Assessment of the eye irritation potential of chemicals: A comparison study between two test methods based on human 3D hemi-cornea models.

We have recently developed two hemi-cornea models (Bartok et al., Toxicol in Vitro 29, 72, 2015; Zorn-Kruppa et al. PLoS One 9, e114181, 2014), which allow the correct prediction of eye irritation potential of chemicals according to the United Nations globally harmonized system of classification and labeling of chemicals (UN GHS). Both models comprise a multilayered epithelium and a stroma with embedded keratocytes in a collagenous matrix. These two models were compared, using a set of fourteen test chemicals. Their effects after 10 and 60 minutes (min) exposure were assessed from the quantification of cell viability using the MTT reduction assay. The first approach separately quantifies the damage inflicted to the epithelium and the stroma. The second approach quantifies the depth of injury by recording cell death as a function of depth. The classification obtained by the two models was compared to the Draize rabbit eye test and an ex vivo model using rabbit cornea (Jester et al. Toxicol in Vitro. 24, 597-604, 2010). With a 60 min exposure, both of our models are able to clearly differentiate UN GHS Category 1 and UN GHS Category 2 test chemicals.

Development of an in vitro ocular test system for the prediction of all three GHS categories.

In the present study we considered a new approach that allows the individual quantification of damages induced in the epithelium and stroma of an in vitro hemi-cornea model after chemical treatment. We aimed at a stand-alone test system for classification according to the classification of the globally harmonized system of classification and labelling of chemicals (GHS). We have modified a previously developed 3D hemi-cornea model by the insertion of a collagen membrane between epithelium and stroma. This membrane allows the separation and independent assessment of these compartments after topical exposure to potential eye irritants. The cell viability quantified by MTT assay was used as the toxicological endpoint. The prediction model based on the results obtained from 30 test chemicals uses a single exposure period and the combination of cut-off values in tissue viability from both epithelium and stroma. The in vitro-in vivo concordance of the test system is 77%. All of the GHS category 1, 80% of the GHS category 2 and 50% of the GHS not categorized chemicals are predicted correctly. In conclusion, the test system predicts and discriminates GHS category 1 and GHS category 2 chemicals, but is over-predictive for GHS not categorized materials.

ESI-MS and MS/MS identification of the first ceramide analogues of fumonisin B1 mycotoxin from a Fusarium verticillioides culture following RP-HPLC separation.

Following the earlier detection of six new esterified fumonisin B1 (EFB1) isomers containing three acyl groups in a Fusarium verticillioides-inoculated rice culture, it was assumed that linoleic, palmitic or oleic acid esterifies one of the free OH groups on the fumonisin backbone. On the basis of the results of our recent investigations we now propose that these EFB1 isomers are actually 3-O- and 5-O-acyl derivatives of FB1 (3-O-linoleoyl-FB1, 5-O-linoleoyl-FB1, 3-O-palmitoyl-FB1, 5-O-palmitoyl-FB1, 3-O-oleoyl-FB1 and 5-O-oleoyl-FB1). A F. verticillioides strain was identified that produced not only O-acyl-FB1 isomers, but also low amounts of three N-acyl derivatives (N-linoleoyl-FB1, N-palmitoyl-FB1 and N-oleoyl-FB1), which eluted from the HPLC column after the six O-acyl compounds and in the same sequence as for the O-acyl compounds. The characteristic positive and negative ESI-MS/MS spectra obtained after solid-phase extraction of the culture extract facilitated identification of these N-acyl-FB1 derivatives. The biosynthesis of N-palmitoyl-FB1 by F. verticillioides was verified by spiking the culture extract with synthetic N-palmitoyl-FB1. This is the first report of the separation and mass spectrometric identification of the six O-acyl- and three N-acyl-FB1 derivatives extracted from a F. verticillioides culture.

Identification of the first fumonisin mycotoxins with three acyl groups by ESI-ITMS and ESI-TOFMS following RP-HPLC separation: palmitoyl, linoleoyl and oleoyl EFB1 fumonisin isomers from a solid culture of Fusarium verticillioides.

The aim of this study was to apply RP-HPLC/ESI-ITMS and RP-HPLC/ESI-TOFMS to investigate and characterise six new higher molecular weight fumonisins (three pairs of isomers) extracted from a Fusarium verticillioides-infected solid rice culture. The ITMS and ITMS² spectra clearly indicated the m/z values (960, 984 and 986) of the protonated molecules and the FB1 toxin-like structures of these compounds, respectively. Moreover, the data evaluation software of the TOFMS equipment unambiguously demonstrated the exact masses of the protonated molecules and the suggested empirical formulae (C50H89NO16, C52H89NO16 and C52H91NO16) of the new fumonisins, with mass accuracy in the range between 0.1 and -1.1 ppm. Subtraction of the empirical formula of FB1 toxin (C34H59NO15) from these formulae and correction for the mass of water split-off from the fumonisin molecule during ester formation resulted in the empirical formulae of the fumonisin backbone esterifying agents (fatty acids): C16H32O2 (palmitic acid, PA), C18H32O2 (linoleic acid, LA) and C18H34O2 (oleic acid, OA). We denoted the new compounds as esterified FB1 (EFB1) toxins, with the suggested names EFB1 PA, iso-EFB1 PA, EFB1 LA, iso-EFB1 LA, EFB1 OA and iso-EFB1 OA. The total amount of these new compounds comprised 0.1% of the FB1 concentration, which may be rated as significant when it is considered that these new components are significantly more apolar than earlier-described fumonisins, and their uptake into and toxicity elicited in the various tissues of living organisms may therefore also be significantly different from those of other fumonisins.

