Search results for "ACID"

Pyrazole amino acids: hydrogen bonding directed conformations of 3-amino-1H-pyrazole-5-carboxylic acid residue

2017

A series of model compounds containing 3-amino-1H-pyrazole-5-carboxylic acid residue with N-terminal amide/urethane and C-terminal amide/hydrazide/ester groups were investigated by using NMR, Fourier transform infrared, and single-crystal X-ray diffraction methods, additionally supported by theoretical calculations. The studies demonstrate that the most preferred is the extended conformation with torsion angles ϕ and ψ close to ±180°. The studied 1H-pyrazole with N-terminal amide/urethane and C-terminal amide/hydrazide groups solely adopts this energetically favored conformation confirming rigidity of that structural motif. However, when the C-terminal ester group is present, the second con…

CCDC 1576743: Experimental Crystal Structure Determination

2019

Related Article: Arkalekha Mandal, Kari Rissanen, Prasenjit Mal|2019|CrystEngComm|21|4401|doi:10.1039/C9CE00561G

Steroidal derivatives of nitrogen containing compounds as potential gelators

2013

(2-Pyridyl)sulfonyl Groups for ortho -Directing Palladium- Catalyzed Carbon-Halogen Bond Formation at Functionalized Arenes

2017

International audience; We describe an efficient palladium-catalyzed selective C-H ortho-monohalogenation (X=I, Br, Cl, F) of various functionalized (2-pyridyl) aryl-sulfones. ortho-, meta-and para-functionalization is tolerated at the arene group which undergoes C-H halogenation. Some modifications are also possible on the 2-(arylsulfonyl) heteroaryl directing groups. A comparison of the halogenation efficiency suggests that bromination is the practical method of choice, while chlorination and fluorination are possible but more challenging. Under forcing conditions ortho-dihalogenation can also be achieved.

Combined Spectroscopic and TD-DFT Analysis to Elucidate Substituent and Acidochromic Effects in Organic Dyes: A Case Study on Amino- versus Nitro-Sub…

2020

Made available in DSpace on 2020-12-12T01:33:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 A combined spectroscopic and TD-DFT case study was performed, to identify a robust method to calculate the complex near UV/Vis absorption spectra of various amino- vs. nitro-substituted 2,4-diphenylquinolines, which vary strongly under neutral and successively acidic conditions. For this, different DFT functionals were tested for geometry optimization and the TD part to calculate the neutral and different protonated species in a fast screening approach, i. e. using single point calculations in an implicit solvent. Offset-corrected M06HF, hitherto only applied to polymers, was identif…

Redox reaction between amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid and dopaquinone is responsible for the apparent inhibitory effect on tyrosin…

2002

Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid, the phosphonic analog of 3,4‐dihydroxyphenylglycine, had been previously reported as a potent inhibitor of tyrosinase. The mechanism of the apparent enzyme inhibition by this compound has now been established. Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid turned out to be a substrate and was oxidized to o‐quinone, which evolved to a final product identified as 3,4‐dihydroxybenzaldehyde, the same as for 3,4‐dihydroxyphenylglycine. Monohydroxylated compounds (amino‐(3‐hydroxyphenyl)methyl phosphonic acid and amino‐(4‐hydroxyphenyl)methyl phosphonic acid) were not oxidized, neither was 4‐hydroxy‐l‐phenylglycine. However, the relatively hig…

RAB18 Loss Interferes With Lipid Droplet Catabolism and Provokes Autophagy Network Adaptations

2020

Autophagy is dependent on appropriate lipid supply for autophagosome formation. The regulation of lipid acquisition and the autophagy network response to lipid-limiting conditions are mostly elusive. Here, we show that the knockout of the RAB GTPase RAB18 interferes with lipid droplet catabolism, causing an impaired fatty acid release. The resulting reduced lipid-droplet-derived lipid availability influences autophagy and provokes adaptive modifications of the autophagy network. These adjustments include increased expression and phosphorylation of ATG2B as well as augmented formation of the ATG12-ATG5 conjugate. Moreover, ATG9A shows an enhanced phosphorylation at amino acid residues tyrosi…

Inhibition of Rac1 signaling by lovastatin protects against anthracycline-induced cardiac toxicity

2011

Normal tissue damage limits the efficacy of anticancer therapy. For anthracyclines, the clinically most relevant adverse effect is cardiotoxicity. The mechanisms involved are poorly understood and putative cardioprotectants are controversially discussed. Here, we show that the lipid-lowering drug lovastatin protects rat H9c2 cardiomyoblasts from doxorubicin in vitro. Protection by lovastatin is related to inhibition of the Ras-homologous GTPase Rac1. It rests on a reduced formation of DNA double-strand breaks, resulting from the inhibition of topoisomerase II by doxorubicin. Doxorubicin transport and reactive oxygen species are not involved. Protection by lovastatin was confirmed in vivo. I…

Rac1-Regulated Endothelial Radiation Response Stimulates Extravasation and Metastasis That Can Be Blocked by HMG-CoA Reductase Inhibitors

2011

Radiotherapy (RT) plays a key role in cancer treatment. Although the benefit of ionizing radiation (IR) is well established, some findings raise the possibility that irradiation of the primary tumor not only triggers a killing response but also increases the metastatic potential of surviving tumor cells. Here we addressed the question of whether irradiation of normal cells outside of the primary tumor augments metastasis by stimulating the extravasation of circulating tumor cells. We show that IR exposure of human endothelial cells (EC), tumor cells (TC) or both increases TC-EC adhesion in vitro. IR-stimulated TC-EC adhesion was blocked by the HMG-CoA reductase inhibitor lovastatin. Glycyrr…

Phenolic Profiles, Antioxidant and Anti-Inflammatory Activities of Hydrodistillation Wastewaters from Five Lamiaceae Species

2022

Distillation is the most widely used method to obtain an essential oil from plant material. The biomass used in the process is returned as a solid residue together with variable amounts of water rich in water-soluble compounds, which currently are not addressed to any further application. The scope of this work was to evaluate the phytochemical composition of wastewaters coming from hydrodistillation (DWWs) of five aromatic plants belonging to the Lamiaceae family, and to assess their in vitro antioxidant and anti-inflammatory activities. The phenolic profiles of the DWWs were determined by HPLC-DAD and HPLC-ESI/MS. Free radical scavenging ability, oxygen radical antioxidant capacity and su…