TY - JOUR
T1 - Status of glutathione and other thiols and disulfides in human plasma
AU - Kleinman, Wayne A.
AU - Richie, John P.
N1 - Funding Information:
We thank Lisa Skowronski and Patricia Abraham for their technical assistance and Marie-Ange Brunnemann for assisting in the preparation of this manuscript. This research was supported by USPHS Grants CA17613, CA68384, and AG14102.
PY - 2000/7
Y1 - 2000/7
N2 - While plasma thiols, including homocysteine (HCys), glutathione (GSH), and cysteine (Cys), are being investigated as potential indicators of disease risk and health status, low levels, poor stability, and the lack of comprehensive methodologies have hampered their accurate assessment. Using our previously described HPLC with electrochemical detection method, our goal was to assess levels, stability, and distribution of biologically relevant thiols and disulfides in human plasma. In fresh plasma, processed immediately after collection, low levels of Cys, cystine, Cys-Gly, and the mixed disulfide Cys-GSH (CSSG) were consistently observed, whereas the levels of GSH and Cys-Gly disulfide were often below the limits of detection. These profiles were a consequence of poor thiol stability, as thiol standards added to human plasma were lost rapidly due to autoxidation or formation of mixed disulfides. A 75% loss of added GSH observed after 30 min was accounted for completely by the formation of GSH disulfide (24%) and CSSG (74%). Similar changes were found with other thiols when added to plasma. Thiols lost to oxidation were recovered quantitatively by reducing samples with potassium borohydride (KBH4) prior to analysis. In a study of 106 healthy adults, mean total thiol levels in plasma were: Cys (201 μM) > Cys-Gly (101 μM) > HCys (7 μM) > γ-Glu-Cys (5 μM) > GSH (4 μM). All together, these results account for the poor stability of thiols in plasma and provide a method for their comprehensive and accurate determination. Copyright (C) 2000 Elsevier Science Inc.
AB - While plasma thiols, including homocysteine (HCys), glutathione (GSH), and cysteine (Cys), are being investigated as potential indicators of disease risk and health status, low levels, poor stability, and the lack of comprehensive methodologies have hampered their accurate assessment. Using our previously described HPLC with electrochemical detection method, our goal was to assess levels, stability, and distribution of biologically relevant thiols and disulfides in human plasma. In fresh plasma, processed immediately after collection, low levels of Cys, cystine, Cys-Gly, and the mixed disulfide Cys-GSH (CSSG) were consistently observed, whereas the levels of GSH and Cys-Gly disulfide were often below the limits of detection. These profiles were a consequence of poor thiol stability, as thiol standards added to human plasma were lost rapidly due to autoxidation or formation of mixed disulfides. A 75% loss of added GSH observed after 30 min was accounted for completely by the formation of GSH disulfide (24%) and CSSG (74%). Similar changes were found with other thiols when added to plasma. Thiols lost to oxidation were recovered quantitatively by reducing samples with potassium borohydride (KBH4) prior to analysis. In a study of 106 healthy adults, mean total thiol levels in plasma were: Cys (201 μM) > Cys-Gly (101 μM) > HCys (7 μM) > γ-Glu-Cys (5 μM) > GSH (4 μM). All together, these results account for the poor stability of thiols in plasma and provide a method for their comprehensive and accurate determination. Copyright (C) 2000 Elsevier Science Inc.
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U2 - 10.1016/S0006-2952(00)00293-8
DO - 10.1016/S0006-2952(00)00293-8
M3 - Article
C2 - 10807941
AN - SCOPUS:0034011876
SN - 0006-2952
VL - 60
SP - 19
EP - 29
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 1
ER -
