Synthesis,conformation and cytotoxicity of new,branched polymeric polypeptides containing hydrophobic amino acid or arginine moiety

In this paper we report on the synthesis and solution conformation of a new set of structurally related polycationic branched chain polypeptides (poly[Lys(X _i -dl-Ala _m )]) with hydrophobic (Ile, Nle, Val) or cationic (Arg) amino acids at the N-terminal end of the side chains as well as their cytotoxic effect on murine bone marrow derived macrophages. Solution conformation of the polypeptides was studied with circular dichroism spectroscopy under different conditions (pH, ionic strength). The results of these comparative studies indicate that a) polypeptides could adopt an ordered (mainly helical) conformation at physiological pH and salt concentration (pH 7.4, 0.2 M NaCl); b) the nature of side chain terminal amino acid (X) could determine under which conditions the ordered structure was formed. Thus, the solution conformation of branched polypeptides could be modulated by the selection of amino acid X under physiological conditions. All polypeptides with hydrophobic amino acid at the terminal position were essentially non-toxic on macrophages, whereas the polypeptide with terminal Arg proved to be markedly cytotoxic.

     

Synthesis, characterization and cytotoxicity of new rotundic acid derivatives

Rotundic acid (RA, 1), a natural compound, exhibits potent tumor cell growth inhibiting properties. To date there are no reports on derivatives of RA. Furthermore, the 28-COOH position of RA might make it unstable and induced serious gastrointestinal side effects when it was applied in vivo. Therefore, in order to explore and make use of this compound, eight new amino acid derivatives of RA at the 28-COOH position were synthesized and evaluated for their cytotoxicities in vitro on three tumor cell lines including A375, HepG2 and NCI-H446. As a result, a few of these new amino acid derivatives showed stronger cytotoxicity. Compound 5a was found to have the best inhibition activity on the three tested human tumor cell lines with IC(50) values of less than 10 μM compared with RA treatment. Meanwhile, the cytotoxicity of compound 6b was significantly higher than that of RA on the A375 cell line and almost the same as RA on the HepG2 and NCI-H446 cell lines. Hence, compounds 5a and 6b may serve as potential lead compounds for the development of new anti-tumor drugs.     

Endic acid diamides. Synthesis and reactivity

A number of symmetric and unsymmetric endo-cis-dicarboxamides of the norbornene series containing dimethyl- and diethylamine, morpholine, perhydroazepine, and p-bromoaniline fragments were synthesized starting from endic anhydride with the aid of N,N′-dicyclohexylcarbodiimide. Oxidation of these amides with organic peroxy acids according to Prilezhaev gave exo-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0^3,7]-nonane-endo-9-carboxylic acid salts. The structure of the obtained products was confirmed by IR and ¹H NMR spectroscopy.     

Synthesis,insecticidal activities and SAR studies of novel anthranilic diamides containing trifluoroethoxyl substituent and chiral amino acid moieties

Based on the structures of ryanodine receptors (RyRs) activators anthranilic diamide insecticidal agents and FKI- 1033, a series of 18 novel trifluoroethoxyl-containing chiral anthranilic diamides Ia–i and IIa–i were synthesized. Their insecticidal activities were evaluated systematically and the SAR was discussed.     

Synthesis and conformational analysis of new troponyl aromatic amino acid

Synthetic peptides are in huge demand in expansion of potential peptide mimics, which may have improved or comparable function as natural one. With these concerns, phenyl bearing aromatic amino acids and peptides has extensively explored, because phenyl residue has high probability in forming stable secondary structure, owing to the presence of an extra stabilizing factor as π–π non-covalent interactions. Apart from phenyl bearing benzenoid aromatic amino acids, a few non-benzenoid aromatic derivatives such as tropolone and related compounds are also occurred in nature, but troponyl containing amino acids and peptides are very poorly understood. Tropolonyl derivatives also contain carbonyl functional group, which may play an important role to provide stable conformation in peptide. Herein we report the synthesis, and conformational analysis of rationally designed new unnatural δ-amino acid, troponyl aminoethylglycine (Tr-aeg), which contains troponyl residue as side chain in flexible aminoethylglycine (aeg) amino acid backbone. We also demonstrate the role of troponyl carbonyl of Tr-aeg residue in hydrogen bonding with adjacent amide NH of their hybrid di/tri-peptides with NMR methods and DFT calculations. In future, Tr-aeg amino acid would be a potential building block in development of promisable peptide mimics.     

