title: A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: implications in measuring biological effects of arsenic compounds.
abstract: BACKGROUND
  Glutathione, a major cellular non-protein thiol (NPSH), serves a central role in repairing damage induced by cancer drugs, pollutants and radiation and in the detoxification of several cancer chemotherapeutic drugs and toxins. Current methods measure glutathione levels only, which require cellular extraction, rather than the glutathione recycling dependent antioxidant activity in intact cells. Here, we present a novel method using a bioactive probe of the oxidative pentose phosphate cycle, termed the OxPhos™ test, to quantify glutathione recycling dependent antioxidant activity in whole blood and intact human and rodent cells without the need for the isolation and cytoplasm extraction of cells.
  
  
  METHODS
  OxPhos™ test kit (Rockland Immunochemicals, USA), which uses hydroxyethyldisulfide (HEDS) as a probe for the oxidative pentose phosphate cycle, was used in these studies. The results with OxPhos™ test kit in human blood and intact cells were compared with total thiol and high pressure liquid chromatography/electrochemical detection of HEDS metabolism.
  
  
  RESULTS
  The OxPhos™ test measured glutathione-dependent antioxidant activity both in intact human and rodent cells and breast cancer patient's blood with a better correlation coefficient and biological variability than the thiol assay. Additionally, human blood and mammalian cells treated with various arsenicals showed a concentration-dependent decrease in activity.
  
  
  CONCLUSIONS
  The results demonstrate the application of this test for measuring the antioxidant capacity of blood and the effects of environmental pollutants/toxins. It opens up new avenues for an easy and reliable assessment of glutathione-dependent antioxidant capacity in various diseases such as stroke, blood borne diseases, infection, cardiovascular disease and other oxidative stress related diseases and as a prognostic indicator of chemotherapy response and toxicity. The use of this approach in pharmacology/toxicology including screening drugs that improve the glutathione-dependent antioxidant capacity and not just the glutathione level is clinically relevant since mammalian cells require glutathione dependent pathways for antioxidant activity.
authors.affiliation: Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA.
authors.forename: Donglan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA; Department of Biological Sciences, Drexel University, Philadelphia, PA 19104, USA.
authors.forename: Pearl A
authors.initials: PA
authors.lastname: Jefferson
authors.affiliation: Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Ward
authors.affiliation: Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood PA 19096 USA; Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA. Electronic address: iraayene@hotmail.com.
authors.forename: Iraimoudi S
authors.initials: IS
authors.lastname: Ayene
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001152:Arsenicals / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D016466:CHO Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D003412:Cricetulus; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction / Q000187:drug effects; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D013438:Sulfhydryl Compounds / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001152:Arsenicals; D013438:Sulfhydryl Compounds; D005978:Glutathione
keywords: Antioxidant activity; Arsenicals; Biomarker; Blood; DTNB; G6PD; GRase; GRx; GSH; GSSG; GST; Glutathione; Glutathione recycling; HEDS; Human cells; ME; NPSH; OPPC; OxPhos™ test; PSH; Total thiol; Toxins; dithiobisnitrobenzoic acid; glucose-6-phosphate dehydrogenase; glutaredoxin; glutathione; glutathione S-transferase; glutathione reductase; hydroxyethyldisulfide; mercaptoethanol; non-protein thiol; oxidative pentose phosphate cycle; oxidized glutathione; protein thiol