propylthiouracil and benzylthiouracil

Thiocarbamides were converted to their di-N-pentafluorobenzyl (PFB) derivatives and analysed by gas chromatography/negative-ion chemical-ionization mass spectrometry with methane as reagent gas. The PFB derivatives of the 2-thiouracils gave mass spectra in which the ion current was carried largely by an ion arising from [M-PFB]-. The derivative was used in the determination of the uptake and metabolism of thiocarbamides by cultures of melanoma cells.

Topics: Gas Chromatography-Mass Spectrometry; Melanoma; Methimazole; Methylthiouracil; Propylthiouracil; Thiouracil; Tumor Cells, Cultured

The binding interactions of some thioureylene compounds to human serum albumin were studied in vitro by ultraviolet spectroscopy and equilibrium dialysis. Binding of 6-n-propyl-2-thiouracil, 6-n-benzyl-2-thiouracil and 2-thiouracil to human serum albumin results in a red shift of the ultraviolet absorption maximum, suggesting that the binding site is a hydrophobic area of the protein. Bindings of 6-n-propyl-2-thiouracil and 6-n-benzyl-2-thiouracil to human serum albumin are characterized by two classes of sites while 6-n-propyl-uracil and 2-thiouracil bind to one low-affinity binding site. In addition, an identification of those sites was performed by measuring the displacement of these drugs. The data show that the moderate-affinity site is common with the warfarin site while the low-affinity site is likely to be shared by benzodiazepines. It is concluded that the binding is enhanced by the hydrophobicity of the substituent in the thioureylene compounds, and it is further shown that thiol-group substitutions in the thioureylene ring will weaken the binding.

Topics: Antithyroid Agents; Diazepam; Humans; Propylthiouracil; Serum Albumin; Spectrophotometry, Ultraviolet; Thiouracil; Uracil; Warfarin