Conformational behaviour of biologically active ferulic acid derivatives

Abstract

a b s t r a c tThe conformational behaviour of several biologically relevant hydroxycinnamic systems -ferulic acid and its methyl, ethyl, propyl and butyl esters -was studied by quantum mechanical calculations, at the DFT level. A full geometry optimisation was carried out, as well as a Fourier analysis of the main internal rotations within these molecules. The geometrical preferences of these compounds result from a balance between the stabilising resonance and hydrogen bonding effects and the destabilising non-bonding repulsions, the most stable conformers displaying an s-cis conformation and hydroxyl/methoxyl substituent groups coplanar to the aromatic ring. The results thus obtained allow a better understanding of the well recognised in vitro and in vivo antioxidant and growth-inhibiting properties of this type of phenolic systems.

An inelastic neutron scattering study of dietary phenolic acids

“…6,21,24,27 All energy minima have a planar geometry that favours the stabilizing effect of the p-electron delocalization between the ring and the C 9 C 10 and C 11 O 12 double bonds. A typical structural feature of cinnamic acids and their derivatives is the partial double bond character of (C 3 -C 9 ) and (C 10 -C 11 ) (d = 145-147 pm 21,24,27 ), reflecting the effective electron delocalization between the aromatic ring, the unsaturated pendant chain and the carboxylic moiety. In fact, the Wiberg indexes calculated for this series of compounds vary within the range 1.11-1.13 and 1.05-1.06 for the (C 3 -C 9 ) and (C 10 -C 11 ) bonds, respectively.…”

“…Their main conformational characteristics were previously determined by Raman spectroscopy, combined with DFT calculations, for the isolated molecule, their dimeric species and the solution species. 3,6,9,16,21,[24][25][26][27][28] Particular emphasis is given to the investigation of the hydrogenbonding profile of this kind of systems, aiming at a better understanding and prediction of their antioxidant activity. Location of low-frequency modes due to H-bonding is envisaged, namely the (OÁ Á ÁH) stretching.…”

Structure, electronic properties, and radical scavenging mechanisms of daidzein, genistein, formononetin, and biochanin A: A density functional study

“…Kohn noted in his Nobel lecture about DFT that this theory has been most useful for systems with very many electrons and yields better results than other approaches [10], including QSAR studies and the AM1 semi-empirical model. Owing to progress in research regarding the density functional theory, the pioneering research of Wright and his colleagues in predicting the activity of phenolic antioxidants was followed for several years and has produced many important findings [7,11,12].…”

Characterization of antioxidant olive oil biophenols by spectroscopic methods

“…2.1 Å), while the saturated pendant arm containing the hydroxyl (in the HT and MOPET alcohols) or carboxylate moieties (in DOPAC and HVA) is tilted by 90–120° relative to the ring, thus minimizing unfavourable steric repulsions within the molecule. Actually, it is interesting to note that the only conformational difference detected between HVA and its unsaturated analogue ferulic acid (FA)30 is the non‐planar orientation of the CH 2 COOH group in the former as opposed to the complete planarity of the FA molecule (Fig. 3), due to the presence of the carbon chain double bond, which favours a planar geometry through conjugation with the aromatic ring.…”