Effect of Rhodiola rosea Rhizome and Punica granatum Fruit Peel on the Metabolic Processes and Physiological Activity of Rats Fed with Excessively Fat Diet.

Research background: Rhodiola rosea (golden root) and Punica granatum (pomegranate), as well as a number of other species of medicinal plants, exert an array of biological effects: adaptogenic, antioxidant and anti-inflammatory. However, there are not enough contemporary studies of their influence on metabolic processes, especially in cases of imbalanced diet. Lipid dysregulation is the main reason for many diseases, including obesity, cardiovascular disorders, non-alcoholic fatty liver disease, hypertension, atherosclerosis and insulin resistance. Recently, a growing amount of evidence has suggested the positive effects of certain natural nutrients on lipid metabolism. The work aims to define the general effect of golden root rhizome and pomegranate peel on physiological activity and metabolic processes in model animals fed with excessively fat diet. This study is relevant for the development of drugs and food additives for treatment and prophylaxis of metabolism disorders.

Experimental approach: In a 30-day experiment, we determined the effect of golden root (Rhodiola rosea L.) rhizome and pomegranate (Punica granatum L.) peel on the physiological activity and metabolic processes of 24 laboratory rats consuming a high-fat diet. The physical activity was evaluated according to the mass gain of animals and change in the relative mass of the internal organs, and also the functional conditions of the central nervous system, as demonstrated by the indicators of the locomotor activity and emotional status, determined in the open field test. The influence on the metabolic processes was revealed by biochemical and clinical blood analyses.

Results and conclusions: Body mass of rats fed with golden root (R. rosea) reached 125.8 % of the initial body mass; when fed on pomegranate (P. granatum), it reached 123.9 %; and the control group reached only 111.5 % of the initial body mass. The rhizomes of R. rosea in the diet of male rats during the month of the experiment did not cause significant changes in the relative organ mass, and the pomegranate peel fruits led to a decrease in the thymus relative mass, as well as liver and brain. R. rosea rhizomes in the rats' diet led to an increase in the activity of alkaline phosphatase, and also to a decrease in the concentration of urea and urea nitrogen. Diet supplemented with R. rosea also contributed to a strong decrease in plasma concentrations of bilirubin and triglycerides (up to 57.0 % compared with the concentration in the control group). The rhizomes of R. rosea contributed to an unreliable decrease in the atherogenicity index. The pomegranate peel also greatly increased alkaline phosphatase activity and reduced plasma triglyceride concentrations. In addition, in rats consuming the peel of P. granatum, blood glucose concentration decreased. Under the influence of P. granatum, a strong increase in the atherogenic index of plasma (up to 518.6 % of the control) was observed because of a decrease in the concentration of high-density lipoproteins (up to 57.1 %) and a simultaneous elevation of the concentration of low-density lipoproteins (up to 158.3 % of the control). Open field test between groups remained without significant changes.

Novelty and scientific contribution: The results indicate that the rhizome of R. rosea and peel of P. granatum are safe as food additives to high-fat diet and did not cause pathological changes and side effects, and at the same time significantly influence the metabolic processes (lipid and carbohydrate). Our study theoretically substantiates the use of R. rosea rhizome and P. granatum peel for the production of nutraceutical and pharmacological products for the correction of metabolic disorders of people and animals. Doses and periods of their application require further research.