The antidiarrheal and spasmolytic activities of Phyllanthus emblica are mediated through dual blockade of muscarinic receptors and Ca2+ channels

Aim of the study

This study was aimed at providing the possible mechanisms for the medicinal use of Phyllanthus emblica in diarrhea.

Materials and methods

The in vivo studies were conducted in mice, while isolated rabbit jejunum and guinea-pig ileum were used for the in vitro experiments.

Results

The crude extract of Phyllanthus emblica (Pe.Cr), which tested positive for alkaloids, tannins, terpenes, flavonoids, sterols and coumarins, caused inhibition of castor oil-induced diarrhea and intestinal fluid accumulation in mice at 500-700 mg/kg. In isolated rabbit jejunum, Pe.Cr relaxed carbachol (CCh) and K⁺ (80 mM)-induced contractions, in a pattern similar to that of dicyclomine. The preincubation of guinea pig-ileum with Pe.Cr (0.3 mg/mL), caused a rightward parallel shift in the concentration-response curves (CRCs) of acetylcholine without suppression of the maximum response. While at the next higher concentration (1 mg/mL), it produced a non-parallel rightward shift with suppression of the maximum response, similar to that of dicyclomine, suggesting anticholinergic and Ca²⁺ channel blocking (CCB)-like antispasmodic effect. The CCB-like activity was further confirmed when pretreatment of the tissue with Pe.Cr, shifted the CRCs of Ca²⁺ to the right with suppression of the maximum response, similar to nifedipine or dicyclomine. The activity-directed fractions of Pe.Cr showed a combination of Ca²⁺ antagonist and anticholinergic like components in all fractions but with varying potency.

Conclusion

These results indicate that the Phyllanthus emblica fruit extract possesses antidiarrheal and spasmolytic activities, mediated possibly through dual blockade of muscarinic receptors and Ca²⁺ channels, thus explaining its medicinal use in diarrhea.     

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%), α-humulene (14.44%), α-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 μM) 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.     

Coriander fruit exhibits gut modulatory,blood pressure lowering and diuretic activities

Aim of the study

Coriander (Coriandrum sativum) is traditionally used for various gastrointestinal and cardiovascular disorders and this study was designed to rationalize its use in dyspepsia, abdominal colic, diarrhea, hypertension and as diuretic.

Materials and methods

Coriander crude extract (Cs.Cr) was evaluated through in vitro and in vivo techniques.

Results

Cs.Cr caused atropine sensitive stimulatory effect in isolated guinea-pig ileum (0.1–10 mg/ml). In rabbit jejunum preparations, Cs.Cr evoked a similar contractile response but in the presence of atropine, it exhibited relaxation against both spontaneous and high K⁺ (80 mM)-induced contractions as well as shifted the Ca²⁺ concentration–response curves to right, similar to that caused by verapamil. Cs.Cr (1–30 mg/ml) caused fall in arterial blood pressure of anesthetized animals, partially blocked by atropine. Cs.Cr produced vasodilatation against phenylephrine and K⁺ (80 mM)-induced contractions in rabbit aorta and cardio-depressant effect in guinea-pig atria. Cs.Cr produced diuresis in rats at 1–10 mg/kg. Bio-assay-directed fractionation revealed the separation of spasmogenic and spasmolytic components in the aqueous and organic fractions respectively.

Conclusions

These results indicate that coriander fruit exhibits gut stimulatory, inhibitory and hypotensive effects mediating possibly through cholinergic, Ca²⁺ antagonist and the combination of these mechanisms respectively. Diuretic activity adds value to its use in hypertension.     

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 (0.03–10 mg/mL) relaxation of jejunum spontaneous contractions. Av.Cr inhibited the carbachol (CCh, 1 μM) and K⁺ (80 mM)-induced contractions in a pattern, similar to that of dicyclomine. Av.Cr shifted the Ca²⁺ 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 μM) 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 Ca²⁺ antagonist mechanisms, which provides pharmacological basis for its folkloric use in the hyperactive gut and airways disorders, such as abdominal colic, diarrhea and asthma.     

