Study of the mechanism of the relaxant action of (+)-glaucine in rat vas deferens

Glaucine inhibits breast cancer cell migration and invasion by inhibiting MMP-9 gene expression through the suppression of NF-κB activation

Matrix metalloproteinase-9 (MMP-9) plays a central role in the invasion and metastasis of various types of cancer cells. Here, we demonstrate that glaucine, an alkaloid isolated from the plant Corydalis turtschaninovii tuber (Papaveraceae), can inhibit the migration and invasion of human breast cancer cells. We further show that glaucine significantly blocks phorbol 12-myristate 13-acetate (PMA)-induced MMP-9 expression and activity in a dose-dependent manner. Results from reporter gene and electrophoretic mobility shift assays revealed that glaucine inhibits MMP-9 expression by suppressing activation of the nuclear transcription factor nuclear factor-κB (NF-κB). Moreover, glaucine attenuates PMA-induced IκBα degradation and nuclear translocation of NF-κB. Finally, we also found that glaucine inhibits invasion and MMP-9 expression in the highly metastatic MDA-MB-231 breast cancer cell line. Taken together, our findings indicate that the MMP-9 inhibitory activity of glaucine and its abilities to attenuate IκBα and NF-κB activities may be therapeutically useful as a novel means of controlling breast cancer growth and invasiveness.

Monoaminergic, Ion Channel and Enzyme Inhibitory Activities of Natural Aporphines, their Analogues and Derivatives

The aporphine alkaloids constitute the second-largest group of isoquinoline alkaloids. Nevertheless, only a relatively small number of natural aporphines and their derivatives have been studied from a pharmacological viewpoint. Here we review the pharmacological data available for these compounds as related to their dopaminergic, noradrenergic and serotonergic activities, and also some results pertaining to their effects on ion channels and enzymes.

In vivo and in vitro pharmacological studies of a new hypotensive compound (QF0301B) in rat: comparison with prazosin, a known alpha1-adrenoceptor antagonist

In this work, we studied the in vivo and in vitro pharmacological effects of the novel compound QF0301B (2-[2-(N-4-o-methoxyphenyl-N-1-piperazinyl)ethyl]-1-tetralone) and compared with those of prazosin. In anaesthetized normotensive rats, both QF0301B and prazosin (0.1-0.2 mg/kg iv) caused a pronounced and prolonged fall in mean arterial blood pressure accompanied by bradycardia. Neither QF0301B nor prazosin (0.2 mg/kg iv) significantly modified the cardiovascular effects of either 5-hydroxytryptamine (serotonin, 5-HT, 75 microg/kg iv) or the selective alpha(2)-adrenoceptor agonist B-HT 920 (0.2 mg/kg iv), but both markedly inhibited the hypertensive effect of noradrenaline (5 microg/kg iv), a nonselective alpha-adrenergic receptor agonist. In isolated rubbed rat aorta rings, QF0301B and prazosin showed marked alpha(1)-adrenoceptor blocking activity, with pA(2) values of 9.00+/-0.12 and 9.75+/-0.14, respectively. In addition, QF0301B reversed and competitively antagonized the inhibitory action produced by clonidine in electrically stimulated rat vas deferens and inhibited the force and rate of contraction in rat isolated atria (pA(2)=5.91+/-0.43), competitively antagonized the contractile effect of 5-HT in rat aorta (pA(2)=6.75+/-0.06) and in rat stomach fundus (pA(2)=7.13+/-0.48) and the contractions induced by histamine in isolated guinea pig longitudinal ileal muscle (pA(2)=7.40+/-0.40). QF0301B showed noncompetitive low action in 5-HT(3), muscarinic and nicotinic receptors, or as Ca(2+) antagonist. These results indicate that a alpha(1)-adrenoceptor blocking lead has been obtained with a new chemical structure and interesting pharmacological properties, which only alpha(1)-adrenoceptor blocking activity seems to be responsible for its cardiovascular effects.

