Anti-aromatase activity of the constituents from damiana (Turnera diffusa)

Ethnopharmacological relevance: Damiana (Turnera diffusa Willd. Ex Schult) has traditionally been used as an herbal aphrodisiac. Aim of the study: The study was aimed to investigate the anti-aromatse activity and the estrogenic activity of the constituents isolated from Turnera diffusa. Materials and methods: The methanolic extract and 24 compounds isolated from the leaves of Turnera diffusa were evaluated for aromatase activity by using a tritiated-water release assay and for estrogenic activity by using yeast estrogen screen (YES) assay. Results: The methanolic extract demonstrated a dose-dependent inhibitory activity of the aromatase enzyme with the IC50 value of 63.1 mu g/ml. Among the 24 tested compounds, pinocembrin and acacetin showed the most potent inhibition with IC50 values of 10.8 and 18.7 mu M, respectively. Estrogenic activity was also observed in the extract and three compounds including apigenin 7-glucoside, Z-echinacin and pinocembrin with EC50 values of 10, 20 and 67 mu M, respectively. Conclusions: The extract of Turnera diffusa and two isolated compounds pinocembrin and acacetin could significantly suppress aromatase activity. Moreover, apigenin 7-glucoside, Z-echinacin and pinocembrin showed estrogenic activity. Published by Elsevier Ireland Ltd