OSWG Recommended Approaches to the Nonclinical Pharmacokinetic (ADME) Characterization of Therapeutic Oligonucleotides

This white paper summarizes the recommendations of the absorption, distribution, metabolism, and excretion (ADME) Subcommittee of the Oligonucleotide Safety Working Group for the characterization of absorption, distribution, metabolism, and excretion of oligonucleotide (ON) therapeutics in nonclinical studies. In general, the recommended approach is similar to that for small molecule drugs. However, some differences in timing and/or scope may be warranted due to the greater consistency of results across ON classes as compared with the diversity among small molecule classes. For some types of studies, a platform-based approach may be appropriate; once sufficient data are available for the platform, presentation of these data should be sufficient to support development of additional ONs of the same platform. These recommendations can serve as a starting point for nonclinical study design and foundation for discussions with regulatory agencies.

Variant-selective stereopure oligonucleotides protect against pathologies associated with C9orf72-repeat expansion in preclinical models

A large G₄C₂-repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Neuronal degeneration associated with this expansion arises from a loss of C9orf72 protein, the accumulation of RNA foci, the expression of dipeptide repeat (DPR) proteins, or all these factors. We report the discovery of a new targeting sequence that is common to all C9orf72 transcripts but enables preferential knockdown of repeat-containing transcripts in multiple cellular models and C9BAC transgenic mice. We optimize stereopure oligonucleotides that act through this site, and we demonstrate that their preferential activity depends on both backbone stereochemistry and asymmetric wing design. In mice, stereopure oligonucleotides produce durable depletion of pathogenic signatures without disrupting protein expression. These oligonucleotides selectively protect motor neurons harboring C9orf72-expansion mutation from glutamate-induced toxicity. We hypothesize that targeting C9orf72 with stereopure oligonucleotides may be a viable therapeutic approach for the treatment of C9orf72-associated neurodegenerative disorders.

Restenosis of a drug eluting stent on the previous bioresorbable vascular scaffold successfully treated with a drug-coated balloon: A case report

BACKGROUND

The in-stent restenosis (ISR) rates are reportedly inconsistent despite the increased use of second-generation drug eluting stent (DES). Although bioresorbable vascular scaffold (BVS) have substantial advantages with respect to vascular restoration, the rate of scaffold thrombosis is higher with BVS than with DES. Optimal treatment strategies have not been established for DES-ISR to date.

CASE SUMMARY

We report on a case of a 60-year-old man patient with acute coronary syndrome. He had a history of ST-segment elevation myocardial infarction associated with very late scaffold thrombosis and treated with a DES. Coronary angiography revealed significant stenosis, suggesting DES-ISR on the previous BVS. Optical coherence tomography (OCT) identified a plaque rupture and a disrupted scaffold strut in the neointimal proliferation of DES. To treat the DES-ISR on the previous BVS, we opted for a drug-coated balloon (DCB) after a balloon angioplasty using a semi-compliant and non-compliant balloon. The patient did not experience adverse cardiovascular events on using a DCB following the use of intensive dual antiplatelet therapy and statin for 24 mo.

CONCLUSION

This case highlights the importance of OCT as an imaging modality for characterizing the mechanism of target lesion failure. The use of a DCB following the administration of optimal pharmacologic therapy may be an optimal strategy for the treatment and prevention of recurrent BVS thrombosis and DES-ISR.

Discovery of Brigatinib (AP26113), a Phosphine Oxide-Containing, Potent, Orally Active Inhibitor of Anaplastic Lymphoma Kinase

In the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC), secondary mutations within the ALK kinase domain have emerged as a major resistance mechanism to both first- and second-generation ALK inhibitors. This report describes the design and synthesis of a series of 2,4-diarylaminopyrimidine-based potent and selective ALK inhibitors culminating in identification of the investigational clinical candidate brigatinib. A unique structural feature of brigatinib is a phosphine oxide, an overlooked but novel hydrogen-bond acceptor that drives potency and selectivity in addition to favorable ADME properties. Brigatinib displayed low nanomolar IC50s against native ALK and all tested clinically relevant ALK mutants in both enzyme-based biochemical and cell-based viability assays and demonstrated efficacy in multiple ALK+ xenografts in mice, including Karpas-299 (anaplastic large-cell lymphomas [ALCL]) and H3122 (NSCLC). Brigatinib represents the most clinically advanced phosphine oxide-containing drug candidate to date and is currently being evaluated in a global phase 2 registration trial.

