Polymer conjugates with potential biological activity based on new derivatives of 2-mercaptobenzoxazole-synthesis and characterization

New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, ¹H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.      

The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime

The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.      

In vitro biological activity comparison of some hydroxyapatite-based composite materials using simulated body fluid

Hydroxyapatite composites are the main biomaterials used for metal implant coatings. Their in vitro study is very important. That is why their behavior was monitored in simulated body fluid (SBF), which is a solution with ion concentrations and pH value similar to those of human blood plasma. Silica, chitosan and gelatin-doped hydroxyapatite-based biomaterials were studied in SBF; the samples were characterized pre-, during and post-SBF immersion using infra-red, scanning and transmission electron spectroscopy and X-ray diffraction methods. The solubility of materials in SBF was determined, and the variation of Ca²⁺ and phosphorus concentration was also recorded during SBF experiments. The results were compared and their in vitro biological activity was determined.      

Synthesis, reactions and antineoplastic activity of 3-(2-oxo-2H-chromen-3-yl)-2-oxo-2H,5H-pyrano[3,2-c]chromene derivatives

The key 3-(2-oxo-2H-chromen-3-yl)-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl acetates 3 were synthesized in high yields by cyclocondensation of 4-oxo-4H-chromen-3-carbaldehydes 1 with coumarin-3-acetic acids 2 under mild conditions. The reaction pathway involves aldol condensation and subsequent intramolecular lactonization to afford 2-oxo-2H,5H-pyrano[3,2-c]chromene skeleton 3. Further treatment of acetates 3 with alcohols, water or nitrogen containing compounds led to 5-alkoxy-, 5-hydroxy- or 5-acylamino-2H,5H-pyrano[3,2-c]chromen-2-ones 4-6 via nucleophilic substitution of acetyloxy group at C-5. Acetates and hydroxyl derivatives 3 and 5 undergo facile rearrangement in an acid medium yielding 5-hydroxypyrano[2,3-b]chromen-2(10aH)-ones 7. Twelve prepared compounds were evaluated on their antineoplastic activities on 60 human tumour cell line panels in NCI USA. The obtained biological results confirmed that 3-(2-oxo-2H-chromen-3-yl)-2H,5H-pyrano[3,2-c]chromen-2-one represents a new leading skeleton suitable for further antitumour activity study.     

Copper(I) π-complexes with allyl derivatives of heterocyclic compounds: structural survey of their crystal engineering

In this review an exhaustive crystallochemical analysis of copper(I) π-complexes with allyl derivatives of heterocyclic compounds has been performed. Structural genesis of inorganic constituents starting from the simplest units to the most complicated aggregates was considered taking into account the specific role of Cu-(C=C) interaction, the construction of the organic ligands, the basicity and nucleophilic activity of their heteroatoms, as well as olefin Cu(I) π-complex preparation route.      

Application of UV detection in HPLC in the total antioxidant potential assay

HPLC has been already used for the TAP estimation. Phenylalanine, salicylic, p-hydroxybenzoic (pHBA) or terephthalic (TPA) acids have been used as sensor compounds. Products of their reaction with the hydroxyl radicals, generated in the Fenton-like reaction, were analyzed using electrochemical or fluorescence detection. This paper describes the TAP assay based on the hydroxyl radicals reaction with pHBA, reversed-phase-HPLC separation and UV photometric detection. The elaborated assay has been used to evaluate TAP values of some apiculture products.      

Metals content of soil,leaves and wild fruit from Serbia

The concentrations of Zn, Mn, Fe, Pb, Ni, Cu and Cd in soil, leaves and edible wild fruit (Crataegus laevigata L., Cornus mas L. and Prunus spinosa L.) from southeast Serbia were determined by atomic absorption spectroscopy. Metal translocations from soil to fruit were calculated as well as their oral intake and health risk indices. Positive correlations were found among metal concentrations in soil, leaves and fruit.      

Salutaridine and its derivatives as thebaine-equivalents in the synthesis of aporphines

Here we report the transformation of tetracyclic morphinan salutaridine (1) into 2,3,10,11-tetrasubstituted (R)-aporphines. This method serves as another chemical proof of the previously verified biosynthetic connection with pentacyclic morphinan-6,8-diene-type thebaine. In the presence of nucleophiles, this procedure could lead to pharmacologically interesting new tetrasubstituted aporphinoids. The enantioselective synthesis of 7S-salutaridinol (2) has been also achieved in order to investigate the acid-catalyzed reactions of this natural morphinan.      

Enantioselective Michael additions of aldehydes to nitroalkenes catalyzed with ionically tagged organocatalyst

Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable.      

Rapid flow injection electrochemical detection of 3,3′,4,4′ tetrachlorobiphenyl using stabilized lipid membranes with incorporated sheep antibody

An electrochemical biosensor based on a supported polymerized lipid film with incorporated sheep anti-3,3′,4,4′ tetrachlorobiphenyl (PCB congener 77) antibody using flow injection analysis was developed. The polymerized lipid film contained 85% (w/w) dipalmitoylphosphatidylcholine (DPPC) and 15% (w/w) dipalmitoylphosphatidic acid (DPPA), methacrylic acid, ethylene glycol dimethacrylate, AIBN and sheep anti-congener 77 antiserum. Congener 77 was injected into flowing carrier electrolyte and the flow stopped to detect the antigen. These membranes gave only a single transient proportional to log [congener 77] from 10^?8 to 10^?5 M, with a detection limit of ca. 10^?8 M. A membrane containing 35% (w/w) DPPA was used to examine regeneration. The maximum number of cycles was about 5.      

