In-vitro characterization of the pharmacological effects induced by (-)-α-bisabolol in rat smooth muscle preparations

The Nephroprotective Effects of α-Bisabolol in Cisplatin-Induced Acute Kidney Injury in Mice

Cisplatin (CP) treatment has been long associated with the development of acute kidney injury (AKI) through mechanisms involving inflammation and oxidative stress. α-Bisabolol (BIS), a sesquiterpene alcohol isolated from the essential oil of various plants, including chamomile, has garnered popularity lately due to its antioxidant, anti-inflammatory, and anticancer properties. Therefore, we investigated the nephroprotective effects of BIS in the murine model of CP-induced AKI and the underlying mechanism of action. BALB/c mice were given BIS orally at 25 mg/kg for 7 days. On day 7, they were given a single dose of CP at 20 mg/kg intraperitoneally. BIS treatment continued for 3 more days. The animals were sacrificed at the end of the experiment (day 11). Kidneys, plasma, and urine were collected, and subsequently, various physiological, biochemical, and histological parameters were assessed. BIS has significantly normalized the alterations of water intake, urine volume, relative kidney weight, and the concentrations of urea and creatinine, as well as the creatinine clearance induced by CP treatment. BIS significantly mitigated the effects of CP-induced kidney injury by reducing kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, adiponectin, and cystatin C. Likewise, the renal concentrations of proinflammatory cytokines, tumor necrosis factor α, interleukin (IL)-6 and IL-1β that were elevated in CP group were significantly reduced in mice treated with BIS and CP. A similar significant reduction was also observed in the CP-induced augmented levels of markers of oxidative stress, as well as the metabolite pteridine. Moreover, BIS significantly reduced the CP–induced renal DNA damage, and markedly lessened the acute tubular necrosis observed in kidney histology. Additionally, BIS significantly reduced the CP-induced increase in the phosphorylated nuclear factor κB (NFκB) in the kidney. These data strongly suggest that BIS exerts a protective action against CP-induced nephrotoxicity by mitigating inflammation and oxidative stress through the inhibition of NFκB activation. No overt adverse effects were noted with BIS treatment. Additional investigations should be done to consider BIS as an efficacious nephroprotective agent against CP.

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.

α-Bisabolol, a Dietary Bioactive Phytochemical Attenuates Dopaminergic Neurodegeneration through Modulation of Oxidative Stress, Neuroinflammation and Apoptosis in Rotenone-Induced Rat Model of Parkinson's disease

Rotenone (ROT), a plant-derived pesticide is a well-known environmental neurotoxin associated with causation of Parkinson’s disease (PD). ROT impairs mitochondrial dysfunction being mitochondrial complex-I (MC-1) inhibitor and perturbs antioxidant-oxidant balance that contributes to the onset and development of neuroinflammation and neurodegeneration in PD. Due to the scarcity of agents to prevent the disease or to cure or halt the progression of symptoms of PD, the focus is on exploring agents from naturally occurring dietary phytochemicals. Among numerous phytochemicals, α-Bisabolol (BSB), natural monocyclic sesquiterpene alcohol found in many ornamental flowers and edible plants garnered attention due to its potent pharmacological properties and therapeutic potential. Therefore, the present study investigated the neuroprotective effects of BSB in a rat model of ROT-induced dopaminergic neurodegeneration, a pathogenic feature of PD and underlying mechanism targeting oxidative stress, inflammation and apoptosis. BSB treatment significantly prevented ROT-induced loss of dopaminergic neurons and fibers in the substantia nigra and striatum respectively. BSB treatment also attenuated ROT-induced oxidative stress evidenced by inhibition of MDA formation and GSH depletion as well as improvement in antioxidant enzymes, SOD and catalase. BSB treatment also attenuated ROT-induced activation of the glial cells as well as the induction and release of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and inflammatory mediators (iNOS and COX-2) in the striatum. In addition to countering oxidative stress and inflammation, BSB also attenuated apoptosis of dopaminergic neurons by attenuating downregulation of anti-apoptotic protein Bcl-2 and upregulation of pro-apoptotic proteins Bax, cleaved caspases-3 and 9. Further, BSB was observed to attenuate mitochondrial dysfunction by inhibiting mitochondrial lipid peroxidation, cytochrome-C release and reinstates the levels/activity of ATP and MC-I. The findings of the study demonstrate that BSB treatment salvaged dopaminergic neurons, attenuated microglia and astrocyte activation, induction of inflammatory mediators, proinflammatory cytokines and reduced the expression of pro-apoptotic markers. The in vitro study on ABTS radical revealed the antioxidant potential of BSB. The results of the present study are clearly suggestive of the neuroprotective effects of BSB through antioxidant, anti-inflammatory and anti-apoptotic properties in ROT-induced model of PD.

