Isoeugenolol: a selective beta1-adrenergic antagonist with tracheal and vascular smooth muscle relaxant properties

Ocimum sanctum [Tulsi] as a Potential Immunomodulator for the Treatment of Ischemic Injury in the Brain

Stroke causes brain damage and is one of the main reasons for death. Most survivors of stroke face long-term physical disabilities and cognitive dysfunctions. In addition, they also have persistent emotional and behavioral changes. The two main treatments that are effective are reperfusion with recombinant tissue plasminogen activator and recanalization of penumbra using mechanical thrombectomy. However, these treatments are suitable only for a few patients due to limitations such as susceptibility to hemorrhage and the requirement for administering tissue plasminogen activators within the short therapeutic window during the early hours following a stroke. The paucity of interventions and treatments could be because of the multiple pathological mechanisms induced in the brain by stroke. The ongoing immune response following stroke has been attributed to the worsening brain injury. Hence, novel compounds with immunomodulatory properties that could improve the outcome of stroke patients are required. Natural compounds and medicinal herbs with anti-inflammatory activities and having minimal or no adverse systemic effect could be beneficial in treating stroke. Ocimum sanctum is a medicinal herb that can be considered an effective therapeutic option for ischemic brain injury. Ocimum sanctum, commonly known as holy basil or "Tulsi," is mentioned as the "Elixir of Life" for its healing powers. Since antiquity, Tulsi has been used in the Ayurvedic and Siddha medical systems to treat several diseases. It possesses immuno-modulatory activity, which can alter cellular and humoral immune responses. Tulsi can be considered a potential option as an immuno-modulator for treating various diseases, including brain stroke. In this review, we will focus on the immunomodulatory properties of Tulsi, specifically its effect on both innate and adaptive immunity, as well as its antioxidant and antiinflammatory properties, which could potentially be effective in treating ongoing immune reactions following ischemic brain injury.

The nitric oxide/soluble cyclic guanylase/cyclic guanosine monophosphate pathway is involved in the cardiovascular effects of a novel α1- and β-adrenoceptor antagonist

The compound MH-78 ((+/-)-1-(2,6-dimethylphenoxy)-3-{4-[2-(2-methoxyphenoxy)ethyl]-piperazin-1-yl}propan-2-ol dihydrochloride) contains structural elements that are typical for α1- and β-blockers. This study aimed to investigate the hypotensive activity as well as the in vitro and in vivo cardiovascular effects of a novel α1- and β-adrenoceptor antagonist (MH-78) and compare it with carvedilol and urapidil. The procedures were performed on aortic rings of normotensive anesthetized rats. MH-78 decreased the blood pressure and heart rate after intravenous and oral administration. MH-78 possesses both α1- and β-adrenoceptor blocking activity, which was confirmed in the in vivo study. In biofunctional assays, MH-78 displayed vasorelaxant activity due to α1-adrenoceptor antagonism and calcium channel blocking properties. Moreover, in endothelium-intact aortic rings, pretreatment with Nω-nitro-L-arginine methyl ester (L-NAME) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) reduced the MH-78-induced vasorelaxation to a level that is characteristic for MH-78 affinity to α1-adrenoceptors. Our results demonstrated that MH-78 possesses α1- and β-adrenoceptor blocking properties and induces potent hypotensive and vasorelaxant effects. Moreover, it relaxes vascular smooth muscle not only due to α1-adrenoceptor blocking activity, but also via the endothelium-dependent nitric oxide/soluble guanylyl cyclase/cyclic guanosine monophosphate signalling pathway.

