The effects of chloride ion on the production of acutumine and dechloroacutumine, by Menispermum dauricum root culture, were studied. The chloride ion content in the medium plays a key role in the production of both alkaloids. A low chloride medium promoted production of dechloroacutumine and suppressed that of acutumine. Production of the two alkaloids during the 60 day culture period was closely associated with root biomass. Both alkaloids accumulated in the roots and a relatively small proportion was exuded into the medium. The intact plant produced very low amounts of both alkaloids. On the average, cultured roots contained 22- and 75-fold more acutumine and dechloroacutumine, respectively, than intact plants. (C) 1999 Elsevier Science Ltd. All rights reserved.