Olive leaf (Olea europaea L. folium) extract influences liver microsomal detoxifying enzymes in rats orally exposed to 2-amino-l-methyI-6-phenyI-imidazo pyridine (PhIP)

Olive tree (Olea europaea, Oleaceae) leaf extract (OLE) exerts many biological activities. One of the most common polycyclic aromatic hydrocarbons (PAHs) that pollute the environment is 2-amino-l-methyI-6-phenyI-imidazo pyridine (PhIP). It is a food-derived carcinogen that is present in fish and meat that has been cooked at high temperatures. Due to the generation of reactive electrophilic species, phase I enzymes have the potential to cause oxidative damage. In order to safely remove these reactive species from the body, phase II detoxification (conjugation) enzymes are necessary. It is not known whether OLE could influence their activities and hence reduce the carcinogenic effects of PhIP. This study evaluated whether OLE could modulate phase I detoxifying enzymes as well as phase II enzymes that metabolize PhIP in rat liver microsomes. Four groups of rats were used: group I: no treatment; group II: OLE (10 mg/kg bw orally); group III: PhIP (0.1 mg/kg bw orally); and group IV: PhIP followed by OLE. After 4 weeks, the activities of phase I enzymes such as CYP1A1 (ethoxyresorufin O-deethylase), CYP2E1 (p-nitrophenol hydroxylase), CYP1A2 (methoxyresorufin O-demethylase), UDP-glucuronyl transferase, sulphotransferase, and glutathione-S transferase were evaluated in rat liver microsomes. Analysis of OLE by gas chromatography-mass spectrometry (GC/MS) showed various active ingredients in OLE, including 3,5-Heptadienal (C10H14O), 3,4-dimethoxy benzoic acid (C8H10O3), 4-hydroxy-3-methoxy (C8H8O4), 1,3,5-Benzenetriol (C6H6O3), hexadecanoic acid (C16H32O2), and hexadecanoic acid ethyl ester (C18H36O2). Our results showed that rats given PhIP were found to have a statistically significant (p < 0.001) reduction in the activities of CYP1A1, CYP1A2, and CYP2E1 in comparison with the control group. However, treatment with OLE enhanced their activities but not to a normal level compared with untreated groups. Administration of PhIP decreased the activities of phase II enzymes (glutathione S-transferase, UDP-glucuronyltransferase, or sulphotransferase) (p < 0.01) in comparison with the control group. Histological examination of rat livers was consistent with the biochemical changes. The administration of OLE improved the phase II enzyme activities in animals injected with PhIP. We conclude that OLE influences phase I and phase II detoxification enzymes exposed to PhIP, which may represent a new approach to attenuating carcinogenesis induced by it.

Epitomic Characterization of the Specificity of the Anti-Amyloid Aβ Monoclonal Antibodies 6E10 and 4G8

The monoclonal antibodies 6E10 and 4G8 are among the first anti-amyloid monoclonal antibodies against Aβ and the most widely used antibodies in Alzheimer's disease research. Although the epitopes for 6E10 and 4G8 have been reported to correspond to residues 1-16 and 17-24, a more recent high-resolution mapping approach indicates that 6E10 maps to residues 4-10 while 4G8 maps to residues 18-23. To characterize the binding specificity of both antibodies in greater detail, we used immunoselection of random sequences from phage display library followed by deep sequencing and analysis of resulting patterns from thousands of immunoselected sequences. We found that the minimum sequence required for 6E10 binding is R-x-D with over half (53%) of the immunoselected sequences conforming to this pattern. The vast majority of these sequences contain an H at position x (R-H-D), corresponding to residues 5-7 of the Aβ target sequences, but Y is also permitted at this position in a minority of sequences. For 4G8 we found that the most frequent pattern is F-x-A contained in approximately 30% of the sequences, followed by F-A, L-x(3)-A, L-x-F, and F-F each accounting for approximately 18% of the sequences. The F-x-A motif also occurs in islet amyloid poly peptide which may explain why 4G8 also recognizes amyloid fibrils of this peptide. Immunoselection of random sequences and deep sequencing may also be a facile and efficient means of determining residues critical for antibody binding and validating the specificity of monoclonal antibodies and polyclonal antisera.

Urinary levels of triclosan and triclocarban in several Asian countries, Greece and the USA: Association with oxidative stress

Triclosan (TCS) and Triclocarban (TCC) are widely used as antimicrobial preservatives in personal care products (PCPs). Because of their potential for endocrine disrupting effects, human exposure to these chemicals is a concern. Biomonitoring studies of human exposure to TCS and TCC have shown widespread exposure of populations in western European countries and the USA. However, exposure to TCC and TCS by populations in Asian countries is less well known. In this study, concentrations of TCS and TCC were determined in human urine collected from seven Asian countries (China, India, Korea, Kuwait, Japan, Saudi Arabia, and Vietnam), and Greece and the USA. A total of 430 urine samples were analyzed for TCS and TCC, of which 355 (83%) and 82 (19%), respectively, contained measurable levels of these chemicals. The overall geometric mean [GM] concentrations of TCS and TCC, were 1.36 and 0.03ng/mL, respectively. The highest mean concentration of TCS was found in urine from China (100ng/mL) and the lowest concentration was found in urine from Vietnam (2.34ng/mL). We also analyzed urinary 8-OHdG, a marker of oxidative stress, to elucidate the association with TCS and TCC levels for samples from Saudi Arabia (n=130) and a positive correlation between Ln-transformed TCC levels and 8-OHdG was found, although this was not statistically significant. This is the first study to report urinary levels of TCS and TCC in several Asian countries, especially for Vietnam, Kuwait, and Japan.