scholarly journals Chemical Stability of Ascorbic Acid Integrated into Commercial Products: A Review on Bioactivity and Delivery Technology

Antioxidants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 153
Author(s):  
Xin Yin ◽  
Kaiwen Chen ◽  
Hao Cheng ◽  
Xing Chen ◽  
Shuai Feng ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Active Site ◽  
De Novo ◽  
Food Matrix ◽  
De Novo Synthesis ◽  
Nutritional Characteristics ◽  
Gulonolactone Oxidase ◽  
Key Enzyme ◽  
Commercial Applications ◽  
Delivery Technology

The L-enantiomer of ascorbic acid is commonly known as vitamin C. It is an indispensable nutrient and plays a key role in retaining the physiological process of humans and animals. L-gulonolactone oxidase, the key enzyme for the de novo synthesis of ascorbic acid, is lacking in some mammals including humans. The functionality of ascorbic acid has prompted the development of foods fortified with this vitamin. As a natural antioxidant, it is expected to protect the sensory and nutritional characteristics of the food. It is thus important to know the degradation of ascorbic acid in the food matrix and its interaction with coexisting components. The biggest challenge in the utilization of ascorbic acid is maintaining its stability and improving its delivery to the active site. The review also includes the current strategies for stabilizing ascorbic acid and the commercial applications of ascorbic acid.

scholarly journals An enzymatic activation of formaldehyde for nucleotide methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Bou-Nader ◽  
Frederick W. Stull ◽  
Ludovic Pecqueur ◽  
Philippe Simon ◽  
Vincent Guérineau ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Crystallographic Structure ◽  
De Novo Synthesis ◽  
Active Site Residues ◽  
Enzymatic Activation ◽  
Enzyme Cofactors ◽  
Unique Ability

AbstractFolate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.

Fatty acid synthase is a prognostic marker and associated with immune infiltrating in gastric cancers precision medicine

2020 ◽  
Vol 14 (3) ◽  
pp. 185-199
Author(s):  
Yangying Zhou ◽  
Weiping Su ◽  
Huan Liu ◽  
Taili Chen ◽  
Naseruddin Höti ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Fatty Acid ◽  
Fatty Acid Synthase ◽  
De Novo ◽  
Survival Outcome ◽  
De Novo Synthesis ◽  
Bioinformatics Analyses ◽  
Key Enzyme ◽  
Tumor Types

Aim: Fatty acid synthase (FASN), a key enzyme for de novo synthesis of fatty acids, has been identified as an oncogene in some tumor types; however, the function of FASN in gastric cancer (GC) is poorly elucidated. Method: Integrative bioinformatics analyses were performed to unveil the role of FASN in tumor progression and cancer-associated immunology of GC. Result: FASN was overexpressed in the GC tissues and correlated with an inferior survival outcome, and largely contributed to the carcinogenesis of GC. Moreover, FASN expression was closely associated with the immune-infiltrating levels of CD8+ T, CD4+ T, neutrophils, macrophages and dendritic cells. Conclusion: FASN was closely associated with GC and may be involved in the tumorigenesis and cancer–immune interactions, and could be a promising prognostic and therapeutic biomarker in GC.

Juvenile Lobster (Homarus americanus) Do Not Require Dietary Ascorbic Acid

1985 ◽  
Vol 42 (2) ◽  
pp. 368-370 ◽  
Author(s):  
J. C. Kean ◽  
J. D. Castell ◽  
D. J. Trider
Keyword(s):  
Ascorbic Acid ◽  
De Novo ◽  
Homarus Americanus ◽  
De Novo Synthesis ◽  
Experimental Conditions ◽  
Deficient Diet ◽  
Significant Difference ◽  
Dry Diet ◽  
Dietary Treatments ◽  
Ascorbic Acid Supplementation

We found no dietary ascorbic acid requirement for juvenile lobsters (Homarus americanus) (37–42 mg). The lobsters were fed semipurified diets containing 0, 0.6, 1.2, 2.4, or 12 g L-ascorbic acid/kg dry diet for 20 wk. At termination, the hepatopancreases were removed and assayed for ascorbic acid. There was no significant difference in growth or mortality among any of the dietary treatments. Lobsters fed the deficient diet had hepatopancreatic ascorbic acid levels that were not significantly different from animals fed the supplemented diets. Juvenile lobster, therefore, did not require dietary ascorbic acid under these experimental conditions. We suggest that juvenile lobsters do not require ascorbic acid supplementation in the diet and may be capable of de novo synthesis of this vitamin.

