| Abstract [eng] |
Effects of Sample Preparation and Storage Conditions on Serum Carotenoid Concentrations The aim of the study: To evaluate the effects of sample preparation and storage conditions on serum carotenoid concentrations. Objectives: To determine changes of carotenoid concentrations in serum samples that were stored at –80 °C. To determine changes of carotenoid concentrations, extracted from serum sample, considering the time taken before the analysis. To evaluate concentration changes of lycopene isomers from extracted serum samples after 24, 72 and 167 hours. Methods: 60 serum samples of different patients were used in this research. 20 of the samples were involved in a long term investigation, where carotenoid concentrations were determined and compared in 2012 and in 2018. 40 patients serum samples were used in carotenoid stability analysis, where extracted serum samples were stored at 22 °C for 24, 72 and 167 hours. Concentration of carotenoids was measured using a high performance liquid chromatography (HPLC) method. Microsoft Office Excel 2007 and R 3.5.0 programs were used for the statistical analysis. Results and conclusions:Carotenoid concentrations decreased significantly (p <0,05) when serum samples were stored at –80 °C for six years: lutein by 31 %, canthaxanthin by 30 %, cryptoxanthin by 41 %, α-carotene by 19 %, β-carotene by 40 %, lycopene by 53 % and the total carotenoid concentration by 42 %. It was found that carotenoids extracted from serum samples were stable at 22°C for up to 72 hours, except α-carotene, which concentration decreased significantly (p <0,05). After 168 hours initial concentration of all carotenoids was changed significantly. It was also determined that concentration of Z-lycopene isomer changes are similar to E-lycopene’s and it was not detected that decreasing of E-lycopene’s concentration is related to increasing of Z-lycopene isomers concentration. |
