Interactions of a standardized flavonoid fraction from Tilia americana with Serotoninergic drugs in elevated plus maze.

ETHNOPHARMACOLOGICAL RELEVANCE: Tilia americana var. mexicana (Schltdl) Hardin (Tiliaceae) aerial parts (bracts and flowers) are used in the traditional Mexican medicine to treat nervous disorders, as sedative and to treat insomnia. A fraction of this species called FC1 (organic fraction from this plant) was proposed, described as anxiolytic and characterized by the presence of flavonoids. In the present work, this fraction was standardized, and its interaction with different serotonergic drugs was tested. We used the elevated plus maze model as anxiety test and the open field test so as to observe a possible effect on mice׳s motor behavior. MATERIAL AND METHODOLOGY: HPLC technique was used to quantify the flavonoids contained in a fraction called F1C. Different doses of F1C were administered to ICR mice (12.5, 25, 37.5 and 50mg/kg, oral pathway) then they were exposed to elevated plus maze or open field test. After, each dose of F1C fraction was co-administered with different drugs, in order to evaluate the animal׳s behavior: DOI agonist (2.0mg/kg) and KET antagonist (0.03mg/kg) of 5-HT2A receptors; 8-OH-DPAT (0.1mg/kg) selective agonist and WAY100635 (0.5mg/kg) antagonist of 5HT1 receptors. RESULTS: The HPLC quantitative analysis revealed the F1C composition (mg/g of extract): tiliroside (28.56), glucoside of quercetin (16.25), quercitrin (7.96), rutin (3.93), Kaempferol (2.83). The Emax for F1C curve was 80.6% for time to open arms with an ED50 of 15.09 mg/kg. The combination of F1C with DOI gives a significant increase of the F1C anxiolytic effect (Emax=111% and ED50=13.51 mg/kg), while KET blocks it completely (Emax=12.25% and ED50=2.4 mg/kg). The administration of F1C with 8-OH-DPAT does not generate significant changes on the time to open arms, although it does induce a decrement in F1C potency (Emax=83.3% and ED50=33.3mg/kg). When F1C and WAY-100365 are combined, the anxiolytic activity of the fraction decreases (Emax=33.3% and ED50=102.10mg/kg). CONCLUSIONS: The medicinal use attributed to Tilia americana for their effect on central nervous system, could be in part in the flavonoid fraction (F1C) with anxiolytic activity which is dose dependent, and has the ability to interact with the serotonergic system. It is necessary to advance in the study of the mechanism of action, using other techniques such in vitro analysis.

Antidepressant effect and pharmacological evaluation of standardized extract of flavonoids from Byrsonima crassifolia.

Byrsonima crassifolia (Malpighiaceae) has been used in traditional medicine for the treatment of some mental-related diseases; however, its specific neuropharmacological activities remain to be defined. The present study evaluates the anxiolytic, anticonvulsant, antidepressant, sedative effects produced by the extracts of Byrsonima crassifolia, and their influence on motor activity in ICR mice. Additionally, we determine the acute toxicity profiles of the Byrsonima crassifolia extracts and the presence of neuroactive constituents. Our results show that the methanolic extract of Byrsonima crassifolia produces a significant (P<0.05) antidepressant effect in the forced swimming test in mice at 500 mg/kg dose. However, it does not possess anxiolytic, sedative, or anticonvulsant properties, and does not cause a reduction of mice locomotion (P>0.05). Although the main compound of the methanolic extract was identified as quercetin 3-O-xyloside (12 mg/kg), our findings suggest that flavonoids, such as rutin (4.4 mg/kg), quercetin (1.4 mg/kg) and hesperidin (0.7 mg/kg), may be involved in the antidepressant effects. To the best of our knowledge, the present study constitutes the first report on the presence of the flavonoids with neuropharmacological activity rutin and hesperidin in Byrsonima crassifolia. In conclusion, the present results showed that the methanolic extract standardized on flavonoids content of Byrsonima crassifolia possesses potential antidepressant-like effects in the FST in mice, and could be considered as relatively safe toxicologically with no deaths of mice when orally administered at 2000 mg/kg.

The antidepressant-like effects of Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) in mice.

