Synthesis and spectroscopic examination of various substituted 1,3-dibenzoylmethane, active agents for UVA/UVB photoprotection.

We describe the synthesis of eighteen variously substituted 1,3- dibenzoylmethane (1,3-DBM) and their change in absorption spectra depending of the nature of donor or acceptor substituents on one or the two aromatic moieties. These compounds were prepared in two steps starting from the corresponding acetophenones, phenol and benzoyl chlorides. The phenyl benzoate was obtained by condensation of benzoyl chloride with phenol in a classical way.

Scaling behavior in beta-wave amplitude modulation and its relationship to alertness.

We performed an experimental study of beta waves occurring in human electroencephalographic signals obtained from six healthy subjects that were monitored during the performance of a task requiring attention to auditory signals. We use wavelet analysis to study whether the fluctuations in the modulation of the beta-wave amplitude related to an indirect measurement of alertness. We found that these fluctuations exhibit a power-law behavior.

Vibrational and theoretical study of the 2',6'-dimethoxyflavone cis-formic acid inclusion compound.

The FT-infrared and Raman microscopy spectra of the 2',6'-dimethoxyflavone and its 1:1 complex with formic acid in solid state have been recorded and analysed. Some vibrational components appear as specific to the cis-rotamer of formic acid in the crystalline sample, especially the CH group stretching vibration feature. The broad and intense infrared absorption observed in the range 3400-1900 cm(-1) and assigned to the hydrogen bonded OH group stretching vibration exhibits the characteristic ABC structure of strong hydrogen bonded complexes.

Antioxidant properties of hydroxy-flavones.

The antioxidant properties of 24 hydroxy-flavones were evaluated. Results show that 2',3',4'-OH substitution on the B ring plays a crucial role in radical scavenger activity in the DPPH assay and in the inhibitory effect on pereoxydation of tissue lipids in the MDA test. The formation of stable radicals for this type of compounds has been studied by ESR.

Structural and conformational studies on bio-active flavonoids. Crystal and molecular structure of a complex formed between 2',6'-dimethoxyflavone and orthophosphoric acid: a model for flavone-nucleotide interactions.

In order to investigate mechanisms of action of flavones at the molecular level, we have prepared a complex between a flavone and orthophosphoric acid which can be considered as a simplest model of interaction between a flavone and a more complex biological phosphate such as nucleotide, coenzyme or DNA. With orthophosphoric acid, the title flavone forms crystals which have 1:2 stoichiometry (C17H14O4.2H3PO4).

Scavenger and antioxidant properties of ten synthetic flavones.

To study the effect of the hydroxyl groups on biological activities of flavones, we synthesized 10 polyhydroxyflavones with varied substitution patterns. The abilities of the 10 compounds to act as radical scavengers were investigated using chemiluminescence in two biological models: the xanthine/xanthine oxidase system and the oxidative burst of rat alveolar macrophages. Stable radical formation was observed by electron spin resonance (ESR) spectroscopy.