Synthesis of new organothiophosphorus insectoacaricides containingN-acylated amino acid fragments

Methods for the synthesis ofO-alkylS-(N-acyl-N-alkoxycarbonylalkyl)aminomethyl (methyl)thio- and -dithiophosphonates based on the reaction between alkaline-metal salts ofO-alkyl (methyl)thio- and -dithiophosphonates and N-alkoxycarbonyl-N-chloromethylglycine or --alanine esters and by treatment ofO-alkyl (methyl)dithiophosphonoates andN-acylated amino acids or their esters with paraform in the presence of HCl were developed. The compounds obtained exhibit high insectoacaricide activity and selectivity.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1294–1301, July, 1994.     

Synthesis,characterization and cytotoxicity of platinum(II) complexes containing reduced amino acid ester Schiff bases

Nine platinum(II) complexes containing reduced amino acid ester Schiff bases were synthesized and characterized using spectroscopy (¹H NMR, ¹³C NMR, infrared), elemental analysis and molar conductivity. The interaction of these complexes with salmon sperm DNA was investigated by means of ultraviolet and circular dichroism spectroscopies. The potential antitumor activity of all compounds was tested in vitro on HeLa and A549 tumor cell lines. Almost all the complexes exhibited better cytotoxic activity than cisplatin against these cell lines.     

2,2′-Dipyridyl-6,6′-dicarboxylic acid diamides: Synthesis,complexation and extraction properties

New ligands for complexing of the post-transition metals – diamides of 2,2′-bipyridyl-6,6′-dicarboxylic acid were developed, synthesised and characterised. They were proposed to be effective extractants towards americium. The structures of the amides were studied in solid as well as in solution. The extraction of Am and lanthanides depending on diamide structure, chlorinated cobalt dicarbollide (CCD) – diamide ratio, type of diluent was studied. The optimal conditions for Am/REE separation were determined. The properties of new potentiometric sensors on the base of 2,2′-dipyridyl-6,6′-dicarboxylic acid diamides were studied. The correlation structure vs. properties of ionophores (i.e. extractants), their sensitivity and selectivity in sensor analysis and extraction are discussed.     

Synthesis of a new metal chelating amino acid: Terpyridyl-alanine

In past years, terpyridine-containing substances have been found useful in polynucleotide chemistry and enzymatic engineering applications. Therefore, the construction of a noncanonical amino acid with a terpyridine side chain may offer promising features for in vitro and in vivo applications, such as the direct bio-expression of proteins with these substances as building blocks. The first step towards these goals is to establish a synthetic protocol for a terpyridine analog bearing an amino acid moiety. Here, we demonstrate the synthesis of terpyridyl-alanine for the first time in five steps and an overall yield of 50%. A metal complex with Fe(II) ions was prepared by crystallization of a protected terpyridyl-alanine derivative and analyzed by X-ray crystallography. Complex formation in aqueous solution was studied by ¹H-NMR, UV/Vis and fluorescence spectroscopy. The comparison of five transition metal ions revealed a metal dependent shift in the UV-absorption and a strong fluorescence in the presence of Zn(II) ions.     

Synthesis of bulgecinine: a new amino acid in bulgecins

Bulgecinine, a new proline type amino acid in bulgecins, was synthesized stereospecifically by use of D-glucose as a chiral precursor.     

