METHOD OF DETOXIFYING A HARMFUL COMPOUND

Abstract
It is an object of the present invention to provide a beneficial method of detoxifying a harmful compound in order to detoxify the harmful compound containing arsenic etc. effectively.
Description
TECHNICAL FIELD

The present invention relates to a method of detoxifying a harmful compound, especially a method of detoxifying a harmful compound wherein the harmful compound is detoxified by an exposure to light.


BACKGROUND ART

The heavy metal material such as arsenic, antimony and selenium is widely used as an industrial material, for example, semiconductor, but the influence on the organism by being flowed it out into an environment is concerned, since it is harmful material for the organism.


In the past, as a method for treating these heavy metal, a method wherein a flocculating agent such as polychlorinated aluminum (PAC) is added into the wastewater containing an inorganic arsenic such as a harmful arsenous acid, and then the inorganic arsenic is removed by the filtration after the inorganic arsenic is aggregated, adsorbed to the flocculating agent and iron contained in a raw water and then precipitated, or a method wherein an arsenic compound etc. is adsorbed by using an activated alumina, cerium based flocculating agent, are generally known.


On the other hand, it is known in nature that an inorganic arsenic is stored in sea food such as a seaweed, and then a part of the inorganic arsenic is converted to an organic arsenic compound such as dimethyl arsenic by the physiological response (Nonpatent literature 1: Kaise et al., 1998, Organomet. Chem., 12 137-143). And it is generally known that these organic arsenic compound has lower toxicity than that of the inorganic arsenic for the mammal.


Nonpatent literature 1 Kaise et al., 1998, Organomet. Chem., 12 137-143


DISCLOSURE OF THE INVENTION
Problems to be Resolved by the Invention

However, in the above method of removing the heavy metal characterized by the use of the filtration and adsorption, it is necessary to store or reclaim a polluted sludge containing the harmful compound such as the inorganic arsenic which is still harmful, and an absorbent to which the harmful compound is absorbed, under the condition of sealing off the harmful compound with the use of the concrete etc., in order to prevent it from being leaked to the outside. Therefore, there is problem that the mass disposal is difficult since a storage place or a large space for a reclaimed area are required.


Moreover, it is internationally recognized that an arsenic contained in the sea food is a harmless arsenobetaine, in the present invention, it is possible to attain the detoxification by chemically converting the highly toxic inorganic arsenic to the harmless arsenobetaine.


Therefore, it is an object of the present invention to provide a beneficial method of detoxifying a harmful compound in order to detoxify the harmful compound containing arsenic etc. effectively and systematically.


Means of Solving the Problems

In order to accomplish the above objects, the present inventors made strenuous studies on the optimal conditions regarding the methylating reaction of the harmful compound, by making an attempt to methylate, specially dimethylate, and more preferably trimethylate a harmful compound containing arsenic etc., by chemical reactions with the use of a cobalt complex. As a result, the inventors discovered the present invention.


That is, a method of detoxifying a harmful compound according to the present invention is characterized in that a harmful compound containing at least one element selected from the group comprising arsenic, antimony and selenium is detoxified by an exposure to light and/or a heating under the presence of a cobalt complex.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the harmful compound is detoxified by an alkylation of arsenic, antimony and selenium.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that an alkylation reaction is carried out under an exposure to light and/or a heating.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the harmful compound is detoxified under the presence of a reducing agent capable of reducing at least one metal selected from the group comprising arsenic, antimony and selenium.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the reducing agent is a material having SH group.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the material having SH group is at least one selected from the group comprising glutathione, reduced glutathione (GSH), cysteine, S-adenosyl cysteine, sulforaphane, homocysteine and thioglycol.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the cobalt complex is methyl complex comprising at least one compound selected from methylcobalamin (methylated vitamin B12, official name: Coα-[α-5,6-dimethylbenz-1H— imidazole-1-yl-Coβ-methylcobamide]), vitamin B12 such as cyanocobalamin, cobalt(II) acetyl acetonate, cobalt(III) acetyl acetonate, cobalt carbonyl (dicobalt octacarbonyl), cobalt(II)1,1,1,5,5,5-hexafluoro acetyl acetonate, cobalt (II) meso-tetra phenyl porphin, hexafluoro phosphoric acid bis(pentamethyl cyclopenta dienyl)cobalt, N,N′-bis(salicylidene) ethylene diamine cobalt(II), bis(2,2,6,6-tetramethyl-3,5-heptanedionato) cobalt(II), (chlorophthalocyaninnato) cobalt(II), chlorotris(triphenylphosphine) cobalt(I), methyl complex of cobalt(II) acetate, cobalt(II) benzoate, cobalt(II) cyanide, cyclohexane cobalt(II) butyrate, 2-cobalt(II) ethylhexanoate, meso-tetramethoxyphenyl porphyrin cobalt(II), cobalt naphthenate, cobalt(II) phthalocyanine, methyl cobalt(III) protoporphyrin IX, cobalt stearate, cobalt(II) sulfamate, (1R,2R)-(−)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene)cobalt(II), (1S,2S)-(+)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene)cobalt(II), cyclopentadienyl his (triphenylphosphine)phenylphosphine) cobalt(I), cyclopentadienyl cobalt dicarbonyl, dibromo bis(triphenylphosphine) cob alt(II), (tetraminochloro phthalocyaninnato) cobalt(II), (tetra-t-butyl phthalocyaninnato) cobalt(II), or at least one selected from the group comprising cobalt-methyl complex formed by allowing the cobalt compound to coexist with the alkyl halide, especially methyl halide.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the alkylation is a methylation.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the harmful compound is converted to a dimethyl compound, or trimethyl compound by the methylation.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the dimethyl compound is dimethyl arsonyl ethanol (DMAE), dimethyl arsonyl acetate (DMAA), dimethylarsinic acid, or arseno sugar.