(-)-α-Bisabolol reduces nociception and trigeminal central sensitisation in acute orofacial neuropathic pain induced by infraorbital nerve injury

Neuropathic orofacial pain conditions represent a challenge to diagnose and treat. Natural substances are promising therapeutic options for the control of pain.

AIMS

This study aimed to examine whether (-)-α-bisabolol (BISA), a natural terpene, can attenuate nociceptive behaviour and central sensitisation in a rodent model of trigeminal neuropathic pain.

MATERIALS AND METHODS

Infraorbital nerve transection (IONX) or sham operation was performed in adult male rats. Head withdrawal thresholds as a measure of facial mechanical sensitivity were tested with von Frey monofilaments applied bilaterally to the facial vibrissal pad pre-operatively (baseline) and then post-operatively before and at 60, 120, 240 and 360 min after administration of vehicle control per oris (p.o.) or BISA (200 mg/kg p.o.) (n = 8/group). Effects of BISA or vehicle on the activity of nociceptive neurons recorded in the medullary dorsal horn (MDH) were tested on post - operative day 8-10. ANOVA followed by post-hoc Bonferroni tested for statistically significant differences (p < 0.05) across study groups and time points.

KEY FINDINGS

IONX animals (but not sham or naïve animals) showed post-operative facial mechanical hypersensitivity that was unaffected by vehicle. However, administration of BISA at post-operative day 7 significantly reversed the mechanical hypersensitivity in IONX rats; this effect lasted for at least 6 h. BISA also attenuated IONX-induced central sensitisation of MDH nociceptive neurons, as reflected in reversal of their reduced activation thresholds, increased responses to graded mechanical stimuli and enhanced spontaneous activity.

SIGNIFICANCE

BISA may attenuate nociceptive behaviour and central sensitisation in a rat model of acute trigeminal neuropathic pain.

Medicinal properties of terpenes found in Cannabis sativa and Humulus lupulus

Cannabaceae plants Cannabis sativa L. and Humulus lupulus L. are rich in terpenes - both are typically comprised of terpenes as up to 3-5% of the dry-mass of the female inflorescence. Terpenes of cannabis and hops are typically simple mono- and sesquiterpenes derived from two and three isoprene units, respectively. Some terpenes are relatively well known for their potential in biomedicine and have been used in traditional medicine for centuries, while others are yet to be studied in detail. The current, comprehensive review presents terpenes found in cannabis and hops. Terpenes' medicinal properties are supported by numerous in vitro, animal and clinical trials and show anti-inflammatory, antioxidant, analgesic, anticonvulsive, antidepressant, anxiolytic, anticancer, antitumor, neuroprotective, anti-mutagenic, anti-allergic, antibiotic and anti-diabetic attributes, among others. Because of the very low toxicity, these terpenes are already widely used as food additives and in cosmetic products. Thus, they have been proven safe and well-tolerated.