Eugenolol and Glyceryl-Isoeugenol Suppress LPS-Induced INOS Expression by Down-Regulating NF-κB and AP-1 through Inhibition of Mapks and AKT/IκBα Signaling Pathways in Macrophages

Eugenol and isoeugenol, two components of clover oil, have been reported to possess several biomedical properties, such as anti-inflammatory, antimicrobial and antioxidant effects. This study aims to examine the anti-inflammatory effects of eugenol, isoeugenol and four of their derivatives on expression of inducible nitric oxide synthase (iNOS) activated by lipopolysaccharide (LPS) in mouse macrophages (RAW 264.7), and to investigate molecular mechanisms underlying these effects. We found that two derivatives, eugenolol and glyceryl-isoeugenol, had potent inhibitory effects on LPS-induced upregulation of nitrite levels, iNOS protein and iNOS mRNA. In addition, they both suppressed the release of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) induced by LPS. Moreover, they both attenuated the DNA binding of NF-κB and AP-1, phosphorylation of inhibitory κBα (IκBα), and nuclear translocation of p65 protein induced by LPS. Finally, we demonstrated that glyceryl-isoeugenol suppressed the phosphorylation of ERK1/2, JNK and p38 MAPK, whereas eugenolol suppressed the phosphorylation of ERK1/2 and p38 MAPK. Taken together, these results suggest that that eugenolol and glyceryl-isoeugenol suppress LPS-induced iNOS expression by down-regulating NF-κB and AP-1 through inhibition of MAPKs and Akt/IκBα signaling pathways. Thus, this study implies that eugenolol and glyceryl-isoeugenol may provide therapeutic benefits for inflammatory diseases.

In vivo anti-inflammatory action of eugenol on lipopolysaccharide-induced lung injury

Eugenol, a methoxyphenol component of clove oil, suppresses cyclooxygenase-2 expression, while eugenol dimers prevent nuclear factor-kappaB (NF-kappaB) activation and inflammatory cytokine expression in lipopolysaccharide-stimulated macrophages. Our aim was to examine the in vivo anti-inflammatory effects of eugenol. BALB/c mice were divided into four groups. Mice received saline [0.05 ml intratracheally (it), control (Ctrl) and eugenol (Eug) groups] or Escherichia coli LPS (10 microg it, LPS and LPSEug groups). After 6 h, mice received saline (0.2 ml ip, Ctrl and LPS groups) or eugenol (160 mg/kg ip, Eug and LPSEug groups). Twenty-four hours after LPS injection, pulmonary resistive (DeltaP1) and viscoelastic (DeltaP2) pressures, static elastance (E(st)), and viscoelastic component of elastance (DeltaE) were measured. Lungs were prepared for histology. In parallel mice, bronchoalveolar lavage fluid was collected 24 h after LPS injection. TNF-alpha was determined by ELISA. Lung tissue expression of NF-kappaB was determined by EMSA. DeltaP1, DeltaP2, E(st), and DeltaE were significantly higher in the LPS group than in the other groups. LPS mice also showed significantly more alveolar collapse, collagen fibers, and neutrophil influx and higher TNF-alpha levels and NF-kappaB expression than the other groups. Eugenol treatment reduced LPS-induced lung inflammation, improving lung function. Our results suggest that eugenol exhibits in vivo anti-inflammatory action in LPS-induced lung injury.

Prevention of isoproterenol-induced cardiac hypertrophy by eugenol, an antioxidant

Recent reports on the involvement of calcineurin in cardiac hypertrophy and its susceptibility to free radicals, prompted us to examine possible beneficial effects of dietary antioxidants in this regard. In continuation of initialin vitro studies revealing eugenol to be a potent calcineurin inhibitor, we investigated its ability to reverse isoproterenol-induced cardiac hypertrophy in rats. Intraperitoneal administration of isoproterenol (1 mg/kg body wt/day for 10 days) induced cardiac hypertrophy with increased heart weight and enhanced apoptosis of myocytes concomitant with accumulation of reactive oxygen species, decreased glutathione contents, increased activities of calcineurin and protein kinase C in ventricular tissue. Administering eugenol for 3 days (1 mg/kg body wt/twice a day), followed by combined administration of isoproterenol and eugenol resulted in significant reversal of cardiac hypertrophy and restoration of above changes. These results suggest that eugenol, a natural antioxidant of dietary origin, may offer potential benefits in the management of cardiac hypertrophy.

