Catalytic oxidation of ascorbic acid via copper–polypyridyl complex immobilized on glass

RSC Advances ◽  
2014 ◽  
Vol 4 (44) ◽  
pp. 23168-23176 ◽  
Author(s):  
Vikram Singh ◽  
Prakash Chandra Mondal ◽  
Megha Chhatwal ◽  
Yekkoni Lakshmanan Jeyachandran ◽  
Michael Zharnikov
Keyword(s):  
Ascorbic Acid ◽  
Catalytic Oxidation ◽  
High Performance ◽  
Polypyridyl Complexes ◽  
Polypyridyl Complex ◽  
Redox Active ◽  
Glass Support

A monolayer of redox-active copper–polypyridyl complexes on glass support was utilized for catalytic oxidation of ascorbic acid showing high performance.

scholarly journals (−)-Epicatechin—An Important Contributor to the Antioxidant Activity of Japanese Knotweed Rhizome Bark Extract as Determined by Antioxidant Activity-Guided Fractionation

Antioxidants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 133
Author(s):  
Urška Jug ◽  
Katerina Naumoska ◽  
Irena Vovk
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
High Performance ◽  
Radical Scavenging ◽  
Size Exclusion ◽  
Solvent Mixtures ◽  
Japanese Knotweed ◽  
Compound Identification ◽  
Rp Hplc ◽  
Ic50 Value

The antioxidant activities of Japanese knotweed rhizome bark extracts, prepared with eight different solvents or solvent mixtures (water, methanol, 80% methanol(aq), acetone, 70% acetone(aq), ethanol, 70% ethanol(aq), and 90% ethyl acetate(aq)), were determined using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay. Low half maximal inhibitory concentration (IC50) values (2.632–3.720 µg mL−1) for all the extracts were in the range of the IC50 value of the known antioxidant ascorbic acid at t0 (3.115 µg mL−1). Due to the highest extraction yield (~44%), 70% ethanol(aq) was selected for the preparation of the extract for further investigations. The IC50 value calculated for its antioxidant activity remained stable for at least 14 days, while the IC50 of ascorbic acid increased over time. The stability study showed that the container material was of great importance for the light-protected storage of the ascorbic acid(aq) solution in a refrigerator. Size exclusion–high-performance liquid chromatography (SEC-HPLC)–UV and reversed phase (RP)-HPLC-UV coupled with multistage mass spectrometry (MSn) were developed for fractionation of the 70% ethanol(aq) extract and for further compound identification, respectively. In the most potent antioxidant SEC fraction, determined using an on-line post-column SEC-HPLC-DPPH assay, epicatechin, resveratrol malonyl hexoside, and its in-source fragments (resveratrol and resveratrol acetyl hexoside) were tentatively identified by RP-HPLC-MSn. Moreover, epicatechin was additionally confirmed by two orthogonal methods, SEC-HPLC-UV and high-performance thin-layer chromatography (HPTLC) coupled with densitometry. Finally, the latter technique enabled the identification of (−)-epicatechin. (−)-Epicatechin demonstrated potent and stable time-dependent antioxidant activity (IC50 value ~1.5 µg mL−1) for at least 14 days.

scholarly journals Effects of Natural Antioxidants on Phospholipid and Ceramide Profiles of 3D-Cultured Skin Fibroblasts Exposed to UVA or UVB Radiation

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 578
Author(s):  
Agnieszka Gęgotek ◽  
Wojciech Łuczaj ◽  
Elżbieta Skrzydlewska
Keyword(s):  
Ascorbic Acid ◽  
High Performance ◽  
Three Dimensional ◽  
Natural Antioxidants ◽  
Phospholipid Metabolism ◽  
Culture Conditions ◽  
Membrane Properties ◽  
Dimensional System ◽  
Uvb Radiation ◽  
Liquid Chromatograph

Ultraviolet (UV) radiation is one of the primary factors responsible for disturbances in human skin cells phospholipid metabolism. Natural compounds that are commonly used to protect skin, due to their lipophilic or hydrophilic nature, show only a narrow range of cytoprotective activity, which prompts research on their combined application. Therefore, the aim of this study was to examine the effect of ascorbic acid and rutin on the phospholipid and ceramide profiles in UV-irradiated fibroblasts cultured in a three-dimensional system that approximates the culture conditions to the dermis. An ultra-high-performance liquid chromatograph coupled with a quadrupole time-of-flight mass spectrometer was used for phospholipid and ceramide profiling. As a result of UVA and UVB cells irradiation, upregulation of phosphatidylcholines, ceramides, and downregulation of sphingomyelins were observed, while treatment with ascorbic acid and rutin of UVA/UVB-irradiated fibroblast promoted these changes to provide cells a stronger response to stress. Moreover, an upregulation of phosphatidylserines in cells exposed to UVB and treated with both antioxidants suggests the stimulation of UV-damaged cells apoptosis. Our findings provide new insight into action of rutin and ascorbic acid on regulation of phospholipid metabolism, which improves dermis fibroblast membrane properties.