Anti-inflammatory and utero-relaxant effect of α-bisabolol on the pregnant human uterus

The aim of this study was to evaluate the in vitro anti-inflammatory and utero-relaxant effect of α-bisabolol on the pregnant human myometrium. Samples from the pregnant human myometrium were used in functional tests to evaluate the inhibitory effect of α-bisabolol (560, 860, 1,200 and 1,860 µM) on spontaneous myometrial contractions. The intracellular cyclic adenosine monophosphate (cAMP) levels generated in response to α-bisabolol in human myometrial homogenates were measured by ELISA. The anti-inflammatory effect of α-bisabolol was determined through the measurement of two pro-inflammatory cytokines, tumor necrosis factor-α (TNFα) and interleukin (IL)-1β, and the anti-inflammatory cytokine IL-10, in pregnant human myometrial explants stimulated with lipopolysaccharide (LPS). Forskolin was used as a positive control to evaluate the cAMP and cytokine levels. α-Bisabolol was found to induce a significant inhibition of spontaneous myometrial contractions at the highest concentration level (p<0.05). α-Bisabolol caused a concentration-dependent decrease in myometrial cAMP levels (p<0.05) and a concentration-dependent decrease in LPS-induced TNFα and IL-1β production, while IL-10 production did not increase significantly (p>0.05). The anti-inflammatory and utero-relaxant effects induced by α-bisabolol were not associated with an increase in cAMP levels in pregnant human myometrial samples. These properties place α-bisabolol as a potentially safe and effective adjuvant agent in cases of preterm birth, an area of pharmacological treatment that requires urgent improvement.

Protective effect of (−)-α-bisabolol on rotenone-induced toxicity in Drosophila melanogaster

(−)-α-Bisabolol (BISA) is a sesquiterpene alcohol, which has several recognized biological activities, including anti-inflammatory, anti-irritant, and antibacterial properties. In the present study, we investigated the influence of BISA (5, 25, and 250 μmol/L) on rotenone (500 μmol/L)-induced toxicity in Drosophila melanogaster for 7 days. BISA supplementation significantly decreased rotenone-induced mortality and locomotor deficits. The loss of motor function induced by rotenone correlated with a significant change in stress response factors; it decreased thiol levels, inhibited mitochondria complex I, and increased the mRNA expression of antioxidant marker proteins such as superoxide dismutase (SOD), catalase (CAT), and the keap1 gene product. Taken together, our findings indicate that the toxicity of rotenone is likely due to the direct inhibition of complex I activity, resulting in a high level of oxidative stress. Dietary supplementation with BISA affected the expression of SOD mRNA only at a concentration of 250 μmol/L, and did not affect any other parameter measured. Our results showed a protective effect of BISA on rotenone-induced mortality and locomotor deficits in Drosophila; this effect did not correlate with mitochondrial complex I activity, but may be related to the antioxidant protection afforded by eliminating superoxide generated as a result of rotenone-induced mitochondrial dysfunction.

Cardiovascular Activity of the Chemical Constituents of Essential Oils

Cardiovascular diseases are a leading cause of death in developed and developing countries and decrease the quality of life, which has enormous social and economic consequences for the population. Recent studies on essential oils have attracted attention and encouraged continued research of this group of natural products because of their effects on the cardiovascular system. The pharmacological data indicate a therapeutic potential for essential oils for use in the treatment of cardiovascular diseases. Therefore, this review reports the current studies of essential oils chemical constituents with cardiovascular activity, including a description of their mechanisms of action.

α-bisabolol-loaded lipid-core nanocapsules reduce lipopolysaccharide-induced pulmonary inflammation in mice

Acute respiratory distress syndrome (ARDS) is a severe clinical condition of respiratory failure due to an intense inflammatory response with different etiologies. Despite all efforts, therapy remains limited, and ARDS is still associated with high mortality and morbidity. Plants can provide a vast source of active natural products for the discovery of new drugs. α-bisabolol (α-bis), a constituent of the essential oil from chamomile, has elicited pharmacological interest. However, the molecule has some limitations to its biological application. This study was conducted to develop a drug delivery system using lipid-core nanocapsules (LNCs) to improve the anti-inflammatory effects of orally administered α-bis. α-bis-loaded LNCs (α-bis-LNCs) were prepared by interfacial deposition of poly(ε-caprolactone) and orally administered in a mouse model of ARDS triggered by an intranasal administration of lipopolysaccharide (LPS). We found that α-bis-LNCs (30, 50, and 100 mg kg^-1) significantly reduced airway hyperreactivity (AHR), neutrophil infiltration, myeloperoxidase activity, chemokine levels (KC and MIP-2), and tissue lung injury 18 hours after the LPS challenge. By contrast, free α-bis failed to modify AHR and neutrophil accumulation in the bronchoalveolar lavage effluent and lung parenchyma and inhibited elevation in the myeloperoxidase and MIP-2 levels only at the highest dose. Furthermore, only α-bis-LNCs reduced LPS-induced changes in mitogen-activated protein kinase signaling, as observed by a significant reduction in phosphorylation levels of ERK1/2, JNK, and p38 proteins. Taken together, our results clearly show that by using LNCs, α-bis was able to decrease LPS-induced inflammation. These findings may be explained by the robust increase of α-bis concentration in the lung tissue that was achieved by the LNCs. Altogether, these results indicate that α-bis-LNCs should further be investigated as a potential alternative for the treatment of ARDS.

