Trapping effects of green and black tea extracts on peroxidation-derived carbonyl substances of seal blubber oil.
ABSTRACT Green and black tea extracts were employed to stabilize seal blubber oil at 60 degrees C for 140 h. On the basis of the headspace SPME-GC-MS analysis, with the addition of green/black tea extracts, the contents of acetaldehyde, acrolein, malondialdehyde, and propanal, four major lipid peroxidation products, were reduced. The inhibition rates of acrolein formation by green tea and black tea extracts were 98.40 and 96.41% respectively, and were 99.17 and 98.16% for malondialdehyde, respectively, much higher than the inhibition of the formation of acetaldehyde and propanal. Because malondialdehyde and acrolein are reactive carbonyl species (RCS) and recent studies have suggested that phenolics can directly trap RCS, this study also investigated whether green tea polyphenols can trap acrolein or not. Acrolein was reduced by 90.30% in 3 h of incubation with (-)-epigallocatechin-3-gallate (EGCG). Subsequent LC-MS analysis revealed the formation of new adducts of equal molars of acrolein and EGCG. The reaction site for acrolein was elucidated to be the A ring of EGCG as evidenced by LC-MS/MS analysis and by testing of the acrolein-trapping capacities of the analogous individual A, B, and C rings of EGCG. Thus, EGCG's direct trapping of RCS may also contribute to the significant reduction of acrolein and other aldehydes in the peroxidation of seal blubber oil.
- SourceAvailable from: Ka-Wing Cheng[show abstract] [hide abstract]
ABSTRACT: Acrolein (ACR) and 4-hydroxy-trans-2-nonenal (HNE) are two cytotoxic lipid-derived alpha,beta-unsaturated aldehydes which have been implicated as causative agents in the development of carbonyl stress-associated pathologies. In this study, 21 natural polyphenols were screened to identify effective scavenging agents of ACR and/or HNE in simulated physiological conditions. It was found that flavan-3-ols, theaflavins, cyanomaclurin, and dihydrochalcones effectively trapped ACR and HNE by working as sacrificial nucleophiles. The most effective one was phloretin, which quenched up to 99.6% ACR in 90 min and 90.1% HNE in 24 h. Subsequent LC-MS/MS analysis showed that these effective polyphenols formed adducts with ACR and HNE. A major adduct formed from phloretin and ACR was purified, and its structure was characterized by LC-MS and NMR spectroscopy as diACR-conjugated phloretin. The chemical nature of interactions between ACR and polyphenols was proposed as the Michael addition reaction of phloretin to the C horizontal lineC double bond of ACR, followed by the formation of hemiacetal between the hydroxyl group in the A ring of phloretin and the C horizontal lineO carbonyl group in ACR, thus yielding more stable products. Findings of the present study highlighted certain classes of polyphenols as promising sequestering agents of alpha,beta-unsaturated aldehydes to inhibit or restrain carbonyl stress-associated diseases.Chemical Research in Toxicology 10/2009; 22(10):1721-7. · 3.67 Impact Factor