Pharmacological and toxicological evaluation of Alpinia speciosa

Vasorelaxant effect of Alpinia zerumbet's essential oil on rat resistance artery involves blocking of calcium mobilization

Alpinia zerumbet is a plant from the Zingiberaceae family, popularly used for hypertension treatment. Several studies have demonstrated Alpinia zerumbet vasodilator effect on conductance vessels but not on resistance vessels. Thereby, the aim of this study was to verify the vasodilator effect of the essential oil of Alpinia zerumbet (EOAz) on isolated rat resistance arteries and characterize its mechanism of action. Therefore, the effect of EOAz (3 to 3000 μg/mL) was verified in second-order branches of the mesenteric artery (SOBMA) pre-contracted by KCl and U46619. To study the mechanism of action, the influence of several inhibitors (TEA, 4-AP, Glibenclamide, Atropine, L-NAME, ODQ and indomethacin) on the vasodilator effect of EOAz was evaluated. Some protocols were also performed aiming to study the effect of EOAz on Ca2+ influx and release from intracellular storage. Furthermore, the binding energy of the main constituents with calcium channels were evaluated by molecular docking. Results showed an endothelium-independent vasorelaxant effect of EOAz on SOBMA, and only ODQ and L-NAME produced significant alteration on its pEC50. Regarding the calcium assays, contraction reduction caused by incubation with EOAz was observed in all three protocols. Hence, our results suggest that EOAz has a vasodilator effect mediated by inhibition of Ca2+ influx and release from intracellular storage, as well as an activation of the NOS/sGC pathway.

Aroma Profile and Antioxidant Activity of Essential Oil from Alpinia zerumbet

The essential oil of A. zerumbet, obtained from the leaves through steam distillation, has a distinct aroma and shows antioxidant activity. In this study, we evaluated the yields, antioxidant activity, and volatile compound composition of essential oils extracted from the leaves of A. zerumbet to better understand how these characteristics may vary among individual plants, and how they may differ with location of growth and season in which leaves are harvested. Gas chromatography–mass spectrometry (GC/MS) and principal component analysis (PCA) revealed that chemical composition in each individual plant was not affected by harvest season or growth area. Furthermore, GC/MS and antioxidant activity assays revealed that although the antioxidant activity and yield of these essential oils differed significantly between individual plants and collecting seasons, there was a strong inverse correlation between the yields of essential oils and their antioxidant activity. The yield, the major volatile compound compositions, the enantiomeric ratio of the few monoterpenes, and the antioxidant activities of A. zerumbet essential oil varied significantly among individual plants, and probably reflected the genetic variability within the species. This suggests the plausibility of selecting lineages of A. zerumbet to optimize future production of valuable essential oils.

(-)-Terpinen-4-ol changes intracellular Ca2+ handling and induces pacing disturbance in rat hearts

(-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy. It was observed that (-)-terpinen-4-ol reduced contraction force in an isolated left atrium at millimolar concentrations. Conversely, it induced a positive inotropic effect and extrasystoles at micromolar concentrations, suggesting that (-)-terpinen-4-ol may have arrhythmogenic activity on cardiac tissue. In anaesthetized animals, (-)-terpinen-4-ol also elicited rhythm disturbance, such as supraventricular tachycardia and atrioventricular block. To investigate the cellular mechanism underlying the dual effect of (-)-terpinen-4-ol on heart muscle, experiments were performed on isolated ventricular cardiomyocytes to determine the effect of (-)-terpinen-4-ol on L-type Ca²⁺ currents, Ca²⁺ sparks, and Ca²⁺ transients. The arrhythmogenic activity of (-)-terpinen-4-ol in vitro and in vivo may be explained by its effect on intracellular Ca²⁺ handling. Taken together, our data suggest that (-)-terpinen-4-ol has cardiac arrhythmogenic activity.

