L-Citrulline

L-Citrulline is a non-proteinogenic alpha-amino acid, chemically (2S)-2-amino-5-(carbamoylamino)pentanoic acid — also written N5-carbamoyl-L-ornithine — with CAS 372-75-8, molecular formula C6H13N3O3 and molecular weight 175.19. It takes its name from the watermelon, Citrullus lanatus, from which it was first isolated. Unlike arginine, its side chain is a neutral ureide rather than a basic guanidine, so aqueous solutions sit close to neutral; this makes it considerably easier to work with in low-pH beverages, flavoured powders and effervescent systems where a strongly alkaline amino acid would otherwise have to be buffered. Bulk material is manufactured by microbial fermentation on non-GMO substrates rather than extracted from fruit, and is vegan and free of animal-derived inputs. Biochemically, L-citrulline is an intermediate of the urea cycle and is converted to L-arginine through the citrulline-arginine cycle by argininosuccinate synthase and argininosuccinate lyase, principally in the kidney. Because it is not a substrate for intestinal or hepatic arginase, it is routinely used by formulators as an alternative arginine source in amino acid systems. Typical applications are pre-workout and intra-workout powders, EAA and BCAA blends, ready-to-drink sports beverages, gels and shots, capsules and tablets, and clinical and medical nutrition products. No USP-NF or Ph. Eur. monograph exists for L-citrulline, so Thovek supplies it against an FCC-style food and nutraceutical specification: assay 98.0-102.0% on the dried basis, loss on drying not more than 0.5%, sulphated ash not more than 0.1% and heavy metals not more than 10 ppm as lead. Identity is confirmed by infrared absorption and HPLC retention against a reference standard, with assay by titration or HPLC. Each lot ships with a certificate of analysis covering related amino acids, residual solvents, heavy metals, pesticide screening and microbiological limits, together with Kosher, Halal, non-GMO, allergen and BSE/TSE-free declarations. Standard powder passes 40 mesh; 60 and 80 mesh grades are available for dry-blend uniformity.