Method of preparing diaminophenothiazinium

1. A method of preparing an ultrapure diaminophenothiasinium compound with increased solubility in water, the method comprising lyophilizing at least one diaminophenothiasinimum compound from a solvent solution.

2. The method of claim 1 , further comprising, prior to lyophilization:

adding the at least one diaminophenothiasinium compound to a water-MeOH mixture with a water to MeOH ratio in a range of about a 3:1 to about 1:3;

passing the diaminophenothiasinium compound solution through a gradient with mobile phases of about 5 mM to about 20 mM HCl in water (e.g., 12 mM) and about 4 mM to about 20 mM HCl in MeOH (e.g., 12 mM);

collecting fractions;

concentrating the diaminophenothiasinium compound containing fraction;

dissolving the concentrated diaminophenothiasinium compound fraction in the solvent;

performing centrifugation on the concentrated diaminophenothiasinium compound(s) solvent solution; and

filtering the centrifuged diaminophenothiasinium compound(s) to prepare a ultrapure diaminophenothiasinium compound with high solubility.

3. The method of claim 1 , wherein the at least one compound is of the Formula (I) and/or its equivalent resonant structures (as described below):

wherein:

each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is independently selected from the group consisting of: a hydrogen atom ; saturated or unsaturated, linear, branched or cyclic C 1 -C 6 alkyl groups, optionally substituted with one or more functions chosen from a halogen atom, and a C 1 -C 6 alkoxy, C 1 -C 6 alkyloxycarbonyl or —CONH 2 function, aryl groups optionally substituted with one or more functions chosen from: a C 1 -C 4 alkyl, a halogen atom, and a C 1 -C 6 alkoxy, C 1 -C 6 alkyloxycarbonyl or —CONH 2 function;

R 6 and R 7 can be independently selected from methyl, ethyl, or —OH;

R 5 -R 10 can be independently selected from the halogen atoms: F, Cl, Br and I;

Z is an atom selected from O or S; and

X − represents an organic or inorganic anion.

4. The method of claim 3 , wherein X − is selected from: anions of inorganic acids; anions of organic acids; and OH − .

5. The method of claim 2 , further comprising producing a saturated DMSO solution with the ultrapure diaminophenothiasinium compound with high solubility.

6. The method of claim 5 , wherein the saturated DMSO solution of ultrapure diaminophenothiasinium compound with high solubility has a concentration in a range of about 18 mg/mL to about 22 mg/mL .

7. The method of claim 1 , wherein the ultrapure diaminophenothiasinium compound with high solubility is capable of producing a solution in water with a concentration greater than or equal to about 10 mg/mL.

8. The method of claim 2 , wherein filtering the centrifuged diaminophenothiasinium compound(s) is performed with a filter with pores in a range of about 0.22 μm to about 0.8 μm.

9. The method of claim 8 , wherein the pores are about 0.45 μm.

10. The method of claim 1 , wherein the solvent comprises DMSO.

11. The method of claim 10 , wherein the solvent further comprise a co-solvent.

12. The method of claim 11 , wherein the co-solvent is selected from acetic acid, acetone, acetonitrile, benzene, 1-butanol, 2-butanol, 2-butanone, t-butyl alcohol, carbon tetrachloride, chlorobenzene, chloroform, cyclohexane, 1,2-dichloroetane, diethylene glycol, diethyl ether, diglyme, 1,2-dimethoxy-ethane, dimethyl-formamide, 1,4-dioxane, ethanol ethyl acetate, ethylene glycol, glycerin, heptane, hemamethylphophoramie, hexamethylphosphorous triamide, hexane, methanol, methyl t-butyl ether, methylene chloride, N-methyle-2-pyrrolidinone, nitromethane, pentane, petroleum ether, 1-propanol, 2-propanol, pyridine, tetrahydrofuran, toluene, triethyl amine, o-xylene, m-xylene, p-xylene, or any combination thereof.

13. The method of claim 10 , wherein the solvent further comprises a lyophilization excipient.

14. The method of claim 13 , wherein the lyophilization excipient includes at least one of acetic acid, detran, glucose, glycine, hexose, histidine, lactose, L-arginine, mannitol, polyethylene glycol, PVP (K40), raffinose, sorbitol, sucrose, and trehalose.

15. A composition comprising: at least one diaminophenothiasinium compound with a solubility in water of greater than or equal to about 10 mg/mL.

16. The composition of claim 15 , wherein the at least one diaminophenothiasinium compound has a Formula (I):

wherein:

each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 and R 10 is independently selected from the group consisting of: a hydrogen atom; saturated or unsaturated, linear, branched or cyclic C 1 -C 6 alkyl groups, optionally substituted with one or more functions chosen from a halogen atom, and a C 1 -C 6 alkoxy, C 1 -C 6 alkyloxycarbonyl or —CONH 2 function, aryl groups optionally substituted with one or more functions chosen from: a C 1 -C 4 alkyl, a halogen atom, and a C 1 -C 6 alkoxy, C 1 -C 6 alkyloxycarbonyl or —CONH 2 function;

R 6 and R 7 can be independently selected from methyl, ethyl, or —OH;

R 5 -R 10 can be independently selected from the halogen atoms: F, Cl, Br and I;

Z is an atom selected from O or S; and

X − represents an organic or inorganic anion.

17. The composition of claim 16 , wherein X − is selected from: anions of inorganic acids; anions of organic acids; and OH − .

18. A method of preparing an ultrapure diaminophenothiasinium compound with increased solutibility in water, the method comprising:

adding the at least one diaminophenothiasinium compound to a water-MeOH mixture with a water to MeOH ratio in a range of about a 3:1 to about 1:3;

passing the diaminophenothiasinium compound solution through a gradient with mobile phases of about 5 mM to about 20 mM HCl in water (e.g., 12 mM) and about 4 mM to about 20 mM HCl in MeOH (e.g., 12 mM);

collecting fractions;

concentrating the diaminophenothiasinium compound containing fraction;

dissolving the concentrated diaminophenothiasinium compound fraction in the solvent;

performing centrifugation on the concentrated diaminophenothiasinium compound(s) solvent solution;

filtering the centrifuged diaminophenothiasinium compound(s) to prepare a ultrapure diaminopheno thiasinium compound with high solubility; and

lyophilizing at least one diaminophenothiasinimum compound from a solvent solution.