Cardiovascular Effects of the Essential Oil of Croton argyrophylloides in Normotensive Rats: Role of the Autonomic Nervous System

The Role of Essential Oils and Their Main Compounds in the Management of Cardiovascular Disease Risk Factors

Cardiovascular diseases (CVDs) are a global health burden that greatly impact patient quality of life and account for a huge number of deaths worldwide. Despite current therapies, several side effects have been reported that compromise patient adherence; thus, affecting therapeutic benefits. In this context, plant metabolites, namely volatile extracts and compounds, have emerged as promising therapeutic agents. Indeed, these compounds, in addition to having beneficial bioactivities, are generally more amenable and present less side effects, allowing better patient tolerance. The present review is an updated compilation of the studies carried out in the last 20 years on the beneficial potential of essential oils, and their compounds, against major risk factors of CVDs. Overall, these metabolites show beneficial potential through a direct effect on these risk factors, namely hypertension, dyslipidemia and diabetes, or by acting on related targets, or exerting general cellular protection. In general, monoterpenic compounds are the most studied regarding hypotensive and anti-dyslipidemic/antidiabetic properties, whereas phenylpropanoids are very effective at avoiding platelet aggregation. Despite the number of studies performed, clinical trials are sparse and several aspects related to essential oil’s features, namely volatility and chemical variability, need to be considered in order to guarantee their efficacy in a clinical setting.

Cardiovascular Effects of Trans-4-Methoxy-β-Nitrostyrene in Spontaneously Hypertensive Rats: Comparison With Its Parent Drug β-Nitrostyrene

We previously reported that trans-4-methoxy-β-nitrostyrene (T4MN) evoked higher vasorelaxant effects in small resistance arteries from spontaneously hypertensive rats (SHRs) in comparison with its parent drug, the β-nitrostyrene 1-nitro-2-phenylethene (NPe). To further our knowledge of the influence of insertion of an electron-releasing group such as methoxy in the aromatic ring of NPe, we investigated the cardiovascular responses to intravenous (i.v.) injection of T4MN in SHRs and compared with those of NPe. In anesthetized SHRs, i.v. treatment with T4MN (0.03–0.5 mg/kg) and NPe (0.03–3 mg/kg) induced dose-dependent bradycardia and hypotension, which were biphasic (named phases 1 and 2). Magnitude of these responses was significantly higher for T4MN compared with NPe. Phase 1 cardiovascular responses to both T4MN (0.3 mg/kg) and NPe (3 mg/kg) were prevented by cervical bivagotomy or perineural treatment of both cervical vagus nerves with capsaicin, but was unchanged by i.v. pretreatment with capsazepine or ondansetron. After injection into the left ventricle, NPe and T4MN no longer evoked phase 1 responses. In conscious SHRs, NPe (3 mg/kg, i.v.), and T4MN (0.3 mg/kg, i.v.) evoked monophasic hypotensive and bradycardiac effects which were suppressed by i.v. pretreatment with methylatropine. It is concluded that i.v. administration of NPe and T4MN in SHRs induced a vago-vagal hypotensive and bradycardic reflex that did not involve the activation of vanilloid TRPV₁ or 5-HT₃ receptors located on vagal pulmonary sensory nerves. With respect to its parent drug, T4MN was more potent in inducing this reflex. Phase 2 hypotensive response to i.v. NPe and T4MN seems partially resulting from a direct vasodilatory action. It seems that insertion of a methoxy group into the aromatic ring stabilized NPe, which in turn increases its cardiovascular effects.

The effect of asafoetida essential oil on myocardial ischemic-reperfusion injury in isolated rat hearts

OBJECTIVE

Previous studies reported that asafetida from Ferula assa-foetida Linn. species and its essential oil (AEO) have antioxidant effects. In the present study, the effect of AEO was evaluated on ischemic-reperfusion injury in isolated rat hearts.

MATERIALS AND METHODS

Forty-eight male Wistar rats were divided into 6 groups: 1) control group, 2) vehicle group, 3-5) AEO groups and, 6) carvedilol group. In the control group, hearts were only subjected to 30-min global ischemia followed by 120-min reperfusion. Hearts in other groups were perfused with vehicle (Tween 0.1%), AEO (0.125, 0.25 or 0.50 µL/g heart) or carvedilol (10 µM) for 5 min immediately before the induction of ischemia.

RESULTS

Compared to the control group, myocardial dysfunction was significantly more severe only in group 5 in which a significant increase in left ventricular end diastolic pressure and a significant decrease in left ventricular developed pressure and ± dp/dt. Also, the activities of lactate dehydrogenase and creatine kinase as the markers of myocardial injury were significantly higher only in group 5 compared to control group. The size of infarct and the incidence of irreversible fibrillation did not show any significant differences between the control group and groups 3-5.

CONCLUSION

These results showed that perfusion of isolated rat hearts with AEO 0.5 µL/g heart, but not at lower concentrations, might worsen myocardial ischemic-reperfusion injury.

Vasodilatory effect of asafoetida essential oil on rat aorta rings: The role of nitric oxide, prostacyclin, and calcium channels

BACKGROUND

Asafoetida is an oleo-gum resin mainly obtained from Ferula assa-foetida L. species in the apiaceae family. Previous studies have shown that it has antispasmodic effects on rat's and pig's ileums.

PURPOSE

The main goals of this study were to assess the vasodilatory effect of asafoetida essential oil (AEO) on the contractile response of rat's aorta rings and to find the role of nitric oxide, cyclooxygenase, and calcium channels. Thoracic aorta rings were stretched under a steady-state tension of 1 g in an organ bath apparatus for 1 h and then precontracted by KCl (80 mM) in the presence and absence of AEO. L-NAME (blocker of nitric oxide synthase) and indomethacin (blocker of cyclooxygenase) were used to assess the role of nitric oxide (NO) and prostacyclin in the vasodilatory effect of AEO. Also, the effect of AEO on the influx of calcium through the cell membrane calcium channels was determined.

RESULTS

Data showed that AEO had vasodilatory effects on aorta rings with both intact (IC₅₀ = 1.6 µl/l) or denuded endothelium (IC₅₀ = 19.2 µl/l) with a significantly higher potency in intact endothelium rings. The vasodilatory effects of AEO were reduced, but not completely inhibited, in the presence of L-NAME or indomethacin. Adding AEO to the free-calcium medium also significantly reduced the CaCl₂-induced contractions.

CONCLUSION

The results indicated that AEO has a potent vasodilatory effect that is endothelium-dependent and endothelium-independent. Also, it reduced the influx of calcium into the cell through plasma membrane calcium channels.