Polyaminophenol melanization in the process of paracetamol biotransformation by Rhodococcus ruber ИЭГМ 77

Precipitate formed in the process of paracetamol biotransformation by Rhodococcus ruber IEGM 77 was found to include indole and benzofuran ring fragments using 13C NMR spectroscopy and chromatography-mass-spectrometry methods. Mechanisms of the formation of conjugated indole and benzofuran cyclic systems resulting from the fermentative condensation of polyaminophenols contained in the precipitate chemical structure have been proposed. According to our data, polyaminophenol molecules and indole and benzofuran fragments in chemical structure of melanin-like compounds contain symmetric ("Sym") and asymmetric ("Asym") sites comprising aromatic and quinoid rings with equivalent substituents in para- and ortho- positions, respectively. Originally substantiated possibility of enzyme melanization of polyaminophenols by R. ruber IEGM 77 cells is viewed from the perspective of humification hypothesis.