At the level of the central nervous system an aqueous extract of the marine microalga Chlorella stigmatophora (Butcher) (Chlorophyceae) showed anti-dopaminergic-type activity in assays of its effects on spontaneous motor response, rectal temperature, motor coordination, amphetamine-induced hypermotility, exploratory conduct, muscle relaxation, catalepsy, conditioned avoidance responses, oxotremorine-induced cholinergic syndrome, and pentylenetetrazole-induced convulsions.