Andrelina Noronha Coelho-de-Souza

Vasorelaxant effects of the monoterpenic phenol isomers, carvacrol and thymol, on rat isolated aorta

Various essential oils are rich in carvacrol, a monoterpenic phenol isomeric with thymol. This study was undertaken to assess the vasorelaxant effects of thymol and carvacrol in rat isolated aorta and the putative mechanisms underlying these effects. Thymol and carvacrol produced a concentration‐dependent relaxation on the aortic ring preparations pre‐contracted using KCl (IC50 value of 64.40 ± 4.41 and 78.80 ± 11.91 μm, respectively) or using phenylephrine (PHE, 0.1 μm) (IC50 value of 106.40 ± 11.37 and 145.40 ± 6.07 μm, respectively) and inhibited the concentration‐response curves of aortic rings to PHE or KCl. In Ca2+‐free medium with ethylene glycol‐bis(2‐aminoethylether)‐N,N,N′,N′‐tetraacetic acid (2 mm), thymol and carvacrol both at 1000 μm completely abolished the phasic component of PHE‐induced endothelium‐containing ring contractions. At 400 μm, thymol and carvacrol significantly reduced the CaCl2‐induced contractions in Ca2+‐free medium. Furthermore, both thymol and carvacrol (300 and 1000 μm) significantly reduced the contraction evoked by phorbol dibutyrate (1 μm), an activator of protein kinase C. Magnitude of this inhibitory effect was enhanced in the presence of the Ca2+ pump inhibitor, thapsigargin (1 μm). At 1000 μm, neither thymol nor carvacrol altered the resting potential of vascular smooth muscle cells. In conclusion, thymol and carvacrol induced an endothelium‐independent relaxation in rat isolated aorta, an effect that seems mediated through some mechanisms probably involving a transduction pathway between Ca2+ release from sarcoplasmic reticulum and/or regulation of the Ca2+ sensitivity of the contractile system. Moreover, it’s conceivable that thymol and carvacrol, at low concentrations, block the Ca2+ influx through the membrane.

Myorelaxant and antispasmodic effects of the essential oil of Alpinia speciosa on rat ileum

The effects of the essential oil of Alpinia speciosa Schum (EOAS) on rat ileum were studied. EOAS (0.1–600 µg/mL) reversibly relaxed ileal basal tonus. Submaximal contractions induced by 60 mM KCl or acetylcholine were concentration dependently inhibited by EOAS with similar IC50 values (∼ 44 and 48 µg/mL, respectively). These results show that EOAS possesses both relaxant and antispasmodic actions in the ileum. Copyright

Effects of the essential oil of Croton zehntneri, and its constituent estragole on intestinal smooth muscle

The effects on isolated guinea‐pig ileum of the essential oil of Croton zehntneri (CZEO) and of its main constituent estragole (57% of CZEO by weight) were studied. CZEO and estragole (0.1–100 μg/mL) decreased the tonus in 56% and 61.5%, respectively, of the muscles. At concentrations above 10 μg/mL, they induced spontaneous rhythmic movements of small amplitude (less than 11% of the potassium contraction peak to peak). At concentrations from 1 to 100 μg/mL and with similar potencies, these agents blocked the contractions induced by acetylcholine, histamine and 50 mM K+ and caused relaxation of already established potassium contractures. Tested separately, CZEO, estragole and anethole (28% of CZEO by weight) blocked the contraction induced by Ca++ in the presence of 50 mM K+, but CZEO was more potent than estragole or anethole in blocking the Ca++‐induced contractions than those induced by K+. With large increases in the agonist concentration, the action of the oils on the contractions induced by Ca++ was reversible; however, their effect on contractions induced by histamine or ACh was not. The data show that the essential oil of Croton zehntneri has an effect on intestinal smooth muscle that is predominantly antispasmodic, and attributable in part to the effect of estragole, a major constituent.

Antispasmodic effects of essential oil of Pterodon polygalaeflorus and its main constituent β-caryophyllene on rat isolated ileum.