Effects of inhaled glaucine on pulmonary responses to antigen in sensitized guinea pigs

The alkaloid (S)-(+)-1,2,9,10-tetramethoxyaporphine (glaucine) is a phosphodiesterase 4 inhibitor with bronchodilator and anti-inflammatory activity in vitro. In this study, we examined the in vivo effects of glaucine on an animal model of asthma. In ovalbumin sensitized guinea pigs, inhaled glaucine (10 mg ml(-1), 3 min) inhibited the acute bronchoconstriction produced by aerosol antigen (antigen response was 256+/-42 and 95+/-14 cm H(2)O l(-1) s(-1) in control and glaucine-treated animals, respectively; P<0.05). Pretreatment with glaucine (10 mg ml(-1), 10 min inhalation, 30 min pre- and 3 h post-antigen exposure) markedly reduced airway hyperreactivity to histamine, eosinophil lung accumulation, and increased eosinophil peroxidase activity in bronchoalveolar lavage fluid 24 h after exposure of conscious guinea pigs to aerosol antigen. In addition, inhaled glaucine (5-10 mg ml(-1), 3 min) inhibited the microvascular leakage produced after inhaled antigen at all airway levels. These data support the potential interest of phosphodiesterase 4 inhibitors in asthma treatment.

Bronchodilator and anti-inflammatory activities of glaucine: In vitro studies in human airway smooth muscle and polymorphonuclear leukocytes

1. Selective phosphodiesterase 4 (PDE4) inhibitors are of potential interest in the treatment of asthma. We examined the effects of the alkaloid S-(+)-glaucine, a PDE4 inhibitor, on human isolated bronchus and granulocyte function. 2. Glaucine selectively inhibited PDE4 from human bronchus and polymorphonuclear leukocytes (PMN) in a non-competitive manner (Ki=3.4 microM). Glaucine displaced [3H]-rolipram from its high-affinity binding sites in rat brain cortex membranes (IC50 approximately 100 microM). 3. Glaucine inhibited the spontaneous and histamine-induced tone in human isolated bronchus (pD2 approximately 4.5). Glaucine (10 microM) did not potentiate the isoprenaline-induced relaxation but augmented cyclic AMP accumulation by isoprenaline. The glaucine-induced relaxation was resistant to H-89, a protein kinase A inhibitor. Glaucine depressed the contractile responses to Ca2+ (pD'2 approximately 3.62) and reduced the sustained rise of [Ca2+]i produced by histamine in cultured human airway smooth muscle cells (-log IC50 approximately 4.3). 4. Glaucine augmented cyclic AMP levels in human polymorphonuclear leukocytes challenged with N-formyl-Met-Leu-Phe (FMLP) or isoprenaline, and inhibited FMLP-induced superoxide generation, elastase release, leukotriene B4 production, [Ca2+]i signal and platelet aggregation as well as opsonized zymosan-, phorbol myristate acetate-, and A23187-induced superoxide release. The inhibitory effect of glaucine on superoxide generation by FMLP was reduced by H-89. 5. In conclusion, Ca2+ channel antagonism by glaucine appears mainly responsible for the relaxant effect of glaucine in human isolated bronchus while PDE4 inhibition contributes to the inhibitory effects of glaucine in human granulocytes. The very low PDE4/binding site ratio found for glaucine makes this compound attractive for further structure-activity studies.

Contractile effect of (+)-glaucine in the isolated guinea-pig ileum

The intestinal effects of (+)-glaucine [(S)-1,2,9,10-tetramethoxyaporphine] were studied using the guinea-pig ileum. (+)-Glaucine (10-300 microM) induced ileal contractions. The contraction was not affected by tetrodotoxin, atropine, hexamethonium, propranolol, naloxone, methysergide, N(G)-nitro-L-arginine methyl ester, SR141716A (a cannabinoid CB1 receptor antagonist) or SR140333 (a tackykinin NK1 receptor antagonist) plus SR48968 (a tackykinin NK2 antagonist). (+)-Glaucine-induced contraction was reduced by indomethacin, nordihydroguaiaretic acid or bisindolylmaleimide I and abolished by verapamil and nifedipine. These results suggest that (+)-glaucine-induced contraction involves activation of voltage-dependent Ca2+ channels and protein kinase C and could be mediated by the release of arachidonic acid metabolites.