Nephroprotective effects of (-)-α-bisabolol against ischemic-reperfusion acute kidney injury

BACKGROUND

Ischemia/reperfusion (I/R) in kidney is commonly related to acute kidney injury (AKI), essentially through oxidative stress. (-)-α-Bisabolol is a sesquiterpene isolated from the essential oil of a variety of plants, including chamomile, which has important antioxidant activity.

STUDY DESIGN

This study intends to evaluate the nephroprotective activity of (-)-α-bisabolol (Bis) in both in vivo and in vitro models of kidney I/R.

METHODS

Male Wistar rats were submitted to right nephrectomy, followed by ischemia by clamping of the renal artery in the left kidney for 60min. and 48h of reperfusion. The animals were treated orally with Bis (100mg/kg) or vehicle for 24h after reperfusion, and placed in metabolic cages, to evaluate water consumption, diuresis, urinary osmolality, classic biochemical markers and urinary KIM-1 (kidney injury molecule-1). Additionally, the left kidney was collected for histological evaluation and determination of glutathione (GSH) and Thiobarbituric Acid Reactive Substances (TBARS) levels. Tubular epithelial cells LLC-MK2 were used to assess Bis effect on in vitro I/R, by MTT assay. It was performed the cellular respiration tests by flow cytometry: evaluation of the production of cytoplasmic reactive oxygen species by DCFH-DA assay and mitochondrial transmembrane potential analysis with the dye rhodamine 123.

RESULTS

I/R caused alterations in diuresis, water intake, urinary osmolality, plasmatic creatinine, urea and uric acid, creatinine clearance, proteinuria and microalbuminuria. Treatment with Bis ameliorated all of these parameters. Also, KIM-1 level enhanced by I/R was also diminished in groups treated with Bis. The histological examination showed that Bis attenuated the morphological changes caused by I/R, markedly vascular congestion and intratubular deposits of proteinaceous material. Additionally, Bis was able to reduce the changes observed in TBARS and GSH levels in kidney tissue. In in vitro assay, Bis was capable to partially protect the cell lineage against cell damage induced by I/R.

CONCLUSION

(-)-α-Bisabolol has a nephroprotective effect in kidney I/R, with antioxidant effect. Moreover, this result seems to be associated to a direct protective effect on tubular epithelia.

β-Citronellol, an alcoholic monoterpene with inhibitory properties on the contractility of rat trachea

β-Citronellol is an alcoholic monoterpene found in essential oils such Cymbopogon citratus (a plant with antihypertensive properties). β-Citronellol can act against pathogenic microorganisms that affect airways and, in virtue of the popular use of β-citronellol-enriched essential oils in aromatherapy, we assessed its pharmacologic effects on the contractility of rat trachea. Contractions of isolated tracheal rings were recorded isometrically through a force transducer connected to a data-acquisition device. β-Citronellol relaxed sustained contractions induced by acetylcholine or high extracellular potassium, but half-maximal inhibitory concentrations (IC50) for K(+)-elicited stimuli were smaller than those for cholinergic contractions. It also inhibited contractions induced by electrical field stimulation or sodium orthovanadate with pharmacologic potency equivalent to that seen against acetylcholine-induced contractions. When contractions were evoked by selective recruitment of Ca2+ from the extracellular medium, β-citronellol preferentially inhibited contractions that involved voltage-operated (but not receptor-operated) pathways. β-Citronellol (but not verapamil) inhibited contractions induced by restoration of external Ca2+ levels after depleting internal Ca2+ stores with the concomitant presence of thapsigargin and recurrent challenge with acetylcholine. Treatment of tracheal rings with L-NAME, indomethacin or tetraethylammonium did not change the relaxing effects of β-citronellol. Inhibition of transient receptor potential vanilloid subtype 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptors with selective antagonists caused no change in the effects of β-citronellol. In conclusion, β-citronellol exerted inhibitory effects on rat tracheal rings, with predominant effects on contractions that recruit Ca2+ inflow towards the cytosol by voltage-gated pathways, whereas it appears less active against contractions elicited by receptor-operated Ca2+ channels.

