Synthesis of Amides and Related Compounds

Benz, G.

doi:10.1016/b978-0-08-052349-1.00162-1

Cited by 38 publications

(21 citation statements)

References 345 publications

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“…Every synthesized molecule was isolated, purified (TLC, extraction with solvents and crystallization) and analyzed (IR, 1 H‐NMR, 13 C‐NMR, determination of physical constants and elementary analysis) before its biological evaluation (Benz, 1991; Gutte, 1995). See also online supporting information.…”

Section: Methodsmentioning

confidence: 99%

Calpain inhibitors prevent p38 MAPK activation and germ cell apoptosis after heat stress in pubertal rat testes

Lizama

Lagos

Lagos-Cabré

et al. 2009

Journal Cellular Physiology

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Testicular injuries like torsion or cryptorchidism can cause massive germ cell death, which could have great impact on male reproductive health. In addition, it has been proposed that modern life style, in the form of underwear or sedentary work position, could increase the testicular temperature, induce germ cell apoptosis, reduce spermatozoa quality and promote male infertility. In this work we showed that a heat stress stimulus induced massive germ cells apoptosis, which was associated with p38 mitogen-activated protein kinase (MAPK) phosphorylation along with an increase in the levels of mRNA encoding calpain 2. Synthetic calpain inhibitors prevented heat stress-induced germ cell apoptosis through inhibition of p38 MAPK phosphorylation. Thus, our results indicate that the blockage of calpains suppresses p38 MAPK phosphorylation, and identifies calpain activation (most likely calpain 2) as an early event in heat stress-induced male germ cell apoptosis.

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Section: Methodsmentioning

confidence: 99%

Calpain inhibitors prevent p38 MAPK activation and germ cell apoptosis after heat stress in pubertal rat testes

Lizama

Lagos

Lagos-Cabré

et al. 2009

Journal Cellular Physiology

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“…While we keep working along these lines, our reflection no doubt would be stimulated by any concrete experimental outcome around the all- cis stability proposal. In this respect, classical schemes for amide-bond creation in peptides or lactams should not be operative here, − any more than thermal or photochemical cis − trans isomerizations from all- trans isomers. The art of synthesis is, however, full of resources, and we hope there will be synthetic chemists willing to take up the challenge.…”

Section: Discussionmentioning

confidence: 99%

All-cis Cyclic Peptides

Poteau

Trinquier

2005

J. Am. Chem. Soc.

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Amide bonds -NH-CO- preferentially exist in trans conformations, the cis conformation being thermodynamically unfavored with respect to the trans by about 2 kcal/mol. Yet, the main reason most proteins or peptides cannot be made from cis-peptide plaques only lies in that connecting them into open chains appears to be sterically impracticable. It is possible, however, to build all-cis cyclic peptides in which all cis-plaques are efficiently locked. The present work examines, through quantum calculations, the structural and energetic issues associated with these peculiar arrangements. Systematic exploration at DFT-B3LYP level of the potential-energy surfaces for all-cis cyclopolyglycines cG(n)(c) (n = 2-10,15), and to a lesser extent, for all-cis cyclopolyalanines and all-cis cyclopolyphenylalanines confirms that all these structures are true minima. Optimal ring size occurs around eight peptide units, resulting in planar cG7(c), cG8(c), and cG9(c). In smaller systems, the ring strain is relieved through nonplanar cup-like distortions, particularly in cG6(c). From 10 peptide units and beyond, the ring framework distorts into a saddle-edge shape. These molecules disclose some molecular flexibility, as combinatorial tilting of the plaques may give sets of minima close in energy. Indexes based on isodesmic reactions are used to estimate the energy for joining all-cis or all-trans plaques into cyclic peptides. One of them, the mean plaque-junction energy (MPJE) suggests that within sensible sizes from six peptide units and beyond, all-cis plaque association is almost equally favorable as all-trans one. The frame of radiating cis-amide bonds can be considered as defining a new kind of peptidic material, endowed with specific self-assembling properties.

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“…W. Spears, K. Tsuji, T. Tojo, H. Nishimura and T. Ogino Amide coupling with the appropriate acid 9a followed by Dieckmann cyclization would provide the desired material without any regiochemical problems. This method looked appealing because of the many known methods for amide coupling [4], and the many examples of similar Dieckmann cyclizations [5].…”

Section: Jul-aug 2002 799mentioning

confidence: 99%