Absorption of Aminoethyl Cysteine Ketimine Decarboxylated Dimer in Mice: Effect on Plasma Antioxidant Potential

Abstract

Aminoethylcysteine ketimine decarboxylated dimer (AECK-DD) is a natural compound with antioxidant properties of a new family of sulfur-containing amino acids. It has been detected in human urine and plasma, in mammalian cerebellum, and in dietary vegetables. In this study, we first demonstrate the absorption of AECK-DD in mice from AECK-DD-supplemented diet, using both liquid chromatography with electrochemical detection and gas chromatography coupled with mass spectrometry. AECK-DD circulates in the plasma of supplemented mice at a micromolar concentration and is incorporated in liver tissue. The absorption of AECK-DD is dose dependent. The dehydrogenation product of AECK-DD was also identified in plasma and liver of mice fed the AECK-DD-supplemented diet. A significant increase in plasma antioxidant potential was measured in mice fed AECK-DD-supplemented diet with respect to mice fed the control diet. These results demonstrate for the first time the absorption of AECK-DD from diet and the physiological relevance of this compound through its antioxidant action in vivo.

Comment on Absorption of Aminoethyl Cysteine Ketimine Decarboxylated Dimer in Mice: Effect on Plasma Antioxidant Potential

“…As discussed by Piazzon et al, AECK-DD has been reported to be present at micromoles per liter concentrations in normal human plasma, normal human urine and bovine cerebellum . Here, we wish to compare these published results with our previous findings.…”

“…Interestingly, Piazzon et al were able to detect this compound in the plasma of mice fed 0.05% AECK-DD in the diet for 24 h. The concentration of dehydro-AECK-DD was not specified, but from a comparison of the intensity of the AECK-DD peak to that of the dehydro-AECK-DD peak in the GC-SIM-MS chromatographic profile shown by the authors (Figure 3 in ref ), we estimate that the concentration of dehydro-AECKK-DD in the plasma was about 10% that of AECK-DD. The authors also reported a significant increase in the plasma antioxidant activity in the mice fed AECK-DD in the diet compared to that observed in the plasma of mice fed standard laboratory chow . The authors conclude in the last sentence of their abstract that “These results demonstrate for the first time the absorption of AECK-DD from [the] diet and the physiological relevance of this compound through its antioxidant action in vivo.” However, we have several reservations concerning the physiological relevance of the results reported by Piazzon et al…”

“…These dosages correspond to 3.5 mg (15.4 μmol) and 14.0 mg (61.4 μmol) of AECK-DD per day and per mouse, respectively. The levels of hepatic AECK-DD in these animals were reported to be 150.5 ± 12.0 and 432.0 ± 45.0 ng/g liver, respectively, which translates to approximately 0.83 and 2.4 μmol/L, respectively, assuming a water content of about 80%. Previous work has shown that AECK-DD is an antioxidant, comparable to α-tocopherol and even more potent than ascorbate and glutathione .…”

“…Previous work has shown that AECK-DD is an antioxidant, comparable to α-tocopherol and even more potent than ascorbate and glutathione . The compound resulting from oxidation (dehydrogenation) of AECK-DD (named dehydro-AECK-DD by Piazzon et al) is shown in Figure B. Interestingly, Piazzon et al were able to detect this compound in the plasma of mice fed 0.05% AECK-DD in the diet for 24 h. The concentration of dehydro-AECK-DD was not specified, but from a comparison of the intensity of the AECK-DD peak to that of the dehydro-AECK-DD peak in the GC-SIM-MS chromatographic profile shown by the authors (Figure 3 in ref ), we estimate that the concentration of dehydro-AECKK-DD in the plasma was about 10% that of AECK-DD.…”

“…The compound resulting from oxidation (dehydrogenation) of AECK-DD (named dehydro-AECK-DD by Piazzon et al) is shown in Figure B. Interestingly, Piazzon et al were able to detect this compound in the plasma of mice fed 0.05% AECK-DD in the diet for 24 h. The concentration of dehydro-AECK-DD was not specified, but from a comparison of the intensity of the AECK-DD peak to that of the dehydro-AECK-DD peak in the GC-SIM-MS chromatographic profile shown by the authors (Figure 3 in ref ), we estimate that the concentration of dehydro-AECKK-DD in the plasma was about 10% that of AECK-DD. The authors also reported a significant increase in the plasma antioxidant activity in the mice fed AECK-DD in the diet compared to that observed in the plasma of mice fed standard laboratory chow .…”