Mexican Medicinal Plants Research Articles

Mexican medicinal plants as source for new antiprotozoal agents

Amoebiasis caused by Entamoeba histolytica is associated with high morbidity and mortality becoming a major public health problem, especially in developing countries. Because of the side-effects and the resistance that pathogenic protozoa build against the antiparasitic drugs, e.g. metronidazole, much recent attention has been paid to plants used in traditional medicine around the world in order to find new antiprotozoal agents. We collected 32 Mexican medicinal plants and the methanolic extracts of these species were screened for antiprotozoal activity against E. histolytica tropohzoites using in vitro tests. Each extract was dissolved in DMSO (150 µg/mL) and a 50 µl subsample was adjusted with 950µL of E. histolytica at logarithmic phase suspension in peptone, pancreas and liver extract medium containing 10% of bovine serum. Vials were incubated for 72h. After this time, the number of dead trophozoites per milliliter was determined by using a hematocytometer and inhibition percentage was estimated. Only 15 plant extracts showed more than 50% inhibition against E. histolytica and IC50 of these extracts were determined. We are presenting the results of this biological evaluation as well as the preliminary findings of the bioactivity guided isolation of natural products from Lippia graveolens Kunth and Ruta chalepensis Pers that showed the more significant antiprotozoal activity (91.50 and 90.50% growth inhibition with an IC50 of 59.14 and 60.07µg/ml, respectively).

Antimicrobial and Cytotoxic Effects of Mexican Medicinal Plants

The antimicrobial effects of the Mexican medicinal plants Guazuma ulmifolia, Justicia spicigera, Opuntia joconostle, O. leucotricha, Parkinsonia aculeata, Phoradendron longifolium, P. serotinum, Psittacanthus calyculatus, Tecoma stans and Teucrium cubense were tested against several human multi-drug resistant pathogens, including three Gram (+) and five Gram (-) bacterial species and three fungal species using the disk-diffusion assay. The cytotoxicity of plant extracts on human cancer cell lines and human normal non-cancerous cells was also evaluated using the MTT assay. Phoradendron longifolium, Teucrium cubense, Opuntia joconostle, Tecoma stans and Guazuma ulmifolia showed potent antimicrobial effects against at least one multidrug-resistant microorganism (inhibition zone > 15 mm). Only Justicia spicigera and Phoradendron serotinum extracts exerted active cytotoxic effects on human breast cancer cells (IC50 < or = 30 microg/mL). The results showed that Guazuma ulmifolia produced potent antimicrobial effects against Candida albicans and Acinetobacter lwoffii, whereas Justicia spicigera and Phoradendron serotinum exerted the highest toxic effects on MCF-7 and HeLa, respectively, which are human cancer cell lines. These three plant species may be important sources of antimicrobial and cytotoxic agents.

Antimicrobial, anti-inflammatory, antiparasitic, and cytotoxic activities of Galium mexicanum

To study the potential benefit of the traditional Mexican medicinal plant Galium mexicanum Kunth (Rubiaceae). Hexane, chloroform, and methanol extracts as well as various fractions from these extracts were tested to determine antibacterial, antifungal, antiparasitic or anti-inflammatory activities in vitro. Aerial parts of the plant were extracted with various solvents and fractionated accordingly. Their antibacterial and antifungal activities were assessed on nine bacterial and four fungal strains. Leishmania donovani was used as a protozoan strain for antiparasitic activity. The anti-inflammatory activity of the compounds was investigated by measuring the secretion of interleukin-6 when macrophages were exposed to lipopolysaccharide. Various extracts and fractions obtained from this plant exhibit antibacterial, antifungal, antiparasitic, and anti-inflammatory activities. Of special interest was the hexane fraction HE 14 b, which show antibacterial (ranging between 67 and 666 μg/ml) and antifungal (at concentrations of 333 μg/ml) activities. Also the hexane fraction HE 5 exhibited antiparasitic activity (at concentrations of 260 μg/ml), whereas the methanol fraction ME 13-15 showed a potent anti-inflammatory activity when compared to dexamethasone. Chemical analyses of the chloroform extract show the presence of triterpenes, saponins, flavonoids, sesquiterpene lactones, and glucosides, but no tannins were detected in the assayed extract. The benefit of Galium mexicanum as a traditional medicinal plant was confirmed using antibacterial and antifungal assays in vitro. We also report for the first time, and to the best of our knowledge, antiparasitic and anti-inflammatory activities of this plant.

