Effects and mechanisms of eugenol, isoeugenol, coniferylaldehyde and dihydroeugenol on the riboflavin-sensitized photooxidation of α-terpinene in methanol

Food Chem. 2017 Apr 1:220:289-294. doi: 10.1016/j.foodchem.2016.10.006. Epub 2016 Oct 4.

Abstract

The effects of eugenol, isoeugenol, coniferylaldehyde, and dihydroeugenol on the riboflavin-sensitized photooxidation of α-terpinene in methanol were studied. Riboflavin greatly accelerated α-terpinene oxidation in methanol during light illumination, resulting in two major oxidation products (p-cymene and ascaridole). The results clearly showed the involvement of Type I and II mechanisms. All the eugenols exerted strong protective activity on riboflavin sensitized photooxidation of α-terpinene. Dihydroeugenol showed the highest protective activity, followed by isoeugenol, coniferylaldehyde, and eugenol, in a decreasing order. Dihydroeugenol greatly inhibited the production of ascaridole, but showed relatively low inhibitory activity on the formation of p-cymene. The protective activity of dihydroeugenol was higher than those of BHA, BHT and sodium azide. Sodium azide, a specific singlet oxygen quencher, showed strong inhibitory activity on the formation of ascaridole, but very low inhibitory activity on the formation of p-cymene, verifying the feasibility of mechanism study with the present model system.

Keywords: Coniferylaldehyde; Dihydroeugenol; Eugenol; Isoeugenol; Photooxidation; Riboflavin; α-Terpinene.

MeSH terms

  • Acrolein / analogs & derivatives*
  • Acrolein / chemistry
  • Butylated Hydroxyanisole / chemistry
  • Butylated Hydroxytoluene / chemistry
  • Cyclohexane Monoterpenes
  • Cymenes
  • Eugenol / analogs & derivatives*
  • Eugenol / chemistry*
  • Methanol / chemistry
  • Monoterpenes / chemistry*
  • Peroxides / chemistry
  • Riboflavin / chemistry*
  • Singlet Oxygen / chemistry
  • Sodium Azide / chemistry

Substances

  • Cyclohexane Monoterpenes
  • Cymenes
  • Monoterpenes
  • Peroxides
  • coniferaldehyde
  • ascaridole
  • Singlet Oxygen
  • 4-cymene
  • Butylated Hydroxytoluene
  • Butylated Hydroxyanisole
  • Eugenol
  • gamma-terpinene
  • isoeugenol
  • Acrolein
  • Sodium Azide
  • Riboflavin
  • Methanol