Gastrointestial and respiratory activities of Acacia leucophloea

Ethnopharmacological relevance

The barks of Acacia leucophloea (Fabaceae) are used in Pakistan traditional medicine as an astringent, a bitter, a thermogenic, a styptic, a preventive of infections, an anthelmintic, a vulnery, a demulcent, an expectorant, an antipyretic, an antidote for snake bites and in the treatment of bronchitis, cough, vomiting, wounds, ulcers, diarrhea, dysentery, internal and external hemorrhages, dental caries, stomatitis, and intermittent fevers and skin diseases.

Materials and methods

A study was carried out for the possible elucidation of mechanisms justifying the traditional medicinal uses of A. leucophloea (Fabaceae) in gastrointestinal and respiratory diseases. In vitro experiments were carried out over isolated rabbit jejunum and guinea-pig ileum in order to determine spasmolytic and bronchorelaxant activities, while in vivo studies were conducted in mice for antidiarrheal properties.

Results

A methanol crude extract of barks of the plant caused a concentration-dependent relaxation (0.1-3 mg/ml) of isolated rabbit jejunum preparations in a pattern similar to that of nifedipine and dicyclomine, suggesting a Ca²⁺ channel-blocking mechanism in addition to an anticholinergic effect. In guinea-pig ileum the extract caused a parallel shift in the Ach-curves without suppression of maximum contractile response, followed by a non-parallel shift with the suppression of maximum contractile response at higher concentration similar to that caused by dicyclomine. Moreover, in rabbit trachea, it also caused the relaxation of carbachol (1 μM) and high K⁺-induced contractions at a dose ranging between 0.1578 and 0.734 mg/ml and 0.46-0.94 mg/ml, respectively. These findings indicate that the extract possesses spasmolytic and bronchodilator activities, mediated possibly through blockade of Ca²⁺ channels, thus justifying its medicinal use in diarrhea and asthma. Acacia leucophloea methanol extract exhibited dose-dependent (100-500 mg/ml) protective effect against castor oil induced diarrhea.

Conclusions

The data obtained contribute to the validation of the traditional use of Acacia leucophloea bark in treating gastrointestinal and respiratory disorders, providing an hypothesis on the possible mechanisms of action.     

The spasmolytic activity of extracts and some isolated compounds from the leaves of Morinda morindoides (Baker) Milne-Redh. (Rubiaceae)

Aim

The study was aimed to evaluate the in vitro antispasmodic activity of Morinda morindoides leaves aqueous extract, its soluble fractions and isolated compounds to provide the pharmacological basis for its use for the treatment of constipation and diarrhoea in traditional medicine.

Methods

The antispasmodic activity of each sample was evaluated on acetylcholine (ACh) and the depolarized KCl solution induced contractions on guinea-pig isolated ileum suspended in Tyrode's solution.

Results

At a test concentration of 40 μg/ml in organ bath, the aqueous extract and its petroleum ether soluble fraction showed a spasmogenic effect on both agonists. The diethylether, ethyl acetate, n-butanol and residual aqueous phase soluble fractions from the partition of the aqueous extract exhibited spasmolytic activity producing 47–100% inhibition of contractions induced by both agonists with IC₅₀ values ranged from 6 to 15 μg/ml according to the case. In addition, the n-butanol and residual aqueous phase soluble fractions showed an inhibitory effect of 75 and 66% respectively on low high [K⁺] (25 mM) and 65 and 60% respectively on high [K+] (80 mM). Crude flavonoids showed spasmolytic on both agonists while crude saponins only showed spasmolytic activity on ACh and displayed spasmogenic effect on KCl. Quercetin, quercitrin and rutin exhibited significant antispasmodic effect with IC₅₀ values <0.1 μg/ml. Epoxygaertneroside and gaertneroside showed good antispasmodic activity on both agonists (4 < IC₅₀ < 7 μg/ml).

Conclusion

Morinda morindoides leaves possess spasmogenic and spasmolytic properties that can at least explain and support its traditional use against constipation and diarrhoea respectively.     