Unexpected change of the sense of the enantioselective hydrogenation of ethyl pyruvate catalyzed by a Pt-alumina-cinchona alkaloid system.

In the enantioselective hydrogenation of ethyl pyruvate (EtPy) over beta-isocinchonine (beta-ICN) modified Pt-alumina catalysts, the major enantiomer was (R)-ethyl lactate ((R)-EtLt (ee 50%)) in toluene, while in AcOH (S)-EtLt (ee 60%) was formed; the (R) configuration is opposite to what is expected from the absolute configuration of the cinchonine backbone.

Enantioselective Michael addition catalyzed by cinchona alkaloids.

Enantioselective Michael additions of cyclic beta-ketoesters to methyl vinyl ketone catalyzed by cinchona alkaloids were studied. The results revealed that the induced enantioselectivity was significantly influenced by both the structure of the catalyst and that of the substrate. Interesting differences in the effect of the structure of the alkaloid on the enantioselectivity of this reaction in the case of three beta-ketoesters were discovered. High enantioselectivities were obtained in the reaction of ethyl 2-oxocyclopentanecarboxylate and ethyl 2-oxocyclohexanecarboxylate (up to 83 and 80%, respectively) at a low cinchona:reactant ratio of 1:500. As the specific rotations of the product enantiomers were unknown, they were determined by optical rotation and chiral GC measurements and verified by NMR experiments.

Heterogeneous asymmetric reactions. Part 24. Heterogeneous catalytic enantioselective hydrogenation of the C==N group over cinchona alkaloid modified palladium catalyst.

The enantioselective hydrogenation of C==N-C group containing compounds over modified metal catalysts is as yet an uninvestigated research area. This work contains results obtained on the hydrogenation of 1-pyrroline-2-carboxylate esters and sodium salt over cinchona alkaloid-modified alumina-supported Pd catalyst. The effect of the reaction parameters and the structure of the alkaloid molecule on hydrogenation rate and enantioselectivity allowed us to assume that on the catalyst surface only a weak interaction exists between the modifier and the substrate, resulting in the low enantiomeric excesses (up to 20%) obtainable in these reactions.

Asymmetric reactions in sonochemistry.

Sonochemical processes involved in asymmetric synthesis are reviewed. The goal of this overview is to provide a comprehensive picture about the fields of both enantioselective and diastereoselective reactions accelerated or initiated by ultrasounds. Since the most, in many cases comparative, data are available in heterogeneous metal catalysis, the emphasis will be placed on these enantioselective hydrogenations, however, other applications such as phase transfer catalysis etc. will also be cited.

Asymmetric sonochemical reactions enantioselective hydrogenation of alpha-ketoesters over platinum catalysts.

The sonochemical enantioselective hydrogenation of different alpha-ketoesters to the corresponding hydroxy derivatives over cinchona modified Pt catalysts is described. Ultrasonic irradiation was found to be beneficial in improving the optical yields. Besides studying the reaction rates and enantioselectivities, the effect of ultrasonics on the catalyst-modifier system and the scale-up of the process will also be considered.

Ultrasonics in chemoselective heterogeneous metal catalysis sonochemical hydrogenation of unsaturated carbonyl compounds over platinum catalysts.

The hydrogenation of unsaturated aldehydes was studied over ultrasonically pretreated silica supported platinum catalyst. In the hydrogenation of cinnamaldehyde a remarkable reaction rate and cinnamyl alcohol selectivity increase was observed. Using other unsaturated aldehydes the reaction rate and unsaturated alcohol selectivity increased moderately.

New results on the mass spectra of cinchona alkaloids

The electrospray ionization (ESI) mass spectra of 16 cinchona alkaloid compounds were studied for the first time. The electron ionization (EI) spectra of 22 cinchona alkaloids were also recorded, 14 of which had not been examined previously. In the case of EI the characteristic direction of the fragmentation is the scission of the C8-C9 bond. Under EI the cleavage of the C4'-C9 bond occurs only in the case of hydrogenated cinchona alkaloids, whereas the C9-O bond cleavage can be observed in the case of ester and ether derivatives. At a low capillary exit voltage (CapEx) in the ESI measurements there is no fragmentation, and only the [M + H](+) and in some cases the double protonated [M + 2H](2+) ions can be detected. On increasing the CapEx the characteristic primary direction is the cleavage of the C9-O bond, which was observed in the case of epialkaloids and esterified or etherified cinchona derivatives, respectively. Copyright 2000 John Wiley & Sons, Ltd.

Identification of ethyl pyruvate and dihydrocinchonidine adducts by electrospray ionization mass spectrometry.