Furthermore, in a preferred embodiment of the method of detoxifying a harmful compound according to the present invention, the method is characterized in that the trimethyl compound is arsenocholine, arsenobetaine, trimethyl arseno sugar or trimethyl arsine oxide.


EFFECT OF INVENTION

The method of detoxifying a harmful compound according to the present invention has an advantageous effect that a large space such as storage place is not required since it is possible to detoxify the harmful compound without limit. Furthermore, according to the method of the present invention, it has an advantageous effect that the unnecessary byproduct does not generate since it does not use a biological material in itself in a viable condition. Furthermore, according to the present invention, it has an advantageous effect that it is possible to decrease the harmful inorganic arsenic even more with a simple method.







BEST MODE FOR CARRYING OUT THE INVENTION

The method of detoxifying a harmful compound according to the present invention uses a cobalt complex. The cobalt complex used herein is not particularly limited, but an organometallic complex having a cobalt-carbon bond etc., may be recited as an example.


As an example of the organometallic complex having a cobalt-carbon bond may be mentioned below. That is, methylcobalamin (methylated vitamin B12, official name: Coa-[α-5,6-dimethylbenz-1H-imidazole-1-yl-Coβ-methylcobamide]) is preferably used. Furthermore, mention may be made of at least one selected from the group comprising the methyl complex of at least one compound selected from vitamin B12 such as cyanocobalamin, cobalt(II) acetyl acetonate, cobalt(III) acetyl acetonate, cobalt carbonyl(dicobalt octacarbonyl), cobalt(II)1,1,1,5,5,5-hexafluoro acetyl acetonate, cobalt(II) meso-tetra phenyl porphin, hexafluoro phosphoric acid bis(pentamethyl cyclopenta dienyl) cobalt, N,N′-bis(salicylidene)ethylene diamine cobalt(II), bis(2,2,6,6-tetramethyl-3,5-heptanedionato) cobalt(II), (chlorophthalocyaninnato) cobalt(II), chlorotris(triphenylphosphine) cobalt(I), methyl complex of cobalt(II) acetate, cobalt(II) benzoate, cobalt(II) cyanide, cyclohexane cobalt(II) butyrate, 2-cobalt(II) ethylhexanoate, meso-tetramethoxyphenyl porphyrin cobalt(II), cobalt naphthenate, cobalt(II) phthalocyanine, methyl cobalt(III) protoporphyrin IX, cobalt stearate, cobalt(II) sulfamate, (1R,2R)-(−)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene) cobalt(II), (1s, 2S)-(+)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene)cobalt(II), cyclopentadienyl bis(triphenylphosphine) cobalt(I), cyclopentadienyl cobalt dicarbonyl, dibromo bis(triphenylphosphine) cobalt(II), (tetraminochloro phthalocyaninnato) cobalt(II), (tetra-t-butyl phthalocyaninnato) cobalt(II), or at least one selected from the group comprising cobalt-methyl complex formed by allowing the cobalt compound to coexist with the alkyl halide, especially methyl halide. Methylcobalamin is preferable as the organometallic complex having a cobalt-carbon bond, from the viewpoint that it is possible to make it relatively easy to alkylate the harmful compound containing a harmful inorganic arsenic etc., and covert it to an organic material which has a less toxic.


The reason why the cobalt complex is used, is that the use of the cobalt complex makes it possible to proceed the transmethylation reaction in order to transport the methyl group to arsenic etc. An accomplishment of the methylation of arsenic etc., makes it possible to convert a harmful substance into a more harmless substance. Although it is generally known that a toxicity may be further enhanced by the methylation like an example of mercury or lead etc., in the case of arsenic etc., a toxicity may be considerably reduced by the methylation.


In the present invention, an exposure to light and/or a heating make it possible to proceed the transmethylation reaction. Although a detailed mechanism is unclear, but it is estimated that in the case of the use of methylcobalamin as a cobalt complex, the Co—C bond of the Co—Me group of methylcobalamin which is a factor for the methylation, is cleaved by an exposure to light and/or a heating, and thereby making it easy to translocate the methyl group to an atomic element of arsenic etc.


The conditions of the exposure to light may depend on the common procedure, and are not particularly limited. From a viewpoint that the transmethylation reaction may be enhanced, a light intensity is 0.1 to 1000 mW/cm2, more preferably 1 to 1000 mW/cm2. An energy is 1 mJ to 100 J, preferably 100 mJ to 100 J. As a wavelength of light which is irradiated, mention may be made of the ultraviolet ray, the visible light ray, the near-infrared ray, the infrared ray, the far-infrared radiation ray. Preferably, an exposure to light of the wavelength, with a central focus on an wavelength of an absorption maximum (λmax) of the absorption band about a cobalt complex, λmax±500 nm, more preferably, λmax±250 nm, further preferably, λmax±100 nm, makes it possible to effectively proceed the methylating reaction in the present invention.


Further, a condition of a heating is not particularly limited, but a heating temperature is 20 to 250° C., more preferably 50 to 150° C. from a viewpoint that the transmethylation reaction may be enhanced.


At this moment, the term “the harmful compound” used herein means a compound which gives any adverse affect to the organism when it is flowed out into the environment and exposed to the organism.


As a harmful compound containing arsenic among the harmful compound, mention may be made of arsenious acid, arsenic pentoxide, arsenic trichloride, arsenic pentachloride, arsenic sulfide compound, cyano arsenic compound, chloro arsenic compound, and other arsenic inorganic salt and or the like. In these arsenic, for example, LD50 (50% of the fatal dose in mouse) is less or equal to 20, and therefore, it is generally a poisonous value for the organism.