This study investigates the effects of essential oil of Pterodon polygalaeflorus (EOPP) and β‐caryophyllene (β‐CAR). EOPP and β‐CAR relaxed the basal tone of ileum smooth muscle in a concentration‐dependent manner (IC50s = 394.35 ± 62.12 and 68.65 ± 9.51 μg/mL respectively), an effect that was unaltered by hexamethonium, L‐nitroarginine methyl ester or indomethacin. Both EOPP and β‐CAR evoked a concentration‐dependent relaxation of ileum pre‐contracted with KCl with an IC50 value of 107.78 ± 10.47 and 17.35 ± 0.75 μg/mL, respectively. EOPP and β‐CAR inhibited the contractions induced by acetylcholine (ACh) and by KCl. In ileal preparations, the CaCl2‐induced contractions were reduced by EOPP (300 μg/mL) and β‐CAR (100 μg/mL). Furthermore, CaCl2‐induced contractions were also reduced by EOPP (300 μg/mL) and β‐CAR (100 μg/mL) in ileal preparations pretreated with ACh under Ca2+‐free condition and in the presence of verapamil. EOPP (100 and 300 μg/mL) and β‐CAR (30 and 100 μg/mL) reduced the ACh‐induced contractions of isolated rat ileum under Ca2+‐free conditions. In the presence of high KCl and Ca2+‐free conditions, EOPP (300 μg/mL) and β‐CAR (100 μg/mL) reduced the contractions induced by barium. A similar effect was also observed with verapamil. It is concluded that (i) β‐CAR is an important constituent involved in the myorelaxant and antispasmodic effects induced by EOPP; (ii) the inhibitory effect on intestinal contractility is myogenic and seems mainly mediated through an intracellular mechanism. However, the ability of EOPP and β‐CAR to decrease Ca2+ influx through cytoplasmic membrane could not be discounted.

Endothelium-dependent vasorelaxant effects of the essential oil from aerial parts of Alpinia zerumbet and its main constituent 1,8-cineole in rats

Vasorelaxant effects of essential oil of Alpinia zerumbet (EOAZ) and its main constituent, 1,8-cineole (CIN) were studied. In rat isolated aorta preparations with intact endothelium, EOAZ (0.01-3000 microg/ml) induced significant but incomplete relaxation of the phenylephrine-induced contraction, an effect that was abolished by removal of vascular endothelium. However, at the same concentrations (0.01-3000 microg/ml corresponding to 0.0000647-19.5 mM), CIN induced a complete vasorelaxant effects (IC(50)=663.2+/-63.8 microg/ml) that were significantly reduced in endothelium-denuded rings (IC(50)=1620.6+/-35.7 microg/ml). Neither EOAZ nor CIN affected the basal tonus of isolated aorta. Vasorelaxant effects of both EOAZ and CIN remained unaffected by the addition of tetraethylamonium chloride (500 microM) or indomethacin (10 microM) into the bath, but were significantly reduced by N(G)-nitro-L-arginine methyl ester (100 microM). It is concluded that EOAZ induces a potent vasorelaxant effect that could not be fully attributed to the actions of the main constituent CIN, and appears totally dependent on the integrity of a functional vascular endothelium. The data is novel and corroborate the popular use of A. zerumbet for the treatment of hypertension.

Comparative study of the anti-edematogenic effects of anethole and estragole

BACKGROUND Anethole and estragole are monoterpene position isomers and constituents of essential oils from aromatic plants and were used in this study with the aim of analyzing their anti-inflammatory activity. METHODS The anti-edematogenic effects of anethole and estragole were evaluated through plethysmometry in Swiss mice. RESULTS Anethole inhibited carrageenan-induced edema at doses of 3, 10 and 30 mg/kg from 60 to 240 min after induction. However, the inhibitory effects of estragole were observed only from 60 to 120 min at the two highest doses. Anethole and estragole similarly inhibited edema elicited by substance P, bradykinin, histamine and TNF-α but were different in the inhibition of serotonin-elicited edema. In addition, only estragole inhibited sodium nitroprusside-induced edema. CONCLUSIONS Anethole and estragole showed different profiles in the anti-inflammatory response to substance P, bradykinin, histamine, serotonin and TNF-α NO is involved only in the inhibition mechanism of estragole.

The essential oil of Croton zehntneri and trans-anethole improves cutaneous wound healing

ETHNOPHARMACOLOGY RELEVANCE Croton zehntneri is a Euphorbiaceae species native to northeastern Brazil, where teas and beverages made from Croton zehntneri leaves are used as healing agents. To our knowledge, there is no experimental study supporting this claim of pharmacological activity. MATERIALS AND METHODS Full-thickness excisional wounds were made in the left and right sides of the dorsum of anesthetised Swiss mice, and a topical pharmaceutical formulation, developed by including essential oil extracted from the leaves of Croton zehntneri (2% and 20% EOCz) in pluronic-127 (PF-127), was administered to mice twice daily for 15 days post-wounding. To evaluate the contribution of trans-anethole, the major constituent of EOCz (85.7%), in the wound healing activity of EOCz, the effect of the topical administration of trans-AT on wound tissue repair was also evaluated and compared to other groups. A macroscopic analysis of swelling and exudates was performed and scored as 0 (missing), 1 (light), 2 (moderate) and 3 (intense). The number of capillaries and leukocytes was counted in hematoxylin and eosin (HE)-stained sections of the injured tissue. For extracellular matrix remodelling analysis, fibroblasts and collagen fibres present in the photomicrography of the Massons Trichrome (MT)-stained sections were counted. Each experimental group comprised six mice. RESULTS At day 3 post-wounding, it was observed that treatment with 20% EOCz greatly reduced the swelling and exudates with a similar magnitude to the dexamethasone treatment. The inflammatory cell infiltration and angiogenesis were not altered by either the EOCz- or trans-AT treatments. In contrast, an acceleration of the wound closure was observed, with an enhanced number of fibroblasts and collagen fibres in both the 20% EOCz- and trans-AT-treated mice. CONCLUSION Our data indicate that EOCz exerts significant wound healing activity, demonstrating its relevant therapeutic potential.