Effects of estragole on the compound action potential of the rat sciatic nerve

Estragole, a relatively nontoxic terpenoid ether, is an important constituent of many essential oils with widespread applications in folk medicine and aromatherapy and known to have potent local anesthetic activity. We investigated the effects of estragole on the compound action potential (CAP) of the rat sciatic nerve. The experiments were carried out on sciatic nerves dissected from Wistar rats. Nerves, mounted in a moist chamber, were stimulated at a frequency of 0.2 Hz, with electric pulses of 50-100-micros duration at 10-20 V, and evoked CAP were monitored on an oscilloscope and recorded on a computer. CAP control parameters were: peak-to-peak amplitude (PPA), 9.9 +/- 0.55 mV (N = 15), conduction velocity, 92.2 +/- 4.36 m/s (N = 15), chronaxy, 45.6 +/- 3.74 micros (N = 5), and rheobase, 3.9 +/- 0.78 V (N = 5). Estragole induced a dose-dependent blockade of the CAP. At 0.6 mM, estragole had no demonstrable effect. At 2.0 and 6.0 mM estragole, PPA was significantly reduced at the end of 180-min exposure of the nerve to the drug to 85.6 +/- 3.96 and 13.04 +/- 1.80% of control, respectively. At 4.0 mM, estragole significantly altered PPA, conduction velocity, chronaxy, and rheobase (P < or = 0.05, ANOVA; N = 5) to 49.3 +/- 6.21 and 77.7 +/- 3.84, 125.9 +/- 10.43 and 116.7 +/- 4.59%, of control, respectively. All of these effects developed slowly and were reversible upon a 300-min wash-out. The data show that estragole dose-dependently blocks nerve excitability.

Anti-Hypertension Effect of Vanylidilol: A Phenylaldehyde α/β-Adrenoceptor Blocker with Endothelium-Dependent and K+ Channels Opening-Associated Vasorelaxant Activities

The antihypertensive effect of vanylidilol, a new alpha/beta-adrenoceptor antagonist with endothelium-dependent and K(+)-channel-opening activities, was investigated in normotensive and hypertensive Wistar rats. Vanylidilol competitively antagonized (-)isoproterenol-induced positive chronotropic effects, inotropic effects, and tracheal relaxation effects in isolated rat right atria, left atria, and guinea pig tracheal strips in a concentration-dependent manner. Vanylidilol's apparent pA(2) values were 6.36 +/- 0.08 (right atria), 6.41 +/- 0.07 (left atria), and 6.31 +/- 0.06 (trachea). Vanylidilol also produced a competitive antagonism of phenylephrine-induced contraction in the isolated rat aorta with pA(2) values of 6.79 +/- 0.18. In the radioligand binding assay, vanylidilol inhibited [(3)H]CGP-12177 binding to rat ventricle and lung tissues and [(3)H]prazosin binding to brain membranes with Ki values of 535.17, 2,066.69, and 431.11, respectively. In isolated rat thoracic aorta, vanylidilol's vasorelaxant effects on phenylephrine (10 micromol/l)-induced contractions were attenuated by removing endothelium and by the presence of L-N(G)-nitro arginine methyl ester (L-NAME; 100 micromol/l), methylene blue (10 micromol/l), 1H-[1,2,4]oxadiazolol[4,3,-a] quinoxalin-1-one (ODQ; 10 micromol/l), tetraethylammonium (10 mmol/l), glibenclamide (1 micromol/l), apamin (1 micromol/l), and charybdotoxin (0.1 micromol/l). In addition, vanylidilol, in an equally antagonistic activity, inhibited phenylephrine-induced phasic and tonic contractions. Intravenous vanylidilol further reduced mean blood pressure in pentobarbital-anesthetized normotensive Wistar rats in a dose-dependent manner. The oral administration of vanylidilol to conscious spontaneously hypertensive rats had a long-lasting hypotensive effect on the heart rate and decreased it in a dose-dependent manner. Furthermore, vanylidilol's vasodilator effect can be attributed in part to the release of NO or NO-related substance from vascular endothelium, while the endothelium-independent mechanism involved in vanylidilol's relaxation is probably linked to the activation of the K(+) channels and the alpha-adrenoceptor blocking activity in these vessels.

