Cardiovascular effects of 1-nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, in spontaneously hypertensive rats

Natural essential oils: A promising strategy for treating cardio-cerebrovascular diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Essential oils (EO) are volatile compounds obtained from different parts of natural plants, and have been used in national, traditional and folk medicine to treat various health problems all over the world. Records indicate that in history, herbal medicines rich in EO have been widely used for the treatment of CVDs in many countries, such as China.

AIM OF THE STUDY

This review focused on the traditional application and modern pharmacological mechanisms of herbal medicine EO against CVDs in preclinical and clinical trials through multi-targets synergy. Besides, the EO and anti-CVDs drugs were compared, and the broad application of EO was explained from the properties of drugs and aromatic administration routes.

MATERIALS AND METHODS

Information about EO and CVDs was collected from electronic databases such as Web of Science, ScienceDirect, PubMed, and China National Knowledge Infrastructure (CNKI). The obtained data sets were sequentially arranged for better understanding of EO' potential.

RESULTS

The study showed that EO had significant application in CVDs at different countries or regions since ancient times. Aiming at the complex pathological mechanisms of CVDs, including intracellular calcium overload, oxidative stress, inflammation, vascular endothelial cell injury and dysfunction and dyslipidemia, we summarized the roles of EO on CVDs in preclinical and clinical through multi-targets intervention. Besides, EO had the dual properties of drug and excipients. And aromatherapy was one of the complementary therapies to improve CVDs.

CONCLUSIONS

This paper reviewed the EO on traditional treatment, preclinical mechanism and clinical application of CVDs. As important sources of traditional medicines, EO' remarkable efficacy had been confirmed in comprehensive literature reports, which showed that EO had great medicinal potential.

Aniba canelilla (Kunth) Mez (Lauraceae) Essential Oil: Effects on Oxidative Stress and Vascular Permeability

The present study aimed to investigate the antioxidant activity of Aniba canelilla (kunth) Mez (Lauraceae) essential oil (AcEO), exploring its potential for prevention and/or treatment of oxidative stress and associated inflammatory process. With this aim, Wistar rats (n = 6/group) were pre-treated intraperitoneally with saline (0.9%) or AcEO (2 or 5 mg/kg) for 5 days. One hour after the last dose, inflammation and oxidative stress were induced by carrageenan (0.3 mg/kg; ip.) administration. Total antioxidant capacity, reduced glutathione (GSH) and lipid peroxidation levels, protein concentration, and leukocyte migration were evaluated in peritoneal fluid. Lipid peroxidation was also evaluated in plasma. Carrageenan strongly reduced the peritoneal antioxidant capacity and GSH concentration, increasing peritoneal and plasma lipid peroxidation. It also promoted increased plasma leakage and leukocyte migration. Treatment with AcEO (2 and 5 mg/kg), whose major constituent was 1-nitro-2-phenylethane (77.5%), increased the peritoneal antioxidant capacity and GSH concentrations, and reduced lipid peroxidation, both peritoneal and plasma, thus inhibiting the carrageenan-induced oxidative imbalance. AcEO also reduced the carrageenan-induced plasma leakage and leukocyte migration. These data demonstrate the AcEO antioxidant activity and its ability to modulate plasma leakage and leukocyte migration, confirming its potential for treating diseases associated with inflammation and oxidative stress.