Inhibition of lipid peroxidation by sesquiterpenoid in Heterotheca inuloides.

A sesquiterpenoid, 7-hydroxy-3,4-dihydrocadalin, isolated from a Mexican medicinal plant Heterotheca inuloides was evaluated as an antioxidant. This sesquiterpenoid inhibited mitochondrial and microsomal lipid peroxidation induced by Fe(III)-ADP/NADH or Fe(III)-ADP/NADPH. Furthermore, 7-hydroxy-3,4-dihydrocadalin protected red cells against oxidative haemolysis. This sesquiterpene was thus shown to be effective in protecting biological systems against oxidative stresses.

Chemical Composition and Antimicrobial and Spasmolytic Properties of Poliomintha longiflora and Lippia graveolens Essential Oils**

In the present study, we reported a comparative analysis of the chemical composition and pharmacological properties of the essential oils obtained from 2 Mexican oreganos, Poliomintha longiflora and Lippia graveolens. The gas chromatography-mass spectrometry (GC-MS) profiles of the oils showed high amounts of oxygenated monoterpenes, mainly carvacrol (%[mg/100 g dry matter]) (18.36 [459.0] in P. longiflora and 13.48 [164.7] in L. graveolens). In addition, these oils contained marked quantities of p-cymene (14.09 [352.2] and 7.46 [37.3], respectively), β-caryophyllene oxide, β-caryophyllene, and carvacrol acetate. Headspace analyses of the leaves of both species using different coated fibers revealed that γ-terpinene, eucalyptol, and p-cymene were the principal light volatile components. Chromatographic fingerprints and a suitable analytical method for quantifying the main components of both essences were established using high-performance liquid chromatography (HPLC) as analytical tool. The essential oils of both species were not toxic in the acute toxicity studies in mice performed according to the Lorke procedure (DL(50) > 5000 mg/kg). The oils and the major constituents, carvacrol and p-cymene, displayed a moderate in vitro antibacterial activity, with minimum inhibitory concentration values ranging from 128 to 512 μg/mL. In addition, these samples demonstrated a marginal antispasmodic activity in vivo and provoked a concentration-dependent inhibition of the carbachol- and histamine-induced contractions using the isolated guinea-pig ileum preparation. In particular, p-cymene exerts good selective inhibitory activity on the carbachol-induced contractions (IC(50) = 9.85 μg/mL). The analytical methods using GC-MS and HPLC techniques will be useful for establishing quality control as well as preclinical pharmacological and toxicological parameters of the crude drug P. longiflora, which is widely used as substitute of L. graveolens for medicinal and flavorings purposes. This overall information will be also useful for elaborating scientific and pharmacopoeic monographs of this very Mexican medicinal plant.

Mexican medicinal plants used for cancer treatment: Pharmacological, phytochemical and ethnobotanical studies

This review provides a summary of Mexican medicinal flora in terms of ethnobotanical, pharmacology, and chemistry of natural products related to anticancer activity. Bibliographic investigation was carried out by analyzing recognized books and peer-reviewed papers, consulting worldwide accepted scientific databases from the last five decades. Mexican plants with attributed anti-cancer properties were classified into six groups: (a) plant extracts that have been evaluated for cytotoxic effects, (b) plant extracts that have documented anti-tumoral effects, (c) plants with active compounds tested on cancer cell lines, (d) plants with novel active compounds found only in Mexican species, (e) plants with active compounds that have been assayed on animal models and (f) plants with anti-cancer ethnopharmacological references but without scientific studies. Three hundred plant species belonging to 90 botanical families used for cancer treatment have been recorded, of which only 181 have been experimentally analyzed. The remaining 119 plant species are in use in empirical treatment of diseases consistent with cancer symptomatology. Only 88 of the plant extracts experimentally studied in in vitro cellular models have demonstrated active cytotoxic effects in at least one cancer cell line, and 14 out of the 88 have also been tested in vivo with the results that one of them demonstrated anti-neoplasic effects. A total of 187 compounds, belonging to 19 types of plant secondary metabolites, have been isolated from 51 plant extracts with active cytotoxic effects, but only 77 of these compounds (41%) have demonstrated cytoxicity. Seventeen of these active principles have not been reported in other plant species. However, only 5 compounds have been evaluated in vivo, and 3 of them could be considered as active. Clearly, this review indicates that it is time to increase the number of experimental studies and to begin to conduct clinical trials with those Mexican plants and its active compounds selected by in vitro and in vivo activities. Also, the mechanisms of action by which plant extracts and their active compounds exert anti-cancer effects remain to be studied.

