L-Citrulline

L-Citrulline Uses, Dosage, Side Effects, Food Interaction and all others data.

L-Citrulline is an amino acid. It is made from ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from arginine as a by-product of the reaction catalyzed by NOS family. Its name is derived from citrullus, the Latin word for watermelon, from which it was first isolated.

A non-essential amino acid and a precursor of arginine. L-Citrulline supplements have been claimed to promote energy levels, stimulate the immune system and help detoxify ammonia (a cell toxin). L-citrulline is made from L-ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from L-arginine as a by-product of the reaction catalyzed by the enzyme NO synthase. L-citrulline, while being an amino acid, is not involved in protein synthesis and is not one of the amino acids coded for by DNA. Although citrulline cannot be incorporated in proteins during protein synthesis, several proteins are known to contain citrulline as an amino acid. These citrulline residues are generated by a family of enzymes called peptidylarginine deiminases (PADs), which convert the amino acid arginine into citrulline. Proteins that contain citrulline residues include myelin basic protein (MBP), fillagrin and several histone proteins.

Trade Name L-Citrulline
Availability Over the counter
Generic Citrulline
Citrulline Other Names Citrulina, Citrulline, L-Citrulline
Related Drugs acetylcysteine, biotin, Vitamin C, ascorbic acid, multivitamin, Zinc
Type
Formula C6H13N3O3
Weight Average: 175.1857
Monoisotopic: 175.095691297
Groups Investigational, Nutraceutical
Therapeutic Class
Manufacturer
Available Country
Last Updated: September 19, 2023 at 7:00 am
L-Citrulline
L-Citrulline

Uses

Used for nutritional supplementation, also for treating dietary shortage or imbalance.

L-Citrulline is also used to associated treatment for these conditions: Nutritional supplementation

How L-Citrulline works

L-citrulline is converted to L-arginine by argininosuccinate synthase. L-arginine is in turn responsible for citrulline's therapeutic affects. Many of L-arginine's activities, including its possible anti-atherogenic actions, may be accounted for by its role as the precursor to nitric oxide or NO. NO is produced by all tissues of the body and plays very important roles in the cardiovascular system, immune system and nervous system. NO is formed from L-arginine via the enzyme nitric oxide synthase or synthetase (NOS), and the effects of NO are mainly mediated by 3',5' -cyclic guanylate or cyclic GMP. NO activates the enzyme guanylate cyclase, which catalyzes the synthesis of cyclic GMP from guanosine triphosphate or GTP. Cyclic GMP is converted to guanylic acid via the enzyme cyclic GMP phosphodiesterase.

NOS is a heme-containing enzyme with some sequences similar to cytochrome P-450 reductase. Several isoforms of NOS exist, two of which are constitutive and one of which is inducible by immunological stimuli. The constitutive NOS found in the vascular endothelium is designated eNOS and that present in the brain, spinal cord and peripheral nervous system is designated nNOS. The form of NOS induced by immunological or inflammatory stimuli is known as iNOS. iNOS may be expressed constitutively in select tissues such as lung epithelium.

All the nitric oxide synthases use NADPH (reduced nicotinamide adenine dinucleotide phosphate) and oxygen (O2) as cosubstrates, as well as the cofactors FAD (flavin adenine dinucleotide), FMN (flavin mononucleotide), tetrahydrobiopterin and heme. Interestingly, ascorbic acid appears to enhance NOS activity by increasing intracellular tetrahydrobiopterin. eNOS and nNOS synthesize NO in response to an increased concentration of calcium ions or in some cases in response to calcium-independent stimuli, such as shear stress. In vitro studies of NOS indicate that the Km of the enzyme for L-arginine is in the micromolar range. The concentration of L-arginine in endothelial cells, as well as in other cells, and in plasma is in the millimolar range. What this means is that, under physiological conditions, NOS is saturated with its L-arginine substrate. In other words, L-arginine would not be expected to be rate-limiting for the enzyme, and it would not appear that supraphysiological levels of L-arginine which could occur with oral supplementation of the amino acid would make any difference with regard to NO production. The reaction would appear to have reached its maximum level. However, in vivo studies have demonstrated that, under certain conditions, e.g. hypercholesterolemia, L-arginine could enhance endothelial-dependent vasodilation and NO production.

Food Interaction

No interactions found.

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