- Synthesis and anticancer activities of proline-containing cyclic peptides and their linear analogs and congeners
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A solution phase method was adopted for the synthesis of proline-containing cyclic pentapeptide 2 and total synthesis of naturally occurring cyclic heptapeptide Reniochalistatin B 3. For the synthesis of 3, both divergent and convergent strategies were used to improve the overall yield from 12 to 25%. Different N and C terminal modified linear analogs and congeners of 2 and 3 were synthesized. Both cyclic peptides 2 and 3 and their linear analogs/congeners were evaluated for anti-cancer activity against HeLa cell line, among which pentapeptide 2 h and hexapeptide 3n with N-terminal protected hexafluoroisopropyl carbamates (HFIPC) interestingly showed higher cytotoxicity with an IC50 of 2.73 and 4.3 μM, respectively compared to their Boc-protected analogs 2a (IC50 20 μM) and 3c (IC50 38.51 μM) and cyclic peptides 2 (>100 μM) and 3 (47 μM). These results were further validated by biological experiments such as colony formation and wound healing assays.
- Ghosh, Keshab Ch,Duttagupta, Indranil,Bose, Chandra,Banerjee, Priyanjalee,Gayen, Anuran Kumar,Sinha, Surajit
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supporting information
p. 221 - 236
(2019/01/19)
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- Zinc(II) complexes of Pro-Gly and Pro-Leu dipeptides: Synthesis, characterization, in vitro DNA binding and cleavage studies
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Dipeptide (Pro-Gly and Pro-Leu) Zinc(II) complexes 1 and 2 were designed and synthesized for potential use as cancer chemotherapeutic agents. In order to augment the DNA recognition of metallonuclease activity, zinc metal ion was tethered to peptide motif to carry out DNA site specific hydrolytic cleavage. The structural formulation of the complexes 1 and 2 was done by elemental analysis, spectroscopic methods (IR, NMR, electronic) and molar conductance measurements. Their in vitro DNA binding profile was investigated by UV-vis titrations, fluorescence titrations and circular dichroism which revealed that these complexes bind to CT DNA by electrostatic interactions via groove binding mode. Zn(II) Pro-Gly complex 1 showed greater binding affinity to CT DNA as compared to the Zn(II) Pro-Leu complex 2 due to steric constraints in the latter. The supercoiled pBR322 DNA cleavage activity of complex 1, ascertained by gel electrophoresis demonstrated efficient DNA cleaving ability via hydrolytic mechanistic pathway. Further, the molecular docking studies confirmed that complex 1 bind to the minor groove of DNA having AT-rich sequences with relative binding energy of -196.72 kJ mol-1.
- Parveen, Shazia,Arjmand, Farukh,Mohapatra
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- A progressive synthetic strategy for class B synergimycins
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Described are the syntheses of four macrocyclic peptides that are the core structure of class B synergimycins, and the synthesis of a final class B derivative. Our synthetic route to these synergimycin derivatives allows the incorporation of amino acid su
- Robinson, Jennifer L.,Taylor, Rachel E.,Liotta, Lisa A.,Bolla, Megan L.,Azevedo, Enrique V.,Medina, Irene,McAlpine, Shelli R.
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p. 2147 - 2150
(2007/10/03)
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- Synthesis and kinetics of oxidation of some dipeptides with anodically generated manganese(III) sulphate: Mechanistic study
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Dipeptides (DP) namely phenylalanyl-proline (Phe-Pro), isoleucyl-proline (Ile-Pro), and leucyl-proline (Leu-Pro) were synthesized by classical solution method and characterized. The kinetics of oxidation of these DP by Mn(III) have been studied in the presence of sulphate ions in acidic medium at 26°C. The reaction was followed spectrophotometrically at λmax = 500 nm. A first-order dependence of rate on both [Mn(III)]0 and [DP]0 was observed. The rate is independent of the concentration of reduction product, Mn(II), and hydrogen ions. The effects of varying dielectric constant of the medium and addition of anions such as sulphate, chloride, and perchlorate were studied. The activation parameters have been evaluated using Arrhenius and Eyring plots. The oxidation products were isolated and characterized. A mechanism involving the reaction of DP with Mn(III) in the rate-limiting step is suggested.