The aim of the present work is to evaluate the putative antidepressant-like effects of a hydro-ethanolic extract (CEAp) and their fractions from the aerial parts of Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) on the performance of male mice in the forced swimming test (FST). A single dose (100.0mg/kgp.o.) of CEAp, in male mice provoked a significant reduction of the immobility time (p<0.01). Such effect was also observed with short-term treatment (7 days) with single doses of 1.0 (p<0.01), 10.0 (p<0.05) and 100.0 (p<0.05)mg/kg/day of CEAp. Additionally, in a different set of experiments, repeated administration in a 24-h period (24, 18 and 1h before swimming test) with doses of 1.0 (p<0.05) and 10.0 (p<0.05)mg/kg p.o., of CEAp and 10.0mg/kgp.o., (p<0.05) of ethyl acetate fraction, provoked significant reduction of the immobility time of male mice in the FST. Moreover, it was noted important differences in the onset of the antidepressant-like effect in the FST, depending on the modality of treatment with CEAp (acute, short-term or repeated). Both, efficacy and potency were higher when repeated administration of CEAp was used, and surprisingly the dose of 10mg/kg (24, 18 and 1h before swimming test) was more effective than imipramine. In the same way, the short term administration (7 days) improved significantly efficacy and potency of the CEAp in comparison to a single dose treatment. The ethyl acetate fraction submitted to TLC demonstrated that main and minor components are phenolics and terpenes, respectively. In addition, this fraction gives a negative Shinoda's test for flavonoids. These results indicate an antidepressant-like profile of action for the hydro-ethanolic extract and the component(s) of the ethyl acetate fraction obtained from A. polystachya, which deserve further investigation.

The anxiolytic-like effects of Aloysia polystachya (Griseb.) Moldenke (Verbenaceae) in mice.

The aim of the present work is to demonstrate the putative sedative and anxiolytic-like effects of a hydro-ethanolic extract obtained from the aerial parts of Aloysia polystachya (Verbenaceae) in male mice using several behavioural assays. Groups of male mice orally treated with doses of 1.0, 10.0 and 100.0 mg/kg of the extract did not show any significant alteration of their locomotor activity, body temperature or motor coordination. The same treatment increased the duration of the sleeping time induced by 30.0 mg/kg i.p. of sodium pentobarbital. However, the sleeping time induced by ethyl ether was not modified by the oral administration of the extract, not confirming the putative sedative effect of the plant. The ethanolic extract also significantly increased the percentage of both entries (1.0 and 100.0 mg/kg) and the time spent (10.0 and 100.0 mg/kg) into the open arms of the elevated plus maze (EPM). Nevertheless, the binding of (3)H-flunitrazepam ((3)H-FNZ) to the benzodiazepine binding site (BDZ-bs), in washed crude synaptosomal membranes from rat cerebral cortex, was not affected by the semi-purified components from Aloysia polystachya. These results indicate an anxiolytic-like profile of action for the extract of Aloysia polystachya without sedative side effect, being this activity probably mediated by other mechanism than BDZ-bs modulation at the GABA(A) receptors.

The hydroalcoholic extract of Salvia elegans induces anxiolytic- and antidepressant-like effects in rats.

Behavioral effects of a hydroalcoholic (60% ethanol) extract from the leaves of Salvia elegans Vahl (Lamiaceae) were studied in male Sprague-Dawley rats. The extract was administered intraperitoneally and its effects on spontaneous motor activity (total motility, locomotion, rearing and grooming behavior) were monitored. Putative anxiolytic and antidepressant properties of Salvia elegans were studied in the elevated plus-maze test (EPM) and in the forced swimming test (FST), respectively. Deleterious effects of Salvia elegans on learning and memory were also studied by using active and passive avoidance paradigms. The results revealed that all doses (3.12, 12.5, 25 and 50 mg/kg) of the extract caused a significant decrease in total motility, locomotion, rearing and grooming behavior. Only the dose of 12.5 mg/kg increased the exploration of the EPM open arms in a similar way to that of diazepam (1 mg/kg). In the FST, all doses of the extract induced a reduction of immobility, in a similar way to that of fluoxetine (10 mg/kg) and imipramine (12.5 mg/kg), along with a significant increase in the time spent in swimming behavior. Acquisition of active avoidance responses was disrupted by pre-treatment with the extract, but retention of a passive avoidance response was not significantly modified. These results suggest that some of the components of the hydroalcoholic extract of Salvia elegans have psychotropic properties, which deserve further investigation.

Anxiolytic and antidepressant-like activity of a standardized extract from Galphimia glauca.

