PPOs are type-III dicopper enzymes, mainly consisting of tyrosinases (TYRs) and catechol oxidases (COs) . TYRs (Scheme A.1) reduce O 2 to catalyze the o-hydroxylation of monophenols and the subsequent oxidation of the intermediate (or exogenous) o-diphenols to o-quinones (EC 1.14.18.1) , referred to as monophenolase activity. COs (Scheme A.1) show only the latter reaction, referred to as diphenolase activity (EC 1.10.3.1). Understanding a PPO's function requires understanding its substrate scope, and it is assumed that different substrates are accepted based on the amino acids surrounding the active site of PPOs . Thus, knowing which polyphenols are present in specific species might assist in better understanding the function of PPOs and the involvement of both polyphenols and PPOs in biological pathways .