Plasma levels of rosiridin after oral administration of a Rhodiola rosea extracts in rats

Abstract

Extracts from Rhodiola rosea roots and rhizomes (RRE) are used therapeutically as adaptogens to mitigate stress-associated fatigue, attention deficiency, asthenia and anxiety [1]. To date, rosavins and salidroside have mostly been discussed as bioactive constituents. Another main component, rosiridin, a monoterpene, has until now received only limited attention. Although pharmacological activity of rosiridin (e.g. inhibition of MAO) has been described in vitro, data on oral bioavailability are not available. Therefore, in the present study we comparatively evaluated the plasma pharmacokinetics of the main constituents in rats after oral administration of RRE. Eight rats were treated with an RRE (28 mg/kg p.o.) containing rosavins (5.5%), salidroside (1.4%), rosin (0.8%), and rosiridin (5%). EDTA-plasma was collected before and at defined time points after administration. The plasma concentration of the main ingredients was quantified after solid phase extraction by HPLC-MRM-mass spectrometry. All quantified components of the RRE could be detected and displayed distinct Cmax-values at 15 to 30 min after application: rosavins (25.5 ng/ml), salidroside (50.5 ng/ml), rosin (298.3 ng/ml), and rosiridin (501.5 ng/ml). Interestingly, rosiridin was found at the highest concentration in plasma although it is present in RRE in a concentration comparable to that of rosavins. Further pharmacological research is now ongoing to prove whether this compound contributes to the health benefits of Rhodiola rosea.