Rhodiola rosea: A Possible Plant Adaptogen - evaluation of therapeutic properties

Alternative Medicine Review, June, 2001 by Gregory S. Kelly

Two experiments have suggested possible benefit on various aspects of learning and memory in rats under certain experimental conditions. Rhodiola rosea extract administered orally at a dose of 0.1 mL/day for 10 days resulted in a non-significant trend toward protection against impairments in memory, as assessed by step-down passive avoidance, induced by electroshock in rats.[17] Rhodiola rosea extract was administered in a single dose of 0.10 mL. Improvements in both learning and memory retention, as determined by using a maze test with negative reinforcement, were observed. Repeated dosing with the same quantity of the extract over a 10-day period generated significant improvement in long-term memory as assessed by the maze test with negative enforcement and the "staircase" method with positive enforcement. However, in this experiment two other doses were tested (0.02 and 1.0 mL) and were found to have no substantial effect on learning and memory.[1] This suggests the possibility of an efficacious dose of Rhodiola rosea administration, above and below which beneficial physiological effects might be less likely. In the other experimental conditions investigated (active avoidance with negative reinforcement using a "shuttle box" and passive avoidance using "step down" and "step through") no beneficial effects on either learning or memory were observed with any of the administered doses of Rhodiola rosea.[1]

Cardioprotective Activity

Rhodiola rosea has been shown to moderate against stress-induced damage and dysfunction in cardiovascular tissue. Treatment with Rhodiola rosea extract prevents the decrease in cardiac contractile force secondary to environmental stress in the form of acute cooling and contributes to stable contractility. In animals, acute cooling leads to a decrease in myocardial contractile activity that partially recovers during the first 18 hours after the coldstress is removed. This recovery is viewed as only partial, since the heart tissue is incapable of stable contractility during perfusion. Pretreatment with Rhodiola rosea extracts appears to create a beneficial adaptive response in this type of stress. When Rhodiola pretreated rats were exposed to acute cooling, the decrease in contractility was prevented and stable contractility of heart tissue occurred during perfusion.[18]

Other reports suggest administration of Rhodiola rosea protects cardiovascular tissue from stress-induced catecholamine release[12] and mitigates against adrenaline-induced arrhythmias in rats.[13,14,19] The antiarrhythmic effect of Rhodiola rosea is suggested to be secondary to an ability to induce opioid peptide biosynthesis[13] and related to the stimulation of peripheral kappa-opioid receptors.[14]

Anticancer Activity

Administration of Rhodiola rosea appears to have potential as an anticancer agent, and might be useful in conjunction with some pharmaceutical antitumor agents. In rats with transplanted solid Ehrlich adenocarcinoma and metastasizing rat Pliss lymphosarcoma, supplementation with Rhodiola rosea extract inhibited the growth of both tumor types, decreased metastasis to the liver, and extended survival times.[20] Administration of Rhodiola rosea extract also directly suppressed the growth of and the extent of metastasis from transplanted Lewis lung carcinomas.[21] When Rhodiola rosea extract was combined with the antitumor agent cyclophosphamide in these same tumor models, the antitumor and antimetastatic efficacy of drug treatment was enhanced. The authors also commented that, "complete abrogation of the haematotoxicity of cyclophosphamide" was observed.[21] The chemotherapeutic drug Adriamycin is known to induce pronounced liver dysfunction, generally reflected by an increase in transaminase levels. In animal experiments, adding Rhodiola rosea extract to a protocol with Adriamycin resulted in an improved inhibition of tumor dissemination (as compared to that found with Adriamycin alone), and the combined protocol prevented liver toxicity.[22]