In vitro relaxant and spasmolytic effects of constituents from Viburnum prunifolium and HPLC quantification of the bioactive isolated iridoids

Ethnopharmacological relevance

Viburnum prunifolium is a North America shrub used in ethnomedicine because of its spasmolytic, sedative, and anti-asthmatic properties.

Aim of the study

Contrasting results were reported in past literature about the active principles of this plant. Our aim was to clarify this matter by evaluating the relaxant and spasmolytic activities of the main constituents obtained from the drug.

Materials and methods

The pharmacological assays were carried out on rabbit jejunum spontaneous contractions and on guinea-pig carbachol-precontracted trachea.

Results

Cumulative concentration (1–100 μg/ml) of Viburnum prunifolium methanolic extract (MeOH extract), its purified fractions soluble in ethylacetate (EtOAc fraction) and in n-butanol (BuOH fraction), and the iridoid glucosides (2 × 10⁻⁵ to 4 × 10⁻⁴ M): 2′-O-acetyldihydropenstemide (1), 2′-O-trans-p-coumaroyldihydropenstemide (2), 2′-O-acetylpatrinoside (3), and patrinoside (4), isolated from EtOAc fraction (1 and 2) and BuOH fraction (3 and 4), induced both relaxant effect of rabbit jejunum spontaneous contractions and spasmolytic effect on guinea-pig carbachol (5.5 × 10⁻⁷ M)-precontracted trachea. Propranolol (10⁻⁶ M) antagonised all Viburnum prunifolium tested components relaxant and spasmolytic effects. At non-relaxing concentrations (0.5 μg/ml), MeOH extract and its fractions induced a potentiating effect of isoprenaline cumulative concentrations also in both isolated tissues.

Conclusion

In both tissues, the order of potency was EtOAc fraction > BuOH fraction > MeOH extract and 1 > 2 > 3 > 4 suggesting that the major iridoids of EtOAc fraction may be considered among the most active compounds.HPLC analysis of the bioactive iridoids indicates that 1 and 2 are present for 7.38% and 14.90% in EtOAc fraction, and 3 and 4 for 18.47% and 8.86% in BuOH fraction. By comparing the values of EC₅₀ of the fractions and compounds isolated from them, we may assume that the iridoids play a significant role in the biological activity of the corresponding fractions.     

The anti-ulcer activities of bisabolangelone from Angelica polymorpha

Aim of the study

Evaluate the anti-ulcer effects of bisabolangelone from Angelica polymorpha Maxim and provide the basic data to further study for the Angelica polymorpha and bisabolangelone.

Materials and methods

Bisabolangelone was isolated from Angelica polymorpha Maxim collected from Shennongjia Forest District of China. The structure of bisabolangelone was elucidated by NMR and MS spectrums. The anti-ulcer effects were evaluated with length of lesion (mm) and activity of H⁺/K⁺-ATPase in two models induced by ethanol and Pylorus ligation. Experimental groups were administered with different doses of bisabolangelone (3.8, 7.6 and 15.3 mg/kg). The positive control group was administered omeprazole with a dose of 3.3 mg/kg.

Results

Bisabolangelone significantly reduced the length of lesion (3.8, 7.6 and 15.3 mg/kg, P < 0.01), inhibited the activity of H⁺/K⁺-ATPase (3.8, 7.6 and 15.3 mg/kg, P < 0.01), decreased the volume of gastric juice (7.6 and 15.3 mg/kg, P < 0.05), and increased the pH value of gastric juice (7.6 and 15.3 mg/kg, P < 0.01, 3.8 mg/kg, P < 0.05).

Conclusions

Bisabolangelone is the main anti-ulcer active compound of Angelica polymorpha, and remarkably preventive and therapeutic action on gastric ulcer. It is possible that bisabolangelone inhibited the activity of the H⁺/K⁺-ATPase, then reducing the secretion of H⁺, and the anti-ulcer mechanism of bisabolangelone was deserved to be further studied.     