Antimycobacterial agents from selected Mexican medicinal plants

As part of the ICBG program Bioactive Agents from Dryland Biodiversity of Latin America, the present investigation was undertaken to explore the possible antimycobacterial potential of compounds derived from selected Mexican medicinal plants. Bioassay-guided fractionation of the crude extracts of Rumex hymenosepalus (Polygonaceae), Larrea divaricata (Zygophyllaceae), Phoradendron robinsonii (Loranthaceae) and Amphipteryngium adstringens (Julianiaceae) led to the isolation of several antimycobacterial compounds. Four stilbenoids, two flavan-3-ols and three anthraquinones were isolated from R. hymenosepalus. Two flavonols and nordihydroguaiaretic acid were obtained from L. divaricata. Sakuranetin was the antimycobacterial agent isolated from P. robinsonii. Two known triterpenoids and the novel natural product 3-dodecyl-1,8-dihydroxy-2-naphthoic acid were obtained from A. adstringens. In general, the isolates were identified by spectral means. The antimycobacterial activity of the secondary compounds isolated from the analysed species, as well as that of nine pure compounds previously isolated in our laboratories, was investigated; the MIC values ranged from 16 to 128 microg mL-1. Among the tested compounds, the glycolipids, sesquiterpenoids and triterpenoids showed the best antimycobacterial activity. The antimycobacterial property of the glycolipids is reported for the first time. Although the tested compounds showed moderate antimycobacterial activity, their presence in the analysed species provides the rationale for their traditional use in the treatment of tuberculosis.

Antibacterial and Antifungal Activities of Some Mexican Medicinal Plants

In Mexico about 4,000 plant species have some medicinal use. The aim of this work was to evaluate the antimicrobial activity of six Mexican medicinal plants against fungi and Gram-positive and Gram-negative bacteria. Methanolic extracts were prepared from the Mexican medicinal plants Amphypteringium adstrigens, Castella tortuosa, Coutarea latiflora, Ibervillea sonorae, Jatropha cuneata, and Selaginella lepidophylla. The antibacterial and antifungal activities of the plants were determined by the broth microdilution method and the radial growth inhibition assay, respectively. All Mexican plants tested showed antimicrobial activity. Among the six plant extracts analyzed, J. cuneata showed the highest growth-inhibitory activity against fungi, Gram-positive and Gram-negative bacteria (J. cuneata > A. adstrigens > C. latiflora > C. tortuosa > I. sonorae approximately S. lepidophylla). Shigella flexneri and Staphylococcus aureus were the most susceptible bacteria to plant extracts. Complete inhibition of S. flexneri growth was observed with J. cuneata methanolic extract at 90 microg/mL. This plant extract also showed the strongest antifungal activity against Fusarium verticillioides and Aspergillus niger. Our data suggest that the medicinal plants tested have important antimicrobial properties. This is the first report describing the antimicrobial activities of several of the Mexican medicinal plants used in this study.

Hydroxylation of the diterpenes ent-kaur-16-en-19-oic and ent-beyer-15-en-19-oic acids by the fungus Aspergillus niger

The diterpenes ent-kaur-16-en-19-oic acid ( 1) and ent-beyer-15-en-19-oic acid ( 2) are the major constituents of a spasmolytic diterpenic mixture obtained from the roots of Viguiera hypargyrea, a Mexican medicinal plant. Microbial transformation of 1 and 2 was performed with Aspergillus niger. Two metabolites, ent-7α,11β-dihydroxy-kaur-16-en-19-oic acid ( 4) and ent-1β,7α-dihydroxy-kaur-16-en-19-oic acid ( 5), were isolated from the incubation of 1, and one metabolite, ent-1β,7α-dihydroxy-beyer-15-en-19-oic acid ( 6), was isolated in high yield (40%) from 2. The structures were elucidated on the basis of spectroscopic analyses and confirmed by X-ray crystallographic studies. Compounds 1– 4 and 6 and methyl ester derivatives 4a and 6a were evaluated for their ability to inhibit the electrically induced contraction of guinea-pig ileum. Compounds 1, 3, 4, 4a and 5 were significantly active. These results showed that dihydroxylation of 1 at 7β, 11α-, and 1α, 7β-positions resulted in a loss of potency.

