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References and Notes
22. l-Homocysteic acid-mediated neurotoxicity: l-HCA
depletes intracellular glutathione levels in certain cell lines,
and the subsequent oxidative stress-mediated cell death can be
attenuated with antioxidants.33 HT-22 cell culture were pre-
incubated (1 h) with dierent concentrations of the studied
antioxidant. Cells were then exposed to 2 mM l-HCA, in
the presence of antioxidant, for 48 h, and neurotoxicity was
estimated relative to 2 mM l-HCA plus 200 mM vitamin E-
treated cells (0% toxicity), and 2 mM l-HCA alone (100%
toxicity). PC50 was estimated via MTT cellular reduction
assay34 by linear regression analyses.
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24. Aminyl radical 30 has been shown to be the ®rst inter-
mediate in the oxidation of ethoxyquin with alkylperoxyl
radicals.35
7. Knoevenagel, E. Ber. 1921, 54B, 1722.
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2,20-cyclohexyl in this series.
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27. tert-Butylhydroperoxide-mediated lethality in NMRI
mice:36 Male NMRI (28±35 g) mice were injected intraperi-
toneally with the studied antioxidant (150 mg/kg in Tween
saline; 20 mL/kg) 30 min before an intracerebroventricular
injection of tert-butylhydroperoxide (1 mL of a 70% solution).
Lethality was assessed 5 h after administration of t-BuO2H
and was expressed as the percent survival relative to the leth-
ality observed in t-BuO2H plus Tween/saline vehicle-treated
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mL/kg) with either vehicle or the compound under study.
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37. All the compounds described in Tables 1 and 2 gave
spectroscopic data (IR, NMR) and acceptable analysis (CHN)
in agreement with the assigned structures.
17. Synthetic anilines were prepared in a three-step procedure
starting from the corresponding phenols: 1. Alkylation
(Cs2CO3, RX or see ref 17 for hindered phenols); 2. para-
directed nitration (H2SO4, HNO3, 0 ꢀC, 30 min.); 3. NO2
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20. Ethoxyquin (90% purity) was purchased from SIGMA
(ref E8260) and transformed into its hydrochloride salt (99%
purity).
21. Cell culture intrinsic toxicity: HT-22 murine hippocampal
cells, a subclone of HT431 were maintained (1Â104 cells/100 mL
per well) in DMEM/F-12 supplemented with 10% FCS at
37 ꢀC/5% CO2 for 24 h.32 Cellular viability was quanti®ed via
the MTT-reduction assay 48 h after exposition to dierent
concentrations of the studied compound. The maximum tol-
erated concentration (MTC) was determined as the maximum
tested concentration lacking toxic eects, and the TC50 was
estimated by linear regression analyses.