Immunopharmacological activity of aporphinoid alkaloid oxoglaucine

The ability of aporphinoid alkaloid oxoglaucine to influence T- and B-cell immune response was studied in mice models. The substance inhibited in vitro mitogen-induced lymphocyte proliferation and suppressed antibody response to sheep red blood cells (SRBC) and lipopolysaccharide (LPS) in vivo effectively. The action depended on the relative timing of antigen and oxoglaucine administration. The substance manifested stimulatory effect in popliteal lymph node (PLN) reaction and LPS-induced B-cell activation. In the chronic inflammatory model of adjuvant arthritis oxoglaucine exhibited stimulatory or suppressive action related to the kinetics of the process. At low doses (1 or 2 mg kg-1) oxoglaucine improved the outcome of Klebsiella pneumoniae infection, while at higher doses (10 or 20 mg kg-1) the substance caused an impairment of host resistance to infectious agent. The comparison with cyclophosphamide in some tests showed that oxoglaucine was effective in manifold lower doses. In conclusion, oxoglaucine exerted immunomodulatory effects in vivo in a dose-dependent and protocol-dependent manner. Yet, its overall action might be attributed to the different sensitivity of the cells involved in the developing immune response.

A possible structural determinant of selectivity of boldine and derivatives for the alpha 1A-adrenoceptor subtype

1. The selectivity of action of boldine and the related aporphine alkaloids, predicentrine (9-O-methylboldine) and glaucine (2,9-O-dimethylboldine) and alpha 1-adrenoceptor subtypes was studied by examining [3H]-prazosin competition binding in rat cerebral cortex. WB 4101 and benoxathian were used as selective alpha 1A-adrenoceptor antagonists. 2. In the competition experiments [3H]-prazosin (0.2 nM) binding was inhibited by WB 4101 and benoxathian. The inhibition curves displayed shallow slopes which could be subdivided into high and low affinity components (pKi = 9.92 and 8.29 for WB 4101, 9.35 and 7.94 for benoxathian). The two antagonists recognized approximately 37% of the sites with high affinity from among the total [3H]-prazosin specific binding sites. 3. Boldine, predicentrine and glaucine also competed for [3H]-prazosin (0.2 nM) binding with shallow and biphasic curves recognizing 30-40% of the sites with high affinity. Drug affinities (pKi) at the high and low affinity sites were, 8.31 and 6.50, respectively, for boldine, 8.13 and 6.39 for predicentrine, and 7.12 and 5.92 for glaucine. The relative order of selectivity for alpha 1A-adrenoceptors was boldine (70 fold alpha 1A-selective) = predicentrine (60 fold, alpha 1A-selective) > glaucine (15 fold, alpha 1A-selective). 4. Pretreatment of rat cerebral cortex membranes with chloroethylclonidine (CEC, 10 microM) for 30 min at 37 degrees C followed by thorough washing out reduced specific [3H]-prazosin binding by approximately 70%. The CEC-insensitive [3H]-prazosin binding was inhibited by boldine monophasically (Hill slope = 0.93) with a single pKi value (7.76). 5. These results suggest that whereas the aporphine structure shared by these alkaloids is responsible for their selectively of action for the alpha 1A-adrenoceptor subtype in rat cerebral cortex, defined functional groups, namely the 2-hydroxy function, induces a significant increase in alpha 1A-subtype selectivity and affinity.

