In vestigatio n and com pare of a ntioxidant properti es of some of phenolic compound by d ensity fu nctional th eory

Antio xidants are of great interest becau se of their involvement in important biological and industrial processes. In general, compo unds with a ntioxidant activity have been found to posses s anticancer , anti-cardio vascular, an ti-inflamma tion and ma ny other activities. The l iquid-phase autoxidation (peroxidation) of oils and lipids is an important proce ss in chemical and biological systems. The underlying ch emical reactions are des cribed by a free- radical chain mechanism, where the oxygen-derived perox yl radicals of hydrocarbon substrates (ROO.) are the key particip ants. The destructive peroxidation processe s can effectively be in hibited by antioxidants (InH), whi ch trap per oxyl free radicals in a fast reacti on: ROO° + InH ROOH + In° The oxidation cha in is subseq uently terminated by reactions of InÛ with RO OÛ or InÛ .Among many classes of inhibitors, phenols are probably the mos t important chain-breaking antioxidants in bi ochemical s ystems. The high reactiv ity of phen olic antioxidants is frequ ently explained by low energies of the O-H bond, related to thermodynamic st abilization of the aromatic radical InÛ. The effectiveness of their inh ibiting action in oxidative processes is determ ined by a number of factors relating to the st ructure, med ium, and c onditions. One of the m ost important is the bond dissociation energy (BDE) of the p henolic hydroxyl bond.

کلیدواژه ها:

Antio xidant ، DFT ، Phenol ، B DE ، Thymol