In a study of imidazole-4-acetaldehyde presence in the reaction mixture during the coupling reaction of fungal amine oxidase and bacterial aldehyde oxidase for histamine elimination, imidazole 4-acetaldehyde was not detected, which suggests that imidazole 4-acetaldehyde was not produced as a result of the coupling reaction between fungal amine oxidase and aldehyde oxidase, as such, its absence in the reaction mixture implies that the fungal amine oxidase-aldehyde oxidase coupling reaction likely proceeded directly from histamine to [https://pubchem.ncbi.nlm.nih.gov/compound/Imidazoleacetic-acid imidazole-4-acetic acid] with an apparent yield of 100%, without the intermediate formation of imidazole 4-acetaldehyde.