Pro-cognitive effects of Cirsium rivulare extracts in rats

Cirsium rivulare (Jacq.) All. (Asteraceae) is a herbaceous perennial plant occurring in Central Europe. It has been traditionally used in Polish folk medicine to treat anxiety. In the present study methanolic extracts from flowers and leaves of Cirsium rivulare containing flavonoid compounds linarin, pectolinarin, apigenin, hispidulin, their glycosides and a newly isolated compound isokaemferide 7-O-(6''-methylglucuronide) were studied for anxiolytic and pro-cognitive properties.

Male Wistar rats (150-160 g) were used. They were treated orally with standardized methanol extracts of flowers and leaves of Cirsium rivulare and subsequently tested for memory in passive avoidance (PA) and object recognition (OR) tests. Auxiliary tests for motor (open field, OF) and emotional (elevated 'plus' maze, EPM) effects of the above treatments were also employed.

We found that the extract from flowers of Cirsium rivulare, in addition to its anxiolytic effects as measured in the EPM, improves memory of the appetitively (by curiosity, OR) and aversively (by footshook, PA) motivated tasks. This is in contrast to classical anxiolytics as for example benzodiazepines that typically impair memory. The extract from leaves of Cirsium rivulare showed some anxiolytic properties in the EPM, and no effect in both cognitive tests. The examined extracts of Cirsium rivulare did not affect psychomotor exploratory activity of rats tested in the OF.

These results suggest that the flavonoids from Cirsium rivulare possess anxiolytic and pro-cognitive effects, the extract from flowers being more pro-cognitive and that from the leaves more anxiolytic.