SHORT NOTE | doi:10.20944/preprints201707.0096.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: corrosion inhibitor; coumarin; resonance
Online: 31 July 2017 (16:37:19 CEST)
Corrosion inhibitors are the natural or synthetic compounds that have the ability to inhibit the average of corrosion and reduce the damage of the mild steel. Enormous organic inhibitors nowadays employed in the corrosion domain but excluded due to costly. Comparatively cheap, and stable organic compound, namely 3-((4-nitrobenzylidene)amino)coumarin, have been utilized as an excellent corrosion inhibitor in hydrochloric acid for mild steel. The inhibition efficiency has been figured regarding to weight loss method. The corrosion inhibitor was identified according to spectroscopic techniques namely Fourier transform infrared and nuclear magnetic resonance in addition to micro-elemental analysis. Inhibition efficiency for the studied inhibitor was 71.4% that, at the highest studied concentration.
ARTICLE | doi:10.20944/preprints202008.0438.v1
Subject: Chemistry, Organic Chemistry Keywords: acetylcholinesterase; antioxidant; Alzheimer; coumarin; selenazole
Online: 20 August 2020 (07:26:34 CEST)
Inhibition of acetylcholinesterase (AChE) enzyme is a known procedure to treat severe Alzheimer's disease through increasing the acetylcholine level in the brain and thus slowing down the progression of Alzheimer's symptoms. The approved medications are only considered as palliative and addressed some reported deficiencies. Therefore, the demand for safe and effective compounds is substantially increasing. A newly series of coumaryl 1,3-selenazoles derivatives was synthesized in four steps. Then, their antioxidant activities were evaluated using DPPH, ABTS cation radical scavenging assay and cupric reducing antioxidant capacities (CUPRAC). The anticholinesterase activities were evaluated using the Ellman method. Then, the docking studies were carried out to explain the possible correlation between in vitro anticholinesterase activity results and the ligand-receptor interactions. Ten new coumaryl 1,3-selenazoles (5a-5d series and 6a-6f series) derivatives were successfully synthesized. The DPPH radical scavenging assay showed that all tested compounds have IC50 value > 200 μM, for ABTS cation radical scavenging assay the IC50 value > 1000 μM and for CUPRAC assay the IC50 value > 200 μM. Compound 5c was found to be the most active compound against AChE and BChE in its series with IC50 value for AChE is 99.76 μM and IC50 for BChE is 140.28 μM while 6b exhibited the most potent inhibition in its series with IC50 value for AChE is 56.01 μM and IC50 for BChE is 121.34 μM. Besides, the docking studies showed that compound 5c and 6b formed π-π stacking interaction with aromatic residues at the active site of AChE and BChE, which is responsible for inhibiting the enzymes. This shows that the synthesized compounds contain skeletal structures that can interact and inhibit within the enzymes active site.
ARTICLE | doi:10.20944/preprints201809.0349.v1
Subject: Chemistry, Organic Chemistry Keywords: coumarin; one-pot synthesis; catalysis; Wells–Dawson heteropolyacid
Online: 18 September 2018 (11:53:28 CEST)
The development of a method to produce coumarins unsubstituted on the pyranic nucleus catalyzed from Wells–Dawson heteropolyacid (H6P2W18O62), phenol derivatives and ethyl 3,3-diethoxypropionate using Pechmann condensation under solvent-free conditions is described. This catalytic method was also applied successfully to synthesize various substituted coumarins, including the corresponding phenols and ethyl 3,3-diethoxypropionate. This work provides a novel, cheaper and safer way to syhthesize coumarins unsubstituted on the pyranic nucleus.
ARTICLE | doi:10.20944/preprints201708.0021.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: 3-((2-chlorobenzylidene)amino)coumarin; corrosion inhibitor; damage reduction
Online: 7 August 2017 (10:51:42 CEST)
New corrosion inhibitor derived from coumarin-3-amine namely 3-((2-chlorobenzylidene)amino)coumarin was synthesized and characterized by CHN elemental analysis in addition to Fourier transform infrared and nuclear magnetic resonance techniques. The anti-corrosion ability of 3-((2-chlorobenzylidene)amino)coumarin to inhibit the impacts of corrosion has been demonstrated and damage reduction of the mild steel also. 3-((2-chlorobenzylidene)amino)coumarin, has been employed as a good corrosion inhibitor for mild steel in HCL solution. The efficiency of the inhibition was figured according to weight loss method and it was 74.6%.
REVIEW | doi:10.20944/preprints202209.0330.v1
Subject: Life Sciences, Other Keywords: coumarin; 1,2-benzopyrone; Melilotus officinalis; narrative review; primary lymphoedema; secondary lymphoedema; hepatotoxicity
Online: 22 September 2022 (03:20:25 CEST)
Coumarin is an effective treatment for primary lymphoedema, as well as lymphoedema related to breast cancer radiotherapy or surgery. However, its clinical use is limited in several countries due to the possible occurrence of hepatotoxicity, mainly in the form of mild to moderate transaminase elevation. Noteworthy, only few cases of severe hepatotoxicity have been described in literature, with no reported cases of liver failure. Data available on coumarin absorption, distribution, metabolism and excretion have been reviewed, focusing on hepatotoxicity studies carried out in vitro and in vivo. Finally, safety and tolerability data from clinical trials have been thoroughly discussed. On the basis of these data, coumarin-induced hepatotoxicity seems to be restricted to a small subset of patients, probably due to the expression of specific alleles of CYP450 isoform not yet well characterized. In summary, more research is needed in order to identify patients at risk of developing hepatotoxicity following coumarin treatment, in order to improve the risk/benefit ratio of the product and allow more patients to benefit from its therapeutic properties.
ARTICLE | doi:10.20944/preprints201709.0070.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: Coumarin; Mycobacterium tuberculosis; Cholinesterase inhibitor; Monoamine oxidase B inhibitor; Structure activity relationship; Albumin binding, Neuroprotection
Online: 15 September 2017 (17:34:38 CEST)
An in vitro medium-throughput screen using M. tuberculosis H37Rv was employed to screen an in-house library of structurally diverse compounds for antimycobacterial activity. From this initial screen, eleven 7-substituted coumarin derivatives with confirmed monoamine oxidase-B and cholinesterase inhibitory activities, demonstrated growth inhibition of more than 50% at a 50 µM concentration. This prompted further exploration of all the 7-substituted coumarins in our library, nineteen in total, as potential antimycobacterial agents. Four derivatives showed promising antimycobacterial activity with MIC99 values of 8.31 – 29.70 µM and 44.15 – 57.17 µM on M. tuberculosis H37Rv in independent assays using Gaste-Fe and 7H9 + OADC media, respectively. These compounds were found to bind to albumin which may explain the variations in MIC between the two assays. Preliminary antimycobacterial evaluation of moxifloxacin resistant M. tuberculosis show that these compounds are able to maintain their activity in fluoroquinolone resistant mycobacteria. Analysis of structure activity relationships for antimycobacterial versus neuronal enzyme inhibitory activity indicate that structural modification on position 4 and/or 7 of the coumarin scaffold may be utilized to improve selectivity towards either inhibition of neuronal enzymes or antimycobacterial effect. Cytotoxicity evaluations of the compounds indicate moderate cytotoxicity with slight selectivity towards mycobacteria. Further neuroprotective assays on SH-SY5Y human neuroblastoma cells indicate significant neuroprotection for selected compounds irrespective of their neuronal enzyme inhibitory properties. These coumarin molecules are thus interesting lead compounds that may provide insight into the design of new antimicrobacterial and/or neuroprotective agents.