title: L-carnitine is a calcium chelator: a reason for its  useful and toxic effects in biological systems.
abstract: BACKGROUND
  Investigation of the direct link between l-carnitine (LC), a quaternary ammonium compound that facilitates the passage of unsaturated fatty acids into the mitochondrial matrix, and free calcium (Ca2+) is needed to explain a number of varying results obtained from different in vitro and in vivo studies of LC as a supplement.
  
  
  METHODS
  The chemical structure of LC, which contains oxygen ligand atoms, prompted to measure its activity asa Ca2+ chelator. The measurement was carried out spectrophotometri cally by measuring the reduction in the formation of Ca2+-o-cresolphthalein complexone (Ca-CPC) in the presence of different doses of LC (0.075, 0.75, and 7.5 mM) compared to the control (0.0 mM LC).
  
  
  RESULTS
  The effect of LC was measured as a free entity in solution and when added to human serum. Our results showed a significant decrease (p < 0.05) in the average absorbance of Ca-CPC in the presence of LC compared to the control.
  
  
  CONCLUSIONS
  In conclusion, LC exhibits a significant Ca2+ chelating activity. As Ca2+ is vital in the biochemical and physiological processes of living cells, LC could be affecting the calcium-dependent biological systems by limiting the levels of free Ca2+. Examples include decelerating the blood clotting process, amplifying the effect of anticoagulants, reducing nitric oxide synthase activity, inhibiting
authors.forename: Saleem Ali
authors.initials: SA
authors.lastname: Banihani
authors.forename: Mekki
authors.initials: M
authors.lastname: Bayachou
authors.forename: Karem
authors.initials: K
authors.lastname: Alzoubi
mesh_terms: D002118:Calcium / Q000378:metabolism*; D065096:Calcium Chelating Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D002331:Carnitine / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D006801:Humans; D010635:Phenolphthaleins / Q000378:metabolism
chemical_list: D065096:Calcium Chelating Agents; D010635:Phenolphthaleins; C017845:2-cresolphthalexon; D002331:Carnitine; D002118:Calcium