Assessing Potential Efficacy of Rhodiola Extract for Cognitive Symptoms of Stress Using a Bioassay Model of Memory
Rhodiola (Rhodiola rosea, Crassulaceae) is a succulent perennial herb that grows wild throughout arctic Eurasia. The rose-scented root and rhizome have long been included in the pharmacopeias world-wide, including Dioscorides in classical Rome. It is used for symptoms arising from stress and especially valued for its stimulating effect on the mind.
Extracts of Rhodiola are typically standardized to salidroside (1%) and rosavin (3%). Salidroside has been demonstrated to have stress- and neuroprotective effects in animal models, and to increase attention in cognitive tests on healthy human participants, among other benefits. Salidroside and its aglycone tyrosine are common to all species in the genus Rhodiola, as well as dispersed in other plant families. Rosavin, on the other hand, is specific to the species R. rosea and R. sachalinensis. It identifies a sample as the expected species, but there is limited evidence for its medicinal value.
The goal of this study was “to assess the biological activity of a selection of commercial extracts of the underground parts of R. rosea and their analytical markers, salidroside, and rosavin, in a synaptic model of memory: the long-term potentiation (LTP) of synaptic transmission in the hippocampus.” In cases where numerous, poorly characterized active compounds are present, a bioassay may provide better quality control than the quantification of one or two marker compounds. The bioassay used in this study measured long-term potentiation (LTP) of synaptic transmission in isolated slices of rat hippocampus, which according to currently popular hypotheses may be related to memory performance and the amplitude of the population spike (controlled by the number of pyramidal cells activated in response to stimulus).
The researchers obtained seven bulk samples of Rhodiola root and rhizome extract from a variety of suppliers. Other preparations were excluded from the study. SHR-5 extract (Swedish Herbal Institute; Vallberga, Sweden) was included as a control because it has previously been tested for efficacy and safety, although it also contains maltodextrin as a carrier.
Thin-layer chromatography (TLC) and ultra-performance liquid chromatography with ultraviolet detection (UPLC-UV) were used to determine the concentrations of salidroside, tyrosol, rosavin, rosarin, rosin, and cinnamyl alcohol, for which reference standards were available. Quantitative analysis was performed using a UPLC-UV method detailed in the article and in accordance with new regulatory guideline USP 25. In addition to the individual compounds, total phenylethanoids (tyrosol and salidroside), total phenylpropanoids (rosarin, rosavin, rosin, and cinnamyl alcohol), total phenolics (phenylpropanoids and phenylethanoids) and total rosavins (rosavins, rosarin, and rosin) were also calculated. Furthermore, UPLC-UV and HPTLC fingerprints were presented for the reference standards and the EuroPharma product (EPR-7) against the control SHR-5.
The quantities of total phenylpropanoids and total phenylethanoids and their ratios in the samples varied widely. Six samples contained 3.52-8.57% total phenolics, including over 2% phenylpropanoids (including rosavin and related compounds). However, one sample from China contained no detectable phenylpropanoids and only 1.3% phenylethanoids. Of three samples from the Altai region of Russia, a location traditionally associated with Rhodiola, one contained almost no rosavin and the ratio of phenylpropanoids to phenylethanoids was therefore much lower than in other samples.
In the second phase of this study, the researchers performed an in vitro bioassay as a model for memory formation. As the researcher’s state, “of special interest is the response to theta burst stimulation (TBS) resulting in LTP, which relates to an increase of time- and space- dependent memory.” Multiple trials were recorded and the means used to chart the increase in population spike amplitude against test substance concentrations.
At a concentration of 0.5 mg/L isolated salidroside was more effective than isolated rosavin at increasing the population spike. At higher concentrations of 0.75 and 1.5 mg/L rosavin was superior to salidroside. Rosavin, salidroside, and each of the Rhodiola extracts tested significantly increased both single spike (SS) and LTP population spike amplitudes at higher concentrations. There was substantial variation in activity among extracts. The extract with the highest levels of salidroside and rosavin, as well as total phenolics, was the sample known as EPR-7, the product from EuroPharm. This sample significantly increased population spike amplitude at a low concentration compared to all but one of the other samples. From the SS and LTP data, the researchers calculated concentrations to induce the half-maximal effect (EC50). The EC50 data do not correlate with salidroside content, rosavin content, nor combined salidroside and rosavin content. This suggests that other compounds may increase the LTP effect of Rhodiola extracts. For this reason, the researchers propose the bioassay used in this study “should be required” as a better predictor of Rhodiola extract efficacy than quantification of standardized markers.
This study was funded by EuroPharma USA Inc, the manufacturer of one of the samples tested, and one of the authors was a consultant of the company. Laboratory animals were handled in accordance with the German Animal Protection Law.
Dimpfel W, Schombert L, Panossian AG. Assessing the quality and potential efficacy of commercial extracts of Rhodiola rosea L. by analyzing the salidroside and rosavin content and the electrophysiological activity in hippocampal long-term potentiation, a synaptic model of memory. Front Pharmacol. May 24, 2018;9:425. doi: 10.3389/fphar.2018.00425.
Rhodiola Rosea – An Adaptogen Herb
An adaptogen is an herb that can help the body “adapt” by normalizing body systems while increasing the resistance to adverse influences like anxiety, stress, and exhaustion.
Potential Health Benefits of Rhodiola Rosea:
- Increases Energy*
- Boosts Endurance and Stamina*
- Promotes Healthy Sleep*
- Strengthens the Immune System*
- Improves Sexual Performance*
- Reduces Stress*
- Uplifts Mood*
- Boosts Memory*
- Enhances Mental Clarity*
- Reduces Anxiety*
Which Rhodiola Rosea Supplement Should You Buy?
So this becomes the million dollar question…or really the $23.95 question, since that is all it cost to get the best Rhodiola Rosea! Clearly, we believe that our Perfect Rhodiola Rosea is the best Rhodiola Rosea on the market, but let’s be objective about this…
We spent years researching Rhodiola Rosea before ever making our first product. We needed to find the right source for the Rhodiola Rosea, the right way to process it so the nutrients stay intact and of course the right formula and dosage.
Here is What Separates Perfect Rhodiola Rosea From The Pack
Perfect Rhodiola Rosea –
- Rhodiola Rosea Root Sourced Directly From The Siberian Mountains
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- Contains Recommended 3:1 ratio of ROSAVINS to SALIDROSIDE
- 100% Freeze Dried Rhodiola – Keeps Nutrients Intact
- 100% Lab Tested for Purity
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Perfect Rhodiola Rosea – Balance Your Mind and Body
Perfect Rhodiola Rosea is 100% wild-crafted freeze-dried Siberian Rhodiola Rosea root with a minimum 3% Rosavins and 1% Salidroside. During the freeze-drying process, moisture is frozen and vaporized using no chemicals, thereby preserving the maximum level of nutrients from the Rhodiola Rosea root. Rhodiola Rosea has recently been named the best energy boosting herb by Alternative Medicine Magazine.
Suggested Use: 200mg – 400mg per day for use as a dietary supplement.