Annamaria Jakab

Comparative analysis of different plant oils by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

Different vegetable oil samples (almond, avocado, corngerm, grapeseed, linseed, olive, peanut, pumpkin seed, soybean, sunflower, walnut, wheatgerm) were analyzed using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. A gradient elution technique was applied using acetone-acetonitrile eluent systems on an ODS column (Purospher, RP-18e, 125 x 4 mm, 5 microm). Identification of triacylglycerols (TAGs) was based on the pseudomolecular ion [M+1]+ and the diacylglycerol fragments. The positional isomers of triacylglycerol were identified from the relative intensities of the [M-RCO2]+ fragments. Linear discriminant analysis (LDA) as a common multivariate mathematical-statistical calculation was successfully used to distinguish the oils based on their TAG composition. LDA showed that 97.6% of the samples were classified correctly.

Enhanced Mucosal Immunoglobulin A Response and Solid Protection against Foot-and-Mouth Disease Virus Challenge Induced by a Novel Dendrimeric Peptide

ABSTRACT The successful use of a dendrimeric peptide to protect pigs against challenge with foot-and-mouth disease virus (FMDV), which causes the most devastating animal disease worldwide, is described. Animals were immunized intramuscularly with a peptide containing one copy of a FMDV T-cell epitope and branching out into four copies of a B-cell epitope. The four immunized pigs did not develop significant clinical signs upon FMDV challenge, neither systemic nor mucosal FMDV replication, nor was its transmission to contact control pigs observed. The dendrimeric construction specifically induced high titers of FMDV-neutralizing antibodies and activated FMDV-specific T cells. Interestingly, a potent anti-FMDV immunoglobulin A response (local and systemic) was observed, despite the parenteral administration of the peptide. On the other hand, peptide-immunized animals showed no antibodies specific of FMDV infection, which qualifies the peptide as a potential marker vaccine. Overall, the dendrimeric peptide used elicited an immune response comparable to that found for control FMDV-infected pigs that correlated with a solid protection against FMDV challenge. Dendrimeric designs of this type may hold substantial promise for peptide subunit vaccine development.

Polyethyleneglycol-Based Resins as Solid Supports for the Synthesis of Difficult or Long Peptides

An evaluation of the polyethyleneglycol-based ChemMatrix® resin as solid support for the synthesis of challenging peptide sequences is presented. Comparison with conventional polystyrene and polyethyleneglycol-polystyrene resins in several instances of typically difficult solid phase syntheses shows a consistently better performance of the ChemMatrix® resin in terms of end product purity. Representative test sequences include a 15-residue antibiotic, a gp41 ectodomain hybrid sequence, a calcipressin fragment with an N-terminal Arg11 extension, and two chemokines of 69- and 64-amino acid residues. Interestingly, a difference in only five amino-acids between the two chemokine sequences had a remarkable impact on synthetic results, which in the case of the 69-residue peptide required additional refinements (β-sheet-breaking pseudoproline dipeptides) for success.

Determination of the retention behavior of barbituric acid derivatives in reversed-phase high-performance liquid chromatography by using quantitative structure–retention relationships

Retention parameters of 45 barbituric acid derivatives were determined on an amide embedded RP silica column using non-buffered water-dioxan eluent systems. Linear correlations were calculated between the logarithm of the capacity factor and the dioxan concentration in the eluent. Six different retention parameters of each barbituric acid derivative were correlated with different conventional and quantum chemical structural descriptors using quantitative structure-retention relationship (QSRR). The different parameters were: intercept (log k0) and slope (b) values of the linear, the combined retention parameter (log k0/b), asymmetry factor (AF5) and theoretical plate values (N(USP) and N(JP), according to the United States and Japanese Pharmacopoeia calculations). Stepwise regression analysis (SRA) and principal component analysis (PCA) followed by two-dimensional nonlinear mapping were used to determine the retention behavior of barbituric acid derivatives. SRA and PCA led to similar results. The results indicated that the retention of barbituric acid derivatives are mainly governed by the polaric and steric parameters of the substituents.

Structure, enzymatic stability and antitumor activity of sea lamprey GnRH-III and its dimer derivatives.

Direct antitumor activity of sea lamprey (Petromyzon marinus) gonadotropin-releasing hormone III (Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH(2); lGnRH-III) was described on several tumor cells. To improve the selectivity of antitumor effects without increasing the hormone releasing activity and to enhance the enzymatic stability, lGnRH-III dimers were prepared via disulfide bond formation. Our results demonstrate that the lGnRH-III dimer derivatives exhibited higher antiproliferative effect and enzymatic stability in comparison with the native lGnRH-III, while lower LH-releasing potency was determined. In order to find a correlation between the biological and structural features of these compounds, the conformation of lGnRH-III and its dimer derivatives was determined by ECD, VCD, FT-IR and (1)H NMR.

