Background: Rosmarinic acid (RA) is a flavonoid commonly found in plants of the Lamiaceae family. Its antioxidant, antidiabetic, cardioprotective, hepatoprotective, nephroprotective, antiviral, antibacterial, anticancer, antidepressant, antiallergic, antinociceptive, and anti-inflammatory effects have been demonstrated in numerous studies. There is no study in the literature that specifically examines the effects of RA on left ventricular contractility. The aim of our study is to investigate the effects of different doses of RA on the mechanical activities of isolated rat heart left ventricular tissue.Methods: In the study, 16 adult female rats were randomly divided into two groups: the vehicle group (V, 10% ethanol + 90% saline, n=8) and the RA group (n=8). The muscle preparations were stimulated with supramaximal square pulses of 1 ms duration and 0.5 Hz frequency. In the RA group, RA was administered cumulatively at concentrations of 0, 5, 50, 100, 250, and 500 μg per μL. In the control group, the same volume of solvent as in the RA group was applied.Results: RA administered in vitro at concentrations of 250 and 500 µg/mL to left ventricular cardiac tissue led to signif-icant impairments in contractile parameters. In contrast, the vehicle administered in an equivalent volume did not pro-duce any statistically significant changes in mechanical activity. These findings indicate that the observed alterations can be specifically attributed to RA treatment.Conclusions: While the literature discusses many protective and therapeutic effects of RA on cardiac systems, our find-ings indicate that these effects may be limited in a dose-dependent manner.
Akkoca et al. (2026) studied this question.