Several ethyl pyruvate and dihydrocinchonidine adducts, formed by non-covalent interactions with alkali cations, have been identified for the first time using electrospray ionization mass and tandem mass spectrometry. This type of adduct may have an important role in asymmetric reactions of pyruvates in the presence of cinchonas.

Sonochemical hydrosilylation of 2-substituted cyclohexanones in the presence of Wilkinson complex.

The sonochemical hydrosilylation of alkyl substituted cyclohexanones catalyzed by Rh (PPh3)3Cl is described. The application of ultrasonic irradiation during the reaction highly enhances the reaction rates and produces higher yields than those obtained in silent reactions. The stereoselectivity of the reaction has not been changed, the isomeric distribution, i.e. the cis/trans ratio of the 2-substituted cyclohexanols formed, is very close to those obtained in conventional stirred reactions.

Ultrasonics in heterogeneous metal catalysis: sonochemical chemo- and enantioselective hydrogenations over supported platinum catalysts.

Sonochemical chemo- and enantioselective hydrogenations over supported platinum catalysts are described. We disclose our results with respect to a sonochemical modification of the chemoselective hydrogenation of cinnamaldehyde over supported platinum catalysts, and the asymmetric hydrogenation of ethyl pyruvate promoted by various ultrasonic pretreatments. The ultrasonic pretreatment of the supported platinum catalysts was found to be highly beneficial in almost every case, improving both the catalytic activity and selectivity. The effect of additional experimental variables, such as hydrogen pressure, catalyst support, temperature and the ultrasonic insonation time were also studied. The enantioselectivity of the hydrogenation of ethyl pyruvate increased up to 97.1% ee. In the case of cinnamaldehyde hydrogenation, the selective preparation of cinnamyl alcohol became possible. The theoretical aspects of the working mechanisms in comparison with 'silent' reactions will also be provided.

Homogeneous and heterogeneous asymmetric reactions: Part 11. Sonochemical enantioselective hydrogenation of trifluoromethyl ketones over platinum catalysts.

Enantioselective sonochemical hydrogenation of alpha,alpha,alpha-trifluoromethyl ketones, namely, 1,1,1-trifluoroacetophenone and 1,1,1-trifluoro-phenylacetone was carried out over various platinum catalysts modified by cinchonidine in different solvents. Both compounds yielded the (R)-alcohol as major product. The reaction rates and the enantiomeric excesses were determined over Pt/C, Pt/SiO2, Pt/K-10 and Pt/Al2O3 catalysts under conventional conditions. Since Pt/Al2O3 exhibited the best catalytic performance the effect of ultrasound on the catalytic activity and enantioselectivity was tested using this catalyst applying different sonochemical pretreatments. These methods included a pretreatment before the reaction in hydrogen and oxygen or both. The ultrasonic irradiation was found to be highly advantageous in the case of trifluoroacetophenone, whereas only moderate changes were observed using trifluoro-phenylacetone. After insonation of the catalyst, the enantioselectivity was considerably improved. Both the aerobic and anaerobic sonochemical pretreatments resulted in significant improvement in optical yield (up to 49% and 17% ee, at room temperature under 10 bar in 1,2-dichlorobenzene). In parallel, the hydrogenation rates increased to a small extent (1.1-1.2-fold increase) after hydrogenative ultrasonic pretreatment, whereas the rates decreased by a factor of 1.5-2 after aerobic insonation. To obtain more insight into the process, the effect of insonation time on the activity and enantioselectivity and actual changes of the catalyst were also studied.

Sonochemical enantioselective hydrogenation of ethyl pyruvate over platinum catalysts.

Chiral sonochemical hydrogenation of an aliphatic alpha-ketoester, ethyl pyruvate to ethyl lactate was carried out over various platinum catalysts in different solvents under atmospheric hydrogen pressure. The reaction rates and the enantiomeric excesses were determined over Pt/C, Pt/SiO2 and Pt/K-10 catalysts both under conventional and sonochemical conditions. The effect of ultrasounds on the catalytic activity and enantioselectivity was tested applying sonochemical pretreatment before the reaction. The ultrasonic irradiation was found to be highly advantageous in these hydrogenations. After insonation of the catalysts, the enantioselectivity was highly improved over Pt/SiO2 and Pt/K-10 catalysts. In addition, the reactions took place in quantitative yield and with complete chemoselectivity and the hydrogenation rates increased with one order of magnitude despite the very mild (atmospheric hydrogen pressure, room temperature) experimental conditions.

Ki-1 positive (anaplastic, large cell) lymphoma (case reports and review).

Ki-1 positive (anaplastic, large cell) lymphoma is a subgroup of non-Hodgkin lymphomas identified recently by Ki-1 (or BER-H2) (CD 30) monoclonal antibody. The clinicopathological features of two such pediatric cases of lymph node origin described here, and also the available literature emphasize the heterogenous nature of Ki-1 positive lymphomas, in almost every respect. Nevertheless, the Ki-1 antibody serves as an important diagnostic tool to differentiate lymphomas from other anaplastic, large malignancies.