Abstract 2993: Patterns of recurrent mutations in SETBP1 mutated and wild-type atypical Chronic Myeloid Leukemia patients

Atypical Chronic Myeloid Leukemia (aCML) is a heterogeneous disorder belonging to the group of myelodysplastic/myeloproliferative (MDS/MPN) syndromes. The molecular pathogenesis of this disease is still unclear and the outcome is poor with no improvement over the last 20 years.

We applied whole exome sequencing approach in 9 aCML patient samples in order to identify possible recurrent alterations. The analysis revealed the presence of unique mutations in 70 genes with 3 cases of SETBP1 alterations.

Some of the genes identified as mutated in the initial set of 9 patients (IDH2, MTA2, EPHB3, ETNK1, GATA2, IRAK4) and having a score higher than 1 in the oncogenic GeneRanker database were resequenced in a cohort of 40 aCML patients (15 with and 25 without SETBP1 mutations). With the exception of IDH2, no other gene was found mutated in any case apart from the index patient.

Evaluation on a larger cohort of 70 aCML samples revealed recurrent SETBP1 mutations in 24.3% of cases (see designated abstract).

To test the relationship between SETBP1 variants and mutations in oncogenes known to be involved in myeloid malignancies, mutations in ASXL1, CBL, CEBPA, DNMT3A, EED, EZH2, FLT3, IDH1/2, JAK2, JARID2, NPM1, N/KRAS, RBBP4, RUNX1, SF3B1, SUZ12, TET2 and WT1 were evaluated in a population of 61 aCML patients (14 with and 47 without SETBP1 mutations) by Sanger sequencing.

Overall we identified 60 mutations in 14 genes: 28 were missense point mutations, 13 nonsense point mutations, 15 missense ins/del and 4 ins/del leading to a premature stop codon. No mutations were found in IDH1, RBBP4, NPM1, JAK2, FLT3, DNMT3A.

Mutations in ASXL1 were present in 14 patients and appeared more frequent in patients with mutated SETBP1 (36% vs 19%) while the 15 TET2 mutations were more prevalent in patients with SETBP1 WT than in mutated samples(28% vs. 14%). Further associations will be presented at the meeting, although further analysis on larger cohorts of patients will be necessary to determine the significance of this differences. Additional data on epigenetic signature of aCML will clarify the role of epigenetic dysregulation in aCML and related diseases.

Citation Format: Sara Redaelli, Simona Valletta, Rocco Piazza, Nils Winkelmann, Roberta Spinelli, Alessandra Pirola, Laura Antolini, Luca Mologni, Carla Donadoni, Elli Papaemmanuil, Susanne Schnittger, Kim Dong-Wook, Jacqueline Boultwood, Fabio Rossi, Giuseppe Gaipa, Greta De Martini, Paola Francia di Celle, Hyun Gyung Jang, Valeria Fantin, Graham R. Bignell, Vera Magistroni, Torsten Haferlach, Enrico Maria Pogliani, Peter Campbell, Andrew J. Chase, William J. Tapper, Nick C.P. Cross, Carlo Gambacorti Passerini. Patterns of recurrent mutations in SETBP1 mutated and wild-type atypical Chronic Myeloid Leukemia patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2993. doi:10.1158/1538-7445.AM2013-2993

Recurrent SETBP1 mutations in atypical chronic myeloid leukemia

Atypical chronic myeloid leukemia (aCML) shares clinical and laboratory features with CML, but it lacks the BCR-ABL1 fusion. We performed exome sequencing of eight aCMLs and identified somatic alterations of SETBP1 (encoding a p.Gly870Ser alteration) in two cases. Targeted resequencing of 70 aCMLs, 574 diverse hematological malignancies and 344 cancer cell lines identified SETBP1 mutations in 24 cases, including 17 of 70 aCMLs (24.3%; 95% confidence interval (CI) = 16-35%). Most mutations (92%) were located between codons 858 and 871 and were identical to changes seen in individuals with Schinzel-Giedion syndrome. Individuals with mutations had higher white blood cell counts (P = 0.008) and worse prognosis (P = 0.01). The p.Gly870Ser alteration abrogated a site for ubiquitination, and cells exogenously expressing this mutant exhibited higher amounts of SETBP1 and SET protein, lower PP2A activity and higher proliferation rates relative to those expressing the wild-type protein. In summary, mutated SETBP1 represents a newly discovered oncogene present in aCML and closely related diseases.

