6811-73-0Relevant articles and documents
Oxidative degradation kinetics of lycopene, lutein, and 9-cis and all-trans β-carotene
Henry,Catignani,Schwartz
, p. 823 - 829 (2007/10/03)
The thermal and oxidative degradation of carotenoids was studied in an oil model system to determine their relative stabilities and the major β-carotene isomers formed during the reaction. All-trans β-carotene, 9-cis β-carotene, lycopene, and lutein were heated in safflower seed oil at 75, 85, and 95 °C for 24, 12, and 5 h, respectively. The major isomers formed during heating of β-carotene were 13-cis, 9-cis, and an unidentified cis isomer. The degradation kinetics for the carotenoids followed a first-order kinetic model. The rates of degradation were as follows: lycopeneall-trans β-carotene≈9-cis β-carotenelutein. The values for the thermodynamic parameters indicate that a kinetic compensation effect exists between all of the carotenoids. These data suggest that lycopene was most susceptible to degradation and lutein had the greatest stability in the model system of the carotenoids tested. Furthermore, there was no significant difference in the rates of degradation for 9-cis and all-trans β-carotene under the experiment conditions.
Thermal interconversions among 15-cis-, 13-cis-, and all-trans-β-carotene: Kinetics, arrhenius parameters, thermochemistry, and potential relevance to anticarcinogenicity of all-trans-β-carotene
Doering, W. Von E.,Sotiriou-Leventis, Chariklia,Roth
, p. 2747 - 2757 (2007/10/02)
Rates of thermal, cis-trans rearrangement among all-trans-, 15-cis-, and 13-cis-β-carotene have been measured at temperatures in the range 37-69°C. From the resulting specific rate constants, Arrhenius and Eyring parameters are derived. Positions of equilibrium are estimated experimentally and by force field calculations based on the Allinger MM2 program as improved by Roth (MM2-ERW), while enthalpies of activation for cis-trans isomerization to 11-, 9-, and 7-cis-β-carotenes are estimated by application of the Roth program augmented by the inclusion of the quantum mechanical program of Malrieu et al., EVBH (effective valence-bond Hamiltonian), expanded to encompass longer polyenes. Implications of the interaction of strain and delocalization in the rotation about the 7,8 double bond are presented. A procedure has been developed for the small scale preparation of 13-cis-β-carotene by heating all-trans-β-carotene at 80°C for 8 h. Kinetically and thermodynamically accessible at 37°C, 15-cis- or 13-cis-β-carotene or both become candidates for the role of true anticarcinogenic agent, whereupon all-trans-β-carotene would be relegated to the role of reservoir for the active species.
Chlorophyll a Sensitized Trans-Cis Photoisomerization of all-trans-β-Carotene
Jensen, Niels-Henrik,Nielsen, Anne B.,Wilbrandt, Robert
, p. 6117 - 6119 (2007/10/02)
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