Further, as a harmful compound containing antimony, mention may be made of antimony trioxide, antimony pentoxide, antimony trichloride, and antimony pentachloride and or the like.


Further, as a harmful compound containing selenium, mention may be made of selenium dioxide and selenium trioxide etc.


In a preferred embodiment, the method of detoxifying a harmful compound according to the present invention may further carried out under the existence of a reducing agent capable of reducing at least one metal selected from the group comprising arsenic, antimony and selenium. The presence of the reducing agent like this makes it possible to further accelerate the alkylation. Although it is thought that a reducing ability for the arsenic or the transmethylation reaction are likely to be a rate controlling in the conversion to the arsenobetaine, it is thought that the conversion to the arsenobetaine etc., may be accelerated by adding those reducing agents. As the reducing agent like this, for example, a material having the SH group may be mentioned, which may be specifically at least one selected from the groups comprising glutathione, reduced glutathione (GSH), cysteine, S-adenosyl cysteine, sulforaphane, homocysteine and thioglycol. Moreover, any combinations of these materials having the SH group may be used. For example, combinations of glutathione+homocysteine, or glutathione+thioglycol etc., may be mentioned.


In the method according to the present invention, a detoxification reaction according to the exposure to light or the heating may be carried out under an adequate buffer solution. Those generally used for the isolation, purification or preservation of the biomedical materials may be used for the buffer solution, and those are not particularly limited, but mention may be made of the buffer solution such as a tris buffer, a phosphate buffer, a carbonic acid buffer, and a boric acid buffer. Furthermore, in a viewpoint that it is possible to attain the detoxification more safely, a pH of the buffer solution is preferably in the range of 5 to 10. A pH of the composition for the alkylation is more preferably less than 9. The composition for the alkylation of the present invention may further contain H2O2. That is, H2O2 may be added in a viewpoint that an acute toxicity can be decreased by enhancing the oxidation state (from trivalent to pentavalent).


In a preferred embodiment of the method of detoxifying the harmful compound according to the present invention, in the viewpoint that the 50% of an inhibition of cell growth concentration (IC50) or the 50% of a lethal dose (LD50) is greater, and thereby being able to attain more detoxification, the detoxification of the harmful compound is preferably attained by increasing the oxidation number of a valence of the one element contained in the above harmful compound. Specifically, it is possible to increase the oxidation number of a valence of the one element by the alkylation in the method of the present invention as described above. Moreover, it is preferable to convert a trivalent of the oxidation number of a valence to a pentavalent in the case that the element is arsenic or antimony, and it is preferable to convert a tetravalent of the oxidation number of a valence to a hexavalent in the case of selenium.


In the present invention, the detoxification of the harmful compound may be carried out by alkylating the harmful compound. At this moment, the present invention may attain the detoxification by alkylating at least one bond of the one element contained in the above harmful compound. At this moment, as an alkyl group added to the one element, mention may be made of a methyl group, an ethyl group, a propyl group etc. From a viewpoint that it is possible to attain the detoxification more effectively, a methyl group is preferable as an alkyl group.


In the method of detoxifying the harmful compound according to the present invention, from a viewpoint of the safety for the living organism, the 50% of a lethal dose (LD50) (an oral toxicity which render a 50% of the fatal dose in mouse) of the compound detoxified by the above alkylation is preferably greater or equal to 1000 mg/kg, more preferably greater or equal to 5000 mg/kg.


Furthermore, in the method of detoxifying the harmful compound according to the present invention, from a viewpoint of the safety for the living organism, the 50% of an inhibition of cell growth concentration (IC50) of the compound detoxified by the above alkylation or arylation is preferably greater or equal to 1000 μM, more preferably greater or equal to 3000 μM. The term “the 50% of an inhibition of cell growth concentration (IC50)” used herein means a numerical value which gives a necessary concentration of certain substance in order to block or inhibit a 50% of the 100 cell proliferation with the use of the substance. It shows that the smaller the numerical value of IC50, the larger the cytotoxicity. Moreover, IC50 was calculated from a result of the examination of the cytotoxicity which gives a plasmid DNA damage under the condition at 37° C., for 24 hours.


At this moment, IC50 of each arsenic compound is shown in the table 1









TABLE 1







IC50 value (μM)










Arsenic(III) compound
Arsenic(V) compound
















Arsenious acid
10
Arsenic acid
100



MMA(III)
1
MMA(V)
>6000



DMA(III)
1
DMA(V)
3000





TMAO
>6000



Arseno sugar(III)
500
Arseno sugar(V)
>6000







24 h, 37° C.






From the table 1, it is revealed that arseno sugar(III) having a trivalent arsenic(III) has higher cytotoxicity than those of monomethylated arsenic (MMA) and dimethylated arsenic (DMA) having a pentavalent arsenic, but has lower cytotoxicity than those of monomethylated arsenic (MMA), dimethylated arsenic (DMA) having a trivalent, and arsenious acid. On the other hand, it is recognized that monomethylated arsenic(MMA), dimethylated arsenic(DMA) having a trivalent arsenic have higher cytotoxicity than that of arsenious acid (trivalent and pentavalen), but as a whole, the arsenic(V) compound having a pentavalent arsenic has higher safety for the living organism than that of the arsenic(III) compound having a trivalent arsenic in a viewpoint of the cytotoxicity.