Abstract 33: Cancer-associated IDH1 mutations produce 2-hydroxyglutarate

Mutations in the enzyme isocitrate dehydrogenase 1 (IDH1) are a common feature of most gliomas and secondary glioblastomas, as well as approx 10% acute myeloid leukemias. This event results in loss of the enzyme's ability to catalyze conversion of isocitrate to α -ketoglutarate. However, these mutations are all heterozygous and occur at a single amino acid residue of the IDH1 active site consistent with an enzymatic gain of function rather than a simple loss of function. To test this hypothesis we characterized mutant IDH1 (IDH1m) biochemically. We have shown that cancer-associated IDH1 mutations result in a new ability of the enzyme to catalyze the NADPH-dependent reduction of α-ketoglutarate to R(-)-2-hydroxyglutarate (2-HG). Patients with an inherited, neurometabolic disorders called 2-hydroxyglutaric aciduria exhibit an accumulation of 2-HG in their CNS, and an increased risk of developing malignant brain tumors. Similarly, in human malignant gliomas harboring IDH1 mutations, we find elevated levels of 2-HG. Altogether our data demonstrate that the IDH1 mutations result in production of 2-HG, and suggest that the excess 2HG which accumulates in vivo contributes to the formation and malignant progression of gliomas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 33.

Abstract 5452: Cancer-associated metabolite 2-hydroxyglutarate accumulates in AML with IDH1/2 mutations

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), are present in most gliomas and secondary glioblastomas, but are rare in other neoplasms. IDH1/2 mutations are heterozygous, and affect a single arginine residue. Recently, IDH1 mutations were identified in 8% of acute myelogenous leukemia (AML) patients. Our previous study revealed that IDH1 mutations cause a gain of function, resulting in the production and accumulation of 2-hydroxyglutarate (2-HG). Genotyping of 145 AML biopsies identified 11 IDH1 R132 mutant samples. Liquid chromatography-mass spectrometry metabolite screening revealed increased 2-HG levels in IDH1 R132 mutant cells and sera, and uncovered two IDH2 R172K mutations. IDH1/2 mutations were associated with normal karyotypes. Recombinant IDH1 R132C and IDH2 R172K proteins catalyze the novel NADPH -dependent reduction of alpha-ketoglutarate (a-KG) to 2-HG. The IDH1 R132C mutation commonly found in AML reduces the affinity for isocitrate, and increases the affinity for NADPH and a-KG. This prevents the oxidative decarboxylation of isocitrate to a-KG, and facilitates the conversion of a-KG to 2-HG. IDH1/2 mutations confer an enzymatic gain of function that dramatically increases 2-HG in AML. This provides an explanation for the heterozygous acquisition of these mutations during tumorigenesis. 2-HG is a tractable metabolic biomarker of mutant IDH1/2 enzyme activity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5452.

Cancer-associated metabolite 2-hydroxyglutarate accumulates in acute myelogenous leukemia with isocitrate dehydrogenase 1 and 2 mutations

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), are present in most gliomas and secondary glioblastomas, but are rare in other neoplasms. IDH1/2 mutations are heterozygous, and affect a single arginine residue. Recently, IDH1 mutations were identified in 8% of acute myelogenous leukemia (AML) patients. A glioma study revealed that IDH1 mutations cause a gain-of-function, resulting in the production and accumulation of 2-hydroxyglutarate (2-HG). Genotyping of 145 AML biopsies identified 11 IDH1 R132 mutant samples. Liquid chromatography-mass spectrometry metabolite screening revealed increased 2-HG levels in IDH1 R132 mutant cells and sera, and uncovered two IDH2 R172K mutations. IDH1/2 mutations were associated with normal karyotypes. Recombinant IDH1 R132C and IDH2 R172K proteins catalyze the novel nicotinamide adenine dinucleotide phosphate (NADPH)–dependent reduction of α-ketoglutarate (α-KG) to 2-HG. The IDH1 R132C mutation commonly found in AML reduces the affinity for isocitrate, and increases the affinity for NADPH and α-KG. This prevents the oxidative decarboxylation of isocitrate to α-KG, and facilitates the conversion of α-KG to 2-HG. IDH1/2 mutations confer an enzymatic gain of function that dramatically increases 2-HG in AML. This provides an explanation for the heterozygous acquisition of these mutations during tumorigenesis. 2-HG is a tractable metabolic biomarker of mutant IDH1/2 enzyme activity.

