The main goal of the present study was to examine the effect of dandelion root infusion on heart function and oxidative status of rats.
In the first part of the study, the influence of dandelion infusions on the cardiac muscle was studied through assessment of the cardiodynamic parameters of an isolated rat heart. As previously mentioned, by the our best knowledge this the solitary study covering this topic in the available literature. Therefore, we can consider this as a "pioneering" investigation, i.e., a topic that requires a further research.
The study by Majewski and coworkers was primarily concerned with examining the effect of plant extract on rats' antioxidant status and lipid profile [18]. The single cardiodynamic parameter analyzed in this study was heart rate (HR). As in present research, authors used also 8-week-old Wistar albino rats. The differences between the protocols are reflected in the fact that Majewski and coauthors used an ethanolic extract of dandelion leaves and flowers [18].
In contrast, we etimated an aqueous extract of dandelion root. The reason for using a root is our literature-based hypothesis that it`s phytochemical properties remains more stable when infusion is made from this part of a plant [2, 3].
The results of this study, in terms of heart rate (HR), are in agreement with the previous one. In both cases, there was no evident change in heart frequency after applying the dandelion extract, suggesting that dandelion infusion does not modify the function of the heart conducting system.
Indicators of contractile (dp / dt max) and relaxant (dp / dt min) force of the heart were also not affected by estimated dandelion infusion. Similary, dandelion did not impair both systolic (SLVP) and diastolic (DLVP) function of the cardiac muscle as well as reactivity of coronary circulation (CF). Taken together, these results indicated that applied dandelion root infusion did not showed negative impact on all aspects of heart function and perfusion, pointing him out as a safe cardiac supplement. However, the exact mechanism of these effects request more complex experimental approach. One of the rare studies conserning the influence of dandelion on any muscle was recently published [19]. Namely, the effects of ethyl acetate dandelion extract was evaluated on mouse airway smooth muscle. It was found that this extract relaxes mouse smooth muscle via inhibition of L-type voltage-dependent calcium channel and non-selective cationic channel, which at least theoretically, could be the site of action in rat cardiomyocytes.
On the other hand, in the second part of the research, we seek to examine whether, taking into account the antioxidant properties of dandelion, it can disrupt the redox homeostasis of rats which can be also responsible for obtained effects within the heart. It is well known that accumulation of reactive oxygen species (ROS) lead to biochemical, structural and functional disorders of the cells [20]. It has been proven that dandelion successfully prevents synthesis and increased removal of different ROS, especially H2O2 and O2−. The capacity to remove free radicals has been attributed to phenolic compounds in dandelion flowers [21].
Dandelion is widely used as a folk remedy against various disorders such as liver disease, bile, indigestion, and rheumatic diseases. In one research dandelion leaf has been shown to possess a protective effect against acute pancreatitis caused by cholecystinin octapeptide and acute lung and liver damage. This protective effect is achieved by components from dandelion leaves with flavonoids and polyphenols [22]. Plant flavonoids act as scavengers of free radicals and turn them into less reactive or bind metal ions preventing their production [23].
In our study the chronic consumption of dandelion extract was associated with the reduced concentration of one of the most deleterious ROS - O2−, which completely correlated with literature findings [21, 22].
In addition, the concentrations of free radicals depend not only on their production but also on the expression and activity of antioxidant enzymes [24]. Flavonoids found in the dandelion extract have a beneficial effect on cardiovascular function based on their antioxidant features and the ability to increase the expression and activity of antioxidant enzymes [25, 26].
In the present investigation the four week dandelion application showed different impact on estimated antioxidant enzymes. Namely, while CAT and SOD activity was lower, reduced glutathione activity was improved compared to control. The drop in CAT values may be a reflection of the exhaustion of its activity as a consequence of the increased release of H2O2 that we found. Furthermore, previous research examined the hypolipidemic and antioxidant potential of animals treated with dandelion leaf and root extract [27]. The activity of reduced glutathione was strongly improved in the group treated with dandelion root and leaf compared to the control group, while catalase activity was lower, which is in complete correlation with the results of our study.
A study by Park and associates compared the antioxidant and anti-inflammatory activity of methanolic and aqueous extracts of Taraxacum officinale. The activity of reduced glutathione and other antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were restored after using the extract. Methanol extract showed more potent antioxidant and anti-inflammatory abilities than aqueous extract, which can be attributed to the higher total content of phenol, luteolin, and cichoric acid [28].
At the end, present research possess some limitations. Firstly, the longer duration of dandelion consumption and assessment of different doses could have stronger impact on both heart and oxidative status of rats. Second, due to technical limitations, study suffers from mechanistic approach i.e. patch clamp assessment of ionic currents within the cardiomyocytes would provide potential mechanisms of dandelion effects. Pathohistological examination of heart tissue can also serve for this matter.