Maria Militsopoulou

Determination of twelve heparin- and heparan sulfate-derived disaccharides as 2-aminoacridone derivatives by capillary zone electrophoresis using ultraviolet and laser-induced fluorescence detection

In quest for high sensitivities, we developed an ultrahigh capillary electrophoresis (CE) method for the structural analysis of heparin and heparan sulfate (HS) in biologic samples. Heparin and HS were digested with an equi‐unit mixture of heparin lyases I, II and III and the obtained Δ‐disaccharides were derivatized with the fluorophore 2‐aminoacridone. All known twelve non‐, mono‐, di‐ and trisulfated Δ‐disaccharides were completely resolved in a single run, using 50 mM phosphate buffer, pH 3.5, and reversed polarity at 30 kV. Relative standard deviation in migration times and peak areas as well as day‐to‐day variance ranged from 0.9 to 2.4%, suggesting a reproducible and precise method. Detection of 2‐aminoacridone (AMAC)‐derivatives of Δ‐disaccharides by UV at 255 nm showed 2.8 and 10 times higher sensitivity than that of derivatized and nonderivatized ones at 232 nm. Laser‐induced fluorescence detection with an Ar‐ion laser source showed an approximately 100 times higher sensitivity than that obtained at 232 nm of the nonderivatized species. Application of this method to quantitative analysis of Δ‐disaccharides derived from porcine intestinal mucosa heparin and bovine kidney HS showed excellent agreement with previously published methods, suggesting an accurate method. The developed method can be easily applied for the disaccharide analysis of heparin/HS at the attomole level with high accuracy, for distinguishing between heparin and HS and may be of value for studying their interactions with matrix effective molecules.

Capillary electrophoresis: a tool for studying interactions of glycans/proteoglycans with growth factors.

Heparan sulfate (HS) and heparin bind to various growth factors and modulate their activities. Interactions of heparin and HS with members of the fibroblast growth factor (FGF) family are prerequisites for binding of FGFs to their high affinity cell receptors. The sulfation patterns of distinct oligosaccharide domains within heparin and HS chains determine their high affinity binding with basic FGF (bFGF). In order to study the structural basis of interactions of HS with bFGF, we developed a capillary electrophoresis (CE) method in order to monitor the ability of HS-derived oligosaccharides to bind this growth factor. HS was degraded to Delta-di- and Delta-oligosaccharides with digestion with heparitinase and the obtained Delta-saccharides were analyzed by capillary zone electrophoresis (CZE), using 50 mM phosphate, pH 3.5, as operating buffer, reversed polarity (30 kV) and detection at 232 nm. Under these conditions all differently sulfated HS Delta-disaccharides and the various Delta-oligosaccharide groups were resolved. Following incubation of the digest with bFGF and re-electrophoresis of the mixture, the bFGF interacting oligosaccharide groups were easily detected and identified. In view of the obtained results, CE is a multipotent analytical tool for determining disaccharide composition in HS, separating the various oligosaccharide groups produced by the action of heparitinase and identifying those interacting with bFGF.

Simple syntheses of N-alkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A

Abstract Acylation of a variety of amines with succinimidyl N -trityl-β-alanyl-γ-aminobutyrate and N -trityl-γ-aminobutyryl-β-alaninate, readily obtained through coupling of succinimidyl N -trityl-β-alaninate with trimethylsilyl γ-aminobutyrate and of N -trityl-γ-aminobutyric acid with methyl β-alaninate, respectively, followed by LiAlH 4 reduction, produced N -monoalkylated spermidine fragments and analogues of the spermine alkaloid kukoamine A. The applicability of this methodology on the solid phase was also demonstrated.

Simple syntheses of cyclic polyamines using selectively N-tritylated polyamines and succinic anhydride

Abstract Treatment of selectively N -tritylated spermidine and spermine derivatives with succinic anhydride, followed by PyBrOP-mediated intramolecular amide bond formation and LiAlH 4 reduction, allows for an easy and general entry to cyclic polyamine derivatives.

Microemulsion electrokinetic capillary chromatography of sulfated disaccharides derived from glycosaminoglycans.