Chemical Diversity and Therapeutic Effects of Essential Oils of Aniba Species from the Amazon: A Review

Lauraceae families have great diversity in the world's tropical regions and are represented mainly by aromatic shrubs and trees with significant production of essential oils (EOs). This work presents a review of the EO chemical profiles from specimens of Aniba, including their seasonal variations, geographical distributions, and biological activities in the Amazon biome. Based on the survey, 15 species were reviewed, representing 167 oil samples extracted from leaves, twig barks, and woods. Brazilian Amazon was the most representative geographic area in the number of specimens, highlighting the locations Belém, (Pará state, PA) (3 spp., 37 samples), Santarém (PA) (3 spp., 10 samples), Carajás (PA) (3 spp., 7 samples), and Manaus (Amazonas state, AM) (3 spp., 16 samples). The main compound classes identified in oils were benzenoids and phenylpropanoids, represented by 1-nitro-2-phenylethane, benzyl salicylate, benzyl benzoate and methyleugenol, along with terpenoids, especially monoterpenes and sesquiterpenes, such as linalool, α-phellandrene, β-phellandrene, β-selinene, and spathulenol. The EOs from Aniba showed considerable variation in the chemical profiles according to season and collection site. The hierarchical cluster analysis classified the samples into two main groups according to chemical composition. This review highlights its comprehensive and up-to-date information on history, conservation, traditional uses, chemosystematics, pharmacological potential of Aniba species.

Essential Oil Composition and DNA Barcode and Identification of Aniba species (Lauraceae) Growing in the Amazon Region

Lauraceae species are widely represented in the Amazon, presenting a significant essential oil yield, large chemical variability, various biological applications, and high economic potential. Its taxonomic classification is difficult due to the accentuated morphological uniformity, even among taxa from a different genus. For this reason, the present work aimed to find chemical and molecular markers to discriminate Aniba species collected in the Pará State (Brazil). The chemical composition of the essential oils from Aniba canelilla, A. parviflora, A. rosaeodora, and A. terminalis were grouped by multivariate statistical analysis. The major compounds were rich in benzenoids and terpenoids such as 1-nitro-2-phenylethane (88.34-70.85%), linalool (15.2-75.3%), α-phellandrene (36.0-51.8%), and β-phellandrene (11.6-25.6%). DNA barcodes were developed using the internal transcribed spacer (ITS) nuclear region, and the matK, psbA-trnH, rbcL, and ycf1 plastid regions. The markers psbA-trnH and ITS showed the best discrimination for the species, and the phylogenic analysis in the three- (rbcL + matK + trnH - psbA and rbcL + matK + ITS) and four-locus (rbcL + matK + trnH - psbA + ITS) combination formed clades with groups strongly supported by the Bayesian inference (BI) (PP:1.00) and maximum likelihood (ML) (BS ≥ 97%). Therefore, based on statistical multivariate and phylogenetic analysis, the results showed a significant correlation between volatile chemical classes and genetic characteristics of Aniba species.

The soluble guanylate cyclase stimulator, 1-nitro-2-phenylethane, reverses monocrotaline-induced pulmonary arterial hypertension in rats

AIMS

We examined the effects of treatment with 1-nitro-2-phenylethane (NP), a novel soluble guanylate cyclase stimulator, on monocrotaline (MCT)-induced PAH in rats.

MAIN METHODS

At day 0, male adult rats were injected with a single subcutaneous (s.c.) dose of monocrotaline (60 mg/kg). Control (CNT) rats received an equal volume of monocrotaline's vehicle only (s.c.). Four weeks later, MCT-treated rats were treated orally for 14 days with NP (50 mg/kg/day) (MCT-NP group) or its vehicle (Tween 2%) (MCT-V group). At the end of the treatment period and before invasive hemodynamic study, rats of all experimental groups were examined by echocardiography.

KEY FINDINGS

With respect to CNT rats, MCT-V rats showed significant; (1) increases in pulmonary artery (PA) diameter, RV free wall thickness and end-diastolic RV area, and increase of Fulton index; (2) decreases in maximum pulmonary flow velocity, PA acceleration time (PAAT), PAAT/time of ejection ratio, and velocity-time integral; (3) increases in estimated mean pulmonary arterial pressure; (4) reduction of maximal relaxation to acetylcholine in aortic rings, and (5) increases in wall thickness of pulmonary arterioles. All these measured parameters were significantly reduced or even abolished by oral treatment with NP.

