scholarly journals Synthesis and Complexation Studies of Optically Active Aza- and Diazacrown Ethers Containing a Pyrene Fluorophore Unit

2019 ◽  
Vol 64 (1) ◽  
pp. 20-36
Author(s):  
Dávid Pál ◽  
Martin Gede ◽  
Ildikó Móczár ◽  
Péter Baranyai ◽  
Péter Bagi ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Photoinduced Electron Transfer ◽  
Fluorescence Enhancement ◽  
Optically Active ◽  
Primary Amines ◽  
Amino Acid Esters ◽  
Diazacrown Ethers ◽  
Complexation Studies ◽  
Phenylalanine Methyl Ester ◽  
Acid Esters

Novel enantiopure azacrown [(R,R)-1 and (S,S)-1] and diazacrown [(R,R)-2–(R,R)-4 and (S,S)-2–(S,S)-4] ethers containing a pyrene fluorophore unit and two phenyl groups at their chiral centers were obtained in multistep syntheses. The action of these chemosensors is based on the photoinduced electron transfer (PET) process, thus they show fluorescence enhancement in the presence of protonated primary amines and amino acid esters. Their recognition abilities toward the enantiomers of 1-phenylethylamine hydrogen perchlorate (PEA), 1-(1-naphthyl) ethylamine hydrogen perchlorate (NEA), phenylglycine methyl ester hydrogen perchlorate (PGME), and phenylalanine methyl ester hydrogen perchlorate (PAME) were examined in acetonitrile using fluorescence spectroscopy.

THE HYDROLYSIS OF PHENYLALANINE METHYL ESTER BY BOVINE THROMBIN

1966 ◽  
Vol 44 (7) ◽  
pp. 1051-1059 ◽  
Author(s):  
Edmond R. Cole ◽  
J. L. Koppel ◽  
John H. Olwin
Keyword(s):  
Methyl Ester ◽  
Sodium Citrate ◽  
Deae Cellulose ◽  
Amino Acid Esters ◽  
Bovine Thrombin ◽  
Wide Range ◽  
Autoprothrombin C ◽  
Phenylalanine Methyl Ester ◽  
Hydrolysis Of ◽  
Acid Esters

Thrombin, usually regarded as a trypsin-like enzyme capable of hydrolyzing only esters of the amino acids arginine and lysine, was found to hydrolyze certain other amino acid esters which are considered specific chymotrypsin substrates. L-Phenylalanine methyl ester inhibited the activation of purified bovine prothrombin by autoprothrombin C, Ac-globulin, phospholipid, and calcium. It was subsequently shown that thrombin is capable of hydrolyzing L-phenylalanine methyl ester or L-tyrosine ethyl ester. This activity developed simultaneously with fibrogen clotting activity during activation of purified bovine prothrombin in 25% sodium citrate solutions. Moreover, the activity was closely associated with clotting activity on subsequent chromatography on DEAE-cellulose and Amberlite IRC-50 resin columns. All preparations of bovine thrombin, representing a wide range of purity, which have been examined, exhibited this hydrolyzing activity toward L-phenylalanine methyl ester. Further evidence linking this esterase activity with fibrinogen clotting activity was obtained when both activities were inhibited by 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate, an inhibitor of chymotrypsin.

Convenient Preparation of Optically Active N,N’-Disubstituted Piperazines from Various (S)-α-Amino Acid Esters

Synthesis ◽  
1996 ◽  
Vol 1996 (04) ◽  
pp. 452-454 ◽  
Author(s):  
Masaaki Watanabe ◽  
Yoshitane Kojima ◽  
Kenji Kawabe ◽  
Eiji Hatamoto ◽  
Eiji Tsuru ◽  
...  
Keyword(s):  
Amino Acid ◽  
Optically Active ◽  
Amino Acid Esters ◽  
Convenient Preparation ◽  
Acid Esters

Destruction of Leishmania mexicana amazonensis amastigotes by leucine methyl ester: protection by other amino acid esters

Parasitology ◽  
1987 ◽  
Vol 95 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Silvia C. Alfieri ◽  
V. Zilberfarb ◽  
M. Rabinovitch
Keyword(s):  
Amino Acid ◽  
Methyl Ester ◽  
Protective Effect ◽  
Ester Hydrolysis ◽  
Amino Acid Esters ◽  
Protective Activity ◽  
Leishmania Mexicana ◽  
Effective Prevention ◽  
Infected Cells ◽  
Acid Esters

SUMMARYl-Amino acid esters, such as leucine methyl ester (Leu-OMe) can destroy intracellular as well as isolated amastigotes of Leishmania mexicana amazonensis by a mechanism which may involve ester hydrolysis by parasite enzymes. We show here that several other esters prevented the killing of the amastigotes by Leu-OMe. Destruction of Leishmania within macrophages in culture was assessed microscopically and viability of isolated parasites was monitored by reduction of the tetrazolium MTT. The main features of the protective effect were similar for intracellular and for isolated amastigotes. Thus, (i) effective prevention of parasite killing required that the protective ester be present in the medium prior to and during exposure of infected cells or parasites to Leu-OMe; (ii) the same esters protected intracellular and isolated Leishmania against damage by Leu-OMe. Ranks of protective activity, as determined on isolated amastigotes were: Gly-OBz > Tyr-OMe > Ile-OMe > Met-OMe > Val-OMe > Ala-OMe > Gly-OMe > D-Leu-OMe; (iii) several esters were inactive in both systems (Leu-OBz, Trp-OMe and Phe-OMe). Protective activity was associated with leishmanicidal (e.g. Gly-OBz, Tyr-OMe) as well as with non-leishmanicidal (e.g. Ile-OMe, Val-OMe) esters. The results are compatible with the hypothesis that protective esters inhibit the activity of parasite enzyme(s) which hydrolyse Leu-OMe.

