L-DOPA belongs to the category of dopamine precursors, serving as an orally active neurotransmitter metabolic precursor capable of crossing the blood-brain barrier and undergoing conversion to dopamine within the brain. The compound exhibits anti-hyperalgesic properties and finds application in Parkinson's disease research as well as in the induction of disease models.

Briefly, transfected HEK-293 cells, incubated in charcoal-treated Dulbecco's modified Eagle's medium for 24 h, are washed once with Hanks' solution and resuspended in a buffer containing 100 mM NaCl, 1 mM MgCl2, 1 mM EDTA, 1 mM EGTA, 250 mMsucrose, 20 mM Tris-HCl, pH 7.4. Cells are lysed by freezing in liquid nitrogen. Dehydrogenase activity is measured in a final volume of 20 μL containing the appropriate concentration of bile acid, 30 nCi of [3H]cortisol, and unlabeled cortisol to a final concentrations of 50 nM. The reaction is started by mixing cell lysate with the reaction mixture. Alternatively, endoplasmic reticulum microsomes are prepared from transfected HEK-293 cells and incubated with reaction mixture containing various concentrations of cortisol and CDCA. Incubation proceeded for 20 min, and the conversion of cortisol to cortisone is determined by thin layer chromatography (TLC). Because of the inaccuracy of the TLC method at low conversion rates and the end-product inhibition of 11βHSD2 at conversion rates higher than 60-70%, only conversion rates between 10 and 60% are considered for calculation. The inhibitory constant IC50 is evaluated using the curve-fitting program. Results are expressed as means±S.E. and consist of at least four independent measurements.

左旋多巴, Levodopa, 3,4-Dihydroxyphenylalanine

DMSO: Insoluble

H2O: 2.5 mM, Sonication is recommended.