared by diluting the liquid formulation of Example 1 with a 0.36% aqueous solution of grapefruit seed extract to a pH of 8.0.

[0060] In addition, in Example 3 at pH 8.5, Example 4 at pH 9.0, and Example 5 at pH 10.0, the decrease in log TCID50 / ml from the control was 3.0 or more at "120 seconds," and the antiviral activity was sufficient. hydrogen It is sodium.

[0061] Furthermore, in Example 3 (pH 8.5), Example 4 (pH 9.0), and Example 5 (pH 10.0), the logTCID50 / ml was 3.0 or more at "120 seconds," and they all had sufficient antiviral activity. The pH adjuster in Example 3 was sodium carbonate.

[0062] Furthermore, in Example 3 at pH 8.5, Example 4 at pH 9.0, and Example 5 at pH 10.0, the reduction in log TCID50 / ml from the control was 1.5 or more after 30 seconds, demonstrating sufficient antiviral activity even with a short contact time. In particular, in Example 5 at pH 10.0, the reduction in log TCID50 / ml from the control was 3.0 or more after 30 seconds, demonstrating extremely high antiviral activity even with a short contact time. Although not shown, the antiviral activity at pH 10.5 and pH 11.0 was comparable to that of Example 5.

[0063] In addition, in the case of a formulation containing sodium carbonate and sodium bicarbonate at pH 10 but not containing grapefruit seed extract, the log TCID50 / ml did not decrease compared to the control, indicating no antiviral effect. Although not shown, in the case of a formulation containing 0.18% by mass of grapefruit seed extract at pH 3, the log TCID50 / ml decrease from the control at "120 seconds" was approximately 0.3. In the case of a formulation containing 0.36% by mass of grapefruit seed extract at pH 3, the log TCID50 decrease from the control at "120 seconds" was approximately 0.5. In the case of a formulation containing 0.54% by mass of grapefruit seed extract at pH 3, the log TCID50 / ml decrease from the control at "120 seconds" was approximately 1.0. Furthermore, in the case of a formulation containing sodium carbonate and sodium bicarbonate at pH 10 but not containing grapefruit seed extract, the log TCID50 / ml decrease from the control at "120 seconds" was -0.5, indicating low antiviral effect.

[0064] In addition, in the case of a test using influenza virus (A / Udorn / 72 (H3N2)), trypsin may be added to a cell maintenance medium using MDCK cells. The liquid preparations of Examples 1 to 5 also exhibited antiviral activity against influenza virus equivalent to that against feline calicivirus.

[0065] As described above, the virus inactivating agent of this example exhibits sufficient efficacy not only against enveloped viruses such as influenza viruses, but also against non-enveloped viruses such as feline calicivirus. Furthermore, since the virus inactivating agent of this embodiment exhibited sufficient antiviral activity against feline calicivirus, it can be said that the virus inactivating agent of this embodiment is an anti-norovirus agent with sufficient anti-norovirus activity.

[0066] (Antibacterial test) Next, we will explain the antibacterial test. When conducting the antibacterial test, first, 9 0.1 ml of E. coli solution (cfu / ml) was added to 10 ml of the test solution, and 10 7 The sterilization rate is measured as cfu / ml. At this time, a control using 10 ml of saline instead of the test agent is also prepared. After 10 seconds of liquid-liquid contact, 1 ml is withdrawn and placed in 9 ml of SCDLP liquid medium for inactivation. Serial dilutions are then made, and 200 μl is plated on SCDLP agar medium. The number of colonies is counted for the control and each test agent, and the sterilization rate is measured. The sterilization rate is calculated using the formula: number of colonies for the test agent / number of colonies for the control. Examples 1 to 5 and Comparative Examples 1 and 2 were prepared as test agents. The antibacterial test results were 99.99% or higher for all of Examples 1 to 5 and Comparative Examples 1 and 2.

[0067] (pollution) Next, staining properties will be explained. Staining properties can be determined by spraying the test agent onto, for example, a black object, and after it has completely dried, visually checking whether or not any powder remains. If any powder remains, it can be determined that there is staining properties, and if no powder remains, it can be determined that there is no staining properties. Regarding staining properties, all of Examples 1 to 5 and Comparative Examples 1 and 2 showed no staining properties.

[0068] (Effects of the embodiment) As described above, the virus inactivating agent according to this embodiment contains at least a citrus seed extract, a pH adjuster consisting of a salt of a strong alkali and a weak acid, and water. , simple A weak alkalinity can be maintained for a long period of time in a convenient manner, and high efficacy can be stably obtained over time, especially against non-enveloped viruses such as norovirus.

[0069] In particular, when sodium bicarbonate is used as a pH adjuster, the stability of the virus inactivating agent can be increased when the pH of the virus inactivating agent is adjusted to a range of 8 to 8.5.

[0070] The above-described embodiments are merely examples in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0071] As described above, the virus inactivating agent according to the present invention can be used by spraying it onto cooking utensils, for example.

Claims

1. In a method for maintaining a weak alkaline disinfectant containing water for a long period of time, Citrus seed extract, A method for maintaining the weak alkaline state of a disinfectant for a long period of time, characterized in that the disinfectant is made weakly alkaline with a pH of 8 to 10.5, and contains a pH adjuster (excluding cases where glycine is contained) consisting of a strong alkali and a salt of a weak acid, which maintains the weakly alkaline state for up to 3 weeks.

2. The method for maintaining a weak alkaline state of a disinfectant for a long period of time according to claim 1, A method for maintaining a weak alkaline state of a disinfectant for a long period of time, characterized in that the disinfectant does not contain alcohol (excluding alcohol contained in citrus seed extract) as a disinfecting component.

3. The method for maintaining a weak alkaline state of a disinfectant for a long period of time according to claim 1 or 2, A method for maintaining a weak alkaline state of a disinfectant for a long period of time, wherein the pH adjuster contains sodium bicarbonate.

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