Biologically Important Thiols in Various Vegetables and Fruits

Abstract

Biological thiols are important antioxidants, and recent studies showed that their contents vary depending on the groups of foodstuffs. Therefore, we investigated the levels of some biological thiols in various vegetables and fruits by using a sensitive high-performance liquid chromatography (HPLC) technique. Biological thiols measured in some vegetables and fruits include glutathione (L-glutamyl-L-cysteinly glycine, GSH), N-acetylcysteine (NAC), captopril [CAP (C9H15NO3S)], homocysteine (HCYS), cysteine (CYS), and gamma-glutamyl cysteine (GGC). Our results show that biological thiol contents are between 3-349 nM/g wet weight in vegetables and 4-136 nM/g wet weight in fruits. CAP is only found in asparagus (28 nM/g wet weight). Furthermore, none of the biological thiols analyzed were found in cabbages, red grapes, blackberries, apples, and peaches. Therefore, various vegetables and fruits differ significantly in their thiol contents. Oxidation of these important thiols may occur and result in the production of toxic byproducts, if they are exposed to radiation and ozone treatment for sterilization purposes. Further studies should be performed to monitor the levels of these biological thiols.

Biothiols, Taurine, and Lipid-Soluble Antioxidants in the Edible Pulp of Sicilian Cactus Pear (Opuntia ficus-indica) Fruits and Changes of Bioactive Juice Components upon Industrial Processing

“…The red and white cultivars were found to contain about one-half this concentration. While NAC was not found, cysteine levels, without any substantial difference among the cultivars, appeared higher than those reported for the above-mentioned fruits (25). Lipid-soluble compounds such as tocopherols and carotenoids have appeared in lower concentrations than other antioxidants of the cactus pear fruit.…”

“…This work reports that the fruit pulp from Sicilian cultivars contains other antioxidant molecules such as biothiols, which are fundamental to the cell antioxidative defense (36,37). GSH, cysteine, and NAC have recently been measured in a number of fruits (25). The yellow cultivar of the Sicilian cactus pear exhibits GSH amounts as high as 263.59 nmol/g edible pulp, which is higher than those in mango, strawberry, grapefruit, and papaya (25).…”

“…GSH, cysteine, and NAC have recently been measured in a number of fruits (25). The yellow cultivar of the Sicilian cactus pear exhibits GSH amounts as high as 263.59 nmol/g edible pulp, which is higher than those in mango, strawberry, grapefruit, and papaya (25). The red and white cultivars were found to contain about one-half this concentration.…”

Impact of Food Disinfection on Beneficial Biothiol Contents in Vegetables

“…The chemical structure, molecular formula, molecular weight, and CAS number of these biothiols and GSSG, the primary oxidation product of GSH, are summarized in Table 1. Our recent work has shown, for example, that the biothiol contents ranged from 3 to 349 nmol/g (wet weight) in a variety of vegetables (43).…”

Oxidative hemolysis of erythrocytes

“…It is believed that the cysteine -SH group works as a free radical scavenger, whereas the methionine residue acts as a metal chelator [13]. N-Acetylcysteine is a naturally occurring thiol compound found in some vegetables including garlic and onion [14]. N-Acetylcysteine is commonly used as an antioxidant [15] and mucolytic [16] drug.…”