Hypotensive effect and endothelium-dependent vascular action of leaves of Alpinia purpurata (Vieill) K. Schum

The aims of this study were to evaluate the chemical profile, vascular reactivity, and acute hypotensive effect (AHE) of the ethanolic extract of leaves of Alpinia purpurata (Vieill) K. Schum (EEAP). Its chemical profile was evaluated using HPLC-UV, ICP-OES, and colorimetric quantification of total flavonoids and polyphenols. The vascular reactivity of the extract was determined using the mesenteric bed isolated from WKY. AHE dose-response curves were obtained for both EEAP and inorganic material isolated from AP (IAP) in WKY and SHR animals. Cytotoxic and mutagenic safety levels were determined by the micronucleus test. Rutin-like flavonoids were quantified in the EEAP (1.8 ± 0.03%), and the total flavonoid and polyphenol ratios were 4.1 ± 1.8% and 5.1 ± 0.3%, respectively. We observed that the vasodilation action of EEAP was partially mediated by nitric oxide (·NO). The IAP showed the presence of calcium (137.76 ± 4.08 μg mg-1). The EEAP and IAP showed an AHE in WKY and SHR animals. EEAP did not have cytotoxic effects or cause chromosomic alterations. The AHE shown by EEAP could result from its endothelium-dependent vascular action. Rutin-like flavonoids, among other polyphenols, could contribute to these biological activities, and the calcium present in EEAP could act in a synergistic way.

Endothelium-dependent vasodilatation effects of the essential oil from Fructus alpiniae zerumbet (EOFAZ) on rat thoracic aortic rings in vitro

Fructus Alpiniae Zerumbet (FAZ) is an herb widely used to treat vascular disorders in Guizhou province, China, the essential oil has been identified as one of it vasodilation effect active components, and especial, the composition was significantly difference from the leaves. Vasodilation effects and mechanism of essential oil from FAZ (EOFAZ) were investigated. The EOFAZ showed significant vasodilation effect on endothelium-with rat thoracic aortic rings preincubated with norepinephrine (NE, 1.0μM) or KCl (60mM) in a concentration-dependent manner (1.14-72.96μg/ml). The non-selective nitric oxide synthase inhibitor l-NAME, as well as the soluble guanylate cyclase inhibitor MB, attenuated the relaxation of EOFAZ in endothelium-intact rat thoracic aortic rings. However, there were not significantly affected the vasodilation effects pretreated with cyclooxygenase inhibition by indomethacin (Indo) or β-noradrenergic inhibition by propranolol (Prop). The present results first demonstrated that vasodilation effect of EOFAZ depending upon the endothelium and concentration, and the mechanism involvement of NOS-cGMP system. In contrast, prostacyclin and β-adrenoceptor may not be associated with EOFAZ-induced vasorelaxation.

Evidence-based antioxidant activity of the essential oil from Fructus A. zerumbet on cultured human umbilical vein endothelial cells' injury induced by ox-LDL

BACKGROUND

The essential oil from Fructus Alpiniae zerumbet (FAZ) is its principal bioactive ingredient, and is widely used in Miao folk herbs in Guizhou province for the treatment of gastrointestinal and cardiovascular diseases. Several studies have confirmed that FAZ ameliorates hyperlipidemia and atherosclerosis. Because endothelial dysfunction often accompanies cardiovascular diseases, especially hyperlipidemia and atherosclerosis, the present study concentrated on evaluating the endothelial protective effects of the essential oil from FAZ (EOFAZ) on oxidized low-density lipoprotein (ox-LDL)-induced injury of cultured human umbilical vein endothelial cells (HUVECs) and on the regulation of oxidative stress.

METHODS

Cell viability was analyzed with the MTT assay and trypan blue exclusion staining (TBES). Cell injury was assessed by lactate dehydrogenase (LDH) release. Biochemical enzymatic methods were used to evaluate the oxidative stress, including the lipid peroxidation product, malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px).