Moreover, LD50 of each arsenic compound is shown in the table 2












TABLE 2







Chemical species of the arsenic
LD50(mg/kg)




















As(III)
Inorganic arsenic(III(valency))
4.5



As(V)
inorganic arsenic(V(valency))
14-18



MMA
monomethyl arsonic acid
1,800



DMA
dimethylarsinic acid
1,200



AC
arsenocholine
6,000



TMAO
trimethylarsineoxide
10,600



AB
arsenobetaine
10,000










Furthermore, in the method of detoxifying the harmful compound according to the present invention, a biological half-life of the compound detoxified by the above alkylation is preferably less or equal to 8 hours from a viewpoint of the safety for the living organism. In the method of detoxifying the harmful compound according to the present invention, it is preferable to convert the harmful compound to the dimethyl compound or the trimethyl compound by means of the methylation from a viewpoint that they are safer and has a lower toxicity. Moreover, as the dimethyl compound mention may be made of dimethyl arsonyl ethanol (DMAE), dimethyl arsonyl acetate (DMAA), dimethylarsinic acid or arseno sugar. As the trimethyl compound mention may be made of arsenocholine, arsenobetaine, trimethyl arseno sugar or trimethyl arsine oxide.


EXAMPLE

The present invention will be concretely explained in more detail with reference to Examples, but the invention is not intended to be interpreted as being limited to Examples.


Examples 1 to 8

The Examples 1 to 8 of the present invention will be explained. 40 mg (130 μmol) of the reduced glutathione (GSH) and 10 mg (7.4 μmol) of methyl cobalamin (MC), are added into a 50 μL of a buffer solution (40 mM Tris-HCl buffer solution, pH8). To this was added 2 μL (2.7 nmol as arsenic trioxide) of arsenic trioxide (which is a trivalent inorganic arsenic) solution (standard solution for an atomic absorption, 100 ppm). The concentrations of each components existing in the reaction solution are as follows: The reduced glutathione (GSH): 2.6 mmol/L, Methyl cobalamin (MC): 0.15 mmol/L, the trivalent inorganic arsenic: 5 nmol/L. The preparation conditions of the reaction reagent are as shown in the table 3. This was added into an incubator for heating and reacted at a predetermined temperature, at a predetermined hours. The reaction conditions are shown in the table 4. After the reaction was terminated, the reaction solution was treated by 10% of a hydrogen peroxide solution, and diluted 500 fold with an ultrapure water, and carried out qualitative and quantitative analysis by the HPLC-ICP-MS method. The samples are separated into 5 types of chemical species, that is, pentavalent inorganic arsenic, pentavalent monomethyl arsenic (MMA), pentavalent dimethyl arsenic (DMA), pentavalent trimethyl arsenic (TMAO) and tetramethyl arsenic (TeMA), and made an analytical curve by a standard sample and carried out a quantitative analysis. The relative concentrations after the reaction were calculated by the following defined formula.





The relative concentration of iAs(V)=100%×[iAs(V)/(iAs(V)+MMA+DMA+TMAO+TeMA)]





The relative concentration of MMA=100%×[MMA/(iAs(V)+MMA+DMA+TMAO+TeMA)]





The relative concentration of DMA=100%×[DMA/(iAs(V)+MMA+DMA+TMAO+TeMA)]





The relative concentration of TMAO=100%×[TMAO/(iAs(V)+MMA+DMA+TMAO+TeMA)]





The relative concentration of TeMA=100%×[TeMA/(iAs(V)+MMA+DMA+TMAO+TeMA)]


Moreover, a conversion ratio of arsenic was calculated by the following formula.





A conversion ration=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction)





A conversion ration=100%×[(iAs(V)+MMA+DMA+TMAO+TeMA)/iAs  (III)]


The result of this is shown in the table 3. The table 3 shows an additive condition of the reaction reagent.











TABLE 3









Reaction reagent












Reducing
Methylating
Solvent




agent
agent
Buffer
iAs(III)



GSH
MC
solution
(100 ppm)


No.
(mg)
(mg)
(μL)
(μL)














Example 1
0
10
50
2


Reference ex. 1
40
0
50
2


Comparative ex. 1
0
0
50
2


Example 2
0
10
50
2


Reference ex. 2
0
10
50
2


Example 3
0
10
50
2


Reference ex. 3
0
10
50
2


Example 4
0
10
50
2


Reference ex. 4
0
10
50
2


Example 5
40
10
50
10


Reference ex. 5
40
10
50
10


Example 6
40
10
50
2


Reference ex. 6
40
10
50
2


Example 7
40
10
50
2


Reference ex. 7
40
10
50
2


Example 8
40
10
50
2


Reference ex. 8
40
10
50
2









The reaction conditions are shown in the table 4.











TABLE 4









Reaction condition










Heating condition
Exposure condition












Tem.
Time
Light intensity
Energy


No.
(° C.)
(hr)
(mW/cm2)
(J)














Example 1
20
1
5
18


Reference ex. 1
20
1
5
18


Comparative ex. 1
20
1
5
18


Example 2
30
2
5
36


Reference ex. 2
30
2
0
0


Example 3
50
2
5
36


Reference ex. 3
50
2
0
0


Example 4
80
2
5
36


Reference ex. 4
80
2
0
0


Example 5
20
2
5
36


Reference ex. 5
20
2
0
0


Example 6
30
2
5
36


Reference ex. 6
30
2
0
0


Example 7
50
2
5
36


Reference ex. 7
50
2
0
0


Example 8
80
2
5
36


Reference ex. 8
80
2
0
0









The relative ratio of the reaction product and the conversion ratio are shown in the table 5.