Role of NO-cGMP pathway in ovine cervical relaxation induced by Erythroxylum caatingae Plowman

Erythroxylum caatingae Plowman has a myorelaxing effect on smooth muscle tissue. We investigated the effect of the crude ethanolic extract of E. caatingae Plowman (Ec-EtOH) on the contractility of the ovine cervix. In an isometric system, circular strips were subjected to 90mM potassium (K(+)) or 30μM carbamylcholine (CCh)-induced contraction. We then exposed the tissue to cumulative concentrations of Ec-EtOH (1-729 μg/ml). In other bath solutions, the tissues were exposed to l-NG-nitroarginine methyl ester (l-NAME; 100μM), l-NAME (100μM)+l-arginine (300μM), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ; 5μM), 4-aminopyridine (4-AP; 3mM), tetraethylammonium (TEA; 0.3mM), glybenclamide (1μM), atosiban (10μM) or verapamil (3μM), followed by the addition of Ec-EtOH (1-729 μg/ml). We also evaluated the effect of cervical Ec-EtOH infusion (2mg) on cervical contractility in vivo. Ec-EtOH decreased cervical contractility induced by K(+) or CCh, and 729 μg/ml Ec-EtOH decreased 85.4±5.1% the amplitude of basal contractility in vitro, with an EC50 of 17.9±3.7 μg/ml. This effect of Ec-EtOH was prevented by l-NAME or ODQ. l-arginine impaired the blunting effect of l-NAME on cervical relaxation caused by Ec-EtOH. However, the potassium channel blockers 4-AP, TEA, and glybenclamide did not modify this myorelaxation triggered by Ec-EtOH. Ec-EtOH also decreased acetylcholine-induced contractions in tissue preincubated with verapamil. In addition, Ec-EtOH decreased ovine cervical contractions in vivo. Thus, Ec-EtOH had a relaxant effect on ovine cervical contractions. This may involve the nitric oxide signal, mediated by cGMP cellular transduction, and be related to intracellular calcium sequestration.

Inhibitory actions of bisabolol on α7-nicotinic acetylcholine receptors

Bisabolol is a plant-derived monocyclic sesquiterpene alcohol with antinociceptive and antiinflammatory actions. However, molecular targets mediating these effects of bisabolol are poorly understood. In this study, using a two-electrode voltage-clamp and patch-clamp techniques and live cellular calcium imaging, we have investigated the effect of bisabolol on the function of human α7 subunit of nicotinic acetylcholine receptor (nAChR) in Xenopus oocytes, interneurons of rat hippocampal slices. We have found that bisabolol reversibly and concentration dependently (IC50 = 3.1 μM) inhibits acetylcholine (ACh)-induced α7 receptor-mediated currents. The effect of bisabolol was not dependent on the membrane potential. Bisabolol inhibition was not changed by intracellular injection of the Ca(2+) chelator BAPTA and perfusion with Ca(2+)-free solution containing Ba(2+), suggesting that endogenous Ca(2+)-dependent Cl(-) channels are not involved in bisabolol actions. Increasing the concentrations of ACh did not reverse bisabolol inhibition. Furthermore, the specific binding of [(125)I] α-bungarotoxin was not attenuated by bisabolol. Choline-induced currents in CA1 interneurons of rat hippocampal slices were also inhibited with IC50 of 4.6 μM. Collectively, our results suggest that bisabolol directly inhibits α7-nAChRs via a binding site on the receptor channel.