RESULTS

The redox status of HUVECs was significantly exacerbated after exposure to ox-LDL. EOFAZ protected HUVECs against ox-LDL injury as assessed by the MTT assay, TBES and LDH release. Furthermore, EOFAZ ameliorated the oxidative stress by elevating the activities of SOD, CAT and GSH-Px, and increasing the GSH levels, in addition to attenuating the MDA contents.

CONCLUSIONS

The present data provide the first experimental evidence that EOFAZ protects endothelial cells against ox-LDL-induced injury, and indicate that this protection involves ameliorating the redox status.

Inhibition of ketamine-induced hyperlocomotion in mice by the essential oil of Alpinia zerumbet: possible involvement of an antioxidant effect

OBJECTIVES

The antipsychotic, hypnotic, myorelaxant and antioxidant effects of the essential oil of Alpinia zerumbet (EOAZ) were studied.

METHODS

EOAZ (50, 100 and 200 mg/kg i.p.) was administered once to mice for the determination of antipsychotic activity (evaluated by ketamine-induced hyperlocomotion), hypnotic activity (induced by sodium pentobarbital, 40 mg/kg i.p.), motor coordination (rotarod test), antioxidant effects (determination of lipid peroxidation and GSH levels), as well as alterations in nitric oxide levels (determination of nitrite content).

KEY FINDINGS

EOAZ at doses of 100 and 200 mg/kg prevented ketamine hyperlocomotion, as did haloperidol (0.2 mg/kg i.p). EOAZ at a dose of 200 mg/kg decreased sleep latency, while all doses increased sleeping time. There was no effect on motor coordination. The in-vitro antioxidant capacity of the oil caused a decrease in lipid peroxidation and increase in GSH levels. EOAZ also prevented the decrease in nitrite content caused by oxidative stress.

CONCLUSIONS

The results suggest antipsychotic and antioxidant effects for the EOAZ that may have promising efficacy for the treatment of schizophrenia.

Cardiodepressive effect elicited by the essential oil of Alpinia speciosa is related to L-type Ca²+ current blockade

This study was undertaken to elucidate the effect of the essential oil from Alpinia speciosa (EOAs) on cardiac contractility and the underlying mechanisms. The essential oil was obtained from Alpinia speciosa leaves and flowers and the oil was analyzed by GC-MS method. Chemical analysis revealed the presence of at least 18 components. Terpinen-4-ol and 1,8-cineole corresponded to 38% and 18% of the crude oil, respectively. The experiments were conducted on spontaneously-beating right atria and on electrically stimulated left atria isolated from adult rats. The effect of EOAs on the isometric contractions and cardiac frequency in vitro was examined. EOAs decreased rat left atrial force of contraction with an EC₅₀ of 292.2±75.7 μg/ml. Nifedipine, a well known L-type Ca²+ blocker, inhibited in a concentration-dependent manner left atrial force of contraction with an EC₅₀ of 12.1±3.5 μg/ml. Sinus rhythm was diminished by EOAs with an EC₅₀ of 595.4±56.2 μg/ml. Whole-cell L-type Ca²+ currents were recorded by using the patch-clamp technique. EOAs at 25 μg/ml decreased I(Ca,L) by 32.6±9.2% and at 250 μg/ml it decreased by 89.3±7.4%. Thus, inhibition of L-type Ca²+ channels is involved in the cardiodepressive effect elicited by the essential oil of Alpinia speciosa in rat heart.

Central nervous system effects of the essential oil of the leaves of Alpinia zerumbet in mice

Objectives

Alpinia zerumbet, known in Brazil as colônia, is popularly used as a diuretic, antihypertensive, anti-ulcerogenic and sedative. Based on this, we have investigated the central effects of the essential oil isolated from A. zerumbet leaves.

Methods

Mice were treated once with 50 or 100 mg/kg of the essential oil, intraperitoneally, 30 min before being submitted to behavioural models of: locomotor activity (open-field), catalepsy, anxiety (elevated plus maze), depression (forced swimming test and tail suspension tests) as well as apomorphine-induced stereotypy.