Characterization of Monocyte-Associated Factor V

1993 ◽  
Vol 70 (02) ◽  
pp. 273-280 ◽  
Author(s):  
Janos Kappelmayer ◽  
Satya P Kunapuli ◽  
Edward G Wyshock ◽  
Robert W Colman
Keyword(s):  
Monoclonal Antibody ◽  
Light Chain ◽  
Peripheral Blood ◽  
De Novo ◽  
Factor V ◽  
Blood Monocytes ◽  
De Novo Synthesis ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Peripheral Blood Monocytes

SummaryWe demonstrate that in addition to possessing binding sites for intact factor V (FV), unstimulated peripheral blood monocytes also express activated factor V (FVa) on their surfaces. FVa was identified on the monocyte surface by monoclonal antibody B38 recognizing FVa light chain and by human oligoclonal antibodies H1 (to FVa light chain) and H2 (to FVa heavy chain) using immunofluorescence microscopy and flow cytometry. On Western blots, partially cleaved FV could be identified as a 220 kDa band in lysates of monocytes. In addition to surface expression of FVa, monocytes also contain intracellular FV as detected only after permeabilization by Triton X-100 by monoclonal antibody B10 directed specifically to the Cl domain not present in FVa. We sought to determine whether the presence of FV in peripheral blood monocytes is a result of de novo synthesis.Using in situ hybridization, no FV mRNA could be detected in monocytes, while in parallel control studies, factor V mRNA was detectable in Hep G2 cells and CD18 mRNA in monocytes. In addition, using reverse transcriptase and the polymerase chain reaction, no FV mRNA was detected in mononuclear cells or in U937 cells, but mRNA for factor V was present in Hep G2 cells using the same techniques. These data suggest that FV is present in human monocytes, presumably acquired by binding of plasma FV, and that the presence of this critical coagulation factor is not due to de novo synthesis.

Platelets Stimulate Thromboplastin Synthesis in Human Endothelial Cells

1983 ◽  
Vol 49 (02) ◽  
pp. 069-072 ◽  
Author(s):  
U L H Johnsen ◽  
T Lyberg ◽  
K S Galdal ◽  
H Prydz
Keyword(s):  
Endothelial Cells ◽  
De Novo ◽  
Umbilical Vein ◽  
Time Dependent ◽  
De Novo Synthesis ◽  
Human Endothelial Cells ◽  
Tumor Promotor ◽  
Coagulation Assay ◽  
Platelet Aggregates ◽  
Umbilical Vein Endothelial Cells

SummaryHuman umbilical vein endothelial cells in culture synthesize thromboplastin upon stimulation with phytohaemagglutinin (PHA) or the tumor promotor 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The thromboplastin activity is further strongly enhanced in a time dependent reaction by the presence of gel-filtered platelets or platelet aggregates. This effect was demonstrable at platelet concentrations lower than those normally found in plasma, it may thus be of pathophysiological relevance. The thromboplastin activity increased with increasing number of platelets added. Cycloheximide inhibited the increase, suggesting that de novo synthesis of the protein component of thromboplastin, apoprotein III, is necessary.When care was taken to remove monocytes no thromboplastin activity and no apoprotein HI antigen could be demonstrated in suspensions of gel-filtered platelets, platelets aggregated with thrombin or homogenized platelets when studied with a coagulation assay and an antibody neutralization technique.

DE NOVO SYNTHESIS OF STEROIDS BY THE TESTES OF THE HUMAN FOETUS AT MIDGESTATION

1971 ◽  
Vol 68 (1_Supplb) ◽  
pp. S135 ◽  
Author(s):  
R. S. Mathur ◽  
N. Wiqvist ◽  
E. Diczfalusy
Keyword(s):  
De Novo ◽  
De Novo Synthesis ◽  
Human Foetus
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