SIGNIFICANCE

NP reversed endothelial dysfunction and pulmonary vascular remodeling, which in turn reduced ventricular hypertrophy. NP reduced pulmonary artery stiffness, normalized the pulmonary artery diameter and alleviated RV enlargement. Thus, NP may represent a new therapeutic or a complementary approach to treatment of PAH.

Aniba canelilla (Kunth) Mez (Lauraceae): A Review of Ethnobotany, Phytochemical, Antioxidant, Anti-Inflammatory, Cardiovascular, and Neurological Properties

Aniba canelilla (Kunth) Mez, popularly known as “casca preciosa” (precious bark), falsa canela (cinnamon-scented) Casca-do-maranhão (bark of maranhão), and Folha-preciosa (precious leaf), is an aromatic species of the Lauraceae family, widely distributed in the Amazon region. In traditional medicine, it is indicated for the treatment of a great diversity of diseases, including digestive, respiratory, inflam]matory, painful, and central nervous system disorders, it is administered mainly in the form of tea or decoction orally. Its essential oil is referred to as a natural antioxidant for food preservation and disease control, showing great potential for use in the cosmetics, perfumery, and pharmaceutical products sector. The present review aimed to discuss critically and comprehensively the ethnobotanical characteristics, phytochemical constitution, and scientifically tested biological properties of A. canelilla, systematizing the knowledge about the species and proposing new perspectives for research and development. The chemical composition of A. canelilla includes 1-nitro-2-phenylethane, metyleugenol, eugenol, safrol, anabasin, anbin, tannin, α-pinene, b-pinene, b-felandren, b-caryophyllene, b-sesquifelandren, p-cymene, linalool, α-copaene, and spatulenol. Researches with ethanolic extracts, essential oils, and major constituents (1-nitro-2-phenylethane and metyleugenol) have revealed antioxidant, antinociceptive, anti-inflammatory, cardio-modulating, hypotensive (vasorelaxant), hypnotic, anxiolytic, anticholinesterase, and antibiotic properties (trypanomicidal, leishmanicidal, and antifungal). Some of these effects are potentially beneficial for aging-related diseases treatment, such as cardio and cerebrovascular, chronic inflammatory, neurological, and degenerative diseases. However, it is necessary to advance in the research of its clinical use and development of therapeutic products.

Antihypertensive phytocomplexes of proven efficacy and well-established use: Mode of action and individual characterization of the active constituents

Hypertension has become the leading risk factor for worldwide cardiovascular diseases. Conventional pharmacological treatment, after both dietary and lifestyle changes, is generally proposed. In this review, we present the antihypertensive properties of phytocomplexes from thirteen plants, long ago widely employed in ethnomedicines and, in recent years, increasingly evaluated for their activity in vitro and in vivo, also in humans, in comparison with synthetic drugs acting on the same systems. Here, we focus on the demonstrated or proposed mechanisms of action of such phytocomplexes and of their constituents proven to exert cardiovascular effects. Almost seventy phytochemicals are described and scientifically sound pertinent literature, published up to now, is summarized. The review emphasizes the therapeutic potential of these natural substances in the treatment of the 'high normal blood pressure' or 'stage 1 hypertension', so-named according to the most recent European and U.S. guidelines, and as a supplementation in more advanced stages of hypertension, however needing further validation by clinical trial intensification.

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.