Antiplatelet activity of synthetic pyrrolo-benzylisoquinolines

Pyrrolo-benzylisoquinolines were prepared as target compounds and their antiplatelet aggregation activity, adreno-receptor affinity, and cytotoxicity were screened. Compounds 1d-9d showed specific antiplatelet aggregation activity induced by arachidonic acid and collagen. Among them, 8d and 9d exhibited better activity than the reference drug, aspirin and 9d also showed inhibition of platelet aggregation by all four inducers.

Vasorelaxant effects of eugenol on rat thoracic aorta

Eugenol is a natural pungent substance and the main component of clove oil, with vasorelaxant action. To elucidate some of the possible mechanisms involved in this action isometric tension was measured in aortic rings from male Wistar rats precontracted with phenylephrine (PHE, 10(-7) M) or KCl (75 mM). Responses to increasing concentrations of eugenol (10(-6)-10(-2) M) were obtained in the presence and absence of endothelium. In the presence of eugenol, dose-response curves to PHE (10(-9) to 10(-4) M) and KCl (5-125 mM) were displaced downwards. Concentration-dependent relaxation was observed in rings precontracted with PHE (10(-7) M) and KCl (75 mM). The tension increment produced by increasing external calcium concentration (0.25-3 mM) was also reduced by eugenol (300 microM) treatment. The inhibitory effects of eugenol (300 microM) were compared to those induced by nifedipine (0.01 microM), a selective Ca(2+) channel blocker, producing similar relaxant effects. Two other protocols were performed. After precontraction with PHE (10(-7) M), increasing concentrations of eugenol (10(-6)-10(-2) M) were used before and after N(w)-nitro-L-arginine (L-NAME, 10(-4) M) and methylene blue (10(-5) M) treatment. Eugenol-induced relaxation was reduced by endothelial damage (rubbing), L-NAME and methylene blue treatments. Results suggested that eugenol produces smooth muscle relaxation resulting from the blockade of both voltage-sensitive and receptor-operated channels that are modulated by endothelial-generated nitric oxide.

Inhibitory actions of eugenol on rat isolated ileum

The effects of eugenol (1-2000 microM) on rat isolated ileum were studied. Eugenol relaxed the basal tonus (IC50 83 microM) and the ileum precontracted with 60 mM KCl (IC50 162 microM), an action unaltered by 0.5 microM tetrodotoxin, 0.2 mM N(G)-nitro-L-arginine methyl ester, 0.5 mM hexamethonium, and 1 microM indomethacin. Eugenol did not alter the resting transmembrane potential (Em) of the longitudinal muscle layer under normal conditions (5.0 mM K+) or in depolarised tissues. Eugenol reversibly inhibited contractions induced by submaximal concentrations of acetylcholine (ACh) and K+ (40 mM) with IC50 values of approximately 228 and 237 microM, respectively. Eugenol blocked the component of ACh-induced contraction obtained in Ca(2+)-free solution (0.2 mM EGTA) or in the presence of nifedipine (1 microM). Our results suggest that eugenol induces relaxation of rat ileum by a direct action on smooth muscle via a mechanism largely independent of alterations of Em and extracellular Ca2+ influx.

