Biotransformation of isonitrosoacetophenone (2-keto-2-phenyl-acetaldoxime) in tobacco cell suspensions

Nicotiana tabacum cell suspensions, 2 g wet wt/ml, rapidly took up 1 mM isonitrosoacetophenone (INAP), a plant-derived stress metabolite with anti-oxidative and anti-fungal properties, producing 4′-hexopyranosyloxy-3′-methoxyisonitrosoacetophenone in 54 % yield over 18 h. Unconverted INAP was at 33 μM. UPLC-MS/MS analyses with MassFragment software were used for metabolite identification. INAP had been hydroxylated at its meta- and para-positions as well as undergoing subsequent methoxylation and glycosylation. INAP is thus recognized by the enzymatic machinery of the phenylpropanoid pathway and is converted to a molecule with a substitution pattern similar to ferulic acid.