Vasorelaxation induced by methyl cinnamate, the major constituent of the essential oil of Ocimum micranthum, in rat isolated aorta

The aim of the present study was to investigate the vascular effects of the E-isomer of methyl cinnamate (E-MC) in rat isolated aortic rings and the putative mechanisms underlying these effects. At 1-3000 μmol/L, E-MC concentration-dependently relaxed endothelium-intact aortic preparations that had been precontracted with phenylephrine (PHE; 1 μmol/L), with an IC50 value (geometric mean) of 877.6 μmol/L (95% confidence interval (CI) 784.1-982.2 μmol/L). These vasorelaxant effects of E-MC remained unchanged after removal of the vascular endothelium (IC50 725.5 μmol/L; 95% CI 546.4-963.6 μmol/L) and pretreatment with 100 μmol/L N(G) -nitro-l-arginine methyl ester (IC50 749.0 μmol/L; 95% CI 557.8-1005.7 μmol/L) or 10 μmol/L 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (IC50 837.2 μmol/L; 95% CI 511.4-1370.5 μmol/L). Over the concentration range 1-3000 μmol/L, E-MC relaxed K(+) -induced contractions in mesenteric artery preparations (IC50 314.5 μmol/L; 95% CI 141.9-697.0 μmol/L) with greater potency than in aortic preparations (IC50 1144.7 μmol/L; 95% CI 823.2-1591.9 μmol/L). In the presence of a saturating contractile concentration of K(+) (150 mmol/L) in Ca(2+) -containing medium combined with 3 μmol/L PHE, 1000 μmol/L E-MC only partially reversed the contractile response. In contrast, under similar conditions, E-MC nearly fully relaxed PHE-induced contractions in aortic rings in a Ba(2+) -containing medium. In preparations that were maintained under Ca(2+) -free conditions, 600 and 1000 μmol/L E-MC significantly reduced the contractions induced by exogenous Ca(2+) or Ba(2+) in KCl-precontracted preparations, but not in PHE-precontracted preparations (in the presence of 1 μmol/L verapamil). In addition, E-MC (1-3000 μmol/L) concentration-dependently relaxed the contractions induced by 2 mmol/L sodium orthovanadate. Based on these observations, E-MC-induced endothelium-independent vasorelaxant effects appear to be preferentially mediated by inhibition of plasmalemmal Ca(2+) influx through voltage-dependent Ca(2+) channels. However, the involvement of a myogenic mechanism in the effects of E-MC is also possible.

(-)-α-Bisabolol inhibits preferentially electromechanical coupling on rat isolated arteries

Previous findings enable us to hypothesize that (-)-α-bisabolol acts as inhibitor of voltage-dependent Ca(2+) channels in smooth muscle. The current study was aimed at consolidating such hypothesis through the recording of isometric tension, measurement of intracellular Ca(2+) as well as discovery of channel target using in silico analysis. In rat aortic rings, (-)-α-bisabolol (1-1000 µM) relaxed KCl- and phenylephrine-elicited contractions, but the IC50 differed significantly (22.8 [17.6-27.7] and 200.7 [120.4-334.6] µM, respectively). The relaxation of phenylephrine contractions remained unaffected by l-NAME, indomethacin, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, tetraethylammonium, glibenclamide or KT-5720. Under Ca(2+)-free conditions, (-)-α-bisabolol did not alter the contractions evoked by phenylephrine or caffeine whereas it reduced those evoked by CaCl2 in KCl-, but not in PHE-stimulated preparations. Furthermore, it did not significantly alter the contractions evoked by phorbol 12,13-dibutyrate or induced by the extracellular Ca(2+) restoration in cyclopiazonic acid-treated preparations. In mesenteric rings loaded with Fluo-4 AM, (-)-α-bisabolol blunted the tension and the cytosolic levels of Ca(2+) in response to K(+) but not to norepinephrine. Silico docking analysis of the Cavβ2a subunit of voltage-dependent Ca(2+) channel indicated putative docking sites for (-)-α-bisabolol. These findings reinforce the ability of (-)-α-bisabolol to inhibit preferentially contractile responses evoked by Ca(2+) influx through voltage-dependent Ca(2+) channels.