BIOTRANSFORMATION OF BUTYLATED HYDROXYTOLUENE IN HAIRY ROOT CULTURES

''Hairy root'' cultures of the Asteraceae species Bidens sulphureus we re used to test the relationship between lipoxygenase and polyacetylen e biosynthesis. Butylated hydroxytoluene (BHT), a well known Lipid ant ioxidant, was incubated with the root cultures at 0.1-1.0 mM. Surprins ingly, the PI-IT-treated roots accumulated a single yellow compound ex tractable in chloroform. The product was identified as a dimeric stilb enequinone by high resolution mass spectrometry and nuclear magnetic r esonance. Hydroxylamine (1 mM) and KCN (0.01 mM) inhibited stilbenequi none formation by 40% and 60%, respectively. Stilbenequinone formation was also strongly inhibited when ascorbic acid (1 mM) or glutathione (1 mM) were added. These results suggest the involvement of free radic als in BHT biotransformation. In contrast, stilbenequinone formation w as stimulated 50% by a fungal elicitor prepared from the cell wall fil trate of Pythium aphanidermatum. Butylated hydroxytoluene could also b e converted to stilbenequinone in vitro using extracts of B. sulphureu s root cultures or horseradish peroxidase, supporting the involvement of this enzyme and free radicals. Butylated hydroxyanisole, an analog of BHT, was required for stilbenequinone formation in vitro. Stilbeneq uinone (0.69 mM) showed biological activity, inhibiting the growth of B. sulphureus and spinach seedlings, and stimulating the growth of the fungal pathogen Phytophthora drechsleri.