In vitro activity: It has been repoted that isatin treatment at 1-400 μM for 24h could induce a significant dose-dependent increase in MTT metabolism by SH-SY5Y cells, which was not due to the increase in cell division. In addition, isatin at the higher concentrations was able to trigger cell death, though MTT metabolism was still increased, indicating that the surviving cells were hypermetabolic. With a longer treatment, isatin was found to cause cell death in a dose-dependent manner, and the predominant mode of cell death was apoptosis at lower concentrations, while at the highest concentration increasing numbers of necrotic cells were also observed

Cell Assay: Cell viability was estimated by a colorimetric method, which is based on the ability of cellular dehydrogenases of viable cells to reduce MTT from a yellow watersoluble dye to a dark blue insoluble formazan product. SHSY5Y cells were seeded in 96-well plates at 4×104 cells/well/(100 ml) and allowed to attach. The cells were then treated with isatin and returned to the incubator for 24 or 48 h. MTT 25 μl (5 mg/ml) was added to all wells and allowed to incubate in the dark at 37℃ for 2 h followed by cell lysis. The plates were read with an OPTImax microplate reader at wavelength of 562 nm. Controls included untreated cells and medium alone, with all MTT assays performed in triplicate.

Neurochem Int. 2005 Aug;47(3):216-24; Neurotoxicology. 2004 Jan;25(1-2):205-13.