An infusion prepared with aerial parts from Galphimia glauca has been widely used in Mexican traditional medicine as a remedy for nervous excitement. The sedative activity of a methanolic extract from this plant has been demonstrated by neuropharmacological tests. This effect was attributed to the nor-secotriterpene named galphimine B (GB). In the present work, the anxiolytic and antidepressant-like effects of G. glauca methanolic extract (standardized on GB content, 8.3mg/g) were assayed by using the elevated plus-maze, light-dark test and the forced swimming paradigm, on ICR albino mice. This extract, administered orally, three times (24, 18 and 1h before the test), and in different doses (125, 250, 500, 1,000 and 2,000 mg/kg) was able to increase significantly (p<0.05) the number of entries, as well as the time spent in the open arms of the elevated plus-maze, indicating an anxiolytic-like effect. A similar effect was observed in the light-dark paradigm test, the time spent in the light box was increased in treated mice. Nevertheless, this treatment was unable to change any parameter in the forced swimming test. Altogether, these results suggest an anxiolytic-like effect to the methanolic standardized extract of G. glauca on ICR inbred mice.

Central nervous system activity of the hydroalcoholic extract of Casimiroa edulis in rats and mice.

In order to evaluate the effects produced by the hydroalcoholic extract of leaves from Casimiroa edulis on the central nervous system, different behavioral tests and animal models of depression and anxiety were performed. The extract was administered intraperitoneally in male and female rats and tested on spontaneous motor activity, locomotor activity, exploration of an elevated plus-maze (EPM) and in the forced swimming test (FST). In addition, the extract was administered orally in male and female mice and evaluated in the following tests: general observation, pentobarbital-induced hypnosis, EPM, rota-rod, hole-board, and marble-burying. The results revealed that, in rats, the extract caused considerable reduction of locomotor and exploratory activities and increased the exploration of the EPM open arms in a similar way that diazepam. In the FST, the extract was as effective as fluoxetine in inducing shortening of immobility, along with a significant increase on climbing duration. On the other hand, in mice, the extract prolonged pentobarbital-induced hypnosis, increased exploration of the EPM open arms and partially protected from the pentylenetetrazol-induced convulsions. No significant effect was evident on motor coordination, hole-board and marble-burying tests. These results suggest that the hydroalcoholic extract of Casimiroa edulis may contain sedative principles with potential anxiolytic and antidepressant properties, which need further investigation.

The secretagogue effect of the poison from Centruroides limpidus limpidus on the pancreas of mice and the antagonistic action of the Bouvardia ternifolia extract.

In Mexican traditional medicine the plant species Bouvardia ternifolia is used as remedy to treat patients who have been stung by scorpions. In the preceding study, the methanol extract from the roots of this plant was capable of reducing the poisonous effect of Centruroides limpidus limpidus on mice. The poisoning from scorpion C. limpidus limpidus includes manifestations associated with the pancreatitis. This study evaluated the effect produced by the hexane and methanol extract from the root of B. ternifolia upon the acutely inflamed pancreas induced by the venom of C. limpidus limpidus on rats, and the release of amylase in the isolated pancreas of mice. The intravenous administration of venom induced the extravasation of labelled albumin, in a dose dependant manner. The pre-administration of both extracts of Bouvardia ternifolia reduced significantly (p < 0.05) the extravasation by 60%. Upon measuring the secretagogue effect of the venom in the isolated pancreas of mice, the EC50 of the venom was 3.76 x 10(-3) mg ml(-1), whilst in the presence of the methanol and hexane extracts, this EC50 was 9.13 x 10(-3) mg ml(-1) and 0.01629 mg ml(-1). In conclusion, the C. limpidus limpidus venom possesses a secretagogue effect of amylase on the pancreas of mice and produces an inflamed pancreas which is effectively antagonised by the hexane and methanol extracts from the roots of B. ternifolia.

Antitoxin activity of plants used in Mexican traditional medicine against scorpion poisoning.

Scorpions, especially in urban areas of tropical and subtropical regions, present a common risk of poisoning. In Mexico, scorpion envenomation is considered a public health problem. Despite the frequency of scorpion sting cases, there are to date no uniform criteria for their treatment. In Mexican traditional medicine, different plant species have been widely used as a remedy for treating scorpion poisoning. The aim of this work was to evaluate the effect of Bouvardia ternifolia, Aristolochia elegans and Vitex mollis extracts on Centruroides limpidus limpidus venom lethality in mice, and to determine their antagonist activity on guinea pig ileum. The hexane and methanol extract from B. ternifolia modified the LD50 of C. limpidus limpidus venom from 0.750 +/- 0.08 to 1.64 +/- 0.19 and 1.16 +/- 0.14 mg/kg, respectively. The extracts of A. elegans produced lower antitoxic activity, while extracts of V. mollis did not show any protection. On in vitro test, addition of B. ternifolia and A. elegans extracts strongly inhibited, in a concentration-dependent manner, the ileum contractions induced by venom. In general, the results demonstrated the effectiveness of these two plant species in modifying the lethality of C. limpidus limpidus venom in mice.

Effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa in patients with mild to moderate hypertension: a controlled and randomized clinical trial.

In order to compare the antihypertensive effectiveness and tolerability of a standardized extract from Hibiscus sabdariffa with captopril, a controlled and randomized clinical trial was done. Patients from 30 to 80 years old with diagnosed hypertension and without antihypertensive treatment for at least 1 month before were included. The experimental procedure consisted of the administration of an infusion prepared with 10 g of dry calyx from H. sabdariffa on 0.51 water (9.6 mg anthocyanins content), daily before breakfast, or captopril 25 mg twice a day, for 4 weeks. The outcome variables were tolerability, therapeutic effectiveness (diastolic reduction > or = 10 mm Hg) and, in the experimental group, urinary electrolytes modification. Ninety subjects were included, 15 withdrew from the study due to non-medical reasons; so, the analysis included 39 and 36 patients from the experimental and control group, respectively. The results showed that H. sabdariffa was able to decrease the systolic blood pressure (BP) from 139.05 to 123.73mm Hg (ANOVA p < 0.03) and the diastolic BP from 90.81 to 79.52mm Hg (ANOVA p < 0.06). At the end of the study, there were no significant differences between the BP detected in both treatment groups (ANOVA p > 0.25). The rates of therapeutic effectiveness were 0.7895 and 0.8438 with H. sabdariffa and captopril, respectively (chi2, p > 0.560), whilst the tolerability was 100% for both treatments. A natriuretic effect was observed with the experimental treatment. The obtained data confirm that the H. sabdariffa extract, standardized on 9.6mg of total anthocyanins, and captopril 50 mg/day, did not show significant differences relative to hypotensive effect, antihypertensive effectiveness, and tolerability.

Clinical trial of Cecropia obtusifolia and Marrubium vulgare leaf extracts on blood glucose and serum lipids in type 2 diabetics.

Cecropia obtusifolia and Marrubium vulgare have been widely used in Mexican traditional medicine for the control of type 2 diabetes. In order to evaluate the clinical effect produced by the aqueous extract from these species on type 2 non-controlled diabetes mellitus, a total of 43 outpatients were included. Based on the European NIDDM (policy group) criteria, only patients with poor response to the conventional treatment were selected. All patients maintained their medical treatment and also received a prepared infusion of the dry leaves of the plant treatment for 21 days. In a double-blind manner, the patients were randomly grouped as follows: 22 patients were treated with C. obtusifolia and 21 with M. vulgare. The fasting blood glucose values were reduced by 15.25% on patients treated with C. obtusifolia, while cholesterol and triglycerides were decreased by 14.62% and 42.0%, respectively (ANOVA p< 0.02). In the case of patients treated with M. vulgare, the plasma glucose level was reduced by 0.64% and cholesterol and triglycerides by 4.16% and 5.78%, respectively. When the results were compared between groups, significant differences in glucose and cholesterol diminution were found. The obtained results showed that the infusion prepared with the leaves of C. obtusifolia (containing 2.99+/-0.14mg of chlorogenic acid/g of dried plant) produced beneficial effects on carbohydrate and lipid metabolisms when it was administered as an adjunct on patients with type 2 diabetes with poor response to conventional medical treatment.

Galphimine B modulates synaptic transmission on dopaminergic ventral tegmental area neurons.

