Fernando Calzada

Terpenoids isolated from Psidium guajava hexane extract with depressant activity on central nervous system

A bioguided fractionation of the hexane extract obtained from Psidium guajava leaves led to the isolation of sesquiterpenes with depressant activities on the central nervous system. The results demonstrated that the already reported relaxant properties of Psidium guajava hexane extract are largely due to the presence of terpenes, especially caryophyllene‐oxide and β‐selinene, which were by far the largest single components and potentiated pentobarbital sleeping time and the latency of convulsions induced by leptazol in mice. Calcium concentration‐response curves showed a rightward displacement when the active fraction was added to isolated guinea‐pig ileum depolarized with K+ (60 mm) and cumulative concentrations of CaCl2, suggesting that caryophyllene‐oxide, a known Ca2+ antagonist agent could be responsible for the blockade of extracellular Ca2+ observed with the active fraction.

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 300mg/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 10mg/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.

In vitro susceptibility of Entamoeba histolytica and Giardia lamblia to some medicinal plants used by the people of Southern Mexico

The antiprotozoal properties of six medicinal plants, used by the people of Southern Mexico to treat diarrhoea, were evaluated in vitroagainst Entamoeba histolyticaand Giardia lambliatrophozoites, the most active being the methanol extracts of Rubus coriifolius, Cuphea pinetorumand Helianthemum glomeratum. Further activity guided fractionation of Cuphea pinetorumroots extract led to the isolation of kaempferol and quercetin as the active principles.

Synthesis of 3-tetrazolylmethyl-4H-chromen-4-ones via Ugi-azide and biological evaluation against Entamoeba histolytica, Giardia lamblia and Trichomona vaginalis

The synthesis of novel 3-tetrazolylmethyl-4H-chromen-4-ones via an Ugi-azide multicomponent reaction and their biological evaluation against Entamoeba histolytica, Giardia lamblia and Trichomona vaginalis are described. Reported yields are moderate to good and biological results show that these compounds could be considered as candidates to anti-parasitic drugs, especially against G. lamblia.

Hydroxyclerodanes from Salvia shannoni

Six new hydroxyclerodanes (1-6), named sepulturins A-F, and four known diterpenes were isolated from the leaves of Salvia shannoni. The structures of these compounds were established by extensive analysis of their NMR and MS spectroscopic data. The relative configurations of compounds 1 and 2 were determined by NOESY experiments and were confirmed by single-crystal X-ray diffraction studies. All of the isolated diterpenes possess tertiary OH groups. The structure of infuscatin (7), a clerodane previously isolated from S. infuscata, was revised. Cytotoxic, antiprotozoal, and anti-inflammatory activities of these compounds were evaluated.

Antibacterial properties of Helianthemum glomeratum, a plant used in Maya traditional medicine to treat diarrhoea

Ethnobotanical studies indicate that Helianthemum glomeratum is a plant widely used in Maya communities to treat diarrhoeas. A possible mechanism to counteract infectious diarrhoea would be by inhibiting the growth of the enteropathogen causing the disease. The aim of this work was to study the antimicrobial activity of H. glomeratum against bacterial enteropathogens isolated from faeces of children with acute diarrhoea or dysentery. A methanol extract obtained from the leaves and stems was highly active against Shigella spp and Vibrio cholerae; activity against Salmonella spp and Escherichia coli isolates was also present. Acetone/water extract from the roots was also highly active against Shigella and Vibrio isolates. Further chemical fractionation indicated that antibacterial activity was associated with the polyphenolic fraction. Shigella spp causes severe dysentery in children and Vibrio cholerae causes severe watery diarrhoea. Antidiarrhoeal activity of H. glomeratum may be due, at least in part, to the antimicrobial activity of polyphenolics against bacterial enteropathogens commonly associated with the disease.

Structure, absolute configuration, and antidiarrheal activity of a thymol derivative from Ageratina cylindrica.

The leaves of Ageratina cylindrica afforded a thymol derivative that was characterized by physical and spectroscopical methods as (8S)-8,9-epoxy-6-hydroxy-l0-benzoyloxy-7-oxothymol isobutyrate (1). The absolute configuration of 1 was established as 8S by vibrational circular dichroism spectroscopy in combination with density functional theory calculations and by evaluation of the Flack and Hooft X-ray parameters. Compound 1 showed weak antiprotozoal activity against Entamoeba histolytica and Giardia lamblia trophozoites and a high inhibitory effect on hyperpropulsive movement of the small intestine in rats.

Anti-diarrheal activity of (–)-Epicatechin from Chiranthodendron pentadactylon Larreat: Experimental and computational studies