- Kumara,Channe Gowda,Rangappa
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p. 438 - 444
(2007/10/03)
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- Phenylhydrazide as an enzyme-labile protecting group in peptide synthesis
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The enzymatic cleavage of amino acid phenylhydrazides with the enzyme tyrosinase (EC 1.14.18.1) offers a new, mild, and selective method for C-terminal deprotection of peptides. The advantages of the described methodology are the very mild oxidative removal of the protecting group at room temperature and pH 7, a high chemo- and regioselectivity, and the availability of the biocatalyst. Even in oxygen-saturated solution, the oxidation of sensitive methionine residues was not observed. These features make the methodology suitable for the synthesis of sensitive peptide conjugates. Mechanistic data suggest that the hydrolysis of the oxidized adducts proceeds by a free-radical mechanism.
- Voelkert, Martin,Koul, Surrinder,Mueller, Gernot H.,Lehnig, Manfred,Waldmann, Herbert
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p. 6902 - 6910
(2007/10/03)
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- Efficient, non-acidolytic method for the selective cleavage of N-Boc amino acid and peptide phenacyl esters linked to a polystyrene resin
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An efficient, non-acidolytic method for the selective cleavage of phenacyl esters of N-Boc-amino acids and -peptides linked to a polystyrene resin by (CH3)3SnOH (TMTOH) or [(n-C4H9)3Sn]2O (BBTO) is described. We highly recommend the use of trimethyltin hydroxide for the selective cleavage of carboxylic esters based on its favourable properties. The method is compatible with an N-Boc/O-Bn (benzyl ether) strategy and yields enantiomerically pure N-Boc-peptides useful for further manipulation, for segment condensations or for cyclization strategies. A mechanism for the cleavage of methyl phenylacetate in solution by TMTOH is postulated.
- Furlan, Ricardo L. E.,Mata, Ernesto G.,Mascaretti, Oreste A.
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p. 355 - 358
(2007/10/03)
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- Selective deprotection of phenacyl, benzyl and methyl esters of N-protected amino acids and dipeptides and N-protected amino acids benzyl ester linked to resins with bis(tributyltin) oxide
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Phenacyl, methyl and benzyl esters of various N-α-Boc, N-α-Cbz or N,N-dimethylamino protected amino acids and dipeptides, as well as esters of N-α-protected amino acids linked to Wang and Pam resins have been efficiently and chemoselectively cleaved by bis(tributyltin) oxide in aprotic solvents to give the corresponding carboxylic acids in good yields. Moreover, the absence of racemization during the deprotection has been demonstrated. A limitation of the method is the instability of the N-ε-Fmoc group in the amino acid esters 8 and 10, N-α-Fmoc-L-alanine linked to Wang resin 23 and the Cbz protecting groups in N-α-Boc-N-ε-Cbz-L-lysine benzyl and methyl esters (5 and 7), respectively, and N-α-Cbz-L-alanyl-L-alanine methyl ester 19. In the case of N-α-protected dipeptides, there was no evidence of free amino acid which indicates that the peptide bond is unaffected.
- Salomon, Claudio J.,Mata, Ernesto G.,Mascaretti, Oreste A.
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p. 995 - 999
(2007/10/03)
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- Studies on the β-turn of peptides. VII. Syntheses and antibiotic activities of gramicidin S analogs with L-Pro-L-Asn or L-Pro-d-Ala sequence at the β-turn part
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Two analogs of gramicidin S (GS), left bracket L-Pro**4**,**4 prime , L-Asn**5**,**5 prime right bracket -GS and left bracket L-Pro**4**,**4 prime , D-Ala**5**,**5 prime right bracket -GS were synthesized to investigate the possibility of replacing the be
- Sato,Nagai
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p. 3329 - 3336
(2007/10/02)
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- C-Terminal fragment of human chorionic gonadotropin
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A peptide of the formula wherein R: H or R1 -Ser-Ser-Ser-Ser-Lys-Ala-Pro-Pro-Pro group, R1 : H or R2 -R3 -Asp-Asp-Pro-Arg-Phe-Gln-Asp group, R2 : H or R4 -Asp-His-Pro-Leu-Thr group, R4 : H-R5 -Gly-Gly-Pro-Lys group, R5 : Cys or Tyr group, and R3 : Cys or S-acetamidemethyl-Cys group, or salt thereof, has utility for the preparation of antibodies for assaying human chorionic gonadotropin or as a labelling reagent.
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