Method for producing tryptophan decomposition product, method for producing formylkynurenine, method for producing kynurenine, method for producing tryptophan radical-containing aqueous solution, and bactericidal aqueous solution

A method for producing formylkynurenine, the method comprising:

• obtaining an oxygen radical-irradiated aqueous solution that contains formylkynurenine by selectively irradiating a tryptophan-containing aqueous solution that contains tryptophan with oxygen radicals so as to generate a precursor including at least one of a tryptophan radical and tryptophan peroxide from the tryptophan and thereafter generate the formylkynurenine from the precursor;
• and
• separating the formylkynurenine from the oxygen radical-irradiated aqueous solution.

A method for producing kynurenine, the method comprising:

• obtaining an oxygen radical-irradiated aqueous solution that contains kynurenine by selectively irradiating a tryptophan-containing aqueous solution that contains tryptophan with oxygen radicals so as to generate a precursor including at least one of a tryptophan radical and tryptophan peroxide from the tryptophan and thereafter generate the kynurenine from the precursor;
• and
• separating the kynurenine from the oxygen radical-irradiated aqueous solution.

A method for producing a tryptophan radical-containing aqueous solution, wherein a tryptophan-containing aqueous solution that contains tryptophan is selectively irradiated with oxygen radicals to generate tryptophan radicals from the tryptophan to thereby generate a tryptophan radical-containing aqueous solution that contains the tryptophan radicals.

A bactericidal aqueous solution having a bactericidal effect and comprising a tryptophan radical-containing aqueous solution that contains tryptophan radicals.