Vicinal Diol Groups Research Articles

A green and sustainable strategy for recyclable ultraviolet (UV)-curable resin from tartaric acid via three dimensional (3D) printing to reduce plastic pollution

Thermosetting plastics account for approximately 18% of global plastic production, with an annual global production of 65 million tons. The vast majority of thermosetting plastic waste are buried, burned, or discharged into the ocean, causing serious pollution to the natural environment. How to develop a green, energy-saving, and high value-added recycling method is a major challenge in plastic recycling. Ultraviolet (UV)-curable resins derived from renewable resources for constructing high strength vitrimeric materials and 3D printed subjects are important for sustainability and responsive recycling. Herein, a resin (tartaric acid-glycidyl methacrylate, TAGM) containing two methacrylate groups, two ß-hydroxyl ester groups and a vicinal diol group was prepared from biomass tartaric acid via a green and sustainable strategy including one-step & solvent-free procedure. After facile UV-curing of TAGM, thermally reprocessable polymeric networks were obtained and tested to have high glass transition temperature (Tg), mechanical strength, Young's modulus and toughness of 127.6 °C, 104.4 MPa, 1244.2 MPa and 6.3 MJ/m3, respectively. The polar vicinal diol group from tartaric acid (TA) plays a critical role for the advantageous thermomechanical performances, as learned in a comparative study with similarly structured monomers from succinic acid (SA) and L-malic acid (MA). Additionally, the TAGM with 30% diluent of hydroxyethyl methacrylate was utilized for three dimensional (3D) printing, and exhibited smaller penetration depth and high resolution. This work demonstrates a feasible approach to fabricate biobased resin for high strength vitrimeric materials and customized manufacturing via 3D printing.The resulted mechanically robust and vitrimeric subjects with significant comprehensive advantages and will provide important inspiration for plastic recycling and reducing plastic pollution.

Characteristic fragmentation of polyunsaturated fatty acids with allylic vicinal diols in positive-ion LC/ESI-MS/MS

A characteristic fragmentation was observed for PUFAs that contain allylic vicinal diol groups (resolvin D1, D2, D4, E3, lipoxin A4, B4, and maresin 2), which were derivatized with N,N-dimethylethylenediamine (DMED), in positive-ion ESI-MS/MS. The findings indicate that when these compounds contain an allylic hydroxyl group that is located distal to the terminal DMED moiety in the case of resolvin D1, D4, and lipoxin A4, an aldehyde (-CH=O) is predominately formed, which arises from the breakdown in between vicinal diols, whereas, in the case of an allylic hydroxyl group that is located proximal to the DMED moiety, as in resolvin D2, E3, lipoxin B4, and maresin 2, an allylic carbene (-CH=CH-CH:) is formed. These specific fragmentations could be used as diagnostic ions for characterizing the above seven PUFAs. As a result, it was possible to detect resolvin D1, D2, E3, lipoxin A4, and B4 in sera (20 μl) obtained from healthy volunteers by multiple-reaction monitoring using LC/ESI-MS/MS.

Stimuli-Responsive Triblock Terpolymer Conversion into Multi-Stimuli-Responsive Micelles with Dynamic Covalent Bonds for Drug Delivery through a Quick and Controllable Post-Polymerization Reaction

Stimuli-responsive copolymers are of great interest for targeted drug delivery. This study reports on a controllable post-polymerization quaternization with 2-bromomethyl-4-fluorophenylboronic acid of the poly(4-vinyl pyridine) (P4VP) block of a common poly(styrene)-b-poly(4-vinyl pyridine)-b-poly(ethylene oxide) (SVE) triblock terpolymer in order to achieve a selective responsivity to various diols. For this purpose, a reproducible method was established for P4VP block quaternization at a defined ratio, confirming the reaction yield by 11B, 1H NMR. Then, a reproducible self-assembly protocol is designed for preparing stable micelles from functionalized stimuli-responsive triblock terpolymers, which are characterized by light scattering and by cryogenic transmission electron microscopy. In addition, UV-Vis spectroscopy is used to monitor the boron-ester bonding and hydrolysis with alizarin as a model drug and to study encapsulation and release of this drug, induced by sensing with three geminal diols: fructose, galactose and ascorbic acid. The obtained results show that only the latter, with the vicinal diol group on sp2-hybridized carbons, was efficient for alizarin release. Therefore, the post-polymerization method for triblock terpolymer functionalization presented in this study allows for preparation of specific stimuli-responsive systems with a high potential for targeted drug delivery, especially for cancer treatment.

