Edelmira Linares

Anti-Helicobacter pylori activity of plants used in Mexican traditional medicine for gastrointestinal disorders.

AIM OF THE STUDY Helicobacter pylori is the major etiological agent of chronic active gastritis and peptic ulcer disease and is linked to gastric carcinoma. Treatment to eradicate the bacteria failed in many cases, mainly due to antibiotic resistance, hence the necessity of developing better therapeutic regimens. Mexico has an enormous unexplored potential of medicinal plants. This work evaluates the in vitro anti-H. pylori activity of 53 plants used in Mexican traditional medicine for gastrointestinal disorders. MATERIALS AND METHODS To test the in vitro antibacterial activity, agar dilution and broth dilution methods were used for aqueous and methanolic extracts, respectively. RESULTS Aqueous extracts of Artemisia ludoviciana subsp. mexicana, Cuphea aequipetala, Ludwigia repens,and Mentha x piperita (MIC 125 to <250 microg/ml) as well as methanolic extracts of Persea americana, Annona cherimola, Guaiacum coulteri, and Moussonia deppeana (MIC <7.5 to 15.6 microg/ml) showed the highest inhibitory effect. CONCLUSIONS The results contribute to understanding the mode of action of the studied medicinal plants and for detecting plants with high anti-Helicobacter pylori activity.

α-Glucosidase Inhibitors from Brickellia cavanillesii

An aqueous extract from the aerial parts of Brickellia cavanillesii attenuated postprandial hyperglycemia in diabetic mice during oral glucose and sucrose tolerance tests. Experimental type-II DM was achieved by treating mice with streptozotocin (100 mg/kg) and β-nicotinamide adenine dinucleotide (40 mg/kg). These pharmacological results demonstrated that B. cavanillesii is effective for controlling fasting and postprandial blood glucose levels in animal models. The same aqueous extract also showed potent inhibitory activity (IC(50) = 0.169 vs 1.12 mg/mL for acarbose) against yeast α-glucosidase. Bioassay-guided fractionation of the active extract using the α-glucosidase inhibitory assay led to the isolation of several compounds including two chromenes [6-acetyl-5-hydroxy-2,2-dimethyl-2H-chromene (1) and 6-hydroxyacetyl-5-hydroxy-2,2-dimethyl-2H-chromene (2)], two sesquiterpene lactones [caleins B (3) and C (4)], several flavonoids [acacetin (5), genkwanin (6), isorhamnetin (7), kaempferol (8), and quercetin (9)], and 3,5-di-O-caffeoylquinic acid (10). Chromene 2 is a new chemical entity. Compounds 2, 4, 7, and 9 inhibited the activity of yeast α-glucosidase with IC(50) 0.42, 0.28, 0.16, and 0.53 mM, respectively, vs 1.7 mM for acarbose. Kinetic analysis revealed that compounds 4 and 7 behaved as mixed-type inhibitors with K(i) values of 1.91 and 0.41 mM, respectively, while 2 was noncompetititive, with a K(i) of 0.13 mM. Docking analysis predicted that these compounds, except 2, bind to the enzyme at the catalytic site.

Phytotoxic compounds from Flourensia cernua

Bioassay-directed fractionation of a CH(2)Cl(2)-MeOH (1:1) extract of the aerial parts of Flourensia cernua led to the isolation of three phytotoxic compounds, namely, dehydroflourensic acid (1), flourensadiol (2) and methyl orsellinate (3). Dehydroflourensic acid is a new natural product whose structure was established by spectral means. In addition, the known flavonoid ermanin and seven hitherto unknown gamma-lactones were obtained, these being tetracosan-4-olide, pentacosan-4-olide, hexacosan-4-olide, heptacosan-4-olide, octacosan-4-olide, nonacosan-4-olide, and triacontan-4-olide. Compounds 1-3 caused significant inhibition of radicle growth of Amaranthus hypochondriacus and Echinochloa crus-galli, interacted with bovine-brain calmodulin and inhibited the activation of the calmodulin-dependent enzyme cAMP phosphodiesterase.

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

UNLABELLED 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). PRACTICAL APPLICATION 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.

