L-Carnitine is a calcium chelator: A reason for its useful and toxic effects in biological systems

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 as a Ca2+ chelator. The measurement was carried out spectrophotometrically 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 platelet aggregation, and decreasing sperm motility.