In vitro propagation of two antidiabetic species known as guarumbo: Cecropia obtusifolia and Cecropia peltata

Two Cecropia species (Cecropia obtusifolia and C. peltata), known as guarumbo, are employed in Mexican traditional medicine to treat diabetes mellitus; the leaves of both species contain phenolic bioactive compounds such as chlorogenic acid (CA) and isoorientine (ISO), which have been attributed with hypoglycemic, hypolipidemic, and antioxidant properties. An in vitro propagation protocol was developed from existing apical bud meristem from C. obtusifolia seedlings; the shoot generation was induced on Murashige and Skoog (MS) medium supplemented with varying concentrations of 6-benzylaminopurine and kinetin (Kn) combined with either α-naphtalene acetic acid (NAA) or indole-3-acetic acid (IAA) auxins. Best morphogenetic response was developed with Kn 26.64 μM combined with either NAA or IAA 0.57 μM, respectively; likewise, C. peltata-seedling apical buds were subjected to these best selected treatments. Cecropia obtusifolia and C. peltata shoots were rooted in growth regulator-free half-strength MS medium, and regenerated whole plants were adapted successfully under greenhouse conditions and field. Leaves from both Cecropia-micropropagated plants produced the phenolic compounds CA and ISO, with highest concentrations in leaves from 18-month C. obtusifolia (12.28 ± 7.06 mg g−1 dry leaves of CA and 8.30 ± 2.70 mg g−1 dry leaves of ISO) growth in the field. Our results offer a protocol of apical-bud use for multiplication and curative-property conservation of the two previously mentioned important Mexican medicinal plants.

Hypoglycemic Activity of Extracts and Compounds from the Leaves of Hintonia standleyana and H. latiflora: Potential Alternatives to the Use of the Stem Bark of These Species,

The CH(2)Cl(2)-MeOH (1:1) extract of the leaves of Hintonia standleyana and H. latiflora caused significant decrease in blood glucose levels in both normal and streptozotozin (STZ)-induced diabetic rats when compared with vehicle-treated groups (p < 0.05). These extracts were not toxic to mice according to the Lorke criteria. From the hypoglycemic extract of H. standleyana, two new 4-phenylcoumarins, namely, 6''-O-acetyl-5-O-beta-d-galactopyranosyl-7,4'-dihydroxy-4-phenylcoumarin (1) and 6''-O-acetyl-5-O-beta-d-galactopyranosyl-7,3',4'-trihydroxy-4-phenylcoumarin (2), were obtained. The analogous extract of H. latiflora yielded the new 5-O-[beta-d-xylopyranosyl-(1-->6)-beta-d-glucopyranosyl]-7,4'-dimethoxy-4-phenylcoumarin (3) along with several known compounds, including ursolic acid and desoxycordifolinic acid. Phenylcoumarins 1 and 2 showed hypoglycemic activity. HPLC profiles of the leaf extracts of both plants revealed the presence of known hypoglycemic phenylcoumarins as well as chlorogenic acid. The overall results have indicated that the leaves of H. standleyana and H. latiflora possess similar antidiabetic potential to their stem bark. Therefore, the leaves from these species could represent an alternative to the use of their stem bark, which, in turn, would contribute to the conservation of these Mexican medicinal plants.