TABLE 5









Before reaction
After reaction
Conv. ratio



Raw material
Product (relative yield)
Main component/
















iAs (III)
iAs (V)
MMA
DMA
TMA
TeMA
Total
Raw material


No.
(ppm)
(%)
(%)
(%)
(%)
(%)
(%)
(%)


















Example 1
4
92
8
0
0
0
100
95


Reference ex. 1
4
100
0
0
0
0
100
93


Comparative ex. 1
4
100
0
0
0
0
100
~100


Example 2
4
87
13
0
0
0
100
~100


Reference ex. 2
4
100
0
0
0
0
100
93


Example 3
4
91
9
0
0
0
100
~100


Reference ex. 3
4
96
4
0
0
0
100
99


Example 4
4
95
5
0
0
0
100
~100


Reference ex. 4
4
97
3
0
0
0
100
~100


Example 5
20
50
17
21
12
0
100
94


Reference ex. 5
20
51
33
14
2
0
100
96


Example 6
4
51
17
18
14
0
100
93


Reference ex. 6
4
56
27
13
4
0
100
92


Example 7
4
25
12
15
47
0
100
91


Reference ex. 7
4
36
26
18
20
0
100
94


Example 8
4
0
4
3
91
2
100
99


Reference ex. 8
4
0
12
11
76
1
100
99









As it is clear from the comparison of the example 1, the reference example 1 and comparative example 1, in the case of no heating under the existence of no reducing agent, it was revealed that arsenic trioxide was converted into monomethylated arsenic (MMA) having a low toxicity by the exposure to light.


Moreover, as it is clear from the comparison of the example 2, the example 3 and the example 4 with the reference example 2, the reference example 3 and the reference example 4 respectively, it was revealed that arsenic trioxide was converted into monomethylated arsenic (MMA) having a low toxicity by the exposure to light in the existence of no reducing agent.


As it is clear from the comparison of the example 5, the example 6, the example 7 and the example 8 with the reference example 5, the reference example 6, the reference example 7 and the reference example 8 respectively, it was revealed that a methylating reaction is accelerated capable of converting arsenic trioxide into monomethylated arsenic (MMA), dimethylated arsenic (DMA), trimethylated arsenic (TMAO) having a low toxicity by the exposure to light in the existence of the reducing agent. Furthermore, as it is clear from the comparison of the example 5, the example 6, the example 7 and the example 8, it was revealed that a methylating reaction is accelerated capable of converting arsenic trioxide into monomethylated arsenic (MMA), dimethylated arsenic (DMA), trimethylated arsenic (TMAO) having a low toxicity under the conditions of the treatment of heating, and the exposure to light in the existence of the reducing agent.


Example 9

Furthermore, an effect of the exposure to light etc., was examined. The table 6 shows the effects of the reducing agent, the exposure to light and temperature for the methylating reaction in the case of the use of iAs (III) as a stating material.












TABLE 6









Reaction condition
















Starting
Reducing

Exposure

Relative ratio





















material
agent
Temp.
to
Time
iAs (V)
MMA
DMA
TMAO
TeMA
Total
Conv. ratio


Test No.
(As)
GSH
(° C.)
light
(hr)
(%)
(%)
(%)
(%)
(%)
(%)
(%)






















1
iAs (III)

30

2
51
17
18
14
0
100
93


2
iAs (III)
X
30

2
87
13
0
0
0
100
103


3
iAs (III)

30
X
2
56
27
13
4
0
100
92


4
iAs (III)
X
30
X
2
100
0
0
0
0
100
93


5
iAs (III)

50

2
25
12
15
47
0
100
91


6
iAs (III)
X
50

2
91
9
0
0
0
100
104


7
iAs (III)

50
X
2
36
26
18
20
0
100
94


8
iAs (III)
X
50
X
2
100
0
0
0
0
100
99


9
iAs (III)

80

2
0
4
3
91
2
100
99


10
iAs (III)
X
80

2
95
5
0
0
0
100
101


11
iAs (III)

80
X
2
0
12
11
76
1
100
99


12
iAs (III)
X
80
X
2
100
0
0
0
0
100
103


13
iAs (III)

100

2
0
0
0
93
7
100
100


14
iAs (III)
X
100

2
98
2
0
0
0
100
115


15
iAs (III)

100
X
2
0
0
0
95
5
100
97


16
iAs (III)
X
100
X
2
100
0
0
0
0
100
122


17
iAs (III)

120

2
0
0
0
93
7
100
95


18
iAs (III)
X
120

2
99
1
0
0
0
100
117


19
iAs (III)

120
X
2
0
0
0
93
7
100
93


20
iAs (III)
X
120
X
2
97
2
0
0
1
100
119









In the table 6, iAs(III): Trivalent arsenic, iAs (V): pentavalent arsenic, MMA: Monomethylated arsenic acid, DMA: Dimethylated arsinic acid, TMAO: Trimethylarsineoxide, TeMA: tetramethylated arsenic acid, GSH: Glutathione (reduced form), concentration of arsenic of the stating arsenic compound: 2.7 nmol, GSH (Reduced type of Glutathione): 130 μmol, Methylcobalamin: 7.4 μmol, solvent (tris HCL buffer solution, pH 8): 50 μL, light energy: 36 J (5 mW/cm2, 2 hours), respectively. Furthermore, a conversion ratio was calculated by the following formula: A conversion ration (%)=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction).


As it is clear from the comparison of the test number 4 and the test number 2, it was revealed that the methylating reaction of the below formula [Chemical 1] is accelerated by the exposure to light, even if there is no reducing agent, GSH.







As it is clear from the comparison of the test number 3 and the test number 1, it was revealed that the methylating reaction of the below formula [Chemical 2] is remarkably accelerated by the exposure to light, in the case of the existence of the reducing agent, GSH.







As it is clear from the comparison of the test number 9, the test number 15 and the test number 19, it was revealed that the conditions under the exposure to light at 80° C. make it possible to obtain a harmless TMAO at yield of 90% or more, and it was also revealed that this can obtain almost the same degree of effect as those of the reaction carried out under the conditions of no exposure to light at more higher temperature (100° C., 120° C.) (the test number 15 and the test number 19).


