Gastrointestinal, selective airways and urinary bladder relaxant effects of Hyoscyamus niger are mediated through dual blockade of muscarinic receptors and Ca2+ channels

Pharmacological studies on Hypericum perforatum fractions and constituents

CONTEXT

 This study describes the antispasmodic, bronchodilator, and cardiovascular-modulatory activities of Hypericum perforatum Linn. (Hypericaceae) fractions and constituents.

AIM OF STUDY

 Pharmacological investigation of H. perforatum fractions and active principles.

MATERIALS AND METHODS

 H. perforatum extract fractions [petroleum spirit (HpPet), chloroform (HpCHCl(3)), ethyl acetate (HpEtAc), and aqueous (HpAq)] and its compounds (hyperforin, hypericin, and hyperoside) were studied in various isolated tissue preparations.

RESULTS

 In rabbit jejunum, HpCHCl(3), HpEtAc and HpAq, like papaverine, inhibited both spontaneous and K(+) (80 mM)-induced contractions at similar concentrations, whereas HpPet was relatively potent against K(+), as verapamil. All fractions caused rightward of Ca(2+) concentration-response curves (CRCs), similar to verapamil. HpCHCl(3), HpEtAc, and HpAq shifted isoprenaline-inhibitory CRCs to left, like papaverine, while HpPet was devoid of any such effect, as verapamil. In guinea-pig trachea, HpCHCl(3), HpEtAc, and HpAq equipotently relaxed carbachol and K(+)-induced contractions and shifted the isoprenaline-curves to the left, whereas HpPet was more effective against K(+), without potentiating isoprenaline effect. When tested in rabbit aorta, all fractions exhibited vasoconstrictor and vasodilator effects, except HpEtAc, which did not produce vasoconstriction. In guinea-pig atria HpCHCl(3), HpEtAc, and HpAq initially caused cardiac stimulation, followed by inhibition, similar to papaverine, whereas HpPet, like verapamil, caused only cardiac suppression. Hyperforin, hypericin, and hyperoside showed a similar pattern of spasmolytic effect to verapamil.

DISCUSSION AND CONCLUSION

 Thus, all tested fractions of H. perforatum exhibit a combination of Ca(2+) antagonist and phosphodiesterase-inhibition, except petroleum spirit which was devoid of later mechanism. The compounds tested showed only Ca(2+) channel blocking effect.

Bronchodilatory effect of Acorus calamus (Linn.) is mediated through multiple pathways

AIM OF THE STUDY

This study was undertaken to provide a pharmacological basis for traditional use of Acorus calamus in airways disorders.

MATERIALS AND METHODS

Isolated guinea-pig trachea and atria were suspended in organ baths bubbled with carbogen and mechanisms were found using different parameters.

RESULTS

In isolated guinea-pig tracheal segments, crude extract of Acorus calamus was more effective than carbachol in causing relaxation of high K(+) (80 mM) precontractions, similar to verapamil, suggesting blockade of calcium channels. The n-hexane fraction was equipotent against both precontractions, similar to papaverine, while ethylacetate fraction was more potent against carbachol precontractions but had a negligible dilator effect against K(+), similar to atropine and or rolipram. Pretreatment of tracheal preparations with n-hexane or ethylacetate fractions potentiated isoprenaline-induced inhibitory concentration-response curves, similar to papaverine or rolipram. Pretreatment of tracheal preparations with ethylacetate fraction caused a rightward parallel shift in carbachol response curve at lower concentration (0.003 mg/mL) similar to atropine and a non-parallel shift at higher concentrations (0.01 mg/mL), with reduction of maximum response, similar to rolipram. In isolated guinea-pig atrial preparations, crude extracts, its fractions and papaverine inhibited force and rate of contractions at higher concentrations than the smooth muscle while verapamil was equipotent.

CONCLUSION

These data indicate the presence of unique combination of airways relaxant constituents in crude extract of Acorus calamus, a papaverine-like dual inhibitor of calcium channels and phosphodiesterase in n-hexane fraction and a novel combination of anticholinergic, rolipram-like phosphodiesterase4 inhibitor in ethylacetate fraction and associated cardiac depressant effect, provide a pharmacological basis for traditional use of Acorus calamus in disorders of airways.