Stimulation of pulmonary vagal C-fibers by trans-4-methyl-β-nitrostyrene induces bradycardiac and depressor reflex in rats: Role of vanilloid TRPV1 receptors

Previously, we showed that the synthetic nitroderivative trans-4-methyl-β-nitrostyrene (T4MeN) induced vasorelaxant effects in rat isolated aortic rings. Here, we investigated the mechanisms underlying the cardiovascular effects of T4MeN in normotensive rats. In pentobarbital-anesthetized rats, intravenous (i.v.) injection of T4MeN (0.03-0.5 mg/kg) induced a rapid (onset time of 1-2 s) and dose-dependent bradycardia and hypotension. These cardiovascular responses to T4MeN were abolished by bilateral cervical vagotomy or selective blockade of neural conduction of vagal C-fiber afferents by perineural treatment of both cervical vagus nerves with capsaicin. Hypotension and bradycardia were also recorded when T4MeN was directly injected in the right, but not into the left ventricle. Furthermore, they were significantly reduced by i.v. pretreatment with capsazepine but remained unaltered by ondansetron or suramin. In conscious rats, the dose-dependent hypotension and bradycardia evoked by T4MeN were abolished by i.v. methylatropine pretreatment. In conclusion, bradycardiac and depressor responses induced by T4MeN has a vago-vagal reflex origin resulting from the vagal pulmonary afferents stimulation. The transduction mechanism seems to involve the activation of vanilloid TRPV₁, but not purinergic (P2X) or 5-HT₃ receptors located on vagal pulmonary sensory nerves.

Anti-Inflammatory Potential of 1-Nitro-2-Phenylethylene

Inflammation is a reaction of the host to infectious or sterile stimuli and has the physiological purpose of restoring tissue homeostasis. However, uncontrolled or unresolved inflammation can lead to tissue damage, giving rise to a plethora of chronic inflammatory diseases, including metabolic syndrome and autoimmunity pathologies with eventual loss of organ function. Beta-nitrostyrene and its derivatives are known to have several biological activities, including anti-edema, vasorelaxant, antiplatelet, anti-inflammatory, and anticancer. However, few studies have been carried out regarding the anti-inflammatory effects of this class of compounds. Thereby, the aim of this study was to evaluate the anti-inflammatory activity of 1-nitro-2-phenylethene (NPe) using in vitro and in vivo assays. Firstly, the potential anti-inflammatory activity of NPe was evaluated by measuring TNF-α produced by human macrophages stimulated with lipopolysaccharide (LPS). NPe at non-toxic doses opposed the inflammatory effects induced by LPS stimulation, namely production of the inflammatory cytokine TNF-α and activation of NF-κB and ERK pathways (evaluated by phosphorylation of inhibitor of kappa B-alpha [IκB-α] and extracellular signal-regulated kinase 1/2 [ERK1/2], respectively). In a well-established model of acute pleurisy, pretreatment of LPS-challenged mice with NPe reduced neutrophil accumulation in the pleural cavity. This anti-inflammatory effect was associated with reduced activation of NF-κB and ERK1/2 pathways in NPe treated mice as compared to untreated animals. Notably, NPe was as effective as dexamethasone in both, reducing neutrophil accumulation and inhibiting ERK1/2 and IκB-α phosphorylation. Taken together, the results suggest a potential anti-inflammatory activity for NPe via inhibition of ERK1/2 and NF-κB pathways on leukocytes.

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.

Antioxidant, Antimicrobial, and Cytotoxic Properties of Aniba parviflora Essential Oils from the Amazon

Essential oils (EOs) from leaves and branches of Aniba parviflora (Meisn.) Mez were obtained by hydrodistillation and their chemical compositions determined by gas chromatography-mass spectrometry. Oxygenated sesquiterpenoids were the most representative compound class in both EOs ( ≅ 40%). However, the leaf EO was rich in β-phellandrene (15.1%), linalool (14.1%), and γ-eudesmol (12.9%). The EO from the branches showed high concentrations of γ-eudesmol (16.8%), β-caryophyllene (15.7%), linalool (12.4%), β-phellandrene (6.7%), and bicyclogermacrene (6.0%). The EOs were screened for radical-scavenging activity using the DPPH assay. In the DPPH assay, the EOs showed an antioxidant activity with TEAC values of 296.8 ± 20.2 and 357.3 ± 43.8 mg.TE.mL−1, about one-third that of the Trolox standard. The EOs were subjected to antibacterial screening and displayed promising activity against Escherichia coli (MIC < 19.5 μg.mL−1). In addition, the EOs were tested for cytotoxic activity against MCF-7 breast tumor cells and the leaf EO (IC50 = 67.9 ± 3.0 μg.mL−1) was more active than that from the branches (IC50 = 102.2 ± 3.0 μg.mL−1).

