China
Africa
Explore chapters and articles related to this topic
Arsenals of Pharmacotherapeutically Active Proteins and Peptides: Old Wine in a New Bottle
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
6-N-methyllysine is obtained by transmethylation of lysine. Methylation of lysine is important in transcriptional regulation and double-strand break repair of DNA molecule in many organisms [7]. Post translation carboxylation of glutamic acid residues in proteins, results in γ-carboxyglutamate [8]. 4-hydroxyproline and 5-hydroxylysine, unusual amino acids, are an important part of collagen [6]. As these are not essential amino acids, they are synthesized by the organisms and not obtained from the diet. Desmosine is formed by four lysine molecules linked together forming a pyridinium ring. Desmosine helps in the cross-linking of elastin [9]. Ornithine is an important part of the urea cycle and the precursor of citrulline and arginine [10]. Norvaline is a component of antifungal peptides in bacteria. This unusual amino acid is also found to be present in recombinant proteins synthesized using bacterial cells [11].
paniculata (C.B. Clarke) Munir Leaves on Various Gastric Aggressive Factors
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
P. S. Sreeja, K. Arunachalam, Parimelazhagan Thangaraj
Nitric oxide (NO) is a gaseous mediator derived from L-arginine as a consequence of the action of a group of enzymes called nitric oxide synthases (NOS) to form L-citrulline and NO, and it possesses multiple physiological functions. The production of NO has paramount importance in the gastroprotection by preserving the integrity of the gastric epithelium and the mucus barrier. This powerful gas mediator acts as a vasodilator and increases the gastric blood. It also prevents the adhesion of leukocytes to the endothelial cells by acting on the modulation of adhesion molecules and regulates the secretion of hydrochloric acid; thus it assists in the healing of gastric ulcers (Breuillard et al. 2015; Costa et al. 2016).
Acute citrulline-malate supplementation is ineffective during aerobic cycling and subsequent anaerobic performance in recreationally active males
Published in European Journal of Sport Science, 2021
Joshua L. Gills, Jordan M. Glenn, Michelle Gray, Braden Romer, Hocheng Lu
One particular category of ergogenic aids that has recently increased in popularity involves those purported to increase nitric oxide (NO) production. NO is an important modulator of blood flow and mitochondrial respiration during physical exercise (Shen et al., 1994). It is also suggested that the increase in blood flow derived from NO synthesis may improve recovery processes of the activated tissue. However, it is challenging to supplement with NO itself because it is a gas with a short half-life (Bloomer, 2010). Thus, athletes and researchers have used intermediates to the NO pathway as potential supplements. One such precursor is L-arginine; however, when dietary L-arginine is consumed, it is metabolized in the liver reducing its bioavailability. Thus, alternatives for increasing NO bioavailability are being sought. L-citrulline is another NO intermediate that is directly converted to L-arginine, avoiding hepatic metabolism, theoretically making this substance more effective at increasing vasodilation resulting in enhanced athletic performance. L-citrulline – an organic compound and non-essential amino acid naturally found in watermelon – has been promoted as an effective and legal means of increasing athletic performance (Rimando & Perkins-Veazie, 2005).
Effect of citrulline malate supplementation on muscle function and bioenergetics during short-term repeated bouts of fatiguing exercise
Published in Journal of Sports Sciences, 2022
Laura Meimoun, Émilie Pecchi, Christophe Vilmen, David Bendahan, Benoît Giannesini
In this regard, citrulline malate (CM) has been shown to markedly improve muscle mechanical performance in weakened and healthy subjects. In asthenic rats, ingestion of doses of CM at 1 to 2.4 g/kg three times a day during 1 to 2 days extends running endurance during treadmill test (Verleye et al., 1995) and increases lower hindlimb muscle force in response to electrical stimulation (Giannesini et al., 2009; Goubel et al., 1997). Furthermore, chronic (15 days) oral supplementation with 6 g/day CM reduces the sensation of fatigue following repeated finger flexions in sedentary men suffering from asthenia after acute disease (Bendahan, 2002). In healthy rat, CM supplementation (3 g/kg/day during 48 h) produces an ergogenic effect in electrically stimulated gastrocnemius muscle in vivo (Giannesini et al., 2011). These beneficial effects would be mediated by changes in muscle bioenergetics. Because it is a precursor of nitric oxide, a compound known for its vasodilator properties, citrulline has been proposed to increase blood flow during and after exercise (Goubel et al., 1997; Verleye et al., 1995). This increased flow may in return improve oxygen and nutrient delivery to muscle, thereby enhancing the mitochondrial respiration (Brevetti et al., 2003; Tousoulis et al., 2012; Young et al., 1997). Citrulline is also involved in the urea cycle and could facilitate the elimination of by-products of energy metabolism generated during exercise, especially ammonium ions whose intramyoplasmic accumulation would slow down the oxidative ATP production by disrupting the NAD+/NADH ratio (Newsholme & Leech, 1983). In addition, malate is an intermediate of the Krebs cycle and its supplementation could accelerate the mitochondrial synthesis of ATP (Wagenmakers, 1998). Accordingly, an increased oxidative ATP production (Bendahan, 2002) and a reduced oxidative cost of contraction (Giannesini et al., 2011) have been previously reported during a single session of fatiguing exercise in healthy subjects supplemented with CM. Moreover, it is important to emphasize that the resynthesis of PCr during the post-exercise recovery period relies exclusively on oxidative ATP production (Arnold et al., 1984; Giannesini et al., 2002; Kemp et al., 1993). Collectively, these data suggest that CM supplementation accelerates the reconstitution of high-energy phosphorylated compounds reserves during the post-exercise recovery period, hence improving muscle function during any subsequent exercise.