Cyclic and square wave voltammetry of chitooligosaccharides modified by osmium(VI) tetramethylethylenediamine

Compounds containing vicinal diol (glycol) groups, including saccharides, could be modified with sixvalent osmium complexes with nitrogenous ligands, particularly with N,N,N′,N′-tetramethylethylenediamine (Os(VI)tem). The modification products are electrochemically active. Here we show that aminosaccharides can also be modified by Os(VI)tem. We studied chitosan oligosaccharides in their acetylated and deacetylated form in 0.2 M Na-phosphate, pH 6.9. Deacetylated chitosan oligosaccharides with free amino groups modified by Os(VI)tem yielded two peaks (peak I′ at −0.15 V and peak II′ at about −0.38 V) despite the fact that these oligomers contain only one glycol group on the non-reducing end of the molecule. The electrochemical behavior of Os(VI)tem modified deacetylated chitosan oligomers differs from Os(VI)tem modified simple saccharides, containing only glycol groups, predominantly in peak I′. Our results suggest that free amino groups are involved in Os(VI)tem modification of chitosan oligomers.

Enzymatic Kraft lignin demethylation and fungal O-demethylases like vanillate-O-demethylase and syringate O-demethylase catalyzed catechol-Fe3+ complexation method

The ability of enzymatic Kraft Lignin (KL) demethylation was determined using catechol and ferric ion coordination (catechol-Fe3+ complexes) by reduction of Fe3+ to Fe2+ and formation of mono, bis- and/or tris-catechol-Fe3+ complexes has been investigated to identify enzyme that can strip-off O-methyl groups from lignin such as O-demethylase. To detect fungal demethylation and release of catechol-like structures, these were demonstrated using catechol, gallic acid and caffeic acid as standard model compounds to forms mono, bis- and/or tris-catechol-Fe3+ complexes. The catechol-Fe3+ complexes formation controlled by pH via the deprotonation of the catechol hydroxyls was investigated at pH 2.5, 8.0 and 10.0 and demonstrated that catechol formed mono, bis- and/or tris-catechol-Fe3+ complexes, and showed maximum absorbance at 547 nm. Lignin demethylation (O-demethylase) and formation of pyrocatecholic structures was detected using Aspergillus sp. and Galerina autumnalis culture filtrates as the enzyme source. The produced aromatic vicinal diol groups in lignin model compounds (LMCs) and KL were determined using different catecholic-binding reagents with the influence of H2O2, along with 4-antiaminopyrine reagent, was analyzed by the following: i) Fe3+-catechol complexation method, ii) HNO2 method, iii) FAS (Ferric Ammonium-Sulfate) method, iv) Ti(III)-NTA (Titanium (III)- Nitrilotriacetate) method for hydrolytic zone formation. Among the tested methods showing lytic zone formation was Fe3+-catechol complexation. The LMCs and KL treated using Aspergillus sp. culture filtrate showed maximum Fe3+-catechol complexes with 3-methoxy catechol (91 μmol/mL), o-vanillin (44 μmol/mL) and KL (100 μmol/mL). In addition, Galerina autumnalis culture filtrate showed demethylation of vanillin (48 μmol/mL), 3-methoxy catechol (82 μmol/mL), o-vanillin, (33 μmol/mL), 3 4-dimethoxybenzyl alcohol (49 μmol/mL) and KL (41 μmol/mL). The results suggest that lignin demethylation (O-demethylases) activity that strip-off methyl groups in LMCs and KL and produced vicinal diols that covalently bind with Fe3+ to form Fe3+-catechol complexes. The new Fe3+-catechol complexation method has the ability to characterize pyrocatechol and galloyl structures in chemically or biologically modified lignins and to detect O-demethylase activity.