Galphimine B (GB) is a bioactive compound isolated from the plant Galphimia glauca Cav. (Malpighiaceae) and has been shown to have central nervous system depressant properties. In an earlier study, it was reported that both systemic and local administration of GB modified the extracellular spontaneous spiking activity in the ventral tegmental area (VTA) neurons. In the present study we analyzed the synaptic effects of this compound on dopaminergic neurons. Recordings were made in brain slices using intracellular and patch-clamp techniques, in dopaminergic (DA) VTA neurons. Spontaneous miniature excitatory postsynaptic currents (mEPSCs), excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic potentials (IPSPs) were recorded in control situation and after bath infusions of several concentrations of GB (1 microM-5 mM), GABA (1 nM-100 microM) and the GABA A blockers, picrotoxin (100 microM) and bicuculline (10 microM), and GABA B blocker saclofen (200 microM). GB administration reduced the frequency (p < 0.05) but not the amplitude of mESPCs. However, GABA (IC 50 = 645 nM) and GB (IC 50 = 174.5 microM) infusion significantly reduced the amplitude of stimuli induced EPSCs, Bicuculline (10 microM) co-administration only reduced GABA effects and did not modify the GB depressant action. Finally, isolated GABAergic IPSPs were modified by the addition of picrotoxin, but GB had no effect on these evoked synaptic responses. The present results indicate that GB modifies synaptic activity on dopaminergic VTA neurons by a non-GABAergic mechanism.

Polysomnographic evaluation of the hypnotic effect of Valeriana edulis standardized extract in patients suffering from insomnia.

Valeriana edulis ssp. procera, commonly known as "valeriana mexicana", is widely used in Mexican traditional medicine for the treatment of insomnia and anxiety. To evaluate the hypnotic effect and safety of 450 mg of Valeriana edulis standardized hydroalcoholic extract in patients with insomnia, a double-blind, cross-over, controlled study was carried out. Valeriana officinalis extract, at the same doses, was used as a positive control. In a sleep laboratory, polysomnographic (PSG) recordings were performed for analyzing the quantity and architecture of sleep as well as evaluating morning sleepiness, memory quotient, and side effects. The experimental procedures were conducted on four consecutive nights of 8 h each. Twenty patients were admitted. Based on the PSG results, V. edulis reduced the number of awaking episodes while both treatments increased the rapid eye movement (REM) sleep; this last parameter was better improved by V. officinalis extract. Other PSG data did not achieve outstanding statistical differences, but the clinical tendency with both treatments was to increase the sleep efficiency index. These Valeriana extracts produced beneficial effects on sleep architecture because they diminished the time of stages 1 and 2 in non-REM sleep while they increased delta sleep. Validated clinical tests showed that both species reduced notoriously the morning sleepiness, that was further improved by V. officinalis extract, and did not affect anterograde memory. In only three cases were slight side effects observed, one due to the experimental extract. Chemical analysis of the hydroalcoholic extract of V. edulis indicated that this extract contains 0.26 % of dihydroisovaltrate as the main valepotriate, and that it does not contain valerenic acid. In general, the results support the hypnotic effect and safety of acute treatment of Valeriana edulis and Valeriana officinalis on patients suffering insomnia.

Galphimia glauca organic fraction antagonizes LTD(4)-induced contraction in guinea pig airways.

Galphimia glauca is used for the treatment of asthma and allergies in Latin American traditional medicine. The ethylacetate fraction from its aerial parts was assayed for bronchoconstriction induced by antigen and several agonists in guinea pig tracheae. The organic fraction significantly inhibited the contractile response to ovalbumin in tracheae from sensitized guinea pigs, and significantly and selectively inhibited the bronchoconstriction induced by leukotriene D(4) (LTD(4)). The relative potency of the ethylacetate fraction of G. glauca to produce a concentration-dependent rightward shift of LTD(4) concentration-response curve was similar to that reported for SK&F 104353, a well-known competitive LTD(4)-antagonist.

Antimicrobial evaluation of certain plants used in Mexican traditional medicine for the treatment of respiratory diseases.

Eighteen crude extracts, including six hexanic, six chloroformic and six methanolic from six different plant species used in Mexican traditional medicine for the treatment of respiratory infections, were evaluated for potential antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, and Candida albicans. The minimal inhibitory concentration was determined for each extract using a two-fold dilution assay. The results showed that 16 crude extracts (89%) exhibited antimicrobial activity against at least one of the microorganisms tested at concentrations of 5 mg/ml or below. The extracts from Gnaphalium oxyphyllum, Gnaphalium americanum, and Crescentia alata possessed strong antimicrobial activity against the pathogens tested.

Production of the sedative triterpene galphimine B in Galphimia glauca tissue culture.