Antiulcer and gastric antisecretory effects of dichloromethane fraction and piplartine obtained from fruits of Piper tuberculatum Jacq. in rats

Ethnopharmacological relevance

Piper tuberculatum Jacq. (Piperaceae) is medicinally used as an analgesic and as a treatment for gastric complaints. Thus, the current study aimed to investigate the gastroprotective and antisecretory properties of the dichloromethane fraction of the fruit of Piper tuberculatum (DFPT) and piplartine, a compound isolated from the DFPT, in rats.

Materials and methods

Gastric ulcers were induced in fasted rats by oral administration of absolute ethanol and then mucus content and glutathione (GSH) levels were measured. Mechanisms underlying the antisecretory action were studied through gastric H⁺,K⁺-ATPase activity of highly purified rabbit gastric microsomes and pylorus ligature method in rats.

Results

In the acute toxicity test the values of estimated LD₅₀ for oral and intraperitoneal administration of DFPT were 1.6266 and 0.2684 g/kg, respectively. The DFPT (ED₅₀=29 mg/kg, p.o.) and piplartine (4.5 mg/kg, p.o.) promoted gastroprotection against acute lesions induced by ethanol, effect that could be related with the maintenance of GSH levels in the gastric mucosa. However, only DFPT stimulated gastric mucus secretion. In vitro, the DFPT and piplartine inhibited the H⁺,K⁺-ATPase activity and, in vivo DFPT and piplartine also reduced basal gastric acid secretion, as well as that stimulated by pentagastrin.

Conclusions

These results demonstrate that DFPT and piplatine cause marked gastroprotective effects accompanied by the increase and maintenance of gastric mucus and GSH levels, as well as a reduction in gastric acid secretion through the gastrinergic pathway.     

Gastroprotective activity of ethanolic root extract of Potentilla fulgens Wall. ex Hook

Ethnopharmacological relevance

Potentilla fulgens (Wall.) ex Hook. (Rosaceae) is a potent medicinal plant of the Western Himalayas, known under the name “Himalayan Cinquefoil or Bajradanti”, and has been used traditionally to treat ailments including peptic ulcers, mouth ulcers, diarrhea, diabetes and cancer.

Objective

The aim of the present study was to scientifically evaluate the gastric-ulcer protective effect of P. fulgens ethanolic root extract (EPF) on experimental rats.

Material and methods

The gastroprotective activity of EPF was evaluated on four gastric-ulcer models such as pyloric ligation (PL), ethanol (EtOH), cold restrain stress (CRS) and aspirin (ASP)-induced gastric ulcers. The gastric acid obtained from 4 h PL-induced gastric ulcer rats was determined for total volume content, pH and total acid–pepsin output. Total carbohydrates and protein ratio, expressed as index of mucin activity, and DNA content were estimated in the gastric juice and gastric mucosal tissue. The microvascular permeability, H⁺K⁺–ATPase activity, gastric mucus and histamine content were also determined. The levels of antioxidant enzymes (superoxide dismutase, catalase, and glutathione) and malondialdehyde in the stomach tissue (mucosal scrapings) were quantified. A histopathological study of the stomach was evaluated using eosin–haematoxylin stain.

Results

EPF (200–400 mg/kg, p.o.) showed significant protection against acute gastric-ulcer induced by EtOH, PL and CRS (400 mg/kg, p.o.), but was found to be ineffective against ASP-induced ulcerogens. The effect of EPF on gastric juice studies in 4 h PL rats significantly produced an increased level in gastric pH, whereas the effect on gastric volume and acid–pepsin output was observed to decrease significantly. However, EPF was found to have no significant effect on the defensive factors, thus revealing its antisecretory property by inhibiting the aggressive factors. EPF, significantly decreased the histamine level, inhibited the H⁺K⁺–ATPase activity and prevented the microvascular injury caused by ethanol in the rat stomach. Moreover, it was also observed to have antioxidant effects by producing a significant increase in the levels of SOD, CAT, and GSH and decreased the LPO activity. Histopathological studies showed that EPF significantly prevented gastric lesions caused by ethanol.