Boron-chelating membranes based in hybrid mesoporous silica nanoparticles for water purification

Boron is a key element for some biological processes,but it becomes toxic for humans and plants in concentrations above a few ppm. We have design a new approach for boron scavenging, based in hybrid membranes of functional mesoporous silica nanoparticles immobilized in cellulose acetate. The mesoporous silica nanoparticles, with diameters around 150nm, were functionalized with vicinal diol groups that complex boron very efficiently. The functional nanoparticles were covalently immobilized in a cellulose acetate membrane using a di-terminated alkoxisilane that react with the remaining silanol groups at the nanoparticles surfaces and with the hydroxyl groups of the cellulose. The functional nanoparticles and the hybrid membranes show boron removal efficiencies of phenyl boronic acid of up to 93%. The membranes can be used in multistage filtering systems, with sequential membranes modules in continuous operation, in a cheap, simple and efficient process for boron scavenging.

Smart polymeric nanoparticles for boron scavenging

Boron is biologically beneficial but only in trace quantities. It is hard to detect and remove from water, as sometimes required in the treatment of residual waters. We have designed an approach based on thermo-responsive polymer nanoparticles containing vicinal diol groups for boron scavenging. The particles have a core of poly(methyl methacrylate) (PMMA) and a thermosensitive shell with a brush composed of a copolymer of N-isopropylacrylamide (NIPAM), 2-aminoethyl methacrylate (AEMH), and either d-gluconoamidoethyl methacrylate (GAEM) or monodiol methacrylate (MDM) boron chelating monomers. The nanoparticles show boron removal efficiencies of up to 96%, with removal of phenylboronic acid being more efficient than that of boric acid. The best boron scavenging efficiency was obtained for the higher specific surface area particles containing d-gluconoamidoethyl groups. At temperatures above ca. 35°C the particle shell collapses, inducing particle aggregation which allows simple separation and recovery of the nanoparticles. These can be subsequently used for boron scavenging, without loss of efficiency.

Direct Assignment of the Threo and Erythro Configurations in Polyacetylene Glycosides by 1H NMR Spectroscopy.

An approach for discriminating the threo and erythro configurations of polyacetylene glycosides by 1H NMR spectroscopy was developed. Using acetic acid-d4/D2O as the solvent, a relatively larger 3JHH value (7.0 Hz) for the acyclic vicinal diol group was unambiguously assigned to the threo configuration, whereas the smaller value (3.5 Hz) was assigned to the erythro configuration. This convenient method requires no hydrolysis or derivatization and is suitable for micromolar concentrations of polyacetylene glycosides. The underlying mechanism is discussed via visualized conformations.

Structures of Xenopus Embryonic Epidermal Lectin Reveal a Conserved Mechanism of Microbial Glycan Recognition

Intelectins (X-type lectins), broadly distributed throughout chordates, have been implicated in innate immunity. Xenopus laevis embryonic epidermal lectin (XEEL), an intelectin secreted into environmental water by the X. laevis embryo, is postulated to function as a defense against microbes. XEEL is homologous (64% identical) to human intelectin-1 (hIntL-1), which is also implicated in innate immune defense. We showed previously that hIntL-1 binds microbial glycans bearing exocyclic vicinal diol groups. It is unknown whether XEEL has the same ligand specificity. Also unclear is whether XEEL and hIntL-1 have similar quaternary structures, as XEEL lacks the corresponding cysteine residues in hIntL-1 that stabilize the disulfide-linked trimer. These observations prompted us to further characterize XEEL. We found that hIntL-1 and XEEL have similar structural features. Even without the corresponding intermolecular disulfide bonds present in hIntL-1, the carbohydrate recognition domain of XEEL (XEELCRD) forms a stable trimer in solution. The structure of XEELCRD in complex with d-glycerol-1-phosphate, a residue present in microbe-specific glycans, indicated that the exocyclic vicinal diol coordinates to a protein-bound calcium ion. This ligand-binding mode is conserved between XEEL and hIntL-1. The domain architecture of full-length XEEL is reminiscent of a barbell, with two sets of three glycan-binding sites oriented in opposite directions. This orientation is consistent with our observation that XEEL can promote the agglutination of specific serotypes of Streptococcus pneumoniae. These data support a role for XEEL in innate immunity, and they highlight structural and functional conservation of X-type lectins among chordates.