Microemulsion electrokinetic capillary chromatography (MEEKC) is a capillary electrophoresis technique in which neutral and ionized species can be resolved according to their partitioning into moving oil droplets present in the operating buffer. In this report, we present for the first time the application of MEEKC in the analysis of glycosaminoglycans. An efficient method for the separation of the variously sulfated Δ‐disaccharides obtained following digestion of chondroitin and dermatan sulfates with chondro/dermato lyases and derivatization with 2‐aminoacridone is described. Nonsulfated, mono‐, di‐, and trisulfated Δ‐disaccharides were completely separated using the microemulsion octane/butan‐1‐ol/Sodium dodecyl sulfate (SDS) in 10 mM borate buffer, pH 9.3, at 25 kV. Agreement of the obtained disaccharide composition with literature values showed that MEEKC can be used for the analysis of glycosaminoglycans.

Trioxsalen derivatives with lipoxygenase inhibitory activity

Trioxsalen (TRX) is a 4,5′,8-trimethylated psoralen analog presenting interesting biological activities when irradiated with UVA light. A series of TRX derivatives, which where obtained by its chemical modification and incorporation of a variety of unsaturated functions at position 4′ of the psoralen ring-system, were evaluated for their antioxidant activity and their inhibitory activity on soybean lipoxygenase (LOX) and lipid peroxidation. The reducing properties of the compounds were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay and found to be very low, in the range 0–14%, with the exception of the hydroxamic acid 6 which showed almost identical activity to BHT. TRX derivative 3 significantly inhibited LOX, with IC50 9.4 μM. With the exception of TRX, all tested analogs inhibited lipid peroxidation in the range of 35–91%. The most potent compound, namely TRX derivative 3, was studied for its anti-inflammatory activity in vivo on rat paw edema induced by carrageenan, and was found to be of almost identical activity to indomethacin. The results of the biological tests are discussed in terms of structural characteristics.

Emergence of a Staphylococcus aureus Clone Resistant to Mupirocin and Fusidic Acid Carrying Exotoxin Genes and Causing Mainly Skin Infections

ABSTRACT Skin and soft tissue infections (SSTIs) caused by mupirocin-resistant Staphylococcus aureus strains have recently increased in number in our settings. We sought to evaluate the characteristics of these cases over a 43-month period. Data for all community-acquired staphylococcal infections caused by mupirocin-resistant strains were retrospectively reviewed. Genes encoding products producing high-level resistance (HLR) to mupirocin (mupA), fusidic acid resistance (fusB), resistance to macrolides and lincosamides (ermC and ermA), Panton-Valentine leukocidin (PVL) (lukS/lukF-PV), exfoliative toxins (eta and etb), and fibronectin binding protein A (fnbA) were investigated by PCRs in 102 selected preserved strains. Genotyping was performed by SCCmec and agr typing, whereas clonality was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). A total of 437 cases among 2,137 staphylococcal infections were recorded in 2013 to 2016; they were all SSTIs with the exception of 1 case of primary bacteremia. Impetigo was the predominant clinical entity (371 cases [84.9%]), followed by staphylococcal scalded skin syndrome (21 cases [4.8%]), and there were no abscesses. The number of infections detected annually increased during the study years. All except 3 isolates were methicillin susceptible. The rates of HLR to mupirocin and constitutive resistance to clindamycin were 99% and 20.1%, respectively. Among the 102 tested strains, 100 (98%) were mupA positive and 97 (95%) were fusB positive, 26/27 clindamycin-resistant strains (96.3%) were ermA positive, 83 strains (81.4%) were lukS/lukF positive, 95 (93%) carried both eta and etb genes, and 99 (97%) were fnbA positive. Genotyping of methicillin-sensitive S. aureus (MSSA) strains revealed that 96/99 (96.7%) belonged to one main pulsotype, pulsotype 1, classified as sequence type 121 (ST121). The emergence of a single MSSA clone (ST121) causing impetigo was documented. Resistance to topical antimicrobials and a rich toxinogenic profile confer to this clone adaptability for spread in the community.