Conclusions

The present study showed that EPF has potent gastroprotective and antisecretory effects, thus justifying the traditional usage of this herb to treat gastric ulcers.     

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.     

α-Glucosidase inhibitory activity of selected Philippine plants

Ethnopharmacological relevance

Antidesma bunius Spreng. (Phyllantaceae), Averrhoa bilimbi L. (Oxalidaceae), Biophytum sensitivum (L.) DC. (Oxalidaceae), Ceriops tagal (Perr.) C.B. Rob. (Rhizophoraceae), Kyllinga monocephala Rottb. (Cyperaceae), and Rhizophora mucronata Lam. (Rhizophoraceae) are used as remedies to control diabetes. In the present study, these plants were screened for their potential α-glucosidase inhibitory activity.

Materials and methods

The 80% aqueous ethanolic extracts were screened for their α-glucosidase enzyme inhibitory activity using yeast alpha glucosidase enzyme.

Results

Except for A. bilimbi with IC₅₀ at 519.86±3.07, all manifested a significant enzyme inhibitory activity. R. mucronata manifested the highest activity with IC₅₀ at 0.08±1.82 μg mL⁻¹, followed by C. tagal with IC₅₀ at 0.85±1.46 μg mL⁻¹ and B. sensitivum with IC₅₀ at 2.24±1.58 μg mL⁻¹.

Conclusion

This is the first report on the α-glucosidase inhibitory effect of the six Philippine plants; thus, partly defining the mechanism on why these medicinal plants possess antidiabetic properties.     

Anti-secretory,anti-inflammatory and anti-Helicobacter pylori activities of several fractions isolated from Piper carpunya Ruiz & Pav.

Ethnopharmacological relevance

The leaves of Piper carpunya Ruiz & Pav. (syn Piper lenticellosum C.D.C.) (Piperaceae), are widely used in folk medicine in tropical and subtropical countries of South America as an anti-inflammatory, anti-ulcer, anti-diarrheal and anti-parasitical remedy as well as an ailment for skin irritations.

Aims of the study

To study the anti-inflammatory, anti-secretory and anti-Helicobacter pylori activities of different fractions isolated from an ethanolic extract of the leaves of Piper carpunya, in order to provide evidence for the use of this plant as an anti-ulcer remedy. Moreover, to isolate the main compounds of the extract and relate their biological activity to the experimental results obtained with the fractions.

Materials and methods

Sixteen fractions were obtained from the ethanolic extract (F I–XVI) and 16 pure compounds were isolated and identified from these fractions. We studied the effects of the fractions (0.1–400 μg/mL) on the release of myeloperoxidase (MPO) enzyme from rat peritoneal leukocytes, on rabbit gastric microsomal H⁺, K⁺-ATPase activity and anti-Helicobacter pylori anti-microbial activity using the microdilution method (MM). The main compounds contained in the fractions were isolated and identified by ¹H- and ¹³C NMR spectra analysis and comparison with the literature data.

Results

Eight fractions showed inhibition of MPO enzyme (F I–IV, X, XII, XIV and XV). The highest inhibition was observed with F XIV (50 μg/mL, 60.9%, p < 0.001). F X and XII were the most active ones, inhibiting the gastric H⁺, K⁺-ATPase activity with IC₅₀ values equal to 22.3 μg/mL and 28.1 μg/mL, respectively. All fractions, except F XV, presented detectable anti-Helicobacter pylori activity, with a diameter of inhibition zones ranging from 11 mm up to 50 mm. The best anti-Helicobacter pylori activity was obtained with F III and V. Both fractions killed Helicobacter pylori with lowest concentration values, about 6.25 μg/mL. Sixteen pure compounds were isolated, five of them are flavonoids that possess strong anti-oxidant and free radical scavenging activity, e.g. vitexin, isovitexin, and rhamnopyranosylvitexin. Terpenoids like sitosterol, stigmasterol and phytol, which have shown gastroprotective activity, and dihydrochalcones, like asebogenin, with anti-bacterial activity, were also isolated. Furthermore, the rare neolignan 1, that is a DNA polymerase β lyase inhibitor, and (6S, 9S)-roseoside, that shows strong anti-bacterial activity, were isolated, for the first time, from the genus Piper.