Key findings

Results showed a dose-related decrease on locomotor activity and apomorphine-induced stereotypy. There was a decrease to the order of 55% of the grooming behaviour with both doses studied. The essential oil 100 mg/kg increased cataleptic activity (167%) and the immobility time in the forced swimming and tail suspension tests. Pretreatment with haloperidol (0.2 mg/kg, i.p.) alone also decreased locomotion, increased cataleptic activity and immobility time in the tail suspension test. No alterations in the elevated plus maze test were registered.

Conclusions

The essential oil of A. zerumbet leaves had depressant and possible antipsychotic activity, since it could reverse the stereotypy induced by apomorphine, presenting effects comparable with those obtained with haloperidol treatment.

Vasodilator activity of extracts of field Alpinia purpurata (Vieill) K: Schum and A. zerumbet (Pers.) Burtt et Smith cultured in vitro

Nowadays, the high blood pressure is one of the main causes of death and cardiovascular diseases. Vasodilator drugs are frequently used to treat arterial hypertension. Experiments were undertaken to determine whether hydroalcoholic extracts obtained from leaves of field-grown Alpinia purpurata and A. zerumbet cultured in vitro under different plant growth regulators induce a vasodilator effect on Wistar rat mesenteric vascular bed pre-contracted with norepinephrine. Plant extracts were able to induce a long-lasting endothelium-dependent vasodilation. Efficiency on activity of A. purpurata reached 87% at concentration of 60 μg. The extract of A. zerumbet maintained in medium containing IAA, induced the relaxation (17.4%) at 90 μg, as compared to the control (MS0) that showed a better vasodilator effect (60%). These results are in agreement with the quantification of phenolic compounds in the extracts, which were 50% lower for those plants cultured in IAA. A. purpurata was assayed for the first time in relation to its vasodilator activity. This paper showed a strong probability of correlation between the pharmacological activities of A. purpurata with their content in phenolic compounds.

Antihypertensive and endothelium-dependent vasodilator effects of Alpinia zerumbet, a medicinal plant

Alpinia zerumbet (K. Schum), a medicinal plant originated from West Asia, is used in the northeast and southeast of Brazil as infusions or decoctions as a diuretic, antihypertensive, and antiulcerogenic. Experiments were undertaken to determine whether a hydroalcoholic extract obtained from leaves of Alpinia zerumbet (AZE) induces vasodilation in the mesenteric vascular bed (MVB), and an antihypertensive effect was also assessed in rats with DOCA-salt hypertension. In MVB precontracted with norepinephrine, AZE induces a long-lasting endothelium-dependent vasodilation that is not reduced by indomethacin. Inhibition of NO synthase by NG-nitro-L-arginine methyl ester (L-NAME) and guanylyl cyclase by 1H-[1,2,3]oxadiazolo [4,4-a]quinoxalin-1-one (ODQ) reduces the vasodilator effect of AZE. In vessels precontracted with norepinephrine, the vasodilator effect of AZE was not changed by 4-aminopyridine, glibenclamide, or by charybdotoxin plus apamin. Concentrations of atropine, pyrilamine, and yohimbine that significantly reduced the vasodilator effect of acetylcholine, histamine, and clonidine, respectively, did not change the vasodilator effect of AZE. HOE 140, which significantly reduced the vasodilator effect of bradykinin, induced a slight but significant reduction on the vasodilator effect of AZE. Chronic oral administration of AZE induced a significant reduction in systolic, mean, and diastolic arterial pressure in rats with DOCA-salt hypertension. Probably the vasodilator effect of AZE is dependent on the activation of the NO-cGMP pathway and independent of activation of ATP-dependent, voltage-dependent, and calcium-dependent K+ channels. Bradykinin receptors may also participate in the vasodilator effect of AZE. Finally, the vasodilator and antihypertensive effects of AZE demonstrated in the present study provide experimental support for the indication of Alpinia zerumbet as an antihypertensive medicinal plant.