Aerobic oxidation of cumene catalysed by 4-alkyloxycarbonyl-N-hydroxyphthalimide

4-Hexyloxycarbonyl-, 4-dodecyloxycarbonyl- and 4-hexadecyloxycarbonyl-N-hydroxyphthalimides were synthesised using trimellitic anhydride chloride as the starting material. The obtained lipophilic derivatives of N-hydroxyphthalimide were applied as catalysts of the cumene oxidation reaction with oxygen performed in polar acetonitrile, in non-polar tert-butylbenzene and in the absence of a solvent. The courses of reactions catalysed by N-hydroxyphthalimide and its derivatives were compared.      

Organoruthenium(II) thiosemicarbazone complexes: synthesis, spectral characterization, DNA binding and DNA cleavage studies

A series of new ruthenium(II) complexes were synthesized with Schiff bases derived from salicylaldehyde / o-hydroxyacetophenone/ o-vanillin / 2-hydroxy-1-naphthaldehyde with thiosemicarbazide and acetyl furan. They are characterized by elemental analysis, IR, electronic, ¹H NMR, ¹³C NMR and mass spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Four of these complexes were tested for its binding with CT-DNA using absorption spectroscopic studies and two of these complexes exhibit efficient DNA cleavage activity.      

Ionic liquids based on 2-chloroethyltrimethylammonium chloride (CCC) as plant growth regulators

Plant growth regulator — 2-chloroethyltrimethylammonium chloride (CCC) was converted into ionic liquid in the metathesis reaction. New forms of CCC as ILs were stable in air as well in contact with water and organic solvents. The biological action of the cation (CCC) in ILs was preserved. Type of anion determined hydrophobicity and hydrophilicity of the whole molecule and it also influenced the biological activity of the plant growth regulator. All of the investigated salts retarded growth of winter wheat stems and most of them increased yield at the same time, when compared to control and standard 2-chloroethyltrimethylammonium chloride.      

Reaction of barbituric acid with organic azides and phosphonium ylides

Amination by organic azides has been carried out to provide aminobarbiturates by fusion of a triazole ring to the 5,6-positions of barbituric acid followed by cleavage and thermal elimination of nitrogen, whereas aza-Wittig reaction gave phosphoranylidene barbituric acid salts.      

Crystallographic and structural characterization of heterometallic platinum compounds part IV: heterotetranuclear clusters

This review includes over two hundred heterotetranuclear platinum clusters. The clusters are of the compositions Pt₃M, Pt₃M₂, PtM₃, Pt′₂MM′, PtM₂M′ and PtMM′M”. There are twenty five different M atoms (transition and non-transition) as a partner(s) of platinum. The four metal atoms are found in a tetrahedral, planar-rhombohedral, butterfly, spited-triangular, cubane, eight — and oligo-membered rings and a unique structures. There is wide variety of the ligands from uni to- undecadentate, with the most common P and C donor sites. The shortest Pt-M (transition) versus Pt-M (non-transition) bond distances are 2.4833(8)Å (M=Pd) vs. 2.4365(5)Å (Ge). Several relationships between the various structural parameters were found and are discussed.      

Preparation of selectively protected protoescigenin derivatives for synthesis of escin analogs and neoglycoconjugates

Protoescigenin, the main aglycone of horse chestnut saponin mixture known as escin, was selected as substrate for exploratory chemistry towards selective protection, followed by propargyl ether formation and subsequent condensation with azido-monosaccharides, to obtain novel triazole linked conjugates of the triterpene.      

P-Triazinylphosphonium chlorides as a new group of coupling reagents

Tertiary phosphines in reaction with 2-chloro-4,6-dialkoxy-1,3,5-triazines gave unstable quaternary P-triazinylphosphonium chlorides, which readily decomposed with a departure of the alkyl group of the triazine ring substituent. Stable quaternary P-triazinylphosphonium chlorides were obtained only in reaction of 2-chloro-4,6-diphenoxy-1,3,5-triazine. Both, stable quaternary P-triazinylphosphonium chlorides as well unstable analogues prepared in situ activated carboxylic acid yielding “superactive” triazine esters, useful as highly efficient reagents in peptide bond synthesis.      

The synthesis, structure and physical properties of lanthanide(III) complexes with nicotinic acid

This article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln₂[(C₅H₄NCOO)₆(H₂O)₄] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln³⁺ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid.      

Regio- and stereoselectivity of polar [2+3] cycloaddition reactions between (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone and selected (E)-2-substituted nitroethenes

[2+3] Cycloaddition reactions of the highly reactive (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone with (E)-2-R-nitroethenes proceed under mild conditions and yield mixtures of stereoisomeric 2-methyl-3-(3,4,5-trimethoxyphenyl)-4-nitro-5-R-isoxazolidines. The effect of regiospecificity of the cycloadditions may be accounted for by the theory of electrophilicity indexes. Stereoselectivity, however, is determined by a compilation of steric and secondary orbital effects.