Direct Spectroscopic Observation of Singlet Oxygen Quenching and Kinetic Studies of Physical and Chemical Singlet Oxygen Quenching Rate Constants of Synthetic Antioxidants (BHA, BHT, and TBHQ) in Methanol

Abstract

Singlet oxygen quenching by synthetic antioxidants (BHA, BHT, and TBHQ) was directly observed by spectroscopic monitoring of luminescence at 1268 nm. The luminescence data showed unambiguous evidence of singlet oxygen quenching by synthetic phenolic antioxidants with the highest activity for TBHQ, followed by BHA and BHT. The protective activities of these synthetic antioxidants on alpha-terpinene oxidation with chemically-induced singlet oxygen under dark further confirmed their singlet oxygen quenching abilities. Total singlet oxygen quenching rate constants (k(r) + k(q)) of BHA, BHT, and TBHQ were determined in a system containing alpha-terpinene (as a singlet oxygen trap) and methylene blue (as a sensitizer) during light irradiation, and the values were 5.14 x 10(7), 3.41 x 10(6), and 1.99 x 10(8) M(-1)s(-1), respectively. After the k(r) value of alpha-terpinene was first determined, the k(r) values of the synthetic antioxidants were calculated by measuring their relative reaction rates with singlet oxygen to that of alpha-terpinene under the identical conditions. The k(r) values of the BHA, BHT, and TBHQ were 3.90 x 10(5), 1.23 x 10(5), and 2.93 x 10(6), M(-1)s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (k(r) x 100)/(k(r) + k(q)) for BHA, BHT, and TBHQ were 0.76%, 3.61%, and 1.47%, respectively. The results showed that the synthetic antioxidants quench singlet oxygen almost exclusively through the mechanism of physical quenching. This represents the first report on the singlet oxygen quenching mechanism of these synthetic antioxidants. Practical Application: The synthetic antioxidants, especially TBHQ, have been found to have a strong singlet oxygen quenching ability. This article also clearly showed that singlet oxygen quenching by synthetic antioxidants was mainly by the physical quenching mechanism. The results suggested that these synthetic antioxidants, especially TBHQ, could be used practically for the protection of the food components such as edible oils and vitamins against singlet oxygen induced oxidations without significant losses of antioxidant activity during storage under light.

Cy5 labeled single-stranded DNA-polydopamine nanoparticle conjugate-based FRET assay for reactive oxygen species detection

“…As expected, the F R is decreased with increasing the concentration of antioxidant. The half maximal inhibitory concentrations (IC 50 ) of antioxidants follow the order of BHT (0.26 mM) < BHA (0.34 mM) < thiourea (1.03 mM), which is consistent with the results of literature reports [15]. The results suggest that our method has the potential to screen antioxidants and yield quantitative data on the antioxidant capacities of different chemicals.…”

Evaluation of Singlet Oxygen Scavenging Capacity of Peppermint (Mentha Piperita L.), Marjoram (Origanum Majorana L.), Rosemary (Rosmarinus Officinalis L.) And Sage (Salvia Officinalis L.) on Fatty Acid Photooxidation

“…Lipids can be a target of singlet oxygen because of their electrophilic inherent and produce lipid hydroperoxides [3]. DABCO recognized as very efficient quencher of singlet oxygen in the organic media [4] and synthetic antioxidants such as TBHQ, BHA and BHT have been found to have a strong singlet oxygen quenching ability [5]. People receive antioxidant supplements directly from fresh fruits and vegetables and plants.…”

Scavenging effect of pasipay (passiflora incarnate L.) on singlet oxygen generation and fatty acid photooxygenation

“…The use of antioxidants to protect human skin from the harmful effects of UV radiation is a topic that has attracted growing interest in recent years within the world of photoprotection research (Martinez et al, 2017). DABCO recognized as a very efficient quencher of singlet oxygen in the organic media (Lengfelder, Cadenas, & Sies, 1983) and synthetic antioxidants such as TBHQ, BHA, and BHT have been found to have a strong singlet oxygen quenching ability (Lee & Jung, 2010). Recent research has focused on isolation and characterization of effective natural antioxidants (Fang et al, 2017;Nimse & Pal, 2015).…”