Adaptogenic Botanicals with Emphasis on Rhodiola rosea and Withania somnifera

This review addresses the issue of plant adaptogens, botanical products with remarkable anti-stress effects. These actions result from its ability to increase the non-specific organism's resistance process against multiple stressors (physical, chemical or biological). They are capable of exerting a normalizing effect on the human body, being both non-toxic effects and not influencing normal organic functions. Several plants with a complex phytochemical profile meet the criteria for being adaptogens. Many of them have been used in traditional medicine as tonic-vitalizing agents for centuries to treat various health conditions. This review briefly explains the organism's stress responses against stressors and the evolution of the adaptogenic concept from a historic perspective. A rational classification of adaptogens plants is formulated although it does not cover the full variability of botanical adaptogens. Nevertheless, summarizing data from two of the most important plant adaptogens, golden root (Rhodiola rosea) and Indian ginseng (Withania somnifera), are described. This includes their most deserving ethnomedicinal properties, the various families of compounds that constitute their complex phytochemical profiles, pharmacological activities along with putative mechanism of action responsible for some of their multifaceted biological actions, and the multi-therapeutic and health-promoting activities obtained from the most relevant clinical trials performed to date. Additionally, several relevant and current issues regarding the safety and toxicity of both widely used adaptogens are detailed. These include potential negative drugs interactions, putative contraindications and warnings in specific physiological statuses or health conditions. Finally, despite the overlapping activities against stress and stress-related health conditions some superior therapeutic benefits are tentatively assigned both to Withania somnifera and Rhodiola rosea taking into account the overall evidence of efficacy from pharmacological and clinical studies.