Conclusions

We suggest that the flavonoids isolated from F I and II (vitexin, isovitexin, rhamnopyranosylvitexin and isoembigenin) contribute to the anti-MPO activity, as well as to their anti-Helicobacter pylori activity. These flavonoids may also be responsible for the important inhibition of H⁺, K⁺-ATPase activity. Also the phytosterols and phytol obtained from F XIV and XV could be involved in these gastroprotective activities. These results encourage us to continue phytochemical studies on these fractions in order to obtain full scientific validation for this species.     

Effect of plants used in Mexico to treat gastrointestinal disorders on charcoal–gum acacia-induced hyperperistalsis in rats

Ethnopharmacological relevance

A total of 28 plant extracts, belonging to 26 different plant species are commonly used in Traditional Mexican Medicine for the treatment of gastrointestinal disorders such as diarrhea.

Aim of the study

To evaluate the effect of medicinal plant extracts on induced hyperperistalsis in rats.

Materials and methods

Charcoal meal test was used in this study. Extracts were tested at a dose of 300 mg/kg.

Results

From all the plant extracts tested, only Geranium mexicanum (roots) showed 100% of inhibition. The extracts of Artemisia absinthium, Matricaria recutita, Caesalpinia pulcherrima, Lygodium venustum, Chenopodium ambrosoides (green variety), Aloysia triphylla, Artemisia ludoviciana, Chiranthodendron pentadactylon, and Cocos nucifera showed moderate inhibitory activity with values ranging from 30 to 57%. Their activities were greater than that of or equal to loperamide (34% of inhibition at doses of 10 mg/kg) drug used as control. The remaining plants exhibited marginal or null inhibitory effect on hyperpropulsive movement of the small intestine.

Conclusions

The results obtained in this study give some scientific support to the popular use of 23 of the plants tested for the treatment of gastrointestinal disorders such as diarrhea in Mexican traditional medicine. However, roots of Geranium mexicanum should be used in herbal medicine with care to avoid toxicity.     

Evidence of the mechanism of action of Erythrina velutina Willd (Fabaceae) leaves aqueous extract

Ethnopharmacological relevance

Erythrina velutina is traditionally used for sleepiness, convulsions and nervous system excitation in Brazil. Although central effects have been reported for Erythrina velutina, little is known about its mechanism of action.

Aim of the study

To investigate the pharmacological evidences of mechanism of action of Erythrina velutina leaves aqueous extract (AE).

Materials and methods

Terminal segments of the guinea-pig ileum (n = 5–8) were mounted in an organ bath and isotonic contractions were recorded. Phytochemical screening was carried out on AE.

Results

AE (0.025–2.50 mg/ml) produced contractile response in the guinea-pig ileum, yielding typical concentration–response curves (EC₅₀ = 0.63 mg/ml). Electrically evoked contractions were significantly increased in the presence of AE. AE-elicited contractions were significantly reduced by bicuculline, tetrodotoxin, atropine, verapamil or incubation in low calcium–high potassium solution. Atropine along with verapamil abolished AE contractile response. Alkaloids, catechins, steroids, flavonols, flavononols, flavonoids, phenols, saponins, tannins, triterpenoids, and xanthones were detected in AE.

Conclusions

AE contains important constituents for pharmacological activities. AE-induced contractions seem to involve GABA_A receptor activation, acetylcholine release, muscarinic receptor activation, augmentation of Ca²⁺ entry through L-type calcium channels, and calcium release from the intracellular stores. These findings provide further support for Erythrina velutina traditional uses.     

Antiarrhythmic effects of dehydroevodiamine in isolated human myocardium and cardiomyocytes

Ethnopharmacological relevance

Dehydroevodiamine alkaloid (DeHE), a bioactive component of the Chinese herbal medicine Wu-Chu-Yu (Evodiae frutus), exerted antiarrhythmic effect in guinea-pig ventricular myocytes. We further characterize the electromechanical effects of DeHE in the human atrial and ventricular tissues obtained from hearts of patients undergoing corrective cardiac surgery or heart transplantation.

