Fig. 6.

Benzo[a]pyrene degradation pathway. The oxidative degradation routes suggested by novoStoic combine both existing reactions and reaction rules in a mass-balanced fashion. The degradation products pyruvate and catechol were set as targets and benzo[a]pyrene was set as the source metabolite. Known reactions are indicated by solid lines while reactions suggested using reaction rules are denoted with dashed lines. Reaction rule ids are shown in red (see Table 3 for description). Novel intermediates predicted by novoStoic are abbreviated using an alphanumeric scheme (i.e., h1, h2, h3, etc.). The predicted routes are color-coded in blue and green based on the overall conversion. The degradation initiates with the formation of a (poly)aromatic diol in a dioxygenase reaction (R11–R12), while a subsequent oxidation forms a heterocyclic chromene derivative (h3). Next, a ring opening reaction of the chromene derivative (R14) is followed by an aldolase reaction to yield pyruvate and a (poly)aromatic aldehyde (R15). The aldehyde is then oxidized yielding carbon dioxide and a (poly)aromatic diol as a substrate for the next decyclization process (R16, R17)