Cross metathesis of β-carotene with electron-deficient dienes. A direct route to retinoids

2009 ◽  
Vol 50 (33) ◽  
pp. 4734-4737 ◽  
Author(s):  
Agnieszka Wojtkielewicz ◽  
Jadwiga Maj ◽  
Jacek W. Morzycki
Keyword(s):  
Cross Metathesis ◽  
Direct Route ◽  
Β Carotene ◽  
Electron Deficient Dienes

A Direct Route to Bifunctional Aldehyde Derivatives via Self- and Cross-Metathesis of Unsaturated Aldehydes

ChemSusChem ◽  
2009 ◽  
Vol 2 (6) ◽  
pp. 542-545 ◽  
Author(s):  
Xiaowei Miao ◽  
Cédric Fischmeister ◽  
Christian Bruneau ◽  
Pierre H. Dixneuf
Keyword(s):  
Cross Metathesis ◽  
Unsaturated Aldehydes ◽  
Direct Route

Serum Retinol and β-carotene Levels and Risk Factors for Cardiovascular Disease in Morbid Obesity

2010 ◽  
Vol 80 (3) ◽  
pp. 159-167 ◽  
Author(s):  
Gabriela Villaça Chaves ◽  
Gisele Gonçalves de Souza ◽  
Andréa Cardoso de Matos ◽  
Dra. Wilza Abrantes Peres ◽  
Silvia Elaine Pereira ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cardiovascular Disease ◽  
Metabolic Syndrome ◽  
Morbid Obesity ◽  
Serum Levels ◽  
World Health ◽  
Morbidly Obese ◽  
Serum Retinol ◽  
Significant Difference ◽  
Β Carotene

Objective: To evaluate retinol and β-carotene serum levels and their relationship with risk factors for cardiovascular disease in individuals with morbid obesity, resident in Rio de Janeiro. Methodology: Blood serum concentrations of retinol and β-carotene of 189 morbidly obese individuals were assessed. The metabolic syndrome was identified according to the criteria of the National Cholesterol Education Program (NCEP) and World Health Organization (WHO). Lipid profile, insulin resistance, basal insulin, glycemia, blood pressure, and anthropometry and their correlation with retinol and β-carotene serum levels were evaluated. Results: Metabolic syndrome diagnosis was observed in 49.0% of the sample. Within this percentage the levels of β-carotene were significantly lower when body mass index increased. Serum retinol didn't show this behavior. Serum retinol inadequacy in patients with metabolic syndrome (61.3%), according to WHO criterion, was higher (15.8%) than when the whole sample was considered (12.7%). When metabolic syndrome was diagnosed by NCEP criterion, β-carotene inadequacy was higher (42.8%) when compared to the total sample (37.5%). There was a significant difference between average β-carotene values of patients with and without metabolic syndrome (p=0.048) according to the classification of the NCEP. Lower values were found in patients with metabolic syndrome. Conclusion: Considering the vitamin A contribution in antioxidant protection, especially when risk factors for cardiovascular disease are present, it is suggested that great attention be given to morbidly obese. This could aid in prevention and treatment of cardiovascular disease, which affects a significant part of the population.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Endgroup and Sidechain Functionalization of Surface-Initiated ROMP Thin Films: Progress Towards ROMP-Based Molecular Wires

2018 ◽  
Author(s):  
Nicholas Marshall
Keyword(s):  
Thin Films ◽  
Contact Angle ◽  
Cyclic Voltammetry ◽  
Polymer Films ◽  
Conjugated Polymer ◽  
Ring Opening ◽  
Molecular Wires ◽  
Metathesis Polymerization ◽  
Cross Metathesis ◽  
Active Ester

A set of experiments in surface-initiated ring-opening metathesis polymerization, including end-functionalization of growing brushes and contact angle/cyclic voltammetry measurements. We report preparation and CV of two different conjugated polymer films, and several endgroup and sidechain functionalization experiments using cross-metathesis and active ester substitution.<br>

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

Sign in / Sign up

Export Citation Format

Share Document