Growth and alkaloid production in Uncaria tomentosa cell suspension cultures were studied in Murashige and Skoog medium supplemented with 10 muM 2,4-dichlorophenoxyacetic acid, 10 muM kinetin, and 58 mM sucrose for maintenance and with 10 muM indole-3-acetic acid, 10,muM kinetin, and 58 mM sucrose for production. A U. tomentosa pale Uth-3 cell line, cultured in the production medium, showed a reduced lag phase and a specific growth rate (mu) of 0.27 day(-1), while cells growing in the maintenance medium showed mu = 0.20 day(-1). U. tomentosa cells growing in the production medium produced monoterpenoid oxindole alkaloids (MOA) in amounts of 10.2 +/- 1.6 mug g(-1) dry weight (DW). The chemical profile of MOA produced by in vitro cell cultures was similar to that found in the plant. After 10 subcultures, maximum MOA production decreased to 2.0 +/- 0.7 mug g(-1) DW, while tryptamine alkaloids (TA) were produced with a maximum of 6.2 +/-0.4,ug g(-1) DW. The increase of initial sucrose concentration up to 145 mM in the production medium enhanced the cell biomass by 3.2-fold (from 10.2 +/- 0.1 to 32.8 +/- 1.1 g DW L-1), reduced mu from 0.27 to 0.23 day(-1), and provoked a substantial accumulation of TA (23.1 +/-4.7 mug g(-1) DW). A high sucrose concentration stimulated MOA production in the maintenance medium (2.7 +/- 0. 5 mug g(-1) DW), even in the presence of 2,4-dichlorophenoxyacetic acid.