Example 10

Further, the effect related to the exposure to light etc., was also examined about another example. The table 7 shows the effects of the reducing agent, the exposure to light and the temperature for the methylating reaction in the case of the use of iAs (V) as a stating material.












TABLE 7









Reaction condition
















Starting
Reducing

Exposure

Relative ratio





















material
agent
Temp.
to
Time
iAs (V)
MMA
DMA
TMAO
TeMA
Total
Conv. ratio


Test No.
(As)
GSH
(° C.)
light
(hr)
(%)
(%)
(%)
(%)
(%)
(%)
(%)






















21
iAs (V)

30

2
61
19
10
10
0
100
93


22
iAs (V)
X
30

2
100
0
0
0
0
100
104


23
iAs (V)

30
X
2
57
32
9
2
0
100
93


24
iAs (V)
X
30
X
2
100
0
0
0
0
100
105


25
iAs (V)

50

2
34
15
10
42
0
100
93


26
iAs (V)
X
50

2
100
0
0
0
0
100
116


27
iAs (V)

50
X
2
38
35
15
13
0
100
94


28
iAs (V)
X
50
X
2
100
0
0
0
0
100
115


29
iAs (V)

80

2
0
0
1
95
4
100
84


30
iAs (V)
X
80

2
100
0
0
0
0
100
109


31
iAs (V)

80
X
2
0
4
6
86
4
100
88


32
iAs (V)
X
80
X
2
100
0
0
0
0
100
108


33
iAs (V)

100

2
0
0
0
93
7
100
86


34
iAs (V)
X
100

2
100
0
0
0
0
100
108


35
iAs (V)

100
X
2
0
0
0
95
5
100
85


36
iAs (V)
X
100
X
2
100
0
0
0
0
100
110


37
iAs (V)

120

2
0
0
0
93
7
100
87


38
iAs (V)
X
120

2
100
0
0
0
0
100
111


39
iAs (V)

120
X
2
0
0
0
95
5
100
86


40
iAs (V)
X
120
X
2
100
0
0
0
0
100
112









In the table 7, iAs(III): Trivalent arsenic, iAs (V): pentavalent arsenic, MMA: Monomethylated arsenic acid, DMA: Dimethylated arsinic acid, TMAO: Trimethylarsineoxide, TeMA: tetramethylated arsenic acid, GSH: Glutathione (reduced form), concentration of arsenic of the stating arsenic compound: 2.7 nmol, GSH (Reduced type of Glutathione): 130 μmol, Methylcobalamin: 7.4 μmol, solvent (tris HCL buffer solution, pH 8): 50 μL, light energy: 36 J (5 mW/cm2, 2 hours), respectively. Furthermore, a conversion ratio was calculated by the following formula: A conversion ration (%)=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction).


As it is clear from the comparison of the test number 23 and the test number 21, it was revealed that the methylating reaction of the below formula [Chemical 3] is remarkably accelerated by the exposure to light, in the case of the existence of the reducing agent, GSH.







As it is clear from the comparison of the test number 29, the test number 35 and the test number 39, it was revealed that the conditions under the exposure to light at 80° C. make it possible to obtain a harmless TMAO at yield of 90% or more, and it was also revealed that this can obtain almost the same degree of effect as those of the reaction carried out under the conditions of no exposure to light at more higher temperature (100° C., 120° C.) (the test number 35 and the test number 39).


Example 11

Further, the effects related to the exposure to light and the temperature etc., were also examined. The table 8 shows the effects of the reducing agent, the exposure to light and the temperature for the methylating reaction in the case of the use of MMA as a stating material.












TABLE 8









Reaction condition
















Starting
Reducing

Exposure

Relative ratio





















material
agent
Temp.
to
Time
iAs (V)
MMA
DMA
TMAO
TeMA
Total
Conv. ratio


Test No.
(As)
GSH
(° C.)
light
(hr)
(%)
(%)
(%)
(%)
(%)
(%)
(%)






















41
MMA

30

2
0
8
30
62
0
100
92


42
MMA
X
30

2
0
100
0
0
0
100
102


43
MMA

30
X
2
0
27
52
20
2
100
104


44
MMA
X
30
X
2
0
100
0
0
0
100
103


45
MMA

50

2
0
3
6
87
4
100
104


46
MMA
X
50

2
0
100
0
0
0
100
108


47
MMA

50
X
2
0
15
31
50
4
100
115


48
MMA
X
50
X
2
0
100
0
0
0
100
109


49
MMA

80

2
0
0
0
89
11
100
113


50
MMA
X
80

2
0
100
0
0
0
100
103


51
MMA

80
X
2
0
1
2
89
8
100
119


52
MMA
X
80
X
2
0
100
0
0
0
100
105


53
MMA

100

2
0
0
0
84
16
100
113


54
MMA
X
100

2
0
100
0
0
0
100
101


55
MMA

100
X
2
0
0
0
86
14
100
115


56
MMA
X
100
X
2
0
100
0
0
0
100
100


57
MMA

120

2
0
0
0
80
20
100
121


58
MMA
X
120

2
0
100
0
0
0
100
109


59
MMA

120
X
2
0
0
0
75
25
100
79


60
MMA
X
120
X
2
0
100
0
0
0
100
111









In the table 8, iAs(III): Trivalent arsenic, iAs (V): pentavalent arsenic, MMA: Monomethylated arsenic acid, DMA: Dimethylated arsinic acid, TMAO: Trimethylarsineoxide, TeMA: tetramethylated arsenic acid, GSH: Glutathione (reduced form), concentration of arsenic of the stating arsenic compound: 2.7 nmol, GSH (Reduced type of Glutathione): 130 μmol, Methylcobalamin 7.4 μmol, solvent (tris HCL buffer solution, pH 8): 50 μL, light energy: 36 J (5 mW/cm2, 2 hours), respectively. Furthermore, a conversion ratio was calculated by the following formula: A conversion ration (%)=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction).