Antifungal Properties of Some Mexican Medicinal Plants

The antifungal properties of some extracts from Artemisia ludoviciana Nutt., Heliopsis longipes 'A. Gray' Blake., Satureja macrostema Benth. and Tagetes lucida Cav. were analyzed, using the agar disc diffusion method. After 72 h incubation, the plant extracts inhibited the growth of fungi, but the ethyl acetate and methanol-chloroform extracts from A. ludoviciana, H. longipes and T. lucida inhibited all the fungi assayed: Candida albicans, Colletotrichum linde- muthianum, Mucor circinelloides, Saccharomyces cerevisiae, and Sporothrix schenckii. The spore germination inhibition assay suggested that methanol-chloroform extract from A. ludoviciana was the most active against the fungi tested. The methanol-chloroform and ethyl acetate extracts from A. ludoviciana and T. lucida had pronounced antifungal activity against fungi tested. Compounds found in the leaves methanol-chloroform extracts from A. ludoviciana were analyzed by using GC/MS; the major compounds were: 1-8-cineole, camphor, borneol, cis-verbenol, myrtenol, eugenol, cariophyllene, � -farnesene, spathulenol, derivatives of caryophyllene and derivatives of spathulenol.

Antioxidant activity of some Mexican medicinal plants extracts

Phytochemicals are extensively found at different levels in many medicinal plants. This work had two objectives: the first, to evaluate the total phenolic and flavonoid contents of four Mexican medicinal plants (Penstemon barbatus, Pedicularis mexicana, Castilleja tenuiflora and Bacopa monnierii) and second, to determine whether these compounds have an antioxidant capacity towards free radical propagation. The polyphenolic extractions of the dried powdered samples have been performed using methanol. The total phenolic content, analyzed using Folin-Ciocalteu reagent, of the samples varied from 20.7 to 187.8mg/g dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 4.56 to 10.1mg catechin equivalents (CE)/g dry weight. To analyze the antioxidant activity, common stable radicals chromogens, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS(.+)) and DPPH (1,1-Diphenyl-2-picrylhydrazyl) were used. The antioxidant activity measurement, expressed as Trolox equivalent antioxidant capacity (TEAC), ranged from 306.7 to 927.7 mmol Trolox equivalents. P. barbatus and B. monnieri showed the highest antioxidant activities, while C. tenuiflora and P. mexicana the lowest activities. These results suggest that the level of antioxidant activity in these plants varies to a great extent. They also suggest that phenolics in these plants provide substantial antioxidant activity. Upon achievement of this survey, and using more samples, an extra benefit of these medicinal plants may be found. Flora of Mexico appears to be a rich and interesting source for supplementary ethnomedicinal and phytochemical studies. Acknowledgements: This study was financed by grants from CONACyT (Convenio SEP-2003-CO2–43440/280). Bazaldua G. S., and Goytia P. S acknowledge scholarship from CONACyT.

Aqueous crude extract of Rhoeo discolor, a Mexican medicinal plant, decreases the formation of liver preneoplastic foci in rats

There are many plants in Mexico with medicinal properties, some of them used in alternative medicine to treat cancer, such is the case of Rhoeo discolor L. Hér Hance ( Commelinaceae family); however, there are not scientific reports that validate their antitumoral property. The present study shows the protective effects of the Rhoeo discolor aqueous crude extract (ACE) against rat liver cancer using the resistant-hepatocyte model. The carcinogenesis protocol consisted on the initiation with N-diethylnitrosamine, followed by the promotion with 2-acetylaminofluorene and a partial hepatectomy. After 24 days, the γ-glutamyl transpeptidase positive, corresponding to altered hepatocytes foci (AHF), were quantified. Additionally to discard a possible carcinogenic effect of ACE, it was first tested as promoting agent instead 2-acetylaminofluorene, and second, ACE was administered as initiator and promoter instead of the whole carcinogenic treatment. In summary, firstly, ACE administration reduced the number and area of preneoplastic lesions with dose below 20 mg/kg body weight and secondly, ACE administration neither presented a promoting or initiator effects nor induced the development of AHF. Results of this investigation justify continuing with further studies of Rhoeo discolor components to develop chemoprevention strategies as an option in the treatment of cancer.

Two decades of Mexican ethnobotany and research in plant drugs.

