| Lipid peroxidation and associated processes have been linked to a series of pathological events, such as atherosclerosis, carcinogenesis, diabetes, and hepatic diseases. Lycopene, a major carotenoid found in tomatoes, can function as an antioxidant to quench singlet oxygen and scavenge peroxyl radicals. Cervical cancer cell culture studies and a prostate cancer clinical trial were undertaken to understand the effects of lycopene in the prevention of lipid peroxidation.; To evaluate the extent of lipid peroxidation in vivo and in vitro, malondialdehyde (MDA) was selected as a biomarker of lipid peroxidation. Two liquid chromatography tandem mass spectrometry (LC-MS-MS) assays were developed to efficiently quantify MDA as a derivative of diethyl thiobarbituric acid (cervical cancer study) or a thiobartituric acid (prostate cancer study). In the cervical cancer study, a decrease in formation of MDA was observed in cells treated with lycopene. In men with prostate cancer or benign prostate hyperplasia lycopene administered 30 mg/day lycopene for 21 days produced a negative association as measured by the Pearson correlation between MDA variance. This means that as lycopene levels increased as a result of intervention, lipid peroxidation decreased.; beta-carotene is the most active provitamin A carotenoid. Furthermore, vitamin A deficiency is the major cause of night blindness and childhood mortality in the world. Since the bioefficacy (defined as bioavailability plus bioconversion to retinol) of beta-carotene remains uncertain, a clinical study was carried out to help clarify its bioefficacy based on a plateau isotope enrichment approach using carbon-13 labeled beta-carotene and retinol. To facilitate the measurement labeled beta-carotene in human serum and feces, an existing liquid chromatography-mass spectrometry (LC-MS) assay had to be adapted. Saponification was applied in sample preparation to eliminate the interfering triglycerides or diglycerides in serum samples. Negative ion APCI (Atmosphere Pressure Chemical Ionization) was applied in ionization mode to improve selectivity and sensitivity. Finally, the vitamin A activity of 3.1 mug beta-carotene was found to be equivalent to 1 mug retinol. The bioefficacy of beta-carotene is therefore 31% in oil for the healthy adult. |
