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Dandanes smo ljudje zelo obremenjeni s svojim videzom in idejo večne mladosti. Prva stvar, na katero pomislimo, ko slišimo besedo »staranje«, so gube in res je naša koža najboljši pokazatelj le-tega. Koža je prvo, kar opazimo na človeku, zato si velika večina želi, da bi čim dlje izgledala čvrsto, napeto in kar se da mladostno. Na žalost pa se prav na koži najprej opazijo negativne posledice zunanjih dejavnikov, kot so na primer sončenje, kajenje in stres. S pomočjo kozmetičnih izdelkov, ki vsebujejo sestavine z antioksidativnimi lastnostmi, lahko do določene mere upočasnimo znake staranja. V diplomskem delu smo s pomočjo metode, ki temelji na spektrofotometrični meritvi redukcije 2,2-difenil-1-pikrilhidrazila določili antioksidativno kapaciteto desetim izbranim kozmetičnim izdelkom za nego obraza, saj je prav koža obraza najbolj izpostavljena zunanjim dejavnikom. Metodo smo najprej prilagodili: kot optimalno topilo smo izbrali etanol. Za pripravo bistre raztopine smo vzorce ali centrifugirali ali pa filtrirali. Absorbanco smo pomerili na dva načina: na mikrotitrski ploščici in v kivetah za enkratno uporabo. Rezultate, podane kot efektivna koncentracija EC50, smo primerjali med seboj. Vzorci z majhno absorbanco imajo nizkoefektivno koncentracijo in s tem veliko antioksidativno kapaciteto. Ugotovili smo, da so efektivne koncentracije, določene na podlagi meritev absorbance v kivetah, v večini primerov manjše kot tiste, določene na podlagi meritev s čitalcem mikrotitrskih plošč. Najvišjo efektivno koncentracijo in s tem najmanjšo antioksidativno kapaciteto ima kozmetični izdelek Nivea Q10 Power, najnižjo efektivno koncentracijo in s tem najvišjo antioksidativno kapaciteto pa kozmetični izdelek Nivea Vital Soja Anti-Age Eye Cream. Kozmetična izdelka Sans Soucis Anti-Blemish Creme – Aqua Clear Skin in Collistar Special Normal And Dry Skin antioksidativnih lastnosti ne izkazujeta People nowadays are very worried about their looks and the idea of looking young forever. The first thing that we think of when we hear the word 'aging' are wrinkles and our skin really shows it the best. Skin is the first thing we notice about each other, so most of us want it to look firm and youthful. But unfortunately our skin is the first thing that shows our way of life – sunbathing, smoking or stress. Cosmetic products that contain ingredients that work as antioxidants can help us slow down signs of aging. Our thesis was based on determining antioxidant capacity of ten different skincare products that are used on the face, because our skin there is the most exposed. We determined it with the method that is based on spectrophotometric measurement of the reduction of 2,2-diphenyl-1-picrylhydrazyl. We had to adjust the method: we chose ethanol as the optimal solvent. For a clear solution, we tried two methods: centrifugation and filtration of the samples. Two methods to measure absorbance were used: using microtiter plate and cuvettes. Results, given as effective concentrations EC50, were compared. Samples with low absorbance have low effective concentration and thus high antioxidant capacity. For majority of the samples, effective concentrations that were calculated based on absorbance measured in cuvettes were lower than the ones measured in microtiter plate. The highest effective concentrations and thus the lowest antioxidant capacity was determined for cosmetic product Nivea Q10 Power and the lowest effective concentrations and thus the highest antioxidant capacity for cosmetic product Nivea Vital Soja Anti-Age Eye Cream. Cosmetic products Sans Soucis Anti-Blemish Creme - Aqua Clear Skin and Collistar Special Normal And Dry Skin do not show any antioxidant activity. |