Regulation of cytosolic calcium levels in vascular smooth muscle

Ca2+ plays an important role in the contraction of skeletal, cardiac, and smooth muscle, as well as in a number of important processes, such as secretion and neuronal activity. In this review, I focus on the various mechanisms by which cytosolic Ca2+ concentration is regulated in vascular smooth muscle, in the resting state and during activation. Particular attention is paid to the calcium pumps of the plasmalemma and the sarcoplasmic reticulum, to the inositol 1,4,5-trisphosphate- and ryanodine-sensitive calcium channels of the sarcoplasmic reticulum, and to voltage-dependent and voltage-independent calcium channels of the plasmalemma.

Study of the in vivo and in vitro cardiovascular effects of (+)-glaucine and N-carbethoxysecoglaucine in rats

1. The cardiovascular and vasorelaxant effects of (+)-glaucine and of a semisynthetic derivative (N-carbethoxysecoglaucine) were studied in rats. 2. N-carbethoxysecoglaucine did not modify either systolic arterial pressure or heart rate values in conscious (25 mg kg-1, p.o.) and anaesthetized normotensive rats (5 mg kg-1, i.v.). Furthermore, this compound showed no activity in the experiments carried out on rat isolated aorta [contractility and 45Ca2+ influx assays (5 microM)] and did not modify the rate and force of contraction in rat isolated atria (5 microM). 3. In conscious normotensive rats, oral administration of (+)-glaucine (25 mg kg-1) did not modify either systolic arterial pressure or heart rate. 4. In anaesthetized normotensive rats, (+)-glaucine (5 mg kg-1, i.v.) produced a remarkable fall in mean arterial pressure (MAP) accompanied by a significant decrease in heart rate. In the same preparation, (+)-glaucine (5 mg kg-1, i.v.) did not modify the cardiovascular effects induced by noradrenaline (NA) (5 micrograms kg-1) and 5-hydroxytryptamine (5-HT) (300 micrograms kg-1) but markedly inhibited those induced by nicotine (200 micrograms kg-1). 5. In isolated intact aorta of rat, (+)-glaucine (0.15-5 microM) competitively inhibited the contractions induced by NA (with a pA2 value of 7.14) and non-competitively those induced by 5-HT (in normal Krebs solution) and Ca2+ (in depolarizing Ca(2+)-free high-K+ 50 mM solution), with depression of the maximal response and with pD2 values of 5.56 and 5.26, respectively. 6. In experiments in Ca2+-free medium, (+)-glaucine (3 microM) inhibited the contractions induced by NA and had no effect on either 5-HT- or caffeine-induced contractions.7. Furthermore, in the experiments with radioactive Ca2+, (+)-glaucine (3 microM) did not modify the basal uptake of 45Ca2+ but strongly inhibited the influx of 45Ca2+ induced by NA, 5-HT and K+.8. (+)-Glaucine (5microM) had no effect on rate and force of contraction in rat isolated atria.9. These results indicate that: (a) the cardiovascular effects (hypotension and bradycardia) of (+)-glaucine in anaesthetized normotensive rats (5 mg kg-1) may be due, at least in part, to a ganglioplexic effect; (b) the vasorelaxant action of ( + )-glaucine (0.15-5 microM) in rat isolated aorta can be attributed to an alpha1-adrenoceptor blocking property (which may explain its inhibition of noradrenaline-induced 45Ca2+influx and contractions in normal Krebs solution and noradrenaline-induced contractions in Ca2+-free medium) and to a Ca2+-antagonist activity (which may be responsible, at least in part, for the inhibition of 45Ca2+ uptake induced by NA, 5-HT and K+ and the contractions induced by both NA and 5-HT in normal Krebs solution and by Ca2+ in Ca2+-free high-K+ medium) and (c) there is no correlation between the mechanisms of action observed for (+ )-glaucine in vivo and in vitro, which suggests that the vasorelaxant activity of this alkaloid does not contribute to its hypotensive activity.