Materials and methods

The transmembrane potentials of human myocardia were recorded with a traditional microelectrode technique while sarcolemmal Na⁺ and Ca²⁺ currents in single human cardiomyocytes were measured by a whole-cell patch-clamp technique. The intracellular pH (pH_i) and Na⁺–H⁺ exchanger (NHE) activity were determined using BCECF-fluorescence in human atria.

Results

In human atria, DeHE (0.1–0.3 μM) depressed upstroke velocity, amplitude of action potential, and contractile force, both in slow and fast response action potential. Moreover, the similar depressant effects of DeHE were found in human ventricular myocardium. Both in isolated human atrial and ventricular myocytes, DeHE (0.1–1 μM) reversibly, concentration-dependently decreased the Na⁺ and Ca²⁺currents. Moreover, DeHE (0.1 and 0.3 μM) suppressed delayed afterdepolarizations and aftercontractions, induced by epinephrine and high [Ca²⁺]_o in atria. In human ventricular myocardium, the strophanthidin-induced triggered activities were attenuated by pretreating DeHE (0.3 μM). The resting pH_i and NHE activity were also significantly increased by DeHE (0.1–0.3 μM).

Conclusions

We concluded for the first time that, in the human hearts, DeHE could antagonize triggered arrhythmias induced by cardiotonic agents through a general reduction of the Na⁺ and Ca²⁺ inward currents, while increase of resting pH_i and NHE activity.     

Identification of Escherichia coli enterotoxin inhibitors from traditional medicinal herbs by in silico, in vitro, and in vivo analyses

Ethnopharmacological relevance

Glycyrrhiza uralensis has been used for the treatment of gastrointestinal disorders, such as diarrhea, in several ancient cultures. Glycyrrhizin is the principal component of liquorice and lots of pharmacological effects have been demonstrated.

Aim of the study

Heat-labile enterotoxin (LT), the virulence factor of enterotoxigenic Escherichia coli, induces diarrhea by initially binding to the G_M1 on the surfaces of intestinal epithelial cells and consequently leading to the massive loss of fluid and ions from cells. Therefore, we evaluated the inhibitory effects of traditional medicinal herbs (TMH) on the B subunit of LT (LTB) and G_M1 interaction.

Materials and methods

The inhibitory effects of TMH on LTB-G_M1 interaction were evaluated by G_M1-enzyme-linked immunosorbent assay (ELISA). The likely active phytochemicals of these TMH were then predicted by in silico model (docking) and analyzed by in vitro (G_M1-ELISA) and in vivo (patent mouse gut assay) models.

Results

We found that various TMH, which have been ethnomedically used for the treatment of diarrhea, inhibited the LTB-G_M1 interaction. Docking data showed that triterpenoids were the most active phytochemicals and the oleanane-type triterpenoids presented better LTB-binding abilities than other types of triterpenoids. Moreover, by in vitro and in vivo models, we demonstrated that glycyrrhizin was the most effective oleanane-type triterpenoid that significantly suppressed both the LTB-binding ability (IC₅₀ = 3.26 ± 0.17 mM) and the LT-induced fluid accumulation in mice.

Conclusions

We found an LT inhibitor, glycyrrhizin, from TMH by in silico, in vitro, and in vivo analyses.     

Leucas cephalotes regulates carbohydrate and lipid metabolism and improves antioxidant status in IDDM and NIDDM rats

Ethnopharmacological relevance

Leucas cephalotes (Roth.) Spreng. (Laminaceae) is an ayurvedic traditional medicinal plant used in India, Nepal and Pakistan to treat several ailments including diabetes.

Aim of the study

The aim of the present study is to investigate the antidiabetic, antihyperlipaemic and antioxidant activities of Leucas cephalotes for its purported use in diabetes.

