antioxidants are compounds which can prevent biological and chemical substances from oxidative damage by reactive oxygen species. flavonoids are the most important class of polyphenolic compounds that because of their antioxidant characters possess biological activities and pharmacological effects. chrysin-6-c-fucopyranoside and chrysin-3-malonyl-6-c-fucopyranoside are mono c-glycosyl derivativ...

The bond dissociation energy (enthalpy) is also referred to as bond disruption energy, bond energy, bond strength, or binding energy (abbreviation: BDE, BE, or D) . It is defined as the standard enthalpy change of the following fission: R−X → R + X . The BDE, denoted by Do(R−X), is usually derived by the thermochemical equation, Do(R−X) = ∆fH o(R) + ∆fH o(X) – ∆fH o(RX) . The enthalpy of format...

Antioxidants are made for the struggle and reconstruction of the damaged cells, because of their ability in destroying the free radicals. On account of their importance, a theoretical procedure was applied for the study of the molecular structure and radical scavenging activity of six hydroxyphenols which have been introduced as antioxidant compounds. All geometry structures were optimized by M...

antioxidants are made for the struggle and reconstruction of the damaged cells, because of their ability in destroying the free radicals. on account of their importance, a theoretical procedure was applied for the study of the molecular structure and radical scavenging activity of six hydroxyphenols which have been introduced as antioxidant compounds. all geometry structures were optimized by m...

The gas-phase C-H bond dissociation enthalpy (BDE) in 1,3-cyclopentadiene has been determined by time-resolved photoacoustic calorimetry (TR-PAC) as 358 +/- 7 kJ mol(-1). Theoretical results from ab initio complete basis-set approaches, including the composite CBS-Q and CBS-QB3 procedures, and basis-set extrapolated coupled-cluster calculations (CCSD(T)) are reported. The CCSD(T) prediction for...

In this paper, the study of melatonin and 60 meta- and ortho-substituted melatonins is presented. The reaction enthalpies related to the hydrogen atom transfer (HAT), single electron transfer - proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) have been calculated using DFT/B3LYP method in gas-phase and water. Results show that electron-withdrawing substituents incre...

A chemical microsolvation model for solution phase bond dissociation enthalpy (BDE) evaluation by means of molecular dynamics is presented. In this simple model, the primary solvent effect on the BDE values was estimated by placing of fi ve water molecules nearby the studied functional groups evenly. Furthermore, the secondary solvent effect was refl ected using the conductor like screening mod...

In this work, the study of various substituted Kaempferol derivatives is presented. The bond dissociation energies (BDE) have been calculated using B3LYP level and different basis sets in gas-phase. Calculated results show that the BDE values of substituted Kaempferol range from about 77 to100 kcal/mol, demonstrating that Kaempferol is an effective chain-breaking antioxidant that prevents lipid...

In this work, we examine the performance of XYG3, a newly developed doubly hybrid density functional (Zhang, Xu, and Goddard III, Proc Natl Acad Sci USA 2009, 106, 4963), to calculate covalent bond dissociation enthalpy (BDE). We use 5 atoms, 32 molecular radicals, and 116 closed-shell molecules to set up 142 bond dissociation reactions. For the total of 148 heats of formation (HOFs) and 142 BD...

Antioxidants are compounds which can prevent biological and chemical substances from oxidative damage by reactive oxygen species. Flavonoids are the most important class of polyphenolic compounds that because of their antioxidant characters possess biological activities and pharmacological effects. Chrysin-6-C-fucopyranoside and chrysin-3-malonyl-6-C-fucopyranoside are mono C-glycosyl derivativ...