Far UV peaks contribute for identification of carotenoids E/Z isomers

Theoretical FRET Efficiency of an Antenna Material Containing Natural Dyes and Zeolite L

We calculated the Förster resonance energy-transfer (FRET) efficiency of a theoretical host-guest composite formed by all-trans β-cryptoxanthin (BCRY), all-trans zeaxanthin (ZEA), and a zeolite-LTL (Linde Type L) nanochannel with the help of computational chemistry tools. Climate change demands urgently the development of novel renewable energies, and in such a context, artificial photosynthesis arises as a promising technology capable of contributing to satisfying humankind's energy needs. All artificial photosynthetic devices need antennas to harvest and transfer energy to a reaction center efficiently. Antenna materials integrated by highly fluorescent synthetic pigments embedded onto the nanochannels of a zeolite-LTL have already been shown experimentally to be very efficient supramolecular assemblies. However, research work computing the efficiency of an antenna made of nonfluorescent natural pigments and a zeolite-LTL nanochannel has not been undertaken yet, at least to our knowledge. Fortunately, natural dyes possess outstanding features to study them dynamically; they are environmentally friendly, inexpensive, ubiquitous, and abundant. Density functional theory (DFT) methods were chiefly employed along with the CAM-B3LYP functional and the 3-21G*/6-311+G(d,p) basis sets. The ONIOM method enabled geometry and energy calculations of dyes inside the zeolite-LTL (ZL) nanochannel. The Förster resonance energy-transfer (FRET) efficiency and the Förster radius of the composite were 40.9% and 24.9 Å, respectively. Theoretical findings suggested that this composite might contribute to diminishing costs and improving the environmental friendliness of an antenna system.

The determination of lycopene Z-isomer absorption coefficient on C30-HPLC

Both E- and Z-isomers of lycopene are encountered in nature. Although they were separated on C30-HPLC by the mobile phase consisting of CH3CN-MeOH (A) and MTBE (B), the quantification of Z-isomers cannot be archived at present because either their commercially available reference samples are currently lacking, or they are unstable. In this study, both the specific and molar absorption coefficients of 5, 9, and 13 Z-isomers in the mobile phase were determined on the analytical C30-HPLC-PDA-ELSD, and further verified on the preparative C30-HPLC-PDA. The specific and molar absorption coefficients of 5, 9, and 13 Z-isomers were finally verified to be A 1 cm 1 %  = 3,422 and ε mol = 183,717, A 1 cm 1 %  = 2,183 and ε mol = 117,199, and A 1 cm 1 %  = 1,119 and ε mol = 60,076, respectively, in the mobile phase. With these determined coefficients, the quantifications of 5, 9, and 13 Z-isomers were able to be archived on C30-HPLC-PDA with the mobile phase applied in this investigation.

Rat intestinal homogenate and pancreatic juice can induce the Z-isomerization of all-E-lycopene in vitro

Lycopene is one of the carotenoids often consumed by humans in their diet. Although lycopene exists mainly in the form of the all E-isomer in foods, the considerable quantity of its Z-isomers is found in the human plasma and liver. This observation suggested that the lycopene all-E-isomer was converted into Z-isomers in the human body. In this study, the Z-isomerization of the all-E-isomer was induced in vitro by the pancreatic juice and small intestinal homogenate of male rats under the conditions of 37 °C, pH = 7.5, nitrogen and darkness, as well as shaking. After 2 hours, the proportion of the all E-isomer decreased to 25% and Z-isomer amounts increased relatively. The converted products were identified as 5, 9, and 11 Z-isomers by electronic absorption spectroscopy and mass spectrometry (MS). The observations from this experiment suggested that the Z-isomerization site of the lycopene all E-isomer was located in the small intestinal wall of the rat.