Effect of Lemongrass Essential Oil Cymbopogon citratus on the Contractility and Electrical Activity of the Guinea Pig Heart.

Previous studies have highlighted the effects of lemongrass essential oil (Cymbopogon citratus) on the cardiovascular system, particularly its hypotensive and vasodilatory properties. Given the heart's crucial role in blood pressure regulation, this study aimed to investigate the impact of lemongrass essential oil (EOCC) on cardiac excitation-contraction coupling and voltage-gated ion channel currents. Chemical analysis of EOCC, conducted through gas chromatography-mass spectrometry, identified geranial (39.9%) and neral (27.4%) as the primary components. The effect of EOCC on cardiac contractility was assessed using isolated guinea pig atria. The results showed that EOCC decreased both the contraction amplitude and the frequency of spontaneous atrial contraction in a concentration-dependent manner (IC50 values of 106.8 µg/mL, 95% CI=78.9 to 133 µg/mL and 258.4 µg/mL, 95% CI=202.7 to 443.2 µg/mL n = 5 - 8, respectively). Notably, EOCC exhibited arrhythmogenic activity, since it induced spontaneous contractions in isolated atrial preparations. Additionally, in an arrhythmia model induced by ouabain, EOCC significantly reduced the time to arrhythmia onset by 67.8% (n = 4). To further explore the mechanisms of the essential oil in atrial excitability, we employed the patch-clamp technique on isolated ventricular cardiomyocytes to examine EOCC's effects on the L-type calcium current (ICa-L). The human embryonic kidney cell line (HEK293) transiently expressing human NaV 1.5 was used to study the effects on cardiac sodium currents (INa). EOCC reduced the peak amplitude of both INa and ICa-L in a concentration- and voltage-dependent manner, with IC50 values of 299.7 µg/mL (95% CI=241.5 to 358 µg/mL, n = 6 - 7) for INa and 132.8 µg/mL (95% CI=71 to 173.8, n = 9) for ICa-L. In conclusion, the negative inotropic of EOCC may significantly contribute to its hypotensive effects. However, the association of relatively low concentrations of EOCC with cardiac arrhythmias raises concerns about its medicinal use.