The metabolism pathway for PG is depicted in Figure . The proposed mechanism of toxicity for PG and GA arises from the formation of a reactive phenoxy radical species leading to the formation of an unstable o-quinone. The o-quinone then undergoes detoxification by GSH conjugation. While both PG and GA can lead to the formation of phenoxy radical and quinone intermediates, PG is much more lipophilic than GA and is expected to cross cell membranes more readily (Log P for PG is 2.13 and for GA is 0.91) .