scholarly journals New Insights into the Cystine-Sulfite Reaction

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2377 ◽  
Author(s):  
Matteo Zecchini ◽  
Robert Lucas ◽  
Adam Le Gresley
Keyword(s):  
High Resolution ◽  
Uv Light ◽  
Light Exposure ◽  
Maximum Yield ◽  
Reactant Ratio ◽  
Oxidizing Agent ◽  
High Resolution Nmr ◽  
Effective Conditions

The mechanism by which cysteine-S-sulfate is formed from the reaction of sulfite with cystine in the absence of a dedicated oxidizing agent is investigated using high-resolution NMR. Changes to reactant ratio, pH, UV light exposure and temperature were evaluated to determine the most effective conditions to achieve the maximum yield of cysteine-S-sulfate without recourse to conventional oxidizing reagents. Herein evidence is provided for both nucleophilic and radical mechanisms, by which cysteine-S-sulfate can be generated with yields of up to 96%.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

scholarly journals Stability and ocular biodistribution of topically administered PLGA nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sean Swetledge ◽  
Renee Carter ◽  
Rhett Stout ◽  
Carlos E. Astete ◽  
Jangwook P. Jung ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Polymeric Nanoparticles ◽  
Plga Nanoparticles ◽  
Eye Disease ◽  
Control Group ◽  
Eye Tissues ◽  
Nanoparticle Morphology ◽  
The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

Determination of Tautomeric Preference of Fenobam in Solution by High Resolution NMR Spectroscopy

2020 ◽  
Author(s):  
Xuming Sha ◽  
Shaodong Chen ◽  
Xiaojing Zheng ◽  
Xin Ye ◽  
Hailu Zhang ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
High Resolution Nmr
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