Cancer-associated IDH1 mutations produce 2-hydroxyglutarate

Mutations in the enzyme cytosolic isocitrate dehydrogenase 1 (IDH1) are a common feature of a major subset of primary human brain cancers. These mutations occur at a single amino acid residue of the IDH1 active site, resulting in loss of the enzyme's ability to catalyse conversion of isocitrate to alpha-ketoglutarate. However, only a single copy of the gene is mutated in tumours, raising the possibility that the mutations do not result in a simple loss of function. Here we show that cancer-associated IDH1 mutations result in a new ability of the enzyme to catalyse the NADPH-dependent reduction of alpha-ketoglutarate to R(-)-2-hydroxyglutarate (2HG). Structural studies demonstrate that when arginine 132 is mutated to histidine, residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert alpha-ketoglutarate to 2HG. Excess accumulation of 2HG has been shown to lead to an elevated risk of malignant brain tumours in patients with inborn errors of 2HG metabolism. Similarly, in human malignant gliomas harbouring IDH1 mutations, we find markedly elevated levels of 2HG. These data demonstrate that the IDH1 mutations result in production of the onco-metabolite 2HG, and indicate that the excess 2HG which accumulates in vivo contributes to the formation and malignant progression of gliomas.

Cancer-associated IDH1 mutations produce 2-hydroxyglutarate

Mutations in the enzyme cytosolic isocitrate dehydrogenase 1 (IDH1) are a common feature of a major subset of primary human brain cancers. These mutations occur at a single amino acid residue of the IDH1 active site, resulting in loss of the enzyme's ability to catalyse conversion of isocitrate to alpha-ketoglutarate. However, only a single copy of the gene is mutated in tumours, raising the possibility that the mutations do not result in a simple loss of function. Here we show that cancer-associated IDH1 mutations result in a new ability of the enzyme to catalyse the NADPH-dependent reduction of alpha-ketoglutarate to R(-)-2-hydroxyglutarate (2HG). Structural studies demonstrate that when arginine 132 is mutated to histidine, residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert alpha-ketoglutarate to 2HG. Excess accumulation of 2HG has been shown to lead to an elevated risk of malignant brain tumours in patients with inborn errors of 2HG metabolism. Similarly, in human malignant gliomas harbouring IDH1 mutations, we find markedly elevated levels of 2HG. These data demonstrate that the IDH1 mutations result in production of the onco-metabolite 2HG, and indicate that the excess 2HG which accumulates in vivo contributes to the formation and malignant progression of gliomas.

The effect of cationic polymer treatment on adhesion of iron oxide to eyelashes

The aim of this study was to investigate the effect of iron oxide application on improving the volume of eyelashes. Iron oxide, having a negative surface charge in its natural form, was coated with commercial cationic polymers to increase its adhesion. The iron oxides coated with different types and concentrations of these polymers were incorporated into a basic mascara formula to test their volume effects by means of the weight difference of eyelashes.The results indicated that the type and concentration of coating materials affect the surface zeta potential and particle cluster size of iron oxides. The type of cationic polymer, especially, was shown to modify both factors of iron oxide. The obtained results also suggested that the volume effect of mascara increases with a higher positive surface zeta potential and a smaller particle cluster size of the coated iron oxides.