Phlomeoic acid: a new diterpene from Phlomis bracteosa

A new tricyclic clerodane-type diterpenoid, trivially named phlomeoic acid (1), was isolated from the methanolic extract of Phlomis bracteosa, together with two known compounds, ursolic acid and glutinol, isolated for the first time from this species. Their structures were elucidated by means of spectroscopic and mass spectrometric techniques and comparison with literature data.     

Synthesis,spectral and cytotoxicity studies of palladium(II) and platinum(II) amino acid Schiff base complexes

Novel Pd^II and Pt^II complexes of substituted o-hydroxyacetophenone-glycine have been synthesized, and characterized by conductivity measurements, i.r., electronic and ¹H-n.m.r. spectra. The spectral data indicate that the ligands are monobasic bidentate, coordinating through imino nitrogen and the carboxylate group. A four coordinate square planar configuration has been proposed for all the complexes. The ligands, as well as their Pd^II and Pt^II complexes, exhibit potent cytotoxic activity against Ehrlich ascites tumour cells in vitro, but appear to be more active in vivo. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of diterpene glycosides

Summary Mono-, di-, and linear triglycosides of a diterpene alcohol, derived from abietic acid and glucose have been synthesized employing peracetylbromo--D-glucose (4) and maltose derivatives5 and8 as glycosyl donors. The triglycoside14 exhibits slight haemolytic activity.

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Synthese von Diterpenglycosiden

Zusammenfassung Es wird die Synthese von Mono-, Di-, und linearen Triglycosiden aus einem von Abietinsäure abgeleiteten Diterpenalkohol beschrieben. Als Glycosyldonoren wurden neben Peracetobrom--D-glucose (4) die Maltosederivate5 und8 verwendet. Das Triglycosid14 zeigt schwache hämolytische Aktivität.

     

Synthesis based on furancarboxylic acid amides. 2. Synthesis of diamides of the furan series

The corresponding furancarboxylic acid diamides were obtained by the addition of primary amides of furancarboxylic acids to the double bond of vinyl butyl ether and the carbonyl group of various aldehydes..See [2] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1316–1318, October, 1990.     

Synthesis and photophysical properties of a new amino acid possessing a BODIPY moiety

The synthesis of a new amino acid possessing a BODIPY fluorophore, which is of use in peptide synthesis, is described. The influence of the amino acid as well as of benzoxazole moieties on the BODIPY spectral and photophysical properties is discussed. The photophysical properties of this fluorophore were modified only to a small extent compared to those of the parent compound.     

Synthesis and characterization of four new manganese(III) complexes and amino acid (L-aspartic acid, L-asparagine, L-glutamic acid, L-glutamine) Schiff bases

New series of manganese(III) complexes and amino acid Schiff bases have been prepared from 2-hydroxy-1-naphthaldehyde and α-amino acids [L-aspartic acid (Asp), L-asparagine (Asn), L-glutamic acid (Glu) and L-glutamine (Gln)]. The structures of the ligands and manganese complexes were identified using elemental analyses, i.r, electronic spectra, ¹H-n.m.r spectra, magnetic moment measurements and thermogravimetric analyses (t.g.a). The results suggest that H₂L¹: [N-(2-hydroxy-1-naphthylidene) aspartic acid] and H₂L³: [N-(2-hydroxy-1-naphthylidene)glutamic acid] Schiff bases behave as trianionic tetradentate species and coordinate to Mn(III) ion according to the general formula [MnL] · xH₂O complexes. But, H₂L²: [N-(2-hydroxy-1-naphthylidene) asparagine] and H₂L⁴: [N-(2-hydroxy-1-naphthylidene)glutamine] Schiff bases behave as dianionic tridentate and coordinate to Mn(III) ion in the general formula for [MnL(OOCH₃)] · xH₂O complexes.     

Synthesis of an anion-binding amino acid

We achieved the synthesis of a derivative of phenylalanine with a diazamacrocycle on its side chain by macrocyclization of a dichloride on l-DOPA. We also report its incorporation into peptide structures by solid phase peptide synthesis which will lead to the development of artificial anion channels.