Estrogenic activity of Nigella damascena extracts, evaluated using a recombinant yeast screen

We used the yeast estrogen screen (YES) containing a human estrogen receptor to evaluate the estrogenic activity of extracts obtained from Nigella damascena seeds. Alcohol extracts obtained by direct extraction of seeds showed a low estrogenic activity, while the alcohol extract obtained after extraction with solvents of increasing polarity showed a strong estrogenic activity. This suggests the presence in Nigella of polar components whose activity can be clearly demonstrated after previous elimination of interacting apolar components that may mask the activity of more polar components. The response of both alcohol fractions follow a bell-shaped curve indicating a concentration-dependent relationship.