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Micronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
The flavin coenzymes including flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) are derivatives of riboflavin (vitamin B2). Like the nicotinamide coenzymes, the flavin coenzymes participate in redox reactions that affect energy nutrients in the citric acid cycle and in the electron transport system.
Pharmacological actions of chemical constituents
Published in C. P. Khare, Evidence-based Ayurveda, 2019
Nonhydrolyzable tannins, also called condensed tannins, are most resistant to splitting. They are related to the flavonoid pigments such as flavins and catechin. When heated in acid they tend to polymerize to form a red insoluble substance called tannin red or phlobaphenes. The phlobaphenes give a characteristic red color to some plant tissues. The final breakdown product after heating all the condensed tannins is catechol.
Molecular Aspects of the Activity and Inhibition of the FAD-Containing Monoamine Oxidases
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Supported by extensive molecular model chemistry and recent thermodynamic calculations, three mechanisms have been considered for MAO catalysis: the polar nucleophilic mechanism (Orru et al., 2013), the radical (Silverman, 1995), and the hydride transfer mechanism (Kay et al., 2007). The hydride transfer mechanism (Fig. 10.5) is found in other oxidases and is supported by theoretical studies based on transition state theory (Vianello et al., 2016). However, the versatility of flavin catalysis could allow alternative mechanisms with specific chemicals, for example with the cyclopropylamines.
Gut microbiota-derived trimethylamine N-oxide is associated with the risk of all-cause and cardiovascular mortality in patients with chronic kidney disease: a systematic review and dose-response meta-analysis
Published in Annals of Medicine, 2023
Yachun Li, Hongmei Lu, Jing Guo, Meiling Zhang, Huijuan Zheng, Yuning Liu, Weijing Liu
The gut-kidney-heart axis in chronic kidney disease has gradually attracted extensive attention [4,5], that is, the accumulation of gut microbial-derived uremic toxins leads to the occurrence and development of CKD, and increases the risk of cardiovascular events in CKD. Trimethylamine-N-oxide (TMAO), derived from dietary intake of animal-derived choline, L-carnitine, and plant-derived betaine, is one of the uremic toxins that cause kidney-heart damage. When food is transported to the intestinal lumen, it is metabolized by the intestinal flora to produce trimethylamine (TMA), which is absorbed through the hepatic portal venous system and converted to TMAO by flavin-containing monooxygenase (FMO) [6,7]. As we all know, the number of microbes that colonize the human gastrointestinal tract is 10 times greater than the number of the host’s own somatic and germ cells [8], which defends against harmful substances and also produces absorbable nutrients. However, the gut flora in CKD patients becomes unbalanced and disordered [9–12]. It is confirmed that the abundance of TMA-producing gut microbiota is increased in patients with T2DM-CKD [13]. Under physiological conditions, circulating TMAO is excreted almost exclusively by the kidneys in the form of glomerular filtration and tubular secretion [7,14]. Thus, disruption of kidney function, together with dysbiosis of gut microbiota, leads to increased circulating TMAO concentrations in patients with CKD including end-stage kidney disease (ESKD) [15–17], which in turn exacerbates kidney damage by promoting inflammation [18–21].
Differential effects of C-reactive protein levels on voriconazole metabolism at three age groups in allogeneic hematopoietic cell transplant recipients
Published in Journal of Chemotherapy, 2021
Xingxian Luo, Taifeng Li, Lei Hu, Silu Liu, Haiyan Zhao, Jiaqi Zhang, Yufei Feng, Lin Huang
In the present study, the median concentration of VRCZ was highest in adults (1.48 mg/L), followed by children aged 10–18 (0.85 mg/L), and the lowest was children aged 2–10 years (0.65 mg/L), which were partly consistent with wei et al reported.10 Conversely, the order of the magnitude of the MR values was aged in 2–10 years (1.72), then in 11–18 years (1.21) and followed in 19–60 years (0.95), further verifying that metabolic rate of VRCZ exhibits negative relationship with age groups. Mann–Whitney U test suggested that MR values in 11–18 and 19–60 years were significantly lower in age 2–10 years (p < .05), indicating a higher activity of CYP2C19 enzyme in age 2–10 years. Existing evidence support that higher metabolic activity of flavin-containing monooxygenase 3 (FMO3) and CYP2C19 are found in children compared with adults.23 A higher metabolic intensity of VRCZ in younger children would reduce the impact of inflammation on liver microsomal enzyme activity. With the increase of age, the impact of inflammation on VRCZ metabolism seemed to be more and more prominent.
Flavin-containing monooxygenase 3 (FMO3): genetic variants and their consequences for drug metabolism and disease
Published in Xenobiotica, 2020
Ian R. Phillips, Elizabeth A. Shephard
Flavin-containing monooxygenases (FMOs; EC 1.14.13.8) catalyze the oxidative metabolism of a broad range of foreign chemicals, including therapeutic drugs and dietary-derived compounds (Krueger & Williams, 2005; Phillips et al., 2007; Phillips & Shephard, 2017). Much of our knowledge of the catalytic mechanism and substrate preferences of FMOs derives from the pioneering work of Dan Ziegler and colleagues (reviewed in Ziegler, 1993, 2002; Poulsen & Ziegler, 1995). For catalysis, FMOs require FAD as a prosthetic group, NADPH as a cofactor and molecular oxygen as a cosubstrate. Preferred substrates contain, as the site of oxygenation, a soft nucleophilic heteroatom, typically nitrogen or sulfur (Krueger & Williams, 2005). The mechanism of action of FMOs is unusual, as it enables the enzymes to activate oxygen, in the form of a stable C4a hydroperoxide derivative of FAD, in the absence of a bound oxygenatable substrate (Figure 1). Consequently, the enzymes are present in in an activated form capable of oxygenating any soft nucleophile able to gain access to the active site.