A tissue culture method is described for callus formation from Galphimia glauca (Mapighiaceae) in MS (Murashige & Skoog) medium supplemented with various growth regulators. Best induction was achieved when using hypocotyls as explants in medium supplemented with 2 mg/l of 2,4-dichlorophenoxyacetic acid (2,4-D). Major cellular growth of calluses was obtained with naphthaleneacetic acid (2 mg/l) + kinetin (1 mg/l). Subcultivation of calluses using various concentrations of 2,4-D allowed the production of the sedative nor-seco-triterpenoid, galphimine B and a new related compound. The structure of the new constituent was elucidated as 6-acetoxygalphimine B. The highest accumulation of active constituent 1 (1.5 x 10(-2) dry weight) was achieved when 4 mg/l of the hormone were used, and this experimental condition allowed the detection of only galphimine B. A preliminary screening of the methanolic extracts prepared from calluses, using the isolated guinea-pig ileum as a general test system for pharmacological effects, demonstrated that the most active material was the one with the highest concentration of galphimine B. Total accumulation of this sedative triterpene, in the optimized tissue culture conditions, was in the same order of magnitude as the value quantified for wild plants (4.5 x 10(-2) dry weight).

Galphimine-B modifies electrical activity of ventral tegmental area neurons in rats.

Galphimine-B (G-B) is a bioactive compound isolated from the plant Galphimia glauca Cav. (Malpighiaceae) with central nervous system depressant properties previously described. In the present study, extracellular spiking activity records in either somatosensorial cortex or ventral tegmental area (VTA) neurons, were performed in rats after i.p. or local administration of G-B. None of the cortical neurons displayed significant changes induced by any of the applied doses. In VTA cells, two patterns of electrical discharge were recorded, bursting (57%) and nonbursting (43%) types. Systemic administration of G-B induced excitatory effects in neurons with a bursting firing pattern and mixed responses on nonbursting units. When this compound was applied locally by microiontophoresis, most of the bursting and nonbursting spiking neurons showed a firing depression and only a few of the nonbursting neurons showed an increment of discharge frequency. These results are important since VTA is a major dopaminergic center responsible for the innervation of the prefrontal cortex, nucleus accumbens and entorhinal region. These areas are targets for the action of antipsychotic drugs.

Evaluation of the calcium-antagonist, antidiarrhoeic and central nervous system activities of Baccharis serraefolia.

Baccharis serraefolia is a widely used plant to treat diarrhoea in Mexican traditional medicine. Although the methanolic extract of this plant has shown an important dose-dependent spasmolytic activity, its underlying mechanism has not been studied. In the present work, the methanolic extract of B. serraefolia significantly delayed the onset of tonic seizures induced by strychnine and pentylenetetrazol; besides, it diminished the death rate and number of animals that exhibited convulsions. It produced potentiation of the hypnotic effect of pentobarbital. Oral administration produced an inhibition of gastrointestinal transit in mice as effective as that produced by loperamide. As to the effect on smooth muscles, the active extract produced an inhibition of contraction induced electrically, which could not be reversed by naloxone. The calcium concentration-contraction curve showed a rightward displacement when the extract was added to isolated guinea pig ileum depolarized with high K+ and cumulative concentrations of Ca2+. The results suggest that the methanolic extract does not interact with classical opiate receptors and its effects, at least that produced on smooth muscle, may be due to a probable interference with calcium influx and/or calcium release from an intra-cellular store.

Spasmolytic activity of medicinal plants used to treat gastrointestinal and respiratory diseases in the Highland of Chiapas.

Methanolic extracts of 141 different botanical species, used in traditional medicine in the Highland of Chiapas for the treatment of gastrointestinal and respiratory diseases, were submitted to pharmacological testing in order to evaluate the spasmolytic action on electrically-stimulated guinea pig ileum. Of these species, 33.3% showed an inhibition of reflex greater than 80% at a bath concentration of 250 µg/ml. Of the active species, 40.4% belong to the Asteraceae family. Of the active samples, 59.5% were obtained from leaves. The results identify a group of interesting plants, that could be considered for future experimental investigation.

Calcium-antagonist effect of quercetin and its relation with the spasmolytic properties of Psidium guajava L.

The antidiarrheal properties of water and methanolic extracts of Psidium guajava leaves have been demonstrated with anteriority and their spasmolytic effect was attributed to quercetin, a flavonoid contained in this plant. The present paper reports the intestinal smooth muscle relaxation produced by quercetin on isolated guinea pig ileum previously contracted by a depolarizing KCl solution. Quercetin also inhibited intestinal contraction induced by different concentrations of calcium, shifting the contraction curve to the right showing a clear calcium-antagonistic effect. Quercetin effect on ileal and aortic smooth muscles are compared, the ileum being more sensitive to this flavonoid. The calcium-antagonist property of quercetin is discussed and also its contribution to explain the spasmolytic effect of this popular herbal remedy.