Surface-Confined Amorphous Films from Metal-Coordinated Simple Phenolic Ligands

Coordination chemistry of natural polyphenols and transition metals allows rapid self-assembly of conformal coatings on diverse substrates. Herein, we report that this coordination-driven self-assembly process applies to simple phenolic molecules with monotopic or ditopic chelating sites (as opposed to macromolecular, multitopic polyphenols), leading to surface-confined amorphous films upon metal coordination. Films fabricated from gallic acid, pyrogallol, and pyrocatechol, which are the major monomeric building blocks of polyphenols, have been studied in detail. Pyrocatechol, with one vicinal diol group (i.e., bidentate), has been observed to be the limiting case for such assembly. This study expands the toolbox of available phenolic ligands for the formation of surface-confined amorphous films, which may find application in catalysis, energy, optoelectronics, and the biomedical sciences.

Organogermanium compound, Ge-132, forms complexes with adrenaline, ATP and other physiological cis-diol compounds.

In mammals, adrenaline and ATP are life-essential vicinal diol and cis-diol functional groups. Here, we show that interactions between a safe organogermanium compound and these cis-diol compounds have the potential to regulate physiological functions. In addition, we represent a possible new druggable target for controlling the action of cis-diol compounds. We analyzed a single crystal structure of organogermanium 3-(trihydroxygermyl)propanoic acid (THGPA), a hydrolysate of safe Ge-132, in complex with catecholamine (adrenaline and noradrenaline), and evaluated the affinity between several cis-diol compounds and THGPA by NMR. An in vitro study using normal human epidermal keratinocytes was performed to investigate the inhibition of cis-diol compound-stimulated receptors by THGPA. At high concentration, THGPA inhibited the calcium influx caused by adrenaline and ATP. This study demonstrates that THGPA can modify cis-diol-mediated cell-to-cell signaling.

Synthesis and characterization of thiolated β-cyclodextrin as a novel mucoadhesive excipient for intra-oral drug delivery

The objective of the present study was to synthesize and characterize cysteamine conjugated β-cyclodextrin (β-CD-Cys) as a novel mucoadhesive oligomeric excipient for intra-oral drug delivery. β-CD-Cys conjugates were obtained in a two-step synthetic pathway, whereby, vicinal diol groups of the oligomer were oxidized using increasing concentrations of sodium-per-iodate (NaIO4), prior to the covalent coupling of cysteamine via reductive amination. Quantification of immobilized thiol groups through Ellman's test revealed 561.56±81μmol/g, 1054.26±131μmol/g and 1783.92±201μmol/g of free thiol groups attached to the oligomer backbone depending on the extent of oxidation. β-CD-Cys conjugates at concentrations of 0.5% (m/v) showed no toxic effects on Caco-2 cells within 72h. Furthermore, β-CD-Cys conjugates displayed a 4-fold improved water solubility compared to the parent oligomer. β-CD-Cys conjugates (β-CD-Cys561, β-CD-Cys1054 and β-CD-Cys1783) showed 2.86-, 15.09- and 49.08-fold improved retention time on porcine intestinal mucosa and 9.66-, 16.43- and 34.51-fold improved on the porcine buccal mucosa, respectively. Formation of inclusion complexes of miconazole nitrate and β-CD-Cys1054 resulted in 150-fold increased solubility of miconazole nitrate. According to these results, it seems that β-CD-Cys conjugates might provide a new promising tool for delivery of poorly water soluble therapeutic agents, such as miconazole nitrate for intra-oral delivery.