As it is clear from the comparison of the test number 43 and the test number 41, it was revealed that the methylating reaction of the below formula [Chemical 4] is remarkably accelerated by the exposure to light, in the case of the existence of the reducing agent, GSH.







As it is clear from the comparison of the test number 49, the test number 55 and the test number 59, it was revealed that the conditions under the exposure to light at 80° C. make it possible to obtain a harmless TMAO at yield of 80% or more, and it was also revealed that this can obtain almost the same degree of effect as those of the reaction carried out under the conditions of no exposure to light at more higher temperature (100° C., 120° C.) (the test number 55 and the test number 59).


Example 12

Further, the effects related to the exposure to light and the temperature etc., were examined. The table 9 shows the effects of the reducing agent, the exposure to light and the temperature for the methylating reaction in the case of the use of DMA as a stating material.












TABLE 9









Reaction condition
















Starting
Reducing

Exposure

Relative ratio





















material
agent
Temp.
to
Time
iAs (V)
MMA
DMA
TMAO
TeMA
Total
Conv. ratio


Test No.
(As)
GSH
(° C.)
light
(hr)
(%)
(%)
(%)
(%)
(%)
(%)
(%)






















61
DMA

30

2
0
2
29
67
3
100
76


62
DMA
X
30

2
0
0
100
0
0
100
103


63
DMA

30
X
2
0
0
59
38
3
100
89


64
DMA
X
30
X
2
0
0
100
0
0
100
108


65
DMA

50

2
0
0
3
92
5
100
92


66
DMA
X
50

2
0
0
100
0
0
100
103


67
DMA

50
X
2
0
0
28
65
7
100
88


68
DMA
X
50
X
2
0
0
100
0
0
100
97


69
DMA

80

2
0
0
0
83
17
100
106


70
DMA
X
80

2
0
0
100
0
0
100
103


71
DMA

80
X
2
0
0
0
79
21
100
108


72
DMA
X
80
X
2
0
0
100
0
0
100
94


73
DMA

100

2
0
0
0
72
28
100
98


74
DMA
X
100

2
0
0
100
0
0
100
104


75
DMA

100
X
2
0
0
0
70
30
100
108


76
DMA
X
100
X
2
0
0
100
0
0
100
110


77
DMA

120

2
0
0
0
65
35
100
112


78
DMA
X
120

2
0
0
88
2
10
100
120


79
DMA

120
X
2
0
0
0
60
40
100
115


80
DMA
X
120
X
2
0
0
100
0
0
100
112









In the table 8, iAs(III): Trivalent arsenic, iAs (V): pentavalent arsenic, MMA: Monomethylated arsenic acid, DMA: Dimethylated arsinic acid, TMAO: Trimethylarsineoxide, TeMA: tetramethylated arsenic acid, GSH: Glutathione (reduced form), concentration of arsenic of the stating arsenic compound: 2.7 nmol, GSH (Reduced type of Glutathione): 130 μmol, Methylcobalamin 7.4 μmol, solvent (tris HCL buffer solution, pH 8): 50 μL, light energy: 36 J (5 mW/cm2, 2 hours), respectively. Furthermore, a conversion ratio was calculated by the following formula: A conversion ration (%)=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction).


As it is clear from the comparison of the test number 63 and the test number 61, it was revealed that the methylating reaction of the below formula [Chemical 5] is remarkably accelerated by the exposure to light, in the case of the existence of the reducing agent, GSH.







As it is clear from the comparison of the test number 65 and the test number 67, a harmless TMAO at yield of 90% or more can be obtained under the exposure to light at 50° C.


Example 13

The conditions related to the exposure to light and the temperature etc., were examined. The table 10 shows the effects of the reducing agent, the exposure to light and the temperature for the methylating reaction in the case of the use of TMAO as a stating material.












TABLE 10









Reaction condition
















Starting
Reducing

Exposure

Relative ratio





















material
agent
Temp.
to
Time
iAs (V)
MMA
DMA
TMAO
TeMA
Total
Conv. ratio


Test No.
(As)
GSH
(° C.)
light
(hr)
(%)
(%)
(%)
(%)
(%)
(%)
(%)






















