P-carotene bleaching test

Antioxidant activity is also a measure for substance ability to prevent free radical concentration increment, oxidative stress, and risk for development-related diseases. And for the purpose of measuring antioxidant activity, many assays are applied such as 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay, 2,2 -azino-bis(3-ethylbenzthiazoline-6)-sulfonic acid (ABTS) assay, p-carotene bleaching test, ferric and cupric reducing power, and linoleic acid assay (Akrout et ah, 2011 Chabir et ah, 2011 Jia et al, 2010 Serrano et al, 2011). 

Different kinds of methods, such as DPPH assay, ABTS assay, or p-carotene bleaching test, already mentioned in previous text, are used to assess the antioxidative properties of essential oils and their single compounds. Being one of the main topics in many studies for many years, essential... 

The lipid peroxidation inhibitory activities of EOs are assessed by the P-carotene bleaching tests (Yadegarinia et al., 2006). In this method, the ability to minimize the coupled oxidation of P -carotene and linoleic acid is measured with a photospectrometer. The reaction with radicals shows a change in this orange color. The P-carotene bleaching test shows better results than the DPPH assay because it is more specialized in lipophilic compounds. The test is important in the food industry because the test medium is an emulsion, which is near to the situation in food, therefore allowable alternatives to synthetic antioxidants can be found. An only qualitative assertion uses the TLC procedure. A sample of the EOs is applied onto a TLC plate and is sprayed with P-carotene and linoleic acid. Afterwards, the plate is abandoned to the daylight for 45 min. Zones with constant yellow colors show an antioxidative activity of the component (Guerrini et al., 2006). 

Sample DPPH P-Carotene Bleaching Test Photochemiluminescence (mmol of trolox/L)... 

Linalool is one of the main compounds (up to 15%) of the EO obtained from Rosmarinus officinalis L. (rosemary, Lamiaceae). The EO was tested using two different methods radical scavenging with the DPPH assay and the p-carotene bleaching test. The oil was able to reduce the stable free radical DPPH and showed a slightly weaker scavenging activity than the standard trolox. But the efficiency of rosemary oil was clearly weaker than that of the reference oil Thymus porlock. By the P-carotene bleaching test it could be shown that this EO has the ability to prevent the lipid peroxidation with a capacity close to the used standards. 

Another Lauraceae is Laurus nobilis (laurel). The EO obtained from the leaves of wild grown shrubs is characterized by a very high content of eugenol. The biological activities, especially the antioxidative properties, of the extract were studied in different in vitro test methods. The scavenging capacity in the DPPH assay yielded an IC50 value of 0.113 mg/mL. Also the P-carotene bleaching test of the nonpolar fractions was able to protect the lipids from oxidation. After an incubation... 

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