A renewed interest in the systematic study of indigenous medicines and associated medicinal plants arose in the 1970s. In Mexico the government established a national pharmaceutical industry to make use of the valuable colonial heritage of traditional practices combined with European medical concepts and resources. In 1975 the Mexican Institute for the Study of Medical Plants was created to integrate botanical, chemical and pharmacological studies on the Mexican flora. It compiled a database on ethnobotanical information relating to Mexican medicinal plants from the medical literature of the 16th to 19th centuries. A second database contained information on medicinal plants in current use. A medicinal herbarium was established. Taxonomical studies led to classification of the 11,000 voucher specimens in the herbarium and cross-referencing of the information with other databanks. A core group of 1000 plants used in traditional medicine throughout Mexico for almost 400 years was identified. Most of these are used to treat common diseases or basic health problems, usually given orally as decoctions or infusions. 95% of the plants used traditionally are from wild species. Information was collected from almost 3000 small Indian communities over four years on three aspects of traditional medicine--the healer, the disease categories recognized and the therapeutic resources in use. Plants with reported medicinal activity were selected for laboratory screening according to the frequency and commonality of their use, geographical distribution and seasonal availability. Screening involves a collaboration between chemists and pharmacologists: plant extracts are sequentially assayed and fractionated until the pure compound is isolated. Several active compounds are usually obtained from the same extract, frequently from the aqueous fractions. Ethnomedical information influences which plants are selected for screening and the type of assay used.

QSAR Study on the Relaxant Agents from Some Mexican Medicinal Plants and Synthetic Related Organic Compounds

Quantitative Structure-Activity Relationship studies were performed to describe and predict the antispasmodic activity of some molecules isolated from Mexican Medicinal Flora as well as for some synthetic ones based on stilbenoid bioisosteres. The relaxant activity of these molecules was taken from experiments on rat and guinea-pig ileum tissues. Given that there is some evidence of species-specific on the relaxant effects, two data sets were proposed, one for rat ileum and the other for guinea-pig ileum. These data were statistically treated in order to find a Quantitative Structure-Activity Relationship model that could describe the corresponding biological models. The goodness of prediction for the best models was measured in terms of the Leave-One-Out Cross-Validation R(2) (LOO q(2)) and the correlation coefficients of regressions through the origin (RTO R(2)0). Results show that papaverine activity could not be used as reference in rat ileum tests; however, this molecule can be used as a good reference molecule in guinea-pig ileum tests. Our study shows that MATS5p and R8m+ descriptors are the most important descriptors in predicting the rat ileum activity and that atomic polarizability is the main atomic property. On the other hand, the R3u GETAWAY descriptor turns out to be important in predicting the guinea-pig ileum activity where the influence/distance of substituents on these molecules could describe the observed activity.

Effect of Mexican medicinal plant used to treat trichomoniasis on Trichomonas vaginalis trophozoites

Crude methanolic extracts from 22 Mexican medicinal plants were screened for antitrichomonal activity against Trichomonas vaginalis, which is the etiological agent of trichomoniasis. Among the plants tested Carica papaya and Cocos nucifera showed the best antitrichomonal activity with IC 50 values of 5.6 and 5.8 μg/ml, respectively. The extracts of Bocconia frutescens, Geranium mexicanum, and Lygodium venustum showed moderate activity with IC 50 values ranging from 30.9 to 60.9 μg/ml. All the other plant extracts were inactive (IC 50 > 100 μg/ml). All extracts tested were less active than metronidazole (IC 50 0.037 μg/ml), an antiprotozoal drug used as positive control. The results of the antiprotozoal screening support the popular uses of five of the plants tested for the treatment of some urogenital tract disorders in Mexican traditional medicine. However, seeds of Carica papaya and aerial parts of Bocconia frutescens should be used in herbal medicine with care to avoid toxicity.

Acute toxicity and mutagenic activity of Mexican plants used in traditional medicine

The present work was undertaken to determine safety parameters of selected Mexican medicinal plants chosen on the basis of their frequency of medicinal use and commercial importance. The medicinal herbs included Amphipteryngium adstringens, Hintonia standleyana, Hintonia latiflora, Piper sanctum, Haemathoxylon brasiletto, Iostephane heterophylla, Valeriana procera, Arracacia tolucensis, Brickellia veronicaefolia, Scaphyglottis livida, Exostema caribaeum, Hippocratea excelsa, Ligusticum porteri, Poliomintha longiflora and Gnaphalium sp. In the acute toxicity studies in mice performed according to the Lorke procedure, Exostema caribaeum, Hippocratea excelsa, Ligusticum porteri and Poliomintha longiflora were the most toxic with LD 50 values between 1085 and 2 mg/kg. The Ames test revealed that Gnaphalium sp. and Valeriana procera extracts induced mutations of S. typhimurium TA98 with or without the S9 microsomal fraction, and TA100 in the presence of the enzymatic fraction, respectively. The tincture of Valeriana procera, however, was non-mutagenic. Finally, in the Artemia salina lethality test Brickellia veronicaefolia, Arracacia tolucensis, Poliomintha longiflora and Piper sanctum caused significant mortality of the crustacean larvae with LC 50 in the range of 37–227 μg/mL.