Vasorelaxant effects of 1-nitro-2-phenylethene in rat isolated aortic rings

Previously, we showed that nitro-2-phenylethane is a vasorelaxant constituent of the essential oil of Aniba canelilla. Here, we investigated the mechanisms underlying the vascular effects of 1-nitro-2-phenylethene (NPe), a structural analog of 1-nitro-2-phenylethane obtained synthetically, in rat isolated thoracic aortic preparations. At 0.1-100 μg/mL, NPe similarly relaxed endothelium-intact or endothelium-denuded aortic preparations pre-contracted with 60mM KCl or with phenylephrine (PHE, 1 μM). Vasorelaxant effects of NPe against PHE-induced contractions remained unaffected following blockade of potassium channels by TEA, and inhibition of either nitric oxide synthase by l-NAME, cyclooxygenase by indomethacin or guanylate cyclase by ODQ. In preparations maintained under Ca(2+)-free conditions, NPe significantly reduced the contractions induced (i) by PHE, but not those evoked by caffeine, (ii) by CaCl2 in either PHE (in the presence of 1 μM verapamil)- or KCl-stimulated preparations, (iii) by extracellular Ca(2+) restoration in thapsigargin-treated aortic preparations, and (iv) by the activator of protein kinase C phorbol-12,13-dibutyrate or the inhibitor of protein tyrosine phosphatase sodium orthovanadate. It is concluded that NPe induced an endothelium-independent vasorelaxation with potency greater than its structural analog 1-nitro-2-phenylethane. Such action appears to occur intracellularly probably through inhibition of contractile events that are clearly independent of Ca(2+) influx from the extracellular milieu.

Hypnotic, anticonvulsant and anxiolytic effects of 1-nitro-2-phenylethane isolated from the essential oil of Dennettia tripetala in mice

This study investigated the hypnotic, anti-convulsant and anxiolytic effects of 1-nitro-2-phenylethane (BPNE) obtained from the oil of Dennettia tripetala G. Baker (Annonaceae) and established its mechanism of action. The essential oil (EO) from the leaf, fruit and seed was obtained by hydrodistillation, followed by isolation of BPNE purified to 99.2% by accelerated gradient chromatography on silica, and identified by NMR and GC-MS. The pure BPNE and EO of the dried seed (93.6%) were comparatively evaluated for hypnotic, anticonvulsant and anxiolytic effects in mice. The acute toxicity of BPNE was determined and the LD50 was 490 mg/kg, intrapritonealy. The hypnotic activities of the EO and BPNE (50-400 mg/kg, i.p.) were assessed by loss of righting reflex, while sodium pentobarbitone (PBS) and diazepam (DZM) were used as positive controls. The anticonvulsant and anxiolytic effects of the EO and BPNE were evaluated in mice. Both BPNE and EO at doses ≥100 mg/kg induced spontaneous hypnosis with loss of righting reflex, significantly decreased sleep latency (SL) and also increased total sleeping time (TST) dose-dependently. They had comparable activity with NAP in TST. The BPNE exhibited higher hypnotic potency than EO at the same dose levels. The EO and BPNE offered comparable dose-related protections against PTZ- and strychnine-induced convulsions. Flumazenil (2 mg/kg) blocked the hypnotic and anticonvulsant (PTZ-convulsions) effects of both EO and BPNE. The essential oil at 5-20 mg/kg dose levels significantly (p<0.05) increased the percentage time spent and number of entries into the open arms. While at the same dose range BPNE significantly (p<0.05) increased the percentage time spent and the number of entries into the open arms respectively. The study concluded that 1-nitro-2-phenylethane exhibited dose dependent significant hypnotic, anticonvulsant and anxiolytic effects and it is the compound largely responsible for the neuropharmacological effects of the oil.