Vanillylamide-based propanolamine derivative displays alpha/beta-adrenoceptor blocking and vasodilating properties

A propanolamine derivative with vanillylamide base, KMUP 880602, was first investigated under in vivo and in vitro conditions. IV KMUP 880602 (0.1, 0.5, 1.0, and 2.0 mg/kg) produced dose-dependent hypotensive and bradycardia responses in pentobarbital-anesthetized Wistar rats. KMUP 880602 also markedly inhibited both the tachycardia effects induced by (-)isoproterenol and arterial pressor responses induced by phenylephrine. In isolated guinea pig tissues, KMUP 880602 competitively antagonized (-)isoproterenol-induced positive inotropic and chronotropic effects of the atria and tracheal relaxation responses. The apparent pA2 values KMUP 880602 were 7.24 +/- 0.08 (right atria), 7.42 +/- 0.07 (left atria), and 6.24 +/- 0.06 (trachea). KMUP 880602 also produced a competitive antagonism of norepinephrine-induced contraction in the isolated rat aorta with pA2 values of 7.64 +/- 0.18. In the radioligand-binding assay, [3H]CGP-12177 binding to rat ventricle and lung tissues and [3H]prazosin binding to brain membranes were inhibited by KMUP 880602 with pKi values of 7.27, 6.08, and 8.25, respectively. In isolated rat thoracic aorta, the vasorelaxant effects of KMUP 880602 on phenylephrine-induced contractions were attenuated by pretreatment with tetraethylammonium (10-3 M) and charybdotoxin (10-7 M) but not by glibenclamide, 4-aminopyridine, and apamin. In conclusion, KMUP 880602 is an alpha/beta-adrenoceptor blocker, with selective beta1-adrenoceptor blocking and vascular smooth muscle relaxation activities. Particularly, the vasorelaxant effect of KMUP 880602 is partially mediated by the opening of charybdotoxin-sensitive K+ channel.

The new generation dihydropyridine type calcium blockers, bearing 4-phenyl oxypropanolamine, display alpha-/beta-adrenoceptor antagonist and long-acting antihypertensive activities

A new series of dihydropyridine derivatives, bearing oxypropanolamine moiety on phenyl ring at the 4-position of the dihydropyridine base, were prepared. Oxypropanolamine was synthesized by replacing the phenolic OH of vanillin or other compounds, having a phenyl aldehyde group, with epichlorohydrin, followed by cleavaging the obtained epoxide compounds with tert-butylamine, n-butylamine or 2-methoxy-1-oxyethylamino benzene (guaiacoxyethylamine), respectively. Obtained various oxypropanolamine compounds, still remaining a phenyl aldehyde moiety, were then performed by Hantzsch condensation reaction with methylacetoacetate or ethylacetoacetate, respectively, to give our new series of dihydropyridine linked with the 4-phenyl ring. These compounds were evaluated for inotropic, chronotropic, and aorta contractility that associated with calcium channel and adrenoceptor antagonist activities. Dihydropyridine derivatives that with oxypropanolamine side chain on their 4-phenyl ring associated alpha-/beta-adrenoceptor blocking activities created a new family of calcium entry and the third generation beta-adrenoceptor blockers. Optimizing this research to obtain more potent alpha-/beta-adrenoceptor blocking and long-acting antihypertensive oxypropanolamine on the 4-phenyl ring of dihydropyridine series compounds was thus accomplished and classified as third generation dihydropyridine type calcium channel blockers, in comparison with previous short-acting type nifedipine and long-acting type amlodipine. We concluded that compounds 1a, 1b and 1g showed not only markedly high calcium-antagonistic activity but also the highest antihypertensive effect; compounds 1b, 1c, 1f, 1g, 1i and 1j induced sustained antihypertensive effects are major and attributed to their calcium entry and alpha-adrenoceptor blocking activities in the blood vessel due to their introduction of 2-methoxy, 1-oxyethylamino benzene moiety in the side chain on the 4-phenyl ring of dihydropyridine. Bradycardiac effects of all the compounds 1a-1j resulted from calcium entry and beta-adrenoceptor blocking, which attenuate the sympathetic activation-associated reflex tachycardia in the heart. We selected compound 1b as candidate compound for further pharmacological and pre-clinical evaluation studies.

