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United States Department of Agriculture

Agricultural Research Service

Research Project: DISCOVERY AND DEVELOPMENT OF NATURAL PRODUCTS FOR PHARMACEUTICAL AND AGRICHEMICAL APPLICATIONS Title: Anti-Aromatase Activity of the Constituents from Damiana (Turnera diffusa)

Authors
item Zhao, Jianping -
item Dasmahapatra, Asok -
item Khan, Shabana -
item Khan, Ikhlas -

Submitted to: Journal of Ethnopharmacology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 5, 2008
Publication Date: September 26, 2008
Repository URL: http://www.elsevier.com/locate/jethpharm
Citation: Zhao, J., Dasmahapatra, A.K., Khan, S.I., Khan, I.A. 2008. Anti-Aromatase Activity of the Constituents from Damiana (Turnera diffusa). Journal of Ethnopharmacology. 120:387-393.

Interpretive Summary: Damiana (Turnera diffusa Willd. Ex Schult), a so-called herbal aphrodisiac, has been used in southern America for more than one hundred years. Damiana product was once said to be a “powerful invigorant” and can “improve the sexual ability of the enfeebled and aged”. A wide array of damiana products can still be found on the current dietary supplement market. However, there is no sufficient scientific evidence to substantiate the alleged effects. Aromatase plays a vital role in the conversion of androgen to estrogen. Testosterone supplementation has been approved to be able to improve sexual function and libido. We postulated that the components of damiana might act as aromatase inhibitors. In this study, an investigation to assess the anti-aromatse activity and estrogenic activity of the constituents isolated from T. diffusa was conducted. The methanolic extract and 24 compounds isolated from the leaves of T. diffusa were evaluated for aromatase activity by using a tritiated-water release assay and for estrogenic activity by using yeast estrogen screen (YES) assay. The methanolic extract demonstrated a dose dependent inhibitory activity of the aromatase enzyme with the IC50 value of 63.1 ug/ml. Among the 24 tested compounds, pinocembrin and acacetin showed the most potent inhibition with IC50 values of 10.8 and 18.7 µM, 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 µM, respectively. T. diffusa has been used traditionally as an herbal aphrodisiac, and the sexual function is found to be well associated with the testosterone level in body. The present study demonstrated that the extract of T. diffusa can significantly suppress aromatase activity. Accordingly, based on above information, we speculate that consuming this plant as a dietary supplement might result in increasing the testosterone level in blood. However, this observed biological significance and implication cannot be directly extrapolated to the real situation in vivo, further studies are required to verify this postulation.

Technical Abstract: 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 T. diffusa. Material and methods: The methanolic extract and 24 compounds isolated from the leaves of T. 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 µg/ml. Among the 24 tested compounds, pinocembrin and acacetin showed the most potent inhibition with IC50 values of 10.8 and 18.7 µM, 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 µM, respectively. Conclusions: The extract of T. diffusa and two isolated compounds pinocembrin and acacetin could significantly suppress aromatase activity. Moreover, apigenin 7-glucoside, Z-echinacin and pinocembrin showed estrogenic activity.

Last Modified: 10/21/2014
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