Hypoglycemic, vasorelaxant and hepatoprotective effects of Cochlospermum vitifolium (Willd.) Sprengel: A potential agent for the treatment of metabolic syndrome

Cochlospermum vitifolium (Willd.) Sprengel is a Mexican medicinal plant that is used in the folk medicine for the treatment of hypertension, diabetes, hepatitis and related diseases. The purpose of the present study was to assess the pharmacological properties of different extracts from Cochlospermum vitifolium bark as potential agent for the treatment of some factors related with metabolic syndrome (MS), a complex disease produced for several pathophysiological factors such as visceral fat obesity, insulin resistance, hypertension, dyslipidemia and liver steatosis. Hexane (HECv), dichloromethane (DECv) and methanol (MECv) extracts were subjected to some pharmacological assays to determine their vasorelaxant and hypoglycemic activity. On the other hand, MECv was also evaluated to determine its hepatoprotective effect on sub-chronic experimental assay. HECv showed a significant endothelium-independent relaxation on rat aorta rings (intact endothelium: IC 50 = 14.42 ± 5.90 μg/mL, E max = 92.71 ± 8.9%; denuded endothelium: IC 50 = 27.94 ± 4.0 μg/mL, E max = 78.68 ± 4.6%) and MECv produced an endothelium-dependent relaxation (IC 50 = 21.94 ± 6.87 μg/mL, E max = 79.12 ± 7.80%) on this tissue. Furthermore, HECv (at a dose of 120 mg/kg) also showed a significant decrease of blood glucose levels ( p < 0.05) on normoglycemic rats. Moreover, MECv (at a dose of 100 mg/kg) also was administered to bile duct-obstructed rats to determine its hepatoprotective activity, showing a statistically significant decrease of serum glutamic–pyruvic transaminase (PGT, 45%) and alkaline phosphatase (APh, 15%) ( p < 0.05). Finally, we obtained a crystalline polyphenolic compound from MECv by spontaneous precipitation. Those crystals were identified as (±)-naringenin by X-ray diffraction, NMR, IR and GC–MS techniques. Results suggest that Cochlospermum vitifolium could be used as a potential agent against MS since it shows hypoglycemic, vasorelaxant and hepatoprotective properties.

α-Glucosidase inhibitory activity of the methanolic extract from Tournefortia hartwegiana: An anti-hyperglycemic agent

Tournefortia hartwegiana is a Mexican medicinal plant that is used for the treatment of diabetes, diarrhea and kidney pain. In a previous investigation, the methanolic extract of Tournefortia hartwegiana (METh) showed significant hypoglycemic and anti-diabetic properties on normoglycemic and alloxanized rats. In this context, the purpose of the present study was to establish one of the possible modes of action of METh to induce anti-diabetic activity. METh (310 mg/kg) effect on α-glucosidase activity was investigated. METh intragastric administration was conducted to determine oral glucose tolerance test (OGTT), using different substrates: glucose, sucrose and maltose. The increase in plasma glucose level was significantly suppressed ( P < 0.05) by the extract after substrates administration. On the other hand, METh inhibited α-glucosidase activity in vitro, in a concentration-dependent manner (IC 50 of 3.16 mg/mL). These results suggest that METh might exert its anti-diabetic effect by suppressing carbohydrate absorption from intestine, and thereby reducing the post-prandial increase of blood glucose. On the other hand, the bio-guided fractionation of this extract led to the isolation of: β-sitosterol ( 1), stigmasterol ( 2), lupeol ( 3), ursolic acid ( 4), oleanolic acid ( 5), saccharose ( 6) and myo-inositol ( 7), using various chromatographic techniques.