Antioxidant activity of propyl gallate in aqueous and lipid media: a theoretical study.

نویسندگان

  • Manuel E Medina
  • Cristina Iuga
  • Juan Raúl Alvarez-Idaboy
چکیده

In this work, we have carried out a quantum chemistry and computational kinetics study on the reactivity of propyl gallate towards ˙OOH, ˙OOCH3 and ˙OOCHCH2 radicals, in aqueous and lipid media. We have considered three reaction mechanisms: hydrogen transfer (HT), radical adduct formation (RAF) and single electron transfer (SET). Rate constants and relative branching ratios for the different paths contributing to the overall reaction, at 298.15 K, are reported. Our results show that propyl gallate reacts mainly through the HT mechanism, independently of the solvent or the peroxyl radical, contrary to other phenols such as catechols and guayacols previously studied, which react mainly via the SET mechanism. In aqueous media at physiological pH, the calculated rate constants towards the ˙OOH, ˙OOCH3 and ˙OOCHCH2 radicals are 4.56 × 10(8), 1.59 × 10(6) and 4.05 × 10(8) M(-1) s(-1), while in lipid media the rate constants are 2.94 × 10(4), 7.73 × 10(3) and 9.94 × 10(5) M(-1) s(-1). Thus, a propyl gallate molecule acts as a very efficient peroxyl radical scavenger, both in aqueous and lipid media. Since the gallate moiety is a part of other naturally occurring polyphenols such as aflavine gallates and epigallocatechin gallates, the results of this study could be extrapolated to these compounds. Even if these compounds have other antioxidant structures or enhancers, the activity of the gallate moiety could be considered as a lower limit to their antioxidant activity.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Synthesis of antioxidant propyl gallate using tannase from Aspergillus niger van Teighem in nonaqueous media.

Tannase from Aspergillus niger van Teighem has been used for synthesis of food additive antioxidant propyl gallate by direct transesterification of tannic acid. The optimized yield of 86% was obtained by using simultaneously pH tuned enzyme, immobilized on Celite and using the right amount of water in the non aqueous media.

متن کامل

Calotropis procera Root Extract Has the Capability to Combat Free Radical Mediated Damage

The present study reports the antioxidant and membrane protective activities of Calotropis procera aqueous root extract using several in vitro assays along with the determination of phenolic as well as flavonoid contents. Total phenol and flavonoid contents in extract were 15.67 ± 1.52 mg propyl gallate equivalent/g and 1.62 ± 0.05 mg quercetin equivalent/g, respectively. UV-visual spectroscopi...

متن کامل

Antioxidant Activity of Phenolic Compounds in Bulk Camellia Oil and Corresponding Oil in Water (O/W) Emulsions

The antioxidant activities of gallic acid, propyl gallate, (+)-catechin and quercetin in bulk camellia oil and corresponding emulsions were investigated using hydroperoxides and nonanal as indicators of oxidation. In bulk oil, these phenolic compounds showed antioxidant activities with the order of gallic acid>quercetin>propyl gallate> (+)catechin when measured using hydroperoxides and gallic a...

متن کامل

Antioxidant activity of gallates: an electrochemical study in aqueous media.

The electron-donating ability of gallates, which are food and pharmaceutical antioxidants, is quantitatively assessed on the basis of their electrochemical characteristics. Gallic acid and the propyl, i-propyl, butyl, i-butyl, pentyl and i-pentyl gallate derivatives were electrochemically oxidized on the glassy carbon electrode by using differential pulse voltammetry, cyclic voltammetry and hyd...

متن کامل

Expression of Aspergillus oryzae Tannase in Pichia pastoris and Its Application in the Synthesis of Propyl Gallate in Organic Solvent

Gallic acid esters could be synthesized biologically by tannase in organic media, among which is propyl gallate, an antioxidant widely used as a food additive. Efficient intracellular expression of Aspergillus oryzae tannase was achieved in Pichia pastoris under the control of the AOX1 promoter, and the productivity of recombinant tannase was 960 U/L or 64 U/g dry mass. The recombinant P. pasto...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Physical chemistry chemical physics : PCCP

دوره 15 31  شماره 

صفحات  -

تاریخ انتشار 2013