Why is it important to track GSH fluctuation?
Chemotherapy is currently the main treatment for cancer, but tumor cells may develop resistance to chemotherapy regimens. Drug resistance is mediated by multiple factors, among which, high levels of glutathione (GSH) is surmised to be a major contribution. To reveal the detailed role of GSH in drug resistance, it is essential to find a reliable assay for the determination of GSH levels in live cells.
Na-8 is suitable for GSH detection
The poor conjugation and resonance of electron-deficient C(2p)- with the S(3p) lone pair on Na-8, makes the bond highly susceptible to undergo “click chemistry” with nucleophiles such as the thiols on GSH molecules. Dr. Xin Li’s Group constructed a small library of probes that have aryl sulfides attached to the electron-deficient 4-position of the 1,8-naphthalimide fluorophore. Of the compounds generated, probe Na-8 gave the most dramatic fluorogenic response, suitable for tracking endogenous GSH fluctuation in live cells.
Fig. 1. Detection Principle, thiol of GSH reacts efficiently with Na-8
Probe Na-8 advantages
- High Degree of Sensitivity: the maximum fluorescence enhancement with GSH is 2200 times, and has a low detection limit of 25 nM.
- High Degree of Specificity: biological Cys and Hcy would cause little interference to GSH detection.
- Applicable to live cell imaging: Na-8 is membrane permeable, reacts efficiently with GSH. Intracellular Na-8 fluorescence enhancement was demonstrated in HepG2 cells
Fig. 2. 10 uM of Na-8 in hepatocellular carcinoma HepG2 cells showed significantly stronger fluorescence in the cells treated with 1mM of GSH
- Also Applicable in Acidic Environments:the environmental pH in the range of 6.5–10 causes little interference to GSH detection. This is particularly important for tumor tissue microenvironment with extracellular pH of 6.5–6.9.
- Also Applicable in Acidic Environments:the fluorescence response reaches the maximum (Fmax) when GSH concentrations are higher than 3.0 mM, and the natural logarithm of Fmax minus the fluorescence intensity (F) correlats linearly with GSH concentrations ranging from 0 to 3.0 mM.
Fig 3. Relationship observed for ln(Fmax − F) vs. GSH concentration can be fitted linearly. Na-8 could be used to quantify GSH from 0-3 mM
Reference
Jiang, Yuejing, Juan Cheng, Chengyu Yang, Yongzhou Hu, Jia Li, Yifeng Han, Yi Zang, and Xin Li. "An ultrasensitive fluorogenic probe for revealing the role of glutathione in chemotherapy resistance." Chemical science 8, no. 12 (2017): 8012-8018.
J&K Scientific exclusively offers the fluorescent probe Na-8 developed by Dr. Xin Li.
Dr. Li’s Profile
She worked with Prof. E.J. Corey at Harvard University during 2011-2013. She is currently engaged in pharmaceutical chemistry research at Zhejiang University. Tackling the challenge in in-situ detection of biomolecules, her group designs fluorescent probes as sensitive and reliable detection tools and develop techniques for in-depth study of molecular mechanisms in pathological processes. So far, this work has been granted 3 invention patents.
