Fig. 3.
Levels of endogenous production of melatonin and its metabolites depend on race, age and gender. Epidermis was extracted with 75% acetonitrile after homogenizing and applied to qTOF LC-MS (EIC) for quantification using corresponding standards (m/z = 233.1 [M+H]+ for melatonin; 287.1 [M+K]+ for 6(OH)M; 287.1 [M+Na]+ for AFMK, and 174.1 [M+H-NH3]+ for 5MT). *, p < 0.05; ***, p < 0.001 at Student t-test and #, p < 0.05 at Mann–Whitney test. Black (African-Americans) and white (Caucasians): race comparison; Age: age comparison; Sex: male and female comparison.