Antinociceptive effects of the essential oil of Alpinia zerumbet on mice

Alpinia zerumbet (Pers.) Burtt. et Smith is an aromatic plant that is distributed widely in the tropical and sub-tropical regions of the world. In Brazil, where A. zerumbet is called "colonia", it is used widely in folk medicine for the treatment of various diseases, including hypertension. In the present study, the antinociceptive effects of the orally administered essential oil of A. zerumbet (EOAz) were evaluated in male Swiss mice (20-25 g each). In the acetic acid-induced writhing test, EOAz (30, 100 and 300 mg/kg body wt.; n = 10, n = 13 and n = 15, respectively) was effective at all doses. In the hot-plate test, EOAz significantly increased the latency at doses of 100 and 300 mg/kg body wt., but not at 30 mg/kg body wt., at all observation times up to the 180th min (n = 10 for each dose). In the formalin test, EOAz significantly reduced paw licking time in the second phase of the test at 100 mg/kg body wt. (n = 10), but decreased it in both phases at 300 mg/kg body wt. (n = 10). At 30 mg/kg body wt., the effect of EOAz did not differ from control values in either phase of the formalin test (n = 10). Pretreatment with naloxone (5 mg/kgbodywt., i.p.) caused a significant reversal of the analgesic effect of 300 mg/kg body wt. EOAz (n = 8) that was complete for the first phase, but only partial for the second phase of the formalin test. The data show that orally administered OEAz promotes a dose-dependent antinociceptive effect, with a mechanism of action which probably involves the participation of opiate receptors.

Effects of essential oil of Alpinia zerumbet on the compound action potential of the rat sciatic nerve

Alpinia zerumbet, known popularly as "colônia" in Northeastern Brazil, is a medicinal plant that has been used widely in folk medicine as teas and infusions for the treatment of intestinal and cardiovascular diseases, including arterial hypertension. Our previous studies have demonstrated that the essential oil of A. zerumbet (OEAZ) is very active on excitable tissues, such as smooth muscle, and in this study we verified its effects on the compound action potential (CAP) of rat sciatic nerve. EOAZ induced a dose-dependent blockade of the CAP. Control peak-to-peak amplitude and conduction velocity of CAPs were 7.6 +/- 0.43 mV and 80.6 +/- 3.19 m/s, respectively. At 60 microg/ml, EOAZ induced no demonstrable effect. Conduction velocity was significantly reduced at 180 min of preparation exposure to 100 microg/ml of EOAZ. At 300, 600 and 2000 microg/ml doses of EOAZ, the peak-to-peak amplitudes of CAPs following 180 min exposure of the nerve to the drug were reduced significantly, to 75.3 +/- 7.36%, 50.45 +/- 2.17% and 0% respectively, of control value. Conduction velocity was reduced significantly by 300, 600 and 2000 microg/ml of EOAZ, at 180 min, to 83.61 +/- 3.28%, 64.06 +/- 8.21% and 22.7 +/- 5.79%, respectively, of control value. All these effects developed slowly and were reversible upon a 180-min wash.

Antihypertensive effects of the essential oil of Alpinia zerumbet and its main constituent, terpinen-4-ol, in DOCA-salt hypertensive conscious rats

