FT-IR Study of Some Carotenoids (original) (raw)
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FT-IR study of some seco- and apocarotenoids
Journal of Biochemical and Biophysical Methods, 2002
FT-IR spectroscopy was applied to investigate 15 different carotenoids. The following compounds were acid (14); and bixin (15). Some characteristic functional groups (CjC, CjO, CHO, OH, etc.) were identified. We focused on the influence of conjugation of the keto-, aldehyde-and ester groups on the absorption of the CjC bonds. This method is useful in the fast analysis of the biologically important carotenoids especially if there are small samples available. D
Carotenoid radical cations and dications: EPR, optical, and electrochemical studies
Archives of Biochemistry and Biophysics, 2004
Investigations of the structure and properties of paramagnetic carotenoid radical cations and diamagnetic carotenoid dications using electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy in conjunction with electrochemical, optical, and HPLC measurements, and molecular orbital calculations are described. These methods were applied to determine how the carotenoid radical cations and dications can be formed, their electron-transfer properties and stability in various media, and the mechanism by which carotenoid radical cations can isomerize.
Current Research in Nutrition and Food Science Journal, 2015
Carotenoids are a class of natural pigments familiar to all through the orange-red colours of popular foods like oranges, tomatoes and carrots and the yellow colour of many flowers. They have been studied for a number of years because of their diverse roles in photobiology, photochemistry and photo medicine. Carotenoids are also added as colorants to many manufactured foods, drinks, and animal feeds, either in the forms of natural extracts (e.g annatto, paprika or marigold extracts) or as pure compounds manufactured by chemical synthesis. Carotenoids are often described as provitamins A, as this particular vitamin is a product of carotenoid metabolism. The distribution of carotenoids among the different plant groups shows no obvious pattern. b-Carotene is the most abundant in leafy vegetables, though the colour is masked by its co-existence with chlorophyll, and this carotenoid has the highest vitamin A activity. Zeaxanthin, a-carotene and antheraxanthin are also present in small am...
Facile method for spectroscopic examination of radical ions of hydrophilic carotenoids
Physical Chemistry Chemical Physics, 2009
Hydrophilic carotenoids, unusual members of an intrinsically hydrophobic family, and their radical ions are important reactants. An all-optical method for generating singly charged radical ions of a hydrophilic carotenoid (Car) is described. It relies on photolyzing an aqueous mixture of Car and a photoionizable auxiliary solute (A), and making conditions conducive to the capture, by Car, of the hydrated electron (e À aq) or the positive hole in A + or both. When A is Trolox (TOH), only e À aq can be captured, since TOH + deprotonates too rapidly to be a hole donor; when A is Trolox methyl ether (TOMe), both Car À and Car + are formed, since TOMe + lives long enough to transfer its positive hole to Car; formation of Car À is prevented under aerobic conditions.
Spectroscopic and Photochemical Properties of Open-Chain Carotenoids
The Journal of Physical Chemistry B, 2002
The spectroscopic properties of open-chain, all-trans-C 30 carotenoids having seven, eight and nine π-electron conjugated carbon-carbon double bonds were studied using steady-state absorption, fluorescence, fluorescence excitation and time-resolved absorption spectroscopy. These diapocarotenes were purified by high performance liquid chromatography (HPLC) prior to the spectroscopic experiments. The fluorescence data show a systematic crossover from dominant S 1 f S 0 (2 1 A g f 1 1 A g ) emission to dominant S 2 f S 0 (1 1 B u f 1 1 A g ) with increasing extent of conjugation. The low temperatures facilitated the determination of the spectral origins of the S 1 f S 0 (2 1 A g f 1 1 A g ) emissions, which were assigned by Gaussian deconvolution of the experimental line shapes. The lifetimes of the S 1 states of the molecules were measured by transient absorption spectroscopy and were found to decrease as the conjugated chain length increases. The energy gap law for radiationless transitions is used to correlate the S 1 energies with the dynamics. These molecules provide a systematic series for understanding the structural features that control the photochemical properties of open-chain, diapocarotenoids. The implications of these results on the roles of carotenoids in photosynthetic organisms are discussed.
Carotenoid radical chemistry and antioxidant/pro-oxidant properties
Archives of biochemistry …, 2004
The purpose of this review is to summarise the current state of knowledge of (i) the kinetics and mechanisms of radical reactions with carotenoids,(ii) the properties of carotenoid radicals, and (iii) the antioxidant/pro-oxidant properties of carotenoids.
International Journal of Molecular Sciences
Carotenoids are a large and diverse group of compounds that have been shown to have a wide range of potential health benefits. While some carotenoids have been extensively studied, many others have not received as much attention. Studying the physicochemical properties of carotenoids using electron paramagnetic resonance (EPR) and density functional theory (DFT) helped us understand their chemical structure and how they interact with other molecules in different environments. Ultimately, this can provide insights into their potential biological activity and how they might be used to promote health. In particular, some rare carotenoids, such as sioxanthin, siphonaxanthin and crocin, that are described here contain more functional groups than the conventional carotenoids, or have similar groups but with some situated outside of the rings, such as sapronaxanthin, myxol, deinoxanthin and sarcinaxanthin. By careful design or self-assembly, these rare carotenoids can form multiple H-bonds...
The carotenoids as anti-oxidants — a review
Journal of Photochemistry and Photobiology B: Biology, 1997
Carotenoids are abundant in many fruit.,, and vegetables and they play diver~e roles in photobiology, photochemi~,try and medic;he. Thi~ review concerns the reactivity of carotenoidx with singlet oxygen and the interaction of carotenoids with a range of tree radical~. Mcchani~m.~ associated with the anti-and pro-oxidant behaviour of carotencids are discussed including carotenoid interactions v, ith other anti-oxidants. © 1997 Elsevier Science S.A.
General methods for identification of carotenoids
Biotechnology Letters, 2014
General methods for identification of usual carotenoids including C 18 -HPLC retention time and spectroscopic methods, such as absorption spectra, mass spectra, NMR spectra, are briefly summarized.