CYP1A2 (cytochrome P450 family 1 subfamily A member 2) is a major hepatic drug-metabolizing enzyme that catalyzes the oxidative metabolism of numerous endogenous substrates and xenobiotics. As a monooxygenase, CYP1A2 uses molecular oxygen to insert one oxygen atom into substrates while reducing the second to water, with electrons provided by NADPH via cytochrome P450 reductase 12. The enzyme exhibits high catalytic activity for estrogen metabolism, converting estrone and 17β-estradiol to their 2-hydroxy derivatives 23, and metabolizes cholesterol to 25-hydroxycholesterol 4. CYP1A2 also catalyzes retinoic acid biosynthesis through sequential oxidation of retinol 1 and performs stereoselective epoxidation of polyunsaturated fatty acids 5. In xenobiotic metabolism, CYP1A2 processes various drugs including sumatriptan through N-demethylation 6, phenacetin through O-deethylation 7, and caffeine via N3-demethylation. The enzyme's activity is subject to inhibition by natural compounds like quercetin and fucoxanthin 8 and pterostilbene 9. Genetic polymorphisms in CYP1A2 influence drug response, with clinical implications for personalized medicine approaches in conditions like depression 10 and cancer risk assessment 11.