Essential oil of Croton zehntneri and its major constituent anethole display gastroprotective effect by increasing the surface mucous layer

Croton zehntneri, a plant native to northeastern Brazil, is widely used in folk medicine to treat gastrointestinal problems and has rich essential oil content. The effects of the essential oil of Croton zehntneri (EOCZ) and its main constituent anethole on several models of gastric lesions were studied in mice and rats. Oral treatment with EOCZ and anethole, both at doses of 30–300 mg/kg, caused similar and dose‐dependent gastroprotection against ethanol‐ and indomethacin‐induced gastric damage, but did not change cold‐restraint stress‐induced ulcers in rats. Furthermore, EOCZ and anethole (both at 30 and 300 mg/kg) similarly and significantly increased the mucus production by the gastric mucosa, measured by Alcian blue binding, in ethanol‐induced ulcer model. However, at the same doses, neither EOCZ nor anethole promoted significant alteration in gastric production of non‐protein sulfhydryl groups. In pylorus‐ligated model, neither EOCZ nor anethole (both at 30 and 300 mg/kg) had a significant effect on the volume of gastric juice, pH, or total acidity. The results of this study show for the first time that EOCZ possesses a gastroprotective potential, an effect mostly attributed to the action of anethole. This activity is related predominantly to the ability of EOCZ and anethole to enhance the production of gastric wall mucus, an important gastroprotective factor. Furthermore, they suggest that EOCZ has potential therapeutic application for the treatment of gastric ulcers.

Eugenol modifies the excitability of rat sciatic nerve and superior cervical ganglion neurons

Eugenol is a phenylpropene obtained from the essential oils of plants such as clove and basil which has ample use in dentistry. Eugenol possesses analgesic effects that may be related to the inhibition of voltage-dependent Na+ channels and/or to the activation of TRPV1 receptors or both. In the present study, electrophysiological parameters were taken from the compound action potentials of the isolated rat sciatic nerve and from neurons of the superior cervical ganglion (SCG) impaled with sharp microelectrodes under current-clamp conditions. In the isolated rat sciatic nerve, eugenol inhibited the compound action potential in a concentration-dependent manner. Action potentials recorded from SCG neurons were inhibited by eugenol with an IC(50) of 0.31 mM. At high concentrations (2 mM), during brief applications, eugenol caused significant action potential blockade while it did not interfere with the resting membrane potential or the membrane input resistance. Surprisingly, however, at low eugenol concentrations (0.6 mM), during long time applications, a reversible reduction (by about 50%) in the input membrane resistance was observed, suggesting the possible involvement of a secondary delayed effect of eugenol to reduce neuronal excitability.

Effects of 1,8-cineole on electrophysiological parameters of neurons of the rat superior cervical ganglion.

1  1,8‐Cineole is a non‐toxic small terpenoid oxide believed to have medicinal properties in folk medicine. It has been shown to have various pharmacological effects, including blockade of the compound action potential (AP). In the present study, using intracellular recording techniques, we investigated the effects of 1,8‐cineole on the electrophysiological parameters of neurons of the superior cervical ganglion (SCG) in rats. 2  1,8‐Cineole (0.1–6 mmol/L) showed reversible and concentration‐dependent effects on various electrophysiological parameters. At 3 and 6 mmol/L, but not at 0.1 and 1 mmol/L, 1,8‐cineole significantly diminished the input resistance (Ri) and altered the resting potential (Em) to more positive values. At 6 mmol/L, 1,8‐cineole completely blocked all APs within 2.7 ± 0.6 min (n = 12). In neurons exposed to 3 and 1 mmol/L 1,8‐cineole, the effects regarding excitability varied from complete AP blockade to minor inhibition of AP parameters. The depolarization of Em and the decrease in Ri induced by 6 mmol/L 1,8‐cineole were unaltered by 200 µmol/L niflumic acid, a well known blocker of Ca2+‐activated Cl− currents. 3  Significant correlations (Pearson correlation test) were found between changes in Em and decreases in AP amplitude (r = –0.893; P < 0.00282) and maximum ascendant inclination (r = –0.799; P < 0.0173), but not for maximum descendant inclination (r = 0.598; P < 0.117). Application of current to restore the transmembrane potential equal to control Em values in the presence of 6 mmol/L 1,8‐cineole resulted in the partial recovery of AP. 4  The present study shows that 1,8‐cineole effectively blocks the excitability of SCG neurons, probably through various mechanisms, one of which acts indirectly via depolarization of the neuronal cytoplasmatic membrane.