Relaxant effect of the ethanol extract of Helichrysum plicatum (Asteraceae) on isolated rat ileum contractions

Helichrysum plicatum (Turkish Helichrysum) has been used in folk medicine for the treatment of gastric and hepatic disorders. The aim of the present study was to examine the relaxant activity of an extract of H. plicatum flowers on isolated rat ileum. Segments of ileum of rats were suspended in an organ bath. Cumulative concentrations of H. plicatum ethanol extract induced a relaxant effect on spontaneous rat ileum contractions. H. plicatum extract caused a mean contractile response of 81.68 +/- 6.17% (at a dose of 0.01 mg/mL) and 30.08 +/- 9.07% (at a dose of 1 mg/mL). A similar effect was observed with papaverine (0.01-3 microg/mL). H. plicatum extract (0.01-1 mg/mL) relaxed high K+ (80 mM) precontractions, an effect similar to that caused by papaverine (0.01-3 microg/mL). The plant extract (0.03-0.3 mg/mL) also induced a significant depression of the cumulative concentration response curve for acetylcholine (5-1500 nM) (p < 0.01). Atropine (140 nM) abolished the acetylcholine effect. The extract (0.03-0.3 mg/mL) reduced the histamine (1-300 nM) and BaCl2 (3-900 microM) induced contractions (p < 0.01). Our results showed the relaxant effect of the ethanol extract of Helichrysum plicatum flowers on the isolated rat intestine Extract of H. plicatum can inhibit the spontaneous ileum contractions and contractions induced by acetylcholine, histamine, barium and potassium ions.

Antispasmodic and bronchodilator activities of Artemisia vulgaris are mediated through dual blockade of muscarinic receptors and calcium influx

AIM OF THE STUDY

The present study describes antispasmodic, antidiarrheal, bronchodilatory and tracheo-relaxant activities of Artemisia vulgaris to rationalize some of its traditional uses.

MATERIALS AND METHODS

Crude extract of Artemisia vulgaris (Av.Cr) was studied in the isolated tissue preparations of rabbit jejunum and guinea-pig trachea, as well as in the in vivo castor oil-induced diarrhea and bronchodilatory techniques.

RESULTS

Av.Cr which tested positive for alkaloids, coumarins, flavonoids, saponins, sterols, tannins and terpenes caused concentration-dependent (0.03-10mg/mL) relaxation of jejunum spontaneous contractions. Av.Cr inhibited the carbachol (CCh, 1 microM) and K(+) (80 mM)-induced contractions in a pattern, similar to that of dicyclomine. Av.Cr shifted the Ca(2+) concentration-response curves to right, like that caused by verapamil and dicyclomine. Av.Cr produced rightward parallel shift in CCh-curves, followed by non-parallel shift at higher concentration with the suppression of the maximum response, similar to that caused by dicyclomine. It exhibited protective effect against castor oil-induced diarrhea and CCh-mediated bronchoconstriction in rodents. In trachea, Av.Cr relaxed the CCh (1 microM) and K(+) (80 mM)-induced contractions and shifted the CCh-curves to right.

CONCLUSION

These results indicate that Artemisia vulgaris exhibits combination of anticholinergic and Ca(2+) antagonist mechanisms, which provides pharmacological basis for its folkloric use in the hyperactive gut and airways disorders, such as abdominal colic, diarrhea and asthma.

Chemical composition and mechanisms underlying the spasmolytic and bronchodilatory properties of the essential oil of Nepeta cataria L

AIM OF THE STUDY

The study was aimed to investigate the chemical composition and pharmacological basis for traditional use of essential oil of Nepeta cataria L. (Limiaceae) (Nc.Oil) in gastrointestinal and respiratory disorders.

MATERIALS AND METHODS

Chemical analysis was carried out through GC-EIMS, 13C NMR and Kovats Retention Indices while pharmacological study was carried out in isolated tissues preparations.

