Absolute oral bioavailability and metabolic turnover of β-sitosterol in healthy subjects.

The metabolic turnover, absolute oral bioavailability, clearance, and volume of distribution for β-sitosterol were measured in healthy subjects. [(14)C]β-Sitosterol was used as an isotopic tracer to distinguish pulse doses from dietary sources and was administered by both oral and intravenous routes. The administered doses of [(14)C]β-sitosterol were in the region of 3 to 4 μg, sufficiently low as not to perturb the kinetics of β-sitosterol derived from the diet.

Interlaboratory assessment of the GreenScreen HC GADD45a-GFP genotoxicity screening assay: an enabling study for independent validation as an alternative method.

Sixteen coded compounds were blind-tested at 4 laboratories using the recently described GADD45a-GFP genotoxicity assay. The compounds were chosen to include non-genotoxic compounds as well as weak and strong genotoxins. None of the compounds required metabolic activation in order to exhibit genotoxic effects.