Caffeic acid phenethyl ester exerts apoptotic and oxidative stress on human multiple myeloma cells.

Caffeic acid phenethyl ester (CAPE) is a phenolic compound initially identified in bee glue. CAPE is reported to exhibit antitumor activity in many cancer models. However, the effect of CAPE on multiple myeloma (MM) is not well studied.

Theoretical study of novel azo-tetraphenylporphyrins: potential photovoltaic materials.

A density functional theory study was performed to analyze the electron donor-acceptor properties of the cis and trans isomers of a novel azobenzene-containing tetraphenylporphyrin (TPPN2PhC14H29) with different substituents (Br or TMS). In general, the trans isomers are better electron acceptors than the correspondent cis homologues. Their UV-vis spectra were also obtained and a comparison with available experimental results is included.

Cis carotenoids: colorful molecules and free radical quenchers.

We present a density functional theory (DFT) and time-dependent density functional theory (TD-DFT) study on the stability, antioxidant properties with respect to the single electron transfer mechanism, and electronic absorption spectra of some isomers (9-cis, 13-cis, and 15-cis) of carotenoids such as astaxanthin, lycopene, and those present in virgin olive oil (lutein, β-carotene, neoxanthin, antheraxanthin, violaxanthin, neochrome, luteoxanthin, mutatoxanthin, and violaxanthin). In general, the calculated relative stability of the cis isomers appears to be in line with experimental observations. It is predicted that the above-mentioned carotenoids (cis and trans isomers) will transfer one electron to the (•)OH radical.

Carbohydrates and their free radical scavenging capability: a theoretical study.

A density functional theory (DFT) study on the free radical (OH(•) and OOH(•)) scavenging properties of some mono- and polysaccharides is presented. Two mechanisms, single electron transfer (SET) and hydrogen atom transfer (HAT), are considered. The former mechanism is studied by making use of the vertical ionization energy and vertical electron affinity of the radicals and carbohydrates.

Xanthones as antioxidants: a theoretical study on the thermodynamics and kinetics of the single electron transfer mechanism.

Mangosteen (Garcinia mangostana) is considered the queen of the tropical fruits. It has a dark red pericarp that is rich in bioactive compounds including xanthones, which have been classified as very good antioxidants from several experimental results. In this work, the antioxidant properties of twenty xanthones isolated from the pericarp of Garcinia mangostana are studied considering the single electron transfer mechanism (SET).

The metal cation chelating capacity of astaxanthin. Does this have any influence on antiradical activity?

In this Density Functional Theory study, it became apparent that astaxanthin (ASTA) may form metal ion complexes with metal cations such as Ca⁺², Cu⁺², Pb⁺², Zn⁺², Cd⁺² and Hg⁺². The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color.

Density functional theory study of the magnetic circular dichroism spectra of molybdenyl complexes.

We report a density functional theory (DFT) study of the magnetic circular dichroism (MCD) spectra for four molybdenyl complexes: [MoOCl(4)](-), [MoO(S(2)C(2)H(4))(2)](-), [(Tp*)MoO(bdt)], and [(L3S)MoO(bdt)] (Tp* = hydrotris (3,5-dimethyl-1-pyrazolyl) borate; L3S = (2-dimethylethane-thiolate)bis(3,5-dimethylpyrazolyl)-methane; bdt =1,2-benzenedithiolate). The simulation of the temperature dependent MCD-bands (C-terms) that give rise to the spectra was performed using a method based on time-dependent DFT. In this method, the C-parameters are calculated by including spin-orbit perturbations.

Density functional theory study of the electron paramagnetic resonance parameters and the magnetic circular dichroism spectrum for model compounds of dimethyl sulfoxide reductase.

We report a density functional theory (DFT) study of electron paramagnetic resonance (EPR) parameters for complexes modeling the paramagnetic center Mo(V) of the molybdoenzyme dimethyl sulfoxide reductase. We pay special attention to the Mo-OH link to find the most likely geometry and orientation of the metal center in the enzyme and provide an analysis of the physical origin of the g-values in terms of magnetically induced orbital mixing. We also present a study of the magnetic circular dichroism (MCD) spectrum for a complex that models the Mo(V) center of the enzyme.

A theoretical study of the magnetic circular dichroism spectrum for sulfite oxidase based on time-dependent density functional theory.

We present a theoretical study of the temperature-dependent magnetic circular dichroism (MCD) spectrum for complexes modeling the molybdoenzyme sulfite-oxidase (1) in its Mo(V) oxidation state. The theoretical study was based on a newly implemented time-dependent density functional method that takes into account first-order perturbations due to spin-orbit coupling and a constant magnetic field. It was possible, on the basis of the theoretical calculations, to give a full assignment of the MCD spectrum for 1 and interpret the C term of each band in the experimental MCD spectrum in terms of spin-orbit couplings between specific excited states and between excited states and the ground state.

Theoretical study of the oxidation reaction and electron spin resonance parameters involving sulfite oxidase.

We present a density functional theory (DFT) study on the conversion of sulfite to sulfate with a model complex representing the active site of the molybdenum-containing enzyme sulfite oxidase (SO). This study considers the attack of the sulfur lone pair from SO(3)(2-) on the equatorial oxo ligand of the model complex as the initial step in the oxidation process. The good agreement between our energy profile and data derived from experimental kinetic parameters provides some support for the reaction mechanism of the oxidative half-reaction of SO proposed in this study.

NMR solution structure of Cn12, a novel peptide from the Mexican scorpion Centruroides noxius with a typical beta-toxin sequence but with alpha-like physiological activity.

Cn12 isolated from the venom of the scorpion Centruroides noxius has 67 amino-acid residues, closely packed with four disulfide bridges. Its primary structure and disulfide bridges were determined. Cn12 is not lethal to mammals and arthropods in vivo at doses up to 100 microg per animal.