The present study investigated the hypotensive responses to intravenous (i.v.) treatment with the essential oil of Alpinia zerumbet (EOAZ) and its main constituent, terpinen-4-ol (Trp-4-ol), in the experimental model of deoxycorticosterone-acetate (DOCA)-salt hypertensive rat. In both DOCA-salt hypertensive and uninephrectomized, normotensive rats, i.v. bolus injections of EOAZ (1-20 mg/kg) or Trp-4-ol (1-10 mg/kg) decreased mean aortic pressure (MAP) in a dose-related manner. However, hypotensive responses to Trp-4-ol were significantly greater than those evoked by the same doses of EOAZ (1-10 mg/kg). Treatment with DOCA-salt significantly enhanced the maximal percentage decreases in MAP evoked by EOAZ or Trp-4-ol. Likewise, both maximal percentage and absolute decreases in MAP elicited by i.v. injection of the ganglion blocker, hexamethonium (30 mg/kg), were significantly greater in DOCA-salt hypertensive than in control rats. In DOCA-salt hypertensive rats, neither hexamethonium (30 mg/kg, i.v.) nor methylatropine (1 mg/kg, i.v.) pretreatment affected the enhancement of EOAZ-induced hypotension. These results show that i.v. treatment with either EOAZ or Trp-4-ol dose-dependently decreases blood pressure in conscious DOCA-salt hypertensive rats, and this action is enhanced when compared with uninephrectomized controls. This enhancement could be related mainly to an increase in EOAZ-induced vascular smooth muscle relaxation rather than to enhanced sympathetic nervous system activity in this hypertensive model. The data further support our previous hypothesis that hypotensive effects of EOAZ are partially attributed to the actions of Trp-4-ol.

Cardiovascular effects of 1,8-cineole, a terpenoid oxide present in many plant essential oils, in normotensive rats

The cardiovascular effects of i.v. treatment with 1,8-cineole, a monoterpenic oxide present in many plant essential oils, were investigated in normotensive rats. This study examined (i) whether the autonomic nervous system is involved in the mediation of 1,8-cineole-induced changes in mean aortic pressure (MAP) and heart rate (HR) and (ii) whether the hypotensive effects of 1,8-cineole could result from its vasodilatory effects directly upon vascular smooth muscle. In both pentobarbital-anesthetized and conscious, freely moving rats, bolus injections of 1,8-cineole (0.3-10 mg/kg, i.v.) elicited similar and dose-dependent decreases in MAP. Concomitantly, 1,8-cineole significantly decreased HR only at the highest dose (10 mg/kg). Pretreatment of anesthetized rats with bilateral vagotomy significantly reduced the bradycardic responses to 1,8-cineole (10 mg/kg) without affecting hypotension. In conscious rats, i.v. pretreatment with methylatropine (1 mg/kg), atenolol (1.5 mg/kg), or hexamethonium (30 mg/kg) had no significant effects on the 1,8-cineole-induced hypotension, while bradycardic responses to 1,8-cineole (10 mg/kg) were significantly reduced by methylatropine. In rat isolated thoracic aorta preparations, 1,8-cineole (0.006-2.6 mM) induced a concentration-dependent reduction of the contraction induced by potassium (60 mM). This is the first physiological evidence that i.v. treatment with 1,8-cineole in either anesthetized or conscious rats elicits hypotension; this effect seems related to an active vascular relaxation rather than withdrawal of sympathetic tone.

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 microg/mL) reversibly relaxed ileal basal tonus. Submaximal contractions induced by 60 mM KCl or acetylcholine were concentration dependently inhibited by EOAS with similar IC(50) values ( approximately 44 and 48 microg/mL, respectively). These results show that EOAS possesses both relaxant and antispasmodic actions in the ileum.

Timing the radiations of leaf beetles: hispines on gingers from latest cretaceous to recent

Stereotyped feeding damage attributable solely to rolled-leaf hispine beetles is documented on latest Cretaceous and early Eocene ginger leaves from North Dakota and Wyoming. Hispine beetles (6000 extant species) therefore evolved at least 20 million years earlier than suggested by insect body fossils, and their specialized associations with gingers and ginger relatives are ancient and phylogenetically conservative. The latest Cretaceous presence of these relatively derived members of the hyperdiverse leaf-beetle clade (Chrysomelidae, more than 38,000 species) implies that many of the adaptive radiations that account for the present diversity of leaf beetles occurred during the Late Cretaceous, contemporaneously with the ongoing rapid evolution of their angiosperm hosts.