Ethnopharmacological relevance: Chiranthodendron pentadactylon Larreat is frequently used in Mexican traditional medicine as well as in Guatemalan for several medicinal purposes, including their use in the control of diarrhea. Aim of the study: This work was undertaken to obtain additional information that support the traditional use of Chiranthodendron pentadactylon Larreat, on pharmacological basis using the major antisecretory isolated compound from computational, in vitro and in vivo experiments. Materials and methods: ( )-Epicatechin was isolated from ethyl acetate fraction of the plant crude extract. In vivo toxin (Vibrio cholera or Escherichia coli)-induced intestinal secretion in rat jejunal loops models and sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) analysis on Vibrio cholera toxin were used in experimental studies while the molecular docking technique was used to conduct computational study. Results: The antisecretory activity of epicatechin was tested against Vibrio cholera and Escherichia coli toxins at oral dose 10 mg/kg in the rat model. It exhibited the most potent activity on Vibrio cholera toxin (56.9% of inhibition). In the case of Escherichia coli toxin its effect was moderate (24.1% of inhibition). SDS–PAGE analysis revealed that both ( )-epicatechin and Chiranthodendron pentadactylon extract interacted with the Vibrio cholera toxin at concentration from 80 mg/mL and 300 mg/mL, respectively. Computational molecular docking showed that epicatechin interacted with four amino acid residues (Asn 103, Phe 31, Phe 223 and The 78) in the catalytic site of Vibrio cholera toxin, revealing its potential binding mode at molecular level. Conclusion: The results derived from computational, in vitro and in vivo experiments on Vibrio cholera and Escherichia coli toxins confirm the potential of epicatechin as a new antisecretory compound and give additional scientific support to anecdotal use of Chiranthodendron pentadactylon Larreat in Mexican traditional medicine to treat gastrointestinal disorders such as diarrhea. & 2012 Elsevier Ireland Ltd. All rights reserved.ETHNOPHARMACOLOGICAL RELEVANCE Chiranthodendron pentadactylon Larreat is frequently used in Mexican traditional medicine as well as in Guatemalan for several medicinal purposes, including their use in the control of diarrhea. AIM OF THE STUDY This work was undertaken to obtain additional information that support the traditional use of Chiranthodendron pentadactylon Larreat, on pharmacological basis using the major antisecretory isolated compound from computational, in vitro and in vivo experiments. MATERIALS AND METHODS (-)-Epicatechin was isolated from ethyl acetate fraction of the plant crude extract. In vivo toxin (Vibrio cholera or Escherichia coli)-induced intestinal secretion in rat jejunal loops models and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis on Vibrio cholera toxin were used in experimental studies while the molecular docking technique was used to conduct computational study. RESULTS The antisecretory activity of epicatechin was tested against Vibrio cholera and Escherichia coli toxins at oral dose 10 mg/kg in the rat model. It exhibited the most potent activity on Vibrio cholera toxin (56.9% of inhibition). In the case of Escherichia coli toxin its effect was moderate (24.1% of inhibition). SDS-PAGE analysis revealed that both (-)-epicatechin and Chiranthodendron pentadactylon extract interacted with the Vibrio cholera toxin at concentration from 80 μg/mL and 300 μg/mL, respectively. Computational molecular docking showed that epicatechin interacted with four amino acid residues (Asn 103, Phe 31, Phe 223 and The 78) in the catalytic site of Vibrio cholera toxin, revealing its potential binding mode at molecular level. CONCLUSION The results derived from computational, in vitro and in vivo experiments on Vibrio cholera and Escherichia coli toxins confirm the potential of epicatechin as a new antisecretory compound and give additional scientific support to anecdotal use of Chiranthodendron pentadactylon Larreat in Mexican traditional medicine to treat gastrointestinal disorders such as diarrhea.

Evaluation of the antiprotozoal activity of neo-clerodane type diterpenes from Salvia polystachya against Entamoeba histolytica and Giardia lamblia.

Chia (Salvia polystachya Ort., Lamiaceae) is frequently used in Mexican traditional medicine to treat dysentery. In this study the main neo‐clerodane diterpenes (polystachynes A, B and D, as well as linearolactone) were isolated from the aerial parts of chia, and their antiprotozoal activities toward Entamoeba histolytica and Giardia lamblia trophozoites were evaluated in vitro. Linearolactone was the most potent antiamoebic and antigiardial compound with IC50 values of 22.9 μM for E. histolytica and 28.2 μM for G. lamblia. Polystachynes A, B and D, showed moderate antiprotozoal activity against both protozoans with IC50 values ranging from 117.0 to 160.6 μM for E. histolytica and from 107.5 to 134.7 μM for G. lamblia. These data suggest that linearolactone may play an important role in the antidiarrhoeal activity of S. polystachya. Copyright

Antisecretory activity from the flowers of Chiranthodendron pentadactylon and its flavonoids on intestinal fluid accumulation induced by Vibrio cholerae toxin in rats

ETHNOPHARMACOLOGICAL RELEVANCE The flowers of Chiranthodendron pentadactylon Larreat. (Sterculiaceae) has been traditionally used as folk medicine in Mexico for the treatment of gastrointestinal disorders such as diarrhea and dysentery. AIM OF THE STUDY This study aimed to assess the antisecretory activity which supports the therapeutic use of Chiranthodendron pentadactylon and its flavonoids to treat diarrhea. MATERIALS AND METHODS The methanol extract of Chiranthodendron pentadactylon, subsequent fractions, and flavonoids were evaluated on cholera toxin-induced intestinal secretion in rat jejunal loops model. RESULTS Three antisecretory flavonoids were isolated by bioassay-guided purification, namely, isoquercitrin 3, (+)-catechin 4 and (-)-epicatechin 5. Among them, epicatechin exhibited the most potent antisecretory activity with ID(50) of 8.3 microM/kg. Its potency was close that of to loperamide (ID(50) 6.1 microM/kg), drug used as control. Isoquercitrin (ID(50) 19.2 microM/kg) and catechin (ID(50) 51.7 microM/kg) showed moderate and weak activity, respectively. CONCLUSION The results of the present study lend some support to the anecdotal report for the traditional use of the flowers of Chiranthodendron pentadactylon in the control of dysentery.