Glutathione and Cyst(e)ine Profiles of Vegetables Using High Performance Liquid Chromatography with Dual Electrochemical Detection

Glutathione (GSH) is a key antioxidant of cells with many essential metabolic functions. Our research in humans led to the conclusion that high GSH levels are related to longevity and health. Enhanced tissue levels resulting from dietary GSH and its precursors suggested its role as a nutrient. Thus, the present objective was to determine in vegetables the concentration profiles of GSH and cyst(e)ine (Cys), its primary amino acid precursor. Thirty-two vegetables were commercially obtained and analyzed using HPLC with dual electrochemical detection for the simultaneous determination of GSH, Cys, and their oxidized forms. The results indicated that brussel sprouts had the highest concentrations oftotal GSHwith 112 μmol/100 gfreshweight, followed by asparagus top, broccoli flower, cabbage core, and asparagus bottom. On adryweight basis, the highest levels were found in broccoli stem and flower, asparagus bottom, brussel sprouts, and cabbage core.Total Cyslevels were highest in brussel sprouts, kale, cauliflower, cabbage core, and green pepper. However, GSH was undetected in iceberg lettuce, and Cys in celery. Contrary to an assumption that GSH would be increased with high Cys levels, GSH and Cys in the vegetables were not correlated based on eitherfreshweight (r2= 0.334) ordryweight (r2= 0.037).