Principal investigators: Iraimoudi S. Ayene, PhD; U. Margaretha Wallon, PhD
Restoring thiol homeostasis in cells is an imperative to recover from most oxidative stresses. Indeed, oxidative stresses are highly toxic when uncorrected by the natural thiol antioxidant systems present in the body. The most important thiol antioxidant molecule is glutathione (GSH). However, other protein and non-protein thiols contribute to maintaining overall thiol homeostasis. Thus, a simple metabolic test to monitor overall thiol redox status is needed. Addressing this need, LIMR researchers have developed a fast, accurate and inexpensive assay, the ThiOX test, that measures the overall thiol redox status of any biological specimen.
The stability of free thiol groups and disulfide bonds (dithiols) in proteins is essential to maintain proper protein function that, in turn, is vital for cell and tissue functions and homeostasis. ThiOX quickly and accurately measures the overall level of thiol oxidation in tissues, blood, cells or other biological sources, providing an overall determination of thiol antioxidant capacity in the specimen. The test is based on colorimetric detection of beta-mercaptoethanol produced by metabolic reduction of the added dithiol reporter compound hydroxyethyl disulfide.
Currently, there are no straightforward tests to monitor the overall thiol redox activity in a biological specimen. Methods to monitor GSH levels or activity alone are invasive and rely upon tissue extract preparations and complex biochemical methods. Furthermore, they may overestimate the extent of oxidative stress, since GSH depletion measured by biochemical assays may include GSH oxidation caused by cell/tissue extract preparation. ThiOX addresses the need of a rapid test to monitor thiol oxidative stress in live cells and tissues.
The ThiOX test enables research on the role of thiol oxidation stress in metabolic pathology, but it also provides a tool to study thiol redox status as a biomarker of disease states or clinical responses. This test reveals evidence of a natural variation in thiol antioxidant capacity in humans (1). In one application of this discovery, this natural variation appears to predict sensitivity to delayed nausea in cancer patients receiving chemotherapy (2).
Overall, ThiOX offers a simple metabolic test to explore the role of thiol redox stress in health and disease, including in cancer metabolism and ischemic pathology.
Intellectual property positions
Method of determining cell number or viability using hydroxyethyldisulfide. U.S. Patent No. 8,697,391 (issued 15 April 2014).
Methods and kits for measuring toxicity and oxidative stress in live cells. U.S. Patent No. 9,766,226 (issued 19 Sept 2017)
1. Li J, Zhang D, Jefferson PA, Ward KM and Ayene IS. (2014). A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: implications in measuring biological effects of arsenic compounds. J Pharmacol Toxicol Methods 69;39-48.
2. Li J., Ward KM, Zhang D, Dayanandam E, DeNittis AS, Prendergast GC and Ayene IS. (2013). A bioactive probe of the oxidative pentose phosphate cycle: novel strategy to reverse radioresistance in glucose deprived human colon cancer cells. Toxicol In Vitro 27;367-77.