Simultaneous quantification of urinary oxidative stress markers in women using combined oral contraceptives

Abstract

In physiological samples, it is difficult to measure the presence of free radicals. Therefore, secondary oxidative products excreted in urine after detoxification are quantified instead, as they are proportional to the oxidative species. Oxidative stress may initiate cancer or promote its progression, and some of these oxidative stress products are used as cancer markers. Combined oral contraceptives have been shown to induce oxidative stress and are also implicated in breast cancer development, whether these markers are involved in combined oral contraceptive induced oxidative stress is unknown. Most methods are developed for specific target groups such as lipid peroxidation or DNA damage, with only a few obtaining the broader oxidative stress status profile.

Therefore, this study aimed to develop a single analytical method that characterises the global oxidative stress status of an individual. The characterisation includes components of the lipid peroxidation pathways (hydroxynonenal, hydroxynonenal mercapturic acid, malondialdehyde, prostaglandin F2α, and prostaglandin E2), the DNA oxidation pathway (8-hydroxydeoxyguanosine), and both protein nitration and oxidation pathways (nitro-tyrosine and dityrosine). The global characterisation of the oxidative stress status can be used for risk analysis testing that speeds up a clinical diagnosis, whilst shedding the light on cellular mechanisms involved in oxidative stress-induced pathologies, such as cancer.