Hydroxyl-specific fluorescence labeling of ABP-deoxyguanosine, PhIP-deoxyguanosine, and AFB1-formamidopyrimidine with BODIPY-FL

Detection and analysis of DNA adducts resulting from endogenous or exogenous exposures to carcinogens are essential not only for quantifying biologically effective doses but also for establishing relationships between exposure and cancer risk. We have developed and validated a procedure of high sensitivity and specificity based on fluorescence labeling of DNA adducts combined with high-performance liquid chromatography-laser-induced fluorescence detection. The fluorescent dye 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionic acid (BODIPY FL) was used to label the deoxynucleoside adducts N-(2'-deoxyguanosine-8-yl)-4-aminobiphenyl and N-(2'-deoxyguanosine-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and the base adduct aflatoxin B(1)-formamidopyrimidine by acylation. The labeling reaction was carried out on adducts at 1pmol to 30nmol concentrations at 25 degrees C for 4h in dichloromethane with 200- to 5000-fold excess of BODIPY FL. BODIPY FL and its activating agents 1,3-dicyclohexylcarbodiimide and 4-dimethylaminopyridine were used at a molar ratio of 1:2:2. Under these conditions, all of the above adducts were quantitatively converted to bis-labeled products, as confirmed by mass spectrometry. Sites of derivatization of adduct deoxynucleosides were established primarily by nuclear magnetic resonance and by collision-induced dissociation mass spectrometric analysis, which indicated that the bis-BODIPY groups were located predominantely on the 3'- and 5'-hydroxyl groups of the deoxyribose ring.

Classification of CD and absorption spectra in the Soret band of H(2)TMPyP bound to various synthetic polynucleotides

The binding mode of porphyrins, namely meso-tetrakis(N-methyl pyridinium-4-yl)porphyrin (H(2)TMPyP), was classified in this work by absorption and circular dichroism(CD) spectroscopy. The three binding modes of intercalation, minor groove binding and external stacking exhibit their own characteristic absorption and CD spectra. Intercalation occurs for this porphyrin when bound to GC-rich polynucleotides at a low mixing ratio, as expected. This binding mode produces hypochromism and a red shift in the absorption band and a negative CD band in the Soret absorption region. When it is complexed with AT-rich polynucleotides at a low mixing ratio, hypochromism and a red shift in the absorption band and a positive CD peak is apparent, and this species can easily be assigned to the minor groove-binding mode. For both AT- and GC-rich polynucleotides at a high binding ratio, an excitonic CD was apparent. The sign of excitonic CD depends on the order of the DNA bases; the CD spectra of H(2)TMPyP complexed with non-alternating homopolymer (disregarding the nature of base pairs, i.e. AT or GC) are characterized by a positive band at short wavelengths followed by a negative band at long wavelengths. In contrast, those complexed with alternating polynucleotide were opposite to those of non-alternating homopolymers.

Structures and related properties of AgX bearing 3,3'-thiobispyridine (X- = NO3-, BF4-, CLO4-, and PF6-

Infinite molecular helices [Ag(3,3'-Py2S)]X (3,3'-Py2S = 3,3'-thiobispyridine; X- = BF4-, ClO4-, and PF6-) have been rationally constructed or induced. Crystallographic characterization (X- = BF-, monoclinic P2(1)/n, a = 8.946(3) A, b = 14.130(2) A, c = 10.124(2) A, beta = 107.83(2) degrees, V = 1218.3(5) A3, Z = 4, R = 0.0351; X- = ClO4-, monoclinic P2(1)/n, a = 8.884(1) A, b = 14.305(3) A, c = 10.110(1) A, beta = 106.78(1) degrees, V = 1230.1(3) A3, Z = 4, R = 0.0417; X- = PF6-, monoclinic P2(1)/c, a = 10.959(2) A, b = 9.808(2) A, c = 14.065(3) A, beta = 112.03(2) degrees, V = 1401.4(5) A3, Z = 4, R = 0.0442) reveals that the skeletal structure is an oblong cylindrical cationic helix consisting of alternating Ag(I) and 3,3'-Py2S species and that its counteranions are pinched in two columns inside each helix. The formation of the helical coordination polymer appears to be primarily associated with a suitable combination of the skewed conformer of 3,3'-Py2S and the potential linear geometry of the N-Ag(I)-N bond. However, the framework of the nitrate analogue [Ag(3,3'-Py2S)NO3] (monoclinic P2(1)/c, a = 8.177(2) A, b = 10.291(1) A, c = 14.771(2) A, beta = 102.19(1) degrees, V = 1214.9(4) A3, Z = 4, R = 0.0300) is a two-dimensional network consisting of an 18-membered ring unit, where each 3,3'-Py2S acts as a N,N',S- tridentate ligand connecting three tetrahedral silver(I) ions with the monodentate nitrate weakly bonded to the silver (Ag.O = 2.65(1) A) rather than acting as a counteranion. The anion exchange of [Ag(3,3'-Py2S)NO3] with BF4-, ClO4-, or PF6- has been accomplished in aqueous media. The two-dimensional networks are easily converted into the helices via the anion exchange, but the reverse anion exchange proceeds slightly. Thermal analyses indicate a relationship between the thermal stabilities and the structural properties.