81
TMAO

30

2
0
0
4
89
7
100
74


82
TMAO
X
30

2
0
0
0
100
0
100
93


83
TMAO

30
X
2
0
0
0
90
10
100
73


84
TMAO
X
30
X
2
0
0
0
100
0
100
95


85
TMAO

50

2
0
0
0
91
9
100
71


86
TMAO
X
50

2
0
0
0
100
0
100
83


87
TMAO

50
X
2
0
0
0
86
14
100
76


88
TMAO
X
50
X
2
0
0
0
100
0
100
83


89
TMAO

80

2
0
0
0
82
18
100
80


90
TMAO
X
80

2
0
0
0
100
0
100
82


91
TMAO

80
X
2
0
0
0
73
27
100
83


92
TMAO
X
80
X
2
0
0
0
100
0
100
84


93
TMAO

100

2
0
0
0
71
29
100
79


94
TMAO
X
100

2
0
0
0
100
0
100
93


95
TMAO

100
X
2
0
0
0
62
38
100
89


96
TMAO
X
100
X
2
0
0
0
100
0
100
92


97
TMAO

120

2
0
0
0
56
44
100
79


98
TMAO
X
120

2
0
0
0
100
0
100
94


99
TMAO

120
X
2
0
0
0
46
54
100
83


100
TMAO
X
120
X
2
0
0
0
100
0
100
84









In the table 10, iAs(III): Trivalent arsenic, iAs (V): pentavalent arsenic, MMA: Monomethylated arsenic acid, DMA: Dimethylated arsinic acid, TMAO: Trimethylarsineoxide, TeMA: tetramethylated arsenic acid, GSH: Glutathione (reduced form), concentration of arsenic of the stating arsenic compound: 2.7 nmol, GSH (Reduced type of Glutathione): 130 μmol, Methylcobalamin: 7.4 μmol, solvent (tris HCL buffer solution, pH 8): 50 μL, light energy: 36 J (5 mW/cm2, 2 hours), respectively. Furthermore, a conversion ratio was calculated by the following formula: A conversion ration (%)=100%×(The concentration of arsenic after the reaction/The concentration of arsenic before the reaction).


A methylating reaction is shown in the table 10 as a reference example in the case of the use of a harmless TMAO as a stating material. As it is clear from the test numbers 82, 84, 86, 88, 90, 92, 94, 96, 98 and 100, it was revealed that the harmless TMAO maintains its stability in the present reaction conditions with no degradation into iAs (III), iAs(V), MMA or DMA by the exposure to light or the heating.


INDUSTRIAL APPLICABILITY

The present inventions make a significant contribution in the broad fields of treatments of the industrial waste etc., and environmental protections concerning a polluted mud or a soil, since the harmless compounds obtained by converting the harmful compound containing arsenic etc., to more harmless compound according to the method of the present invention, are extremely stable and safe.

Claims
  • 1. A method of detoxifying a harmful compound, wherein a harmful compound containing at least one element selected from the group comprising arsenic, antimony and selenium is detoxified by an exposure to light and/or a heating under the presence of a cobalt complex.
  • 2. A method of detoxifying a harmful compound according to claim 1, wherein the harmful compound is detoxified by an alkylation of arsenic, antimony and selenium.
  • 3. A method of detoxifying a harmful compound according to claim 1, wherein an alkylation reaction is carried out under an exposure to light and/or a heating.
  • 4. A method of detoxifying a harmful compound according to claim 1, wherein the harmful compound is detoxified under the presence of a reducing agent capable of reducing at least one metal selected from the group comprising arsenic, antimony and selenium.
  • 5. A method of detoxifying a harmful compound according to claim 4, wherein the reducing agent is a material having SH group.
  • 6. A method of detoxifying a harmful compound according to claim 5, wherein the material having SH group is at least one selected from the group comprising glutathione, reduced glutathione (GSH), cysteine, S-adenosyl cysteine, sulforaphane, homocysteine and thioglycol.
  • 7. A method of detoxifying a harmful compound according to claim 1, wherein the cobalt complex is methyl complex comprising at least one compound selected from methylcobalamin (methylated vitamin B12, official name: Coα-[α-5,6-dimethylbenz-1H-imidazole-1-yl-Coβ-methylcobamide]), vitamin B 12 such as cyanocobalamin, cobalt(II) acetyl acetonate, cobalt(III) acetyl acetonate, cobalt carbonyl(dicobalt octacarbonyl), cobalt(II)1,1,1,5,5,5-hexafluoro acetyl acetonate, cobalt (II) meso-tetra phenyl porphin, hexafluoro phosphoric acid bis (pentamethyl cyclopenta dienyl) cobalt, N,N′-bis(salicylidene) ethylene diamine cobalt(II), bis(2,2,6,6-tetramethyl-3,5-heptanedionato) cobalt(II), (chlorophthalocyaninnato) cobalt(II), chlorotris(triphenylphosphine) cobalt(I), methyl complex of cobalt(II) acetate, cobalt(II) benzoate, cobalt(II) cyanide, cyclohexane cobalt(II) butyrate, 2-cobalt(II) ethylhexanoate, meso-tetramethoxyphenyl porphyrin cobalt(II), cobalt naphthenate, cobalt(II) phthalocyanine, methyl cobalt(III) protoporphyrin IX, cobalt stearate, cobalt(II) sulfamate, (1R,2R)-(−)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene) cobalt(II), (1S,2S)-(+)-1,2-cyclohexanediamino-N,N′-bis(3,5-di-t-butylsalicylidene) cobalt(II), cyclopentadienyl bis(triphenylphosphine) cobalt(I), cyclopentadienyl cobalt dicarbonyl, dibromo bis (triphenylphosphine) cobalt(II), (tetraminochloro phthalocyaninnato) cobalt(II), (tetra-t-butyl phthalocyaninnato) cobalt(II), or at least one selected from the group comprising cobalt-methyl complex formed by allowing the cobalt compound to coexist with the alkyl halide, especially methyl halide.
  • 8. A method of detoxifying the harmful compound according to claim 2, wherein the alkylation is a methylation.
  • 9. A method of detoxifying the harmful compound according to claim 8, wherein the harmful compound is converted to a dimethyl compound, or trimethyl compound by the methylation.
  • 10. A method of detoxifying the harmful compound according to claim 9, wherein the dimethyl compound is dimethyl arsonyl ethanol (DMAE), dimethyl arsonyl acetate (DMAA), dimethylarsinic acid, or arseno sugar.
  • 11. A method of detoxifying the harmful compound according to claim 9, wherein the trimethyl compound is arsenocholine, arsenobetaine, trimethyl arseno sugar or trimethyl arsine oxide.
Priority Claims (1)
Number Date Country Kind
2007-246470 Sep 2007 JP national
PCT Information
Filing Document Filing Date Country Kind 371c Date
PCT/JP2008/002566 9/18/2008 WO 00 5/27/2010