Group-contribution to limiting partial molar isentropic compressions of small amphiphile molecules in water. The temperature effect

A simple additive scheme based on a multi-parametric least-squares fitting method is described and employed to estimate group-contributions to limiting partial molar isentropic compressions of small amphiphile molecules in water. To complement high quality literature data for aqueous solutions of aliphatic alcohols, alkoxyalcohols, amines, alkoxyamines, aminoalcohols, amino-acids and dipeptides, new accurate densities and ultrasound speeds have been experimentally determined for several very-dilute aqueous solutions of 2-(isopropylamino)ethanol, 2-butoxyethanol and 2-isobutoxyethanol at 5K intervals in the temperature range T=(283.15 to 303.15)K. Reliable limiting partial molar isentropic compressions for 31 amphiphiles in water at five fixed temperatures have been used to estimate group-contribution values and their associate uncertainties of the following eleven structural groups: CH3; CH2; CH; N; NH; NH2; CH2COCH2; CH2OH; CHOH; COOH; and CONH, at five different temperatures. The goodness of the fit of reconstituted against experimental values indicates that a consistent set of group-contribution values has been obtained and that their dependence on temperature deserves credit. These values and their sensibility to temperature changes have been analysed in terms of hydration processes in solution. Deviations of predicted from experimental values are found for molecules containing a vicinal diol group and dipeptides showing hindrance or enhancement of H-bond formation. These deviations for molecules not included in the basic set, are tentatively explained.

Carbohydrate-interactive pDNA and siRNA gene vectors based on boronic acid functionalized poly(amido amine)s

In order to evaluate the influence of incorporation of boronic acid groups on the properties of poly(amido amine)s as gene vectors, a novel poly(amido amine) copolymer p(CBA-ABOL/2AMPBA) containing ortho-aminomethylphenylboronic acid (2AMPBA) moieties was prepared by Michael-type polyaddition of a mixture of 1,4-aminobutanol (ABOL) and 2-((4-aminobutylamino)methyl)phenyl boronic acid to N,N′-cystamine bisacrylamide (CBA). It appeared that the presence of the boronic acid moieties as side groups along the polymer chain strongly enhances the stability of the self-assembled nanoparticles and nanosized polyplexes formed from this polymer; no aggregation was observed after storage for 6days at 37°C. This strong stabilization can be attributed to intermolecular Lewis acid–base interactions between the 2AMPBA groups and the alcohol and amine groups present in the polymer, leading to dynamical (reversible) crosslinking in the nanoparticles. Moreover, since the boronic acids can reversibly form boronic esters with vicinal diol groups, the presence of the 2AMPBA groups add carbohydrate-interactive properties to these polymers that strongly influence their behavior as gene delivery vectors. DNA transfection with p(CBA-ABOL/2AMPBA) polyplexes gave transfection efficiencies that were approximately similar to commercial PEI in different cell lines (COS-7, HUH-6 and H1299-Fluc), but lower than those obtained with reference polyplexes from p(CBA-ABOL). It is hypothesized that the uptake of the boronated polyplexes is suppressed by binding to the glycocalyx of the cells. This is supported by the observation that addition of sorbitol or dextran to the transfection medium significantly enhances the transfection efficiency, which can be attributed to increased cellular uptake of the polyplexes due to boronic ester formation with these agents. AFM, SEM and confocal microscopy showed that polyplexes of p(CBA-ABOL/2AMPBA) become decorated with a dextran layer in the presence of 0.9% (w/v) dextran in the polyplex medium. In siRNA-mediated gene silencing experiments the use of p(CBA-ABOL/2AMPBA) as polymeric vector gave a knockdown of luciferase expression in H1229-Fluc cells of 35%. Also in this case addition of 0.9% (w/v) sorbitol or dextran to the transfection medium strongly increased the knockdown efficiency to 59% and 76%, respectively.

