Gentiana verna L. subsp. pontica (Soltok.) Hayek, G. pyrenaica L., and G. verna L. subsp. balcanica Pritchard from Turkey were tested for their MAO-A inhibitory effects. A photometric peroxidase linked MAO-A bioassay performed on the H2O extracts prepared from the methanolic extracts of the title plants revealed the potential effect of G. verna subsp. pontica and three benzophenone glucosides; 2,3'-dihydroxy-4-methoxy-benzophenone-6-O-beta-glucopyranoside (1), 2,4,3',4'-tetrahydroxy-benzophenone-6-O-beta-glucopyranoside (maclurin-6-O-beta-glucopyranoside) (2) and 2,4,3'-trihydroxy-benzophenone-6-O-beta-glucopyranoside (3) isolated from G. verna subsp. pontica. Among the benzophenone glucosides 1 and 2 exhibited significant inhibition of MAO-A (IC50=31.3 +/- 4 mu M and 41 +/- 4.7 mu M resp.).