Many types of pulp and paper mill effluents have the ability to induce
mixed-function oxygenase (MFO) activity and
vitellogenin (VTG)
protein in exposed male fish. The search for the compounds responsible for MFO induction has led to several classes of compounds, among them
retene and
stilbenes. The objective of this study was to investigate the
biological activities of candidate
stilbene compounds. Three
stilbenes,
3,5-dihydroxystilbene (
pinosylvin; P1), 3-hydroxy-5-methoxystilbene (P2), and
3,5-dimethoxystilbene (P3), were extracted from Scotch pine (Pinus sylvestris) and purified to evaluate their ability to induce MFO activity in vitro using
ethoxyresorufin-O-deethylase (
EROD) activity in a rat
hepatoma cell line (H4IIE). As these compounds may be chlorinated during pulp bleaching, chlorination of P2 was undertaken, producing di- and trichlorinated isomers (Cl-P2), which were also tested. Compounds were tested for
EROD-inducing ability in vivo by exposing juvenile rainbow tout (Oncorhynchus mykiss) to waterborne concentrations (0.010 to 1.0 mg/L) for 4 days. Compounds were also tested for their ability to induce VTG in trout primary liver cells in vitro. The
stilbenes were weak inducers of
EROD and VTG. H4IIE
EROD was induced by all four compounds, with the most potent induction by P3, followed by P1, the Cl-P2 mixture, and then P2. Induction for all four
stilbenes was from 3.13 × 10⁻³ to 3.57 × 10⁻⁴ as potent as
retene and about 1.11 × 10⁻⁵ to 1.20 × 10⁻⁶ as potent as
TCDD. Juvenile rainbow trout did not show
EROD induction after exposures to P1, P2, or the Cl-P2 mixture, whereas P3 caused activity fourfold above that of controls. P1, P3, and Cl-P2 all weakly induced VTG in rainbow trout hepatocytes. The most potent inducer of VTG was Cl-P2, followed by P3 and P1. The results show the ability of wood-derived
stilbenes to cause weak MFO induction in fish and in rat liver cells and to weakly induce
vitellogenin in fish liver cells.