A sensitive assay for palytoxins, ovatoxins and ostreocins using LC-MS/MS analysis of cleavage fragments from micro-scale oxidation

Palytoxin is a highly toxic non-proteinaceous marine natural product that can pass through the food chain and result in human illnesses. A recent review by the European Food Safety Authority concluded that palytoxin requires regulation in seafood and a limit of 30 μg kg−1 for shellfish flesh was suggested. Current methods based on LC-MS detection of intact palytoxins do not have sufficient sensitivity to enforce this limit for palytoxin. To improve sensitivity for trace analysis, a novel screen approach has been developed that uses LC-MS/MS analysis of substructures generated by oxidative cleavage of vicinal diol groups present in the intact toxin. Oxidation of palytoxins, ovatoxins or ostreocins using periodic acid generates two nitrogen-containing aldehyde fragments; an amino aldehyde common to these toxins, and an amide aldehyde that may vary depending on toxin type. Conditions for micro-scale oxidation of palytoxin were optimised, which include a novel SPE cleanup and on-column oxidation step. Rapid analysis of cleavage fragments was established using LC-MS/MS. Linear calibrations were established for the amino aldehyde from a palytoxin reference standard, which is suitable for all known palytoxin-like compounds, and for the confirmatory amide aldehydes of palytoxin and ostreocin-D. Palytoxin recoveries (at 10 μg kg−1) from shellfish and fish tissues were 114–119% (as amine aldehyde) and 90–115% (as amide aldehyde) with RSDs for both of ≤18% (all tissues, n = 12). The method LOD was determined to be approximately 1 ng mL−1 and the LOQ 4 ng mL−1, which corresponds to 10 μg kg−1 in tissue (flesh of shellfish or fish). The method has potential for use in research and is sufficiently sensitive for regulatory testing, should it be required.

English

Morphological and histochemical study of the tongue of ten adult red jungle fowl (RJF), Gallus gallus were carried out at macroscopic and microscopic levels. The tongue was triangular with a wide dorsal and ventrolateral surface with median groove at the rostral part. Between the body and the roots appears a transverse row of the lingual conical papillae which was directed backwards. Behind the laryngeal cleft, there was a single row of pharyngeal papillae. The lingual mucosa showed parakeratinization, while there was a clearly recognizable keratinized band on the ventrolateral surface and the conical papillae. The cell cytoplasm of the medial group (MG) of the anterior lingual glands and the posterior glands contained large amounts of mucin compared with the lateral group (LG). The mucin of the lingual glands contained vicinal diol groups. Moreover, the sulphate containing glycoconjugates indicated in the MG and the posterior glands with a strong acid mucin reaction. Meanwhile, the LG of the anterior lingual glands exhibited carboxylated mucin with weak acid mucin reaction. In conclusion, the differences in the arrangement of the lingual and pharyngeal papillae in the RJF than that in other birds particularly domestic chicken may reflects the changes which occurred for the latter during domestication. The contents of mucins in the medial and lateral groups of the anterior lingual gland were varied, however, no differences histochemistry between the medial group and the posterior lingual gland were observed. Key words : Lingual salivary glands, mucin reaction, red jungle, tongue.

A novel organic-inorganic hybrid monolith for trypsin immobilization

In proteomics, attention has focused on various immobilized enzyme reactors (IMERs) for the realization of high throughput digestion. In this report, a novel organic-inorganic hybrid monolith based IMER was prepared in a 100 μm i.d. capillary with 3-glycidoxypropyltrimethoxysilane (GLYMO) as the monomer and tetraethoxysilane (TEOS) as the crosslinker. Trypsin immobilization was achieved via the reaction between vicinal diol groups, which were obtained from hydrolysis of epoxy groups, and the amino groups of trypsin. Bovine serum albumin was digested thoroughly by this IMER in 47 s. After micro-reverse phase liquid chromatography-tandem mass spectrometry (μRPLC-MS/MS) analysis and database searching, beyond 35% sequence coverage was obtained, and the result was comparable to that of 12 h in solution digestion. The present IMER has potential for high throughput digestion.