Lipid solubility of vasodilatory vanilloid-type beta-blockers on the functional and binding activities of beta-adrenoceptor subtypes

Various vanilloid-type beta-adrenoceptor blockers were studied on guinea pig right atrium and trachea and rat colon. In addition, we also investigated their beta(1)-, beta(2)-, and beta(3)-adrenoceptor binding affinities. All these beta-adrenergic antagonists inhibited (-)isoproterenol-induced positive chronotropic effects of the right atrium and tracheal relaxation responses in a concentration-dependent manner. Some of these agents prevented the inhibition of rat colon spontaneous motility by (-)isoproterenol. Of the agents tested, we found that ferulidilol, eugenodilol, eugenolol, isoeugenolol, and ferulinolol, as well as propranolol and metoprolol, possessed beta(3)-adrenoceptor blocking activities, others were nearly without effectiveness. Furthermore, the binding characteristics of vanilloid-type beta-adrenergic antagonists were evaluated in [3H]CGP-12177, a beta(1)/beta(2)-adrenoceptor blocker and a beta(3)-adrenoceptor agonist, binding to beta(1)-, beta(2)-, and beta(3)-adrenoceptor sites in rat ventricle, lung, and interscapular brown adipose tissue (IBAT) membranes, respectively. Eugenodilol, eugenolol, metoprolol, isoeugenolol, and ferulinolol were less potent than both propranolol and ferulidilol in competing for the beta(3)-adrenoceptor binding sites. From the results of in vitro functional and binding studies, we suggested that propranolol, ferulidilol, eugenodilol, eugenolol, metoprolol, isoeugenolol, and ferulinolol all possessed beta(3)-adrenoceptor blocking activities. On the other hand, we also found that eugenodilol, eugenolol, metoprolol, isoeugenolol, and ferulinolol had a low lipid solubility in comparison with propranolol and ferulidilol. In conclusion, we proposed that beta(3)-adrenoceptor antagonistic actions of these vanilloid-type beta-blockers were positively correlated with their lipid solubility.

Pharmacological effects of an aldehyde type alpha/beta-adrenoceptor blocking agent with vasodilating properties

KMUP 880723 (0.5, 1.0, and 3.0 mg/kg, iv) produced dose-dependent hypotensive and bradycardia responses in pentobarbital-anesthetized Wistar rats. KMUP 880723 (1.0 mg/kg, iv) also markedly inhibited both the tachycardia effects induced by (-)isoproterenol and arterial pressor responses induced by phenylephrine. In the isolated Wistar rat right atria, left atria, and guinea pig tracheal strips, KMUP 880723 competitively antagonized the (-)isoproterenol-induced positive chronotropic effects, inotropic effects, and tracheal relaxation effects in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)isoproterenol suggested that KMUP 880723 was a beta(1)/beta(2)-adrenoceptor competitive antagonist. The apparent pA(2) values were 6.89+/-0.10 in the right atria, 7.02+/-0.09 in the left atria, and 6.59+/-0.11 in the trachea, indicating that KMUP 880723 was a nonselective beta-adrenoceptor blocker. In thoracic aorta experiments, KMUP 880723 also produced a competitive antagonism of norepinephrine-induced contraction with a pA(2) value of 7.14+/-0.06. In isolated rat thoracic aorta, KMUP 880723 more potently relaxed the contractions induced by norepinephrine (3 x 10(-6) M) than those by high K(+) (75 mM). In the radioligand-binding assay, the pK(i) values of [3H]CGP-12177 binding to rat ventricle and lung membranes were 6.56 and 6.40, respectively, and the value of [3H]prazosin binding to rat brain membranes was 6.66. These results further confirmed the alpha/beta-adrenoceptor blocking activities of KMUP 880723 reported in the functional studies. We conclude that KMUP 880723 is a nonselective beta-adrenoceptor antagonist with alpha-adrenoceptor blocking-associated vasorelaxant activity.