Materials and methods

The ethanol extract of leaves of Leucas cephalotes was administered (150, 300 and 450 mg kg⁻¹ bw) to diabetes induced (IDDM and NIDDM) rats and carbohydrate, lipid, antioxidant, urea and creatinine profiles were assessed.

Results

All the three doses of extract decreased plasma glucose and lipid profiles and, improved the antioxidant status of both types of diabetic rats. The extract administration improved hepatic glycogen content and hexokinase activity, decreased glucose-6-phosphatase activity, blood urea, creatinine contents and decreased lipid peroxidation in diabetic rats. Of the three doses used, 450 mg kg⁻¹ bw dose was found to be more potent in its effects comparable to those of glibenclamide and metformin.

Conclusion

Leucas cephalotes regulates both carbohydrate and lipid metabolism and, improves body antioxidant defense systems in both types of diabetes.     

Screening of the topical anti-inflammatory activity of the bark of Acacia cornigera Willdenow, Byrsonima crassifolia Kunth, Sweetia panamensis Yakovlev and the leaves of Sphagneticola trilobata Hitchcock

Ethnopharmacological relevance

An investigation of topical anti-inflammatory activity was undertaken on plants used in Central America traditional medicine.

Aim of study

Four herbal drugs used in the folk medicine of Central America to treat inflammatory skin affections (Acacia cornigera bark, Byrsonima crassifolia bark, Sphagneticola trilobata leaves and Sweetia panamensis bark) were evaluated for their topical anti-inflammatory activity.

Materials and methods

Petroleum ether, chloroform and methanol extracts were obtained for herbal medicines and then extracts were tested on Croton oil-induced ear dermatitis model in mice.

Results

Almost all the extracts reduced the Croton oil-induced ear dermatitis in mice and the chloroform ones showed the highest activity, with ID₅₀ (dose giving 50% oedema inhibition) values ranging from 112 μg/cm² (Byrsonima crassifolia) to 183 μg/cm² (Sphagneticola trilobata). As reference, ID₅₀ of the non-steroidal anti-inflammatory drug indomethacin was 93 μg/cm².

Conclusions

Lipophilic extracts from these species can be regarded as potential sources of anti-inflammatory principles.     

M3 muscarinic receptor- and Ca influx-mediated muscle contractions induced by croton oil in isolated rabbit jejunum

Aim of study

Croton oil is the fruit oil of Croton tiglium L., which is well known in folk medicine for the treatment of gastrointestinal (GI) diseases, including constipation, abdominal pain, peptic ulcer, and intestinal inflammation for a long period. This study was to investigate the pharmacological effect of croton oil on GI tract.

Materials and methods

The effect of croton oil on the smooth muscle contractions was investigated in vitro using the isolated rabbit jejunum model.

Results

Croton oil has a biphasic action contracting and relaxing intestinal tissue. At the concentrations of 20–80 μg/mL, croton oil produced a concentration-dependent increase in the amplitude and tension of muscle contractions, whereas at high concentrations (>200 μg/mL) it decreased the contractile amplitude and had no impact on the tension. Moreover, croton oil was less effective in increasing muscle amplitude and tension than Ach, confirming that the effect of croton oil on muscle contractions is not a simply stimulatory or inhibitory action, but a unique modulatory process depending on the concentration of croton oil. In addition, croton oil concentration-dependently suppressed the frequency of muscle contractions. On the other hand, atropine (10 μM) and 4-DAMP (10 μM) produced a significant inhibition of contractions caused by croton oil, while either hexamethonium (10 μM) or methoctramine (10 μM) was inactive, implying that the regulatory effects of croton oil on GI motility are mediated via the activation of M3 muscarinic receptor. Furthermore, muscle contractions induced by croton oil were dramatically reduced by verapamil (0.1 μM) but not by NE (1 μM), suggesting that the action of croton oil on GI motility is also mediated by Ca²⁺ influx through L-type Ca²⁺ channel.

Conclusions

The results suggest that croton oil possesses spasmogenic and spasmolytic properties and the regulatory effects of croton oil on GI motility are mediated via the activation of M3 muscarinic receptor and Ca²⁺ influx through L-type Ca²⁺ channel.