ChemInform Abstract: A New Method for Acyclic Stereocontrol by Means of Chiral Bisallylic Diols

A method for differentiating allylic diastereofaces of carbon-carbon double bonds has been developed based on the ground state molecular design of allylic compounds in which a protected vicinal (S, S) - or (R, R) -diol unit is incorporated as a controller. The protected vicinal diol groups, if they are the most bulky substituents, should arrange anti to each other and the remaining medium-sized groups involving the allylic carbon-carbon double bonds, for instance, stay gauche accordingly. This situation allows only a pair of diastereofaces exposed outside to be attacked by external reagents because a remaining pair of diastereofaces is mutually shielded from intermolecular processes. Such diastereo-bias has been successfully and diversely employed in diastereoselective processes such as double Michael reaction, osmium tetraoxide-catalyzed vicinal hydroxylation, halo-etherification, and Diels-Alder reaction, giving rise to exceptionally high diastereomeric excess for every case examined, appealing prospect for wide applicability in selective organic syntheses.

Utilization of carboxymethyl cellulose based on bean hulls as chelating agent. Synthesis, characterization and biological activity

Binary and ternary complexes of Ni 2+, Cu 2+, Ag + and UO 2 2+ with the prepared carboxymethyl cellulose in its sodium salt (P-NaCMC) and pyridine (py) as secondary ligand have been prepared. Probable structures of the binary and ternary complexes were inferred via elemental analysis, spectral data (IR, mass and solid reflectance) as well as magnetic susceptibility measurements, thermal and XRPD analysis. The change in the selected vibrational absorption bands in IR spectrum of P-NaCMC upon coordination with metal ions investigates the coordination mode of P-NaCMC to be the two vicinal uncarboxylated diol groups (2- and 3-hydroxyl groups) of the glucopyranose rings in addition to the carbonyl oxygen atom of the carboxylate group while the coordination mode of pyridine ligand is the ring nitrogen. The mass spectra confirmed the proposed structure of the synthesized compounds. The solid reflectance spectral data and magnetic moment measurements suggest the geometrical structures for the metal complexes. Thermal studies suggest a mechanism for degradation of P-NaCMC and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as, Δ E *, Δ H *, Δ S * and Δ G * for the different thermal decomposition steps of P-NaCMC and its metal complexes were calculated. Antimicrobial activities of P-NaCMC and its binary and ternary complexes were studied against S. aureus and S. pyogenes (Gram-positive bacteria), P. phaseolicola and P. fluorescens (Gram-negative bacteria) and the fungi; F. oxysporum and A. fumigates using agar disc diffusion method. The results showed that all the metal complexes, especially Cu 2+ ternary complex have higher antibacterial and antifungal activities than P-NaCMC.

Morphological and histochemical characteristics of the epithelium of ovarian lamellae of Genypterus blacodes (Schneider, 1801)

The physiological significance of the glycoproteins (GPs) secreted by the epithelium of ovarian lamellae is discussed in reference to the reproductive biology of G. blacodes. Histochemical procedures for localising and characterising GPs were used to determine the cytoplasmic components of cells of the epithelium that covers the ovarian lamellae of pink cuskeel, Genypterus blacodes (Schneider, 1801) (Pisces, Ophidiidae), during spawning. This species is one of the most valuable demersal fish resources in the Argentine Sea, mainly due its large size and flesh quality. GPs with oxidizable vicinal diol groups, sialic acid with or without O-acyl substituents, O-acyl sugars, neutral sugars and GPs with carboxyl and sulphate groups were detected. Light microscope examination showed morphological changes in the epithelium of ovarian lamellae during the spawning season, associated with a secretory activity of mucus. Optical density studies revealed the presence of polyploid cells encompassing those morphological changes. Results of the present study suggest that the epithelium of ovarian lamellae of G. blacodes performs a secretory role, which is intensified during ovarian maturity, suggesting that G. blacodes could release masses of eggs enveloped in mucus.