PCA, followed by two-dimensional nonlinear mapping and cluster analysis, versus multilinear regression in QSRR

Retention parameters of 45 different barbituric acid derivatives were determined on an amide embedded RP silica column (Discovery RP-AmideC16) using non-buffered tetrahydrofuran-water mixtures as eluents. Linear correlations were calculated between the lgk values and the tetrahydrofuran concentration in the eluent. Chromatographic parameters of barbituric acid derivatives were correlated with different conventional and quantum chemical structural descriptors in QSRR study (the different parameters were: intercept (lg k 0) and slope (b) values of the linear, the combined retention parameter (lg k 0/b), asymmetry factor (AF) and theoretical plate values (N)). Multilinear regression analysis (SRA) and principal component analysis (PCA), followed by two dimensional nonlinear mapping and cluster analysis techniques, were used to determine the retention behavior of barbituric acid derivatives. Different mathematical-statistical methods indicated that the hydrophobic characteristics of the solutes have marked influence on the retention behavior of barbituric acid derivatives on this amide embedded RP silica column in tetrahydrofuran-water eluent systems. The significant effect of the hydrophobic characteristics of the analytes in the retention behavior indicated that the effects of the interaction between the analytes and the residual silica silanol groups are negligible.

Synthesis and Antibody Recognition of Cyclic Epitope Peptides, Together with Their Dimer and Conjugated Derivatives Based on Residues 9-22 of Herpes Simplex Virus Type 1 Glycoprotein D

The synthesis of new cyclic peptides comprising the 9-22 epitope (9)LKMADPNRFRGKDL(22) sequence derived from HSV gD-1 is reported. In addition, we describe procedures for the preparation of cyclic peptide dimers and conjugates with an oligotuftsin derivative carrier. The binding of a monoclonal antibody, Mab A16, to the synthesized compounds was determined by enzyme-linked immunosorbent assay. It was demonstrated that cyclization decreased the binding activity of the antibody to the epitope. However, dimerization and conjugation could significantly increase the binding capacity of the cyclic epitope peptides. The attachment site in dimers and conjugates, as well as the topology of the construct, had a significant influence on the antibody recognition, while replacement of Met in position 11 by Nle had no marked effect.

Study of the retention parameters of barbituric acid derivatives in reversed phase HPLC by using quantitative structure-retention relationships

SummaryRetention parameters of 45 different barbituric acid derivatives were determined on an amide embedded RP silica column (Discovery RP-AmideC16) using non-buffered methanol-water mixtures as eluents. Linear correlations were calculated between the logk values and the methanol concentration in the eluent. The intercept (logk0) and slope (b) values of the line, the combined retention parameter (logk0/b), asymmetry factor (AF5) and theoretical plate (N) value of each barbituric acid derivative were correlated with different conventional and quantum chemical structural descriptors using Quantitative Structure-Retention Relationship (QSRR). The SRA (stepwise regression analysis) results indicated that the retention is mainly governed by the steric and the lipophilicity properties of the barbituric acid derivatives in water-methanol eluent mixtures.

Influence of physico-chemical parameters of some barbituric acid derivatives on their retention on an amide embedded RP silica column.

Retention parameters of 45 different barbituric acid derivatives were determined on an amide embedded RP silica column (Discovery RP-AmideC16) using non-buffered water-acetonitrile eluent systems. Linear correlation were calculated between the logarithm of the capacity factor and the acetonitrile concentration in the eluent. To determine the retention behavior of barbituric acid derivatives, stepwise regression analysis (SRA) and principal component analysis (PCA) followed by two-dimensional nonlinear and modified nonlinear mapping was used. It can be concluded, the retention of barbituric acid derivatives are governed mainly by the steric parameters of the substituents. Principal component analysis indicated that the barbituric acid derivatives have mixed retention on this amide embedded RP silica column in water-acetonitrile eluent.

Utilization of Cyclodextrins by Trichoderma Species

The growth and the development of thallus of 17 Trichoderma species have been determined by using native � -, � - and � -cyclodextrins (CDs) and 8 different CD derivatives as a unique carbon source. The majority of species can use CD for growth, this ability was related to their intragenic taxonomic position in order of sections Trichoderma > Longibrachiatum > Pachybasium > Saturnisporum T. reesei being the most and T. virens the least active. All CDs have been utilized but their nutritional value was significantly influenced by the chemical structure, the size of molecules had major importance than the flexibility of their rings. Among natural derivatives of CDs Trichodermas preferred the � - and � -CD prior to � -CD, when carboxylation led to reduction of the biodegradation of � - and � -CDs and enhanced that of � - CD. Methylation or polymerization of � -CD also modified its decomposition rate by considered Trichoderma species. As supported by applied a three-way principal components analysis (3D-PCA) the studied here Trichoderma species showed considerable deviations in their capacity to decompose CDs and the stability of CDs towards biodegradation was highly dependent on the chemical structure of CDs.