Amino acid and peptide derivatives of fullerene

A general method for the synthesis of amino acid and peptide derivatives of fullerene (ADF) was developed, and the physicochemical properties of the compounds obtained were studied. ADF were shown to penetrate into liposomes and to exhibit adjuvant properties and antiviral activity. Deceased Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1050–1054, May, 1998.     

New pyrylium derivatives in the indole series

Nitrogen-unsubstituted 2,3-dihydroindole and its homologs, as well as 1,2,3,4-tetrahydro-- carbolines, react with 2,6-dimethyl-4-methoxypyrylium perchlorates to give N-pyrylated derivatives of indole, which are converted to the corresponding pyridine bases by the action of ammonium salts and form 1-aminopyridinium derivatives with hydrazine hydrate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1531–1533, November, 1972.     

Amino acid derivatives of phenylalkylamines

Conclusions The method of polymeric activated esters was used to obtain a number of previously unknown- arylethylamides of L-lysine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2291–2294, October, 1975.     

Amino acid derivatives of aziridine

Aziridines that contain dipeptide fragments in their compositions were obtained by the reaction of esters of dipeptides with methyl 1,2-dibromopropionate. Aziridines with dipeptide fragments in the 1 and 2 positions of the ring were synthesized when activated esters of 1, 2-dibromopropionic acid were used.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1627–1630, December, 1982.     

Amino acid and peptide chemistry on silicones

Poly(dimethylsiloxanes), di-terminated with amino acids, were synthesized by employing the Diels-Alder reaction of cyclopentadiene- or furan-terminated poly(dimethylsiloxanes) with functional dienophiles including N-maleoyl-protected phenylalanine. The amino acid could be chain extended using conventional solution peptide coupling with DCC, DMAP and N-hydroxysuccinimide to give a dipeptide-terminated silicone. The molecular weight of the silicone component of the telechelic system could be increased by acid-catalyzed redistribution with octamethylcyclotetrasiloxane (D₄).     

Amino acid derivatives with anticonvulsant activity

A series of benzylamides of N-alkylated, N-acylated or free nine cyclic and one linear amino acids as potential anticonvulsants have been synthesized. The structures of the obtained compounds were designed on the basis of the previously determined structure and physicochemical properties/anticvonvulsant activity relationship of the formerly synthesized compounds of this type. The obtained compounds were evaluated in mice after intraperitoneal (i.p.) administration, by maximal electroshock seizure test (MES test), subcutaneous (s.c.) pentylenetetrazol test (s.c. PTZ test) and by the rotarod neurotoxicity test (Tox test). The results were the basis for their classification into one of three classes of the Anticonvulsant Screening Project (ASP) of the Antiepileptic Drug Development Program (ADDP) of the NIH. Three selected compounds were tested quantitatively in rats after oral administration. The MES ED50, s.c. PTZ ED50, Tox TD50 were determined and their protective index (PI) values were calculated. Anticonvulsant activity of the most promising compound (15) was examined in different seizure models. The respective ED50 and PI values of this compound were as follows: against bicuculline, 73 and 1.4; against PTZ, 47 and 2.2; against strychnine, 73 and 1.4; against pilocarpine 156, and 0.7; against kainic acid (2-carboxy-4-isopropenyl-3-pyrrolidineacetic acid), 39 and 2.6; against AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), 10 and 10.3 and against NMDA (N-methyl-D-Aspartic acid), 114 and 0.9.     

Amino acid derivatives, VIII [1]: synthesis and antimicrobial evaluation of α-amino acid esters bearing an indole side chain

A series of peptide and dipeptide derivatives conjugated with an indole residue were synthesized. The prepared compounds were tested for antimicrobial activity against two different bacterial and one antifungal species displaying different degrees of antimicrobial activities or inhibitory actions. Correspondence: Adel A.-H. Abdel-Rahman, Department of Chemistry, Faculty of Science, Menoufia University, Shebin El-Koam, Egypt.     

Isolation of indole alkaloid and anthranilic acid derivatives from Indigo Pulverata Levis

A new indole alkaloid, pulveratinol (1), and two new anthranilic acid derivatives (2 and 3) were isolated from Indigo Pulverata Levis, together with 12 known compounds (4–15). The structures of the new compounds (1–3) were determined through spectroscopic methods. The absolute configuration of 1 was confirmed further by electronic circular dichroism (ECD) data analysis and computational method with advanced statistics (DP4). All isolated compounds (1–15) were evaluated for their potential neuroprotective effects through induction of nerve growth factor (NGF) in C6 glioma cells.     

Photo-oxidation of indole derivatives

The UV irradiation of 2- and 3-methylindoles in acetic acid leads to the formation of the corresponding indole-carboxaldehydes as the major products, whereas the employment of ethanol as solvent causes the cleavage of the C₂2-C₃ bond, giving o-acylaminophenylketones.Some aspects of these photo-reactions are discussed.     

Tilted amides in amino acid and peptide derivatives

Background: Amide bonds in peptides and proteins typically adopt planar cis or trans conformations. Conversions between cis and trans amide conformations are necessary for protein folding and for many other processes, but are difficult to achieve since they involve disruption of the planarity of the bond. As a first step to understanding cis-trans isomerization, we set out to synthesize and characterize peptides that mimic the tilted or twisted amide structures that are postulated to form the intermediate states in this process.Results: We have synthesized a model amino acid and four dipeptide derivatives containing a methyl-substituted aziridine residue. Single crystals of phenacyl (2R, 3R)-benzyloxycarbonyl-3-methyl-2-aziridinecarboxylate and phenacyl (2R, 3R)-acetyl-glycyl-3-methyl-2-aziridine-carboxylate were obtained. Using X-ray diffraction analysis, we determined that the amide nitrogens of the aziridine rings have tetrahedral sp³-like geometry with tilt angles in the range of 37–38°. The ¹³C-NMR spectra indicate that the amide carbonyl is dramatically shifted downfield as a consequence of the tilt.Conclusions: In peptides containing a substituted aziridine ring, the orbitals of the amide nitrogen are constrained into a tilted configuration. These peptides may mimic the transition state between cis and trans amide conformations. This technique thus provides a novel strategy for the study of isomerization and other biorecognition processes.