Detection of endocrine-modulating effects of the antithyroid acting drug 6-propyl-2-thiouracil in rats, based on the "Enhanced OECD Test Guideline 407".

The antithyroid acting drug propylthiouracil (PTU) was administered to male and female Wistar rats at 0, 0.1, 1, or 10mg/kg body weight for 4 weeks according to the draft protocol of the "Enhanced OECD Test Guideline 407" (enhanced TG 407) in order to investigate its suitability to detect endocrine-mediated effects. The study was conducted with two identical subsets of five animals per sex and dose each to provide data on sensitivity.

Potential mechanisms of benzamide riboside mediated cell death.

Benzamide riboside (BR) after anabolism to an analogue of NAD, was shown to inhibit the activity of NAD-dependent enzymes such as inosine 5'-monophosphate dehydrogenase (IMPDH), the rate limiting enzyme in de novo guanylate biosynthesis, and malate dehydrogenase which is involved in the citric cycle and respiratory chain. BR exhibits strong anti-carcinogenic effects due to growth retardation and due to induction of apoptosis and necrosis. Apoptosis is ascribed to the inhibition of IMPDH because cell death can be blocked by restoring intracellular guanylate metabolism by the addition of guanosine.

Maintenance of ATP favours apoptosis over necrosis triggered by benzamide riboside.

A new synthetic drug, benzamide riboside (BR) exhibited strong oncolytic activity against leukemic cells in the 5-10 microM range. Higher BR-concentrations (20 microM) predominantly induced necrosis which correlated with DNA strand breaks and subsequent depletion of ATP- and dATP levels. Replenishment of the ATP pool by addition of adenosine prevented necrosis and favoured apoptosis.