RESULTS

Four major components; 1,8-cineol (21.00%), alpha-humulene (14.44%), alpha-pinene (10.43%) and geranyl acetate (8.21%) were identified among the 27 compounds in Nc.Oil. In isolated rabbit jejunum, Nc.Oil, papaverine and verapamil inhibited spontaneous and high K+(80 mM) precontractions, as well as shifted the Ca++ concentration-response curves (CRCs) to right, indicating calcium channel blocking activity. In isolated guinea-pig trachea, Nc.Oil and papaverine inhibited carbachol (1 microM) and K+ precontractions with similar potency, while verapamil was more potent against K+. Nc.Oil also potentiated isoprenaline inhibitory CRCs, similar to papaverine, indicating papaverine-like PDE inhibitor activity. In isolated guinea-pig atria, Nc.Oil caused cardiodepression at around 25-80 times higher concentrations, similar to papaverine.

CONCLUSIONS

These data indicate that Nepeta cataria possesses spasmolytic and myorelaxant activities mediated possibly through dual inhibition of calcium channels and PDE, which may explain its traditional use in colic, diarrhea, cough and asthma.

Ileal relaxation induced by Mentha longifolia (L.) leaf extract in rat

The effect of Mentha longifolia (L.) leaf hydroalcoholic extract (MLE) was examined on rat ileal smooth muscle contractions. Last portion of ileum from male adult Wistar rat was mounted in an organ bath containing Tyrode solution. The tissue was contracted by carbachol (CCh, 10 microM), KCl (60 mM) and BaC12 (4 mM) and then MLE (0.0625-1 mg mL(-1)) was added to the bath cumulatively. The effect of MLE on KCl-induced contraction was examined after tissue incubation with propranolol (1 microM), naloxone (1 microM) and N omega-nitro-L-arginine methyl ester (L-NAME, 100 microM). The effect of MLE on CaCl2-induced ileal contraction in Ca(2+)-free with high potassium Tyrode solution was also evaluated. The role of potassium channels was examined by ileum incubation (5 mim) with tetraethylammonium (TEA, 1 mM). The results showed that KCl-, CCh and BaCl2-induced ileal contractions were inhibited (p < 0.001) by cumulative concentrations of MLE with the same potency. In addition, MLE (0.25-1 mg mL(-1)) inhibited (p < 0.01) ileal contractions induced by CaCl2 (0.45-2.7 mM) in a concentration-related manner. The antispasmodic effect of MLE was affected neither by propranolol, L-NAME nor by naloxone. The MLE concentration-response curve was shifted to the right (p < 0.05) by tissue incubation with TEA. From results it may be suggested that Mentha longifolia hydroalcoholic leaf extract induces its spasmolytic activity mainly through disturbance in calcium mobilization and partly by potassium channels activation. Present results show that Mentha longifolia leaf extract exerts relaxant effects on intestinal smooth muscle, consistent with the traditional use of the plant to treat gastrointestinal disorders such as diarrhea and colic.

Mechanisms underlying the antispasmodic and bronchodilatory properties of Terminalia bellerica fruit

AIM OF THE STUDY

The present investigation was carried out to provide the pharmacological basis for the medicinal use of Terminalia bellerica in hyperactive gastrointestinal and respiratory disorders.

MATERIALS AND METHODS

Crude extract of Terminalia bellerica fruit (Tb.Cr) was studied in in vitro and in vivo.

RESULTS

Tb.Cr caused relaxation of spontaneous contractions in isolated rabbit jejunum at 0.1-3.0mg/mL. Tb.Cr inhibited the carbachol (CCh, 1microM) and K(+) (80mM)-induced contractions in a pattern similar to that of dicyclomine, but different from nifedipine and atropine. Tb.Cr shifted the Ca(++) concentration-response curves to right, like nifedipine and dicyclomine. In guinea-pig ileum, Tb.Cr produced rightward parallel shift of acetylcholine-curves, followed by non-parallel shift at higher concentration with the suppression of maximum response, similar to dicyclomine, but different from nifedipine and atropine. Tb.Cr exhibited protective effect against castor oil-induced diarrhea and carbachol-mediated bronchoconstriction in rodents. In guinea-pig trachea, Tb.Cr relaxed the CCh-induced contractions, shifted CCh-curves to right and inhibited the contractions of K(+). Anticholinergic effect was distributed both in organic and aqueous fractions, while CCB was present in the aqueous fraction.

CONCLUSIONS

These results indicate that Terminalia bellerica fruit possess a combination of anticholinergic and Ca(++) antagonist effects, which explain its folkloric use in the colic, diarrhea and asthma.