Molecular recognition of chiral porphyrins with amino acid esters

2005 ◽  
Vol 09 (01) ◽  
pp. 7-15
Author(s):  
Wen J. Ruan ◽  
Xiao J. Zhao ◽  
Hua Han ◽  
Jing Nan ◽  
Zhi A. Zhu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Electronic Effect ◽  
Association Constants ◽  
Optically Active ◽  
Amino Acid Esters ◽  
Cd Spectra ◽  
Guest Molecules ◽  
H Nmr ◽  
Tripos Force Field ◽  
Acid Esters

Association constants between α,α,α,β- ZnT (o- BocTyr ) TAPP (1), α,α,α,β- ZnT (o- BocAla )- TAPP (2), and a series of amino acid esters were determined in chloroform by means of titrations monitored by UV-vis spectra. Association constants increased in the order K( AlaOMe ) < K( ValOMe ) < K( LeuOMe ), showing the same preference for the electronic effect of bulky amino acid esters. For the guest SerOMe and ThrOMe , the association constants of two hosts showed different orders; the order of 1 is K( SerOMe ) < K( ThrOMe ), and that of 2 is the reverse. The host 2 shows a D -/ L -selectivity of 6.9 for leucine methyl ester at 293 K in CHCl 3, which is the highest enantioselectivity achieved in our study. The host-guest system was studied by 1 H NMR spectra. On association, every proton experiences a small upfield shift. The intensity of circular dichroism (CD) spectra of 1 in the presence of optically active guests were reduced as compared with that of free 1, while that of 2 with optically active guests was of the induced split type. Molecular modeling of the host-guest systems were studied by simulated annealing on the basis of the Tripos force field. The minimal energies of the complexes were calculated, and the results show that the recognition behavior of hosts 1 and 2 toward amino acid esters is very different. The change of the interaction energy of 2 with guest molecules is larger than that of 1.

scholarly journals Synthesis and Atiplatelet of 2-(ethyl amino acid esters), Amino pyridyl 1,3- oxzine

2006 ◽  
Vol 2 (2) ◽  
pp. 91-97
Author(s):  
Mohamad Alajelee
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Methyl Ester ◽  
Elemental Analysis ◽  
Inhibitory Activity ◽  
Amino Acid Esters ◽  
Improved Method ◽  
Acid Esters

2-(N-glycyl ,Alanyl , leucinyl , isoleacinyl , methionyl , phenyl alanyl,  vilinyl methyl ester) , 2-Amino and 4- Amino pyrideyl -1,3- Benzoxazine -4- one were synthesized from the reaction of the corresponding amino acids ester , Amino pyridines with methyl cyano salicylate using improved method. The resulted benzoxazine derivative were tested for their Antiplatelet inhibitory activity , their IR , NMR (1H , 13C) were also studied and checked by elemental analysis.

scholarly journals Synthesis, Fluorescence and NMR Spectroscopic Studies of a Novel Phosphinoxido-18-crown-6 Ether Containing an Anthracene Fluorophore Unit

2019 ◽  
Vol 64 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Hajnalka Szabó-Szentjóbi ◽  
Anna Márton ◽  
Dávid Pál ◽  
Gergő Dargó ◽  
Áron Szigetvári ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Spectroscopic Studies ◽  
Primary Amines ◽  
Methyl Groups ◽  
Amino Acid Esters ◽  
Two Dimensional ◽  
Fluorescent Chemosensors ◽  
One Dimensional ◽  
Stereogenic Centers ◽  
Acid Esters

The synthesis of the (R,R) and (S,S) enantiomers of a new enantiopure monophospha-18-crown-6 ether (1), which contains an anthracene fluorophore unit and methyl groups at its stereogenic centers, was accomplished. The structure of one enantiomer ((S,S)-1) was studied using one-dimensional (1H, 13C{1H}, and 31P{1H}) and two-dimensional NMR spectra. Because (R,R)-1 and (S,S)-1 can act as new fluorescent chemosensors, we examined their enantiomeric differentiation abilities toward the enantiomers of protonated chiral primary amines and amino acid esters (PEA, 1-NEA, PGME, PAME) using UV-Vis and fluorescence spectroscopies. These monophospha-crown ethers showed moderate enantiomeric discrimination abilities.

scholarly journals Synthesis of novel pregnane-based 20-carboxamides via palladium-catalysed aminocarbonylation

2021 ◽  
Author(s):  
Gábor Mikle ◽  
Alexandra Zugó ◽  
Erzsébet Szatnik ◽  
Anita Maxim ◽  
Sándor Mahó ◽  
...  
Keyword(s):  
Amino Acid ◽  
Selective Hydrogenation ◽  
Primary Amines ◽  
Amino Acid Esters ◽  
Acid Esters

Abstract20-Carboxamidopregnene derivatives, such as 3β-acetoxy-5α-pregn-20-ene-20-carboxamides and 5α-pregn-20-ene-20-carboxamides were synthesized from the widely accessible 3β-acetoxy-pregn-5,16-dien-20-one (PDA) using selective hydrogenation, hydrazine and iodoalkene formation, as well as palladium-catalysed aminocarbonylation. The 20-iodo-20-ene derivatives, obtained from the corresponding 20-keto derivatives via their hydrazones, served as substrates. 23 new 20-carboxamides were obtained using various N-nucleophiles ranging from simple primary amines to α-amino acid esters. The novelty of this methodology lies in the application of facile, moderate or high-yielding reactions to obtain otherwise hardly accessible steroidal 20-carboxamides of pharmaceutical importance. In other words, instead of the enzymatic or synthetic degradation of e.g., sterols or cholanic acids, functionalization of the basic skeleton (a ‘building-up’ approach) was used.

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