10E,12Z-9-Hydroxy-10,12-Octadecadiensäure, ein Aromatase-Hemmstoff aus dem Wurzelextrakt von Urtica dioica

(10E,12Z)-9-Hydroxy-10,12-octadecadienoic Acid, an Aromatase Inhibitor from Roots of Urtica dioica Aqueous-methanolic extracts from roots of Urtica dioica were fractionated and tested for aromatase-inhibition activity. After derivatization the most active fraction was separated by GC/ MS. Besides common fatty acids (10E,12Z)-9-hydroxy-10,12-octadecadienoic acid (1) was identified as a main component and confirmed to be the active principle. Lipoxygenase from tomatoes was used for synthesis of (9S)-1, which caused also inhibition of aromatase. Stereo models of the compound showed some structural similarity to steroidal natural substrates of aromatase. For that reason (10E,12Z)-9-oxo-10,12-octadecadienoic acid (2) was also synthesized. It showed an about tenfold higher activity compared to 1.