Vasorelaxant effects of 1-nitro-2-phenylethane, the main constituent of the essential oil of Aniba canelilla, in superior mesenteric arteries from spontaneously hypertensive rats

The present study investigated the mechanisms underlying the vasorelaxant effects of the essential oil of Aniba canelilla (EOAC) and its main constituent 1-nitro-2-phenylethane (NP) in isolated superior mesenteric artery from spontaneously hypertensive rats (SHRs). At 0.1-1000 μg/mL, EOAC and NP relaxed SMA preparations pre-contracted with 75 mMKCl with IC(50) (geometric mean [95% confidence interval]) values of 294.19 [158.20-94.64] and 501.27 [378.60-624.00] μg/mL, respectively); or with phenylephrine (PHE) (IC(50)s=11.07 [6.40-15.68] and 7.91 [4.08-11.74) μg/mL, respectively). All these effects were reversible and remained unaltered by vascular endothelium removal. In preparations maintained under Ca(2+)-free conditions, EOAC and NP (both at 600 μg/mL) reduced the PHE-, but not the caffeine-induced contraction. In Ca(2+)-free and high K(+) (75 mM) medium, the contractions produced by CaCl(2) or BaCl(2) were reduced or even abolished by EOAC and NP at 100 and 600 μg/mL, respectively. EOAC and NP (both at 10-1000 μg/mL) also relaxed the contraction evoked by phorbol dibutyrate (IC(50)=52.66 [10.82-94.64] and 39.13 [31.55-46.72] μg/mL, respectively). It is concluded that NP has a myogenic endothelium-independent vasorelaxant effects and appears to be the active principle of the EOAC. Vasorelaxant effect induced by both EOAC and NP is preferential to receptor-activated pathways and it appears to occur intracellularly more than a superficial action restricted to the membrane environment such as a simple blocking activity on a given receptor or ion channel.

The vasorelaxant effects of 1-nitro-2-phenylethane involve stimulation of the soluble guanylate cyclase-cGMP pathway

1-Nitro-2-phenylethane is the first organic NO₂-containing molecule isolated from plants. It possesses interesting hypotensive, bradycardic, and vasodilator properties, but the mode by which it induces vasorelaxation is still unknown. The underlying mechanism involved in the vasodilator effect of 1-nitro-2-phenylethane was investigated in rat aorta. The vasorelaxant effects of 1-nitro-2-phenylethane did not depend on endothelial layer integrity, and the effects were refractory to L-N(G)-nitroarginine methyl ester (L-NAME)-induced nitric oxide synthase inhibition. Vasorelaxation was similarly resistant to treatment with indomethacin, cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride (MDL-12330A), and KT5720, indicating that neither prostaglandin release nor adenylyl cyclase activation is involved. Conversely, methylene blue- and ODQ-induced guanylate cyclase inhibition reduced the vasorelaxation induced by 1-nitro-2-phenylethane. The pharmacological blockade of K(+) channels with tetraethylammonium, glybenclamide, and 4-aminopyridine also blunted vasorelaxation induced by 1-nitro-2-phenylethane. The effects of 1-nitro-2-phenylethane were reversed by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and comparable to the effects induced by sodium nitroprusside. In silico analysis using an Ns H-NOX subunit of guanylate cyclase revealed a pocket on the macromolecule surface where 1-nitro-2-phenylethane preferentially docked. In vitro, 1-nitro-2-phenylethane increased cyclic guanosine 3',5'-monophosphate (cGMP) levels in rat aortic rings, an effect also reversed by ODQ. In conclusion, 1-nitro-2-phenylethane produces vasodilator effects by stimulating the soluble guanylate cyclase-cGMP pathway.