The vitamins
Geoffrey P. Webb in Nutrition, 2019
Vitamin B6 is a precursor of the important coenzyme pyridoxal phosphate. This coenzyme is essential in many biochemical reactions particularly those involving the metabolism of amino acids. Some of the reactions/pathways where pyridoxal phosphate acts as a coenzyme are the following. Transamination reactions – transfer of amino groups to produce non-essential amino acids. Decarboxylation of amino acids e.g. to produce the nerve transmitters GABA, histamine, dopamine and 5HT (serotonin). The synthesis of niacin from tryptophan. The breakdown of glycogen by the enzyme glycogen phosphorylase. The synthesis of the haem component of haemoglobin.
Osteoporosis: assessment, diagnosis and management
Rajan Madhok, Hilary Capell in The Year in Rheumatic Disorders Volume 4, 2004
Animal studies have suggested that statins can significantly increase bone formation rates by increasing expression of bone morphogenetic protein-2 (BMP-2). These drugs act by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, an enzyme in the mevalonate pathway, and significantly reduce serum cholesterol by inhibiting hepatic cholesterol biosynthesis. Recent data indicate that in vitro the statins also inhibit osteoclast bone resorption and that this is directly related to the level of inhibition of HMG-CoA reductase |13|. Concurrently with these findings the mechanism of action of the bisphosphonates has gradually been explained and it is now known that the N2-containing bisphosphonates cause osteoclast apoptosis due to inhibition of farnesylpyrophosphate synthase and isopentenyl diphosphonate isomerase enzymes also within the mevalonate pathway |14|. These two avenues of research have led to the postulate that the statins may have a
Atherosclerosis
George Feuer, Felix A. de la Iglesia in Molecular Biochemistry of Human Disease, 2020
Many other drugs have also been tested in the management of hyperlipidemias.22,243,423,674 Nicotinic acid has been used successfully by a large number of investigators. There are several suggestions for its mechanism.11,175,228,430,447,489 Cholesterol synthesis requires CoA and nicotinic acid may reduce the amount of the available coenzyme for cholesterol production. Nicotinic acid dilates blood vessels and increases circulation; its competition with nicotinamide nucleotides and participation in cholesterol biosynthesis, or its effects on cyclic AMP production provide some explanation for its actions. Considering the results of many attempts to synthesize a potent antiatherosclerotic drug which blocks cholesterol synthesis, transport, and deposition into the vessels, as well as the results of many trials, successes, and failures of atherosclerosis therapy, it may be that combination treatments may provide a better way of controlling the disease (Figure 40).
Protective effect of dexpanthenol against methotrexate-induced liver oxidative toxicity in rats
Published in Drug and Chemical Toxicology, 2023
Mukaddes Gürler, Engin Burak Selçuk, Beyza Güzide Özerol, Kevser Tanbek, Elif Taşlıdere, Azibe Yıldız, Fatma Hilal Yağın, Elif Gürel
Dexpanthenol or D-(+)-Panthenol (Dex) is a familiar therapeutic agent in dermatology, where experimental and clinical studies revealed its favorable effect on wound healing by triggering fibroblast proliferation (Augustin et al.2019, Heise et al.2019, Gorski et al.2020, Saez-Alcaide et al.2020, Kutlu and Metin 2021). Recently, authors investigated Dex performance on different aspects including nerve injury, sepsis, corneal infection, dry nose, diabetic nephropathy, and many other pathologies especially related with oxidative damage (Tutun et al.2019, Korkmaz et al.2020, Kose et al.2020, Mencucci et al.2020, Thieme et al.2020). Dex is a monocarboxylic acid amide ((2 R)-2.4-Didydroxy-N-(3-hydroxypropyl)-3,3-dimethylbutanamid), and an alcohol derivative of pantothenic acid (vitamin B5). It is essential for the synthesis of coenzyme A (CoA), thus playing a role primarily in lipid metabolism, but also has many other biochemical effects in different sides of metabolism including cell growth, energy generation, and neurotransmitter synthesis (Sanvictores and Chauhan 2020). It supports the cellular defense system against oxidative stress and inflammatory attacks by increasing reduced glutathione and antioxidant enzymes (Ucar et al.2018).
A metabolomic study on the anti-depressive effects of two active components from Chrysanthemum morifolium
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Tong Liu, Ning Zhou, Ruihao Xu, Yangang Cao, Yanli Zhang, Zhen Liu, Xiaoke Zheng, Weisheng Feng
Niacin is one of the 13 essential vitamins, and it can be converted to nicotinamide in the human body [38]. Niacin deficit symptoms include several nervous system pathologies, such as dementia and depression, as well as other symptoms resembling those observed in other neurodegenerative diseases [39]. In our study, a low level of niacin in depressed mice was detected. After the administration of Chr and its two active components, the level of nicotinuric acid increased significantly. In terms of energy metabolism, nicotinamide and phosphoribosyl- pyrophosphate combine to generate nicotinamide mononucleotide, which can continue to react with adenosine triphosphate (ATP) to generate coenzyme I. The generation of coenzyme II (NADP) is the result of the combination of coenzyme I and ATP. Coenzyme I and coenzyme II are coenzymes of dehydrogenase and indispensable substance transfer carriers in the human body that participate in the process of lipid metabolism and saccharide anaerobic decomposition. The symptoms of energy deficiency or fatigue in patients with major depression have been described above [36]. Chr and its two active components could increase the level of nicotinuric acid. Furthermore, as a direct metabolite of niacin, the level of nicotinuric acid increased after Chr/Nar/Api treatment, indicating that more niacin exerts its biological activity in the body. Thus, Chr/Nar/Api improved the energy supply by accelerating the niacin and niacinamide metabolism in depressed mice.
Microbial vitamin production mediates dietary effects on diabetic risk
Published in Gut Microbes, 2022
Daoming Wang, Van T. Pham, Robert E. Steinert, Alexandra Zhernakova, Jingyuan Fu
Both SCFAs and vitamins are beneficial metabolites for humans, and there is a close relationship between microbial vitamin production and fecal SCFA levels. SCFAs and vitamins are crucial participants in host energy metabolism and act in the metabolic interface of host–microbe interaction. SCFAs are mainly derived from non-digestible carbohydrates; they are produced by commensal bacteria in the gut and can be further converted to glucose. Glucose-derived pyruvates can be converted to acetyl-coenzyme A, which is the main input of the tricarboxylic acid (TCA) cycle. Most B group vitamins are necessary participants in a series of biochemical reactions that are part of the TCA cycle and directly contribute to energy metabolism.49 Vitamin B12, for example, can accelerate the metabolic rate of gut bacteria and further increase the level of SCFAs in the intestine, especially butyrate and propionate,50 and we also observed positive associations between vitamin B12 biosynthesis pathways and SCFAs including acetate, butyrate, and propionate. As gut bacteria are essential players in the production of SCFAs and vitamins, the coupling of SCFAs and vitamins in the energy metabolism process highlights the importance of microbiome-targeting interventions for the maintenance and improvement of host energy production.
Related Knowledge Centers
- Cofactor
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- Substrate
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