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

Zhao, Jianping, Dasmahapatra, Asok K., Khan, Shabana I., Khan, Ikhlas A.
Journal of ethnopharmacology 2008 v.120 no.3 pp. 387-393
medicinal plants, medicinal properties, Turnera diffusa, chemical constituents of plants, enzyme inhibitors, estrogenic properties, plant extracts, dose response, enzyme activity, inhibitory concentration 50, flavonoids, herbal medicines
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 63.1μg/ml. Among the 24 tested compounds, pinocembrin and acacetin showed the most potent inhibition with IC₅₀ values of 10.8 and 18.7μM, 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 67μM, 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.