Binding mode of 4',6-diamidino-2-phenylindole and ethidium to poly(dG).poly(dC).poly(dC)(+) triplex and poly(dG).poly(dC) duplex

Optical spectroscopic properties of 4',6-diamidino-2-phenylindole (DAPI) and ethidium bromide complexed with poly(dG).poly(dC).poly(dC)(+) triplex and poly(dG).poly(dC) duplex were compared in this study. When complexed with both duplex and triplex, ethidium is characterized by hypochromism and a red shift in the absorption spectrum, a complicate induced circular dichroism (CD) band in the polynucleotide absorption region, and a negative reduced linear dichroism signal in both polynucleotide and drug absorption regions. The spectral properties for both duplex- and triplex-bound ethidium are identical and both can be understood by the intercalation binding mode. In contrast, the absorption and CD spectra of DAPI complexed with triplex differ from those of the DAPI-duplex complex, although both complexes can be understood by the intercalation binding mode. Considering that the third strand runs along the major groove of the template duplex, we conclude that the DAPI molecule partially intercalates near the major groove of the duplex, where the third strand can affect its spectroscopic properties.

First success of catalytic epoxidation of olefins by an electron-rich iron(III) porphyrin complex and H2O2: imidazole effect on the activation of H2O2 by iron porphyrin complexes in aprotic solvent

An electron-rich iron(III) porphyrin complex (meso-tetramesitylporphinato)iron(III) chloride [Fe(TMP)Cl], was found to catalyze the epoxidation of olefins by aqueous 30% H2O2 when the reaction was carried out in the presence of 5-chloro-1-methylimidazole (5-Cl-1-Melm) in aprotic solvent. Epoxides were the predominant products with trace amounts of allylic oxidation products, indicating that Fenton-type oxidation reactions were not involved in the olefin epoxidation reactions. cis-Stilbene was stereospecifically oxidized to cis-stilbene oxide without giving isomerized trans-stilbene oxide product, demonstrating that neither hydroperoxy radical (HOO*) nor oxoiron(IV) porphyrin [(TMP)FeIV=O] was responsible for the olefin epoxidations. We also found that the reactivities of other iron(III) porphyrin complexes such as (meso-tetrakis(2,6-dichlorophenyl)porphinato)iron(III) chloride [Fe(TDCPP)Cl], (meso-tetrakis(2,6-difluorophenyl)porphinato)iron(III) chloride [Fe(TDFPP)Cl], and (meso-tetrakis(pentafluorophenyl)porphinato)iron(III) chloride [Fe(TPFPP)CI] were significantly affected by the presence of the imidazole in the epoxidation of olefins by H2O2. These iron porphyrin complexes did not yield cyclohexene oxide in the epoxidation of cyclohexene by H2O2 in the absence of 5-Cl-1-MeIm in aprotic solvent; however, addition of 5-Cl-1-MeIm to the reaction solutions gave high yields of cyclohexene oxide with the formation of trace amounts of allylic oxidation products. We proposed, on the basis of the results of mechanistic studies, that the role of the imidazole is to decelerate the O-O bond cleavage of an iron(III) hydroperoxide porphyrin (or H2O2-iron(II) porphyrin adduct) and that the intermediate transfers its oxygen to olefins prior to the O-O bond cleavage.

Effect of oxidized fish oil and alpha-tocopherol on the peroxidation of erythrocyte membrane phospholipids in rats

The effects of dietary oxidized fish oil and alpha-tocopherol on the thiobarbituric acid (TBA) values and phospholipid hydroperoxide levels of the erythrocyte membrane were studied in rats. No significant differences in the TBA values or phospholipid hydroperoxide levels of the membrane were observed between groups fed either oxidized fish oil or control diets. Furthermore, there were no marked differences in these values whether or not the groups were administered diets containing added alpha-tocopherol. These results suggest that the intake of oxidized fish oil and the supplementation with alpha-tocopherol do not influence the level of lipid peroxidation in the erythrocyte membrane.