Iron hexamesityl-5,15-diazaporphyrin: synthesis, structure and catalytic use for direct oxidation of sp3 C–H bonds

2021 ◽  
Author(s):  
Tsubasa Nishimura ◽  
Takahiro Sakurai ◽  
Hiroshi Shinokubo ◽  
Yoshihiro Miyake
Keyword(s):  
Catalytic Oxidation ◽  
High Performance ◽  
Catalyst Deactivation ◽  
Direct Oxidation

Iron hexamesityl-5,15-diazaporphyrin was successfully synthesized. Its use for catalytic oxidation of cyclooctane showed high performance with a total TON up to 731. The introduction of bulky mesityl groups prevented the catalyst deactivation via formation of a μ-oxo dimer.

Determination of ascorbic acid in the retina during chicken embryo development using high performance liquid chromatography and UV detection

2016 ◽  
Vol 8 (27) ◽  
pp. 5441-5447 ◽  
Author(s):  
Débora R. S. Lima ◽  
Marcelo Cossenza ◽  
Carlos Gustavo Garcia ◽  
Camila C. Portugal ◽  
Flávia F. de C. Marques ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Embryo Development ◽  
Chicken Embryo ◽  
High Performance ◽  
Uv Detection

A HPLC-UV method has been developed and validated for the determination of ascorbic acid in chicken embryo retina.

In vitro regeneration of Persian poppy (Papaver bracteatum)

Biologia ◽  
2010 ◽  
Vol 65 (4) ◽  
Author(s):  
Sara Rostampour ◽  
Haleh Sohi ◽  
Ali Dehestani
Keyword(s):  
Ascorbic Acid ◽  
Callus Induction ◽  
High Performance ◽  
High Efficiency ◽  
In Vitro Regeneration ◽  
Naphthalene Acetic Acid ◽  
Dichlorophenoxyacetic Acid ◽  
Papaver Bracteatum ◽  
Callus Proliferation

AbstractPersian poppy (Papaver bracteatum Lindl.) is an important commercial source of medicinal opiates and related compounds. In this research, calli were induced from seeds, roots, cotyledons and hypocotyls of P. bracteatum at a high efficiency. The optimized callus induction media consisted of the Murashige and Skoog (MS) basic media supplemented with 1.0 mg/L 2, 4-dichlorophenoxyacetic acid (2,4-D), 0.1 mg/L kinetin and 15 mg/L ascorbic acid. The concentrations of 2,4-D and ascorbic acid were found critical to callus induction and proliferation. Subsequent subcultures resulted in excellent callus proliferation. Ascorbic acid at concentration 15 mg/L increased the callus proliferation significantly. Maximum callus growth was achieved when the explants were incubated at 25°C. MS salts at full strength were found inhibitory for callus induction, while ľ MS salts were found to favor callus induction. Shoot regeneration of calli in vitro was achieved on ľ MS medium containing 0.5 mg/L benzylamine purine and 1.0 mg/L naphthalene acetic acid. Analysis of alkaloid extracts from Persian poppy tissues by high-performance liquid chromatography showed that thebaine accumulated in the tissues of plants. The thebaine alkaloid profile of the Persian poppy is a well-defined model to evaluate the potential for metabolic engineering of thebaine production in P. bracteatum.

scholarly journals High Performance Reduction/Oxidation Metal Oxides for Thermochemical Energy Storage (PROMOTES)

2016 ◽  
Author(s):  
James E. Miller ◽  
Andrea Ambrosini ◽  
Sean M. Babiniec ◽  
Eric N. Coker ◽  
Clifford K. Ho ◽  
...  
Keyword(s):  
Energy Storage ◽  
Metal Oxides ◽  
High Performance ◽  
Electricity Production ◽  
Power Cycles ◽  
Redox Active ◽  
Active Metal ◽  
Performance Reduction ◽  
Mixed Ionic Electronic Conductors ◽  
Electronic Conductors

Thermochemical energy storage (TCES) offers the potential for greatly increased storage density relative to sensible-only energy storage. Moreover, heat may be stored indefinitely in the form of chemical bonds via TCES, accessed upon demand, and converted to heat at temperatures significantly higher than current solar thermal electricity production technology and is therefore well-suited to more efficient high-temperature power cycles. The PROMOTES effort seeks to advance both materials and systems for TCES through the development and demonstration of an innovative storage approach for solarized Air-Brayton power cycles and that is based on newly-developed redox-active metal oxides that are mixed ionic-electronic conductors (MIEC). In this paper we summarize the system concept and review our work to date towards developing materials and individual components.

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