“…The pyridyl nitrogen is a likely target for electrophilic enzymatic oxidation because of its relatively high electronegativity and its unshared pair of electrons. Indeed, urinary excretion of pyridine N-oxide (40) has been observed after intraperitoneal administration of pyridine to mice, hamsters, rats, guinea-pigs, rabbits, cats and man 7,18,57 ; the N-oxide accounted for up to 40% of the administered dose in some species 18 . In studies on the in vitro N-oxidative transformation of pyridine, 40 was isolated from hepatocytes and subcellular fractions from the livers and lungs of various mammals incubated with the parent amine 28,29,41,56,58 60,92,93 .…”