Antimicrobial and cytotoxic activities of some crude drug extracts from Mexican medicinal plants

31 crude extracts derived from 28 plants highly valued as anti-infective agents in Mexican folk medicine have been screened for antimicrobial activity against four bacteria, a yeast and two molds. The results of the quantitative study indicated that the extracts derived from five species (Malmea depressa, Heliopsis longipes, Datura lanosa, Cnidosculus tehuacanensis and Helianthella quinquenervis) possessed significant antiseptic properties, therefore supporting the ethnomedical uses of these species. The cytotoxic activity was assayed against three cell lines HT-29 (Colon adenocarcinoma), MCF-7 (Breast carcinoma), A-549 (Lung carcinoma) and only the extract of Helianthella quinquenervis possessed significant activity against the MCF-7 cell line.

Biological Diversity of Medicinal Plants in México

Biological diversity can be described as the product of the richness or variety of entities (usually species) and the variance of that richness or its importance value.1 Diversity can be extended to include ecological and biogeographic heterogeneity, and various indices can be used to measure it.2 Biological diversity also can be appreciated by the number of endemic species whose distributions are restricted to a confined geographic area. In recent years, public attention has been given to diversity at the world level3 as well as in the Western Hemisphere4 and Mexico.5

Secondary metabolites from Hintonia latiflora

Abstract Two new glycosides and several known compounds were isolated fron the stem bark Hintonia latiflora . The new metabolites wre characterized by chemical and spectroscopic methods as 3- O -β- d -glucopyranosyl-23,24-dihydrocucurbitacin F and 5- O -β- d -galactopyranosyl-4′-hydroxy-7-methoxy-4-phenylcoumarin.

Antinociceptive effect of extracts and compounds from Hofmeisteria schaffneri

ETHNOPHARMACOLOGICAL RELEVANCE Hofmeisteria schaffneri (Asteraceae) is a medicinal plant widely commercialized in the most important Markets of Mexico City for the treatment of gastro-intestinal complaints and skin afflictions. AIM OF THE STUDY The main goals of this study were to establish the potential acute toxicity and the antinociceptive activity in animal models of several preparations and compounds from Hofmeisteria schaffneri. MATERIALS AND METHODS The aqueous and organic extracts as well as the essential oil of Hofmeisteria schaffneri were prepared by infusion, maceration and hydrodistillation, respectively. Investigation of the acute toxicity was accomplished by the Lorke method. The antinociceptive effect was assessed using the writhing and the hot plate tests. Natural compounds were isolated by standard phytochemical procedures. In addition, a few thymol esters were prepared by chemical synthesis. The stability of natural and synthetic esters was qualitatively analyzed by measuring their susceptibility to hydrolysis by pig liver estearase and mouse plasma at 37 degrees C. RESULTS The LD(50) for each preparation tested was higher than 5000 mg/kg revealing that they were not toxic to mice after exposure for short space of time. On the other hand, the extracts showed significant antinociceptive effect when tested in the hot plate model. The most active natural product as antinociceptive agent was hofmeisterin III (1) which also was the most stable in the stability study. Its pharmacological effect seems to be partially mediated by an opioid mechanism since naloxone inhibits its action. Using compound 1 as a lead molecule, several synthetic thymol esters were prepared and only compounds 13, 15 and 17 were antinoceptive at the dose of 1 mg/kg. CONCLUSIONS The present investigation provided evidence of the efficacy of several preparations of Hofmeisteria schaffneri as antinociceptive agents. The most active preparation was the essential oil which contained large amount of hofmeisterin III (1) and other thymol derivatives. Some novel synthetic analogs of hofmeisterin III with antinociceptive properties were discovered. The nature of the ester chain of these analogs did not have a clear impact on the antinociceptive activity. The phyto-preparations analyzed in this study were not toxic to mice according to the Lorkes test; therefore considering their long term use of the plant they might be secure for human consumption.

Spasmolytic potential of some plants used in Mexican traditional medicine for the treatment of gastrointestinal disorders

The present investigation describes the effect on the isolated rat ileum of methanolic extracts derived from Conyza filaginoides (D. C.) Hieron (Asteraceae), Croton fragilis HBK. (Euphorbiaceae), Dodonaea viscosa Jacq. (Sapindaceae), Gymnosperma glutinosum (Spreng) Less. (Asteraceae), Parthenium tomentosum DC. var. stramonium (Greene) Rollins (Asteraceae), Potentilla thurberi A. Gray (Rosaceae), Pterogonum atrorubens (Englem.) H. Gross (Polygonaceae), Zornia venosa Mohlenbr. (Fabaceae) and Datura lanosa Barclay ex Bye (Solanaceae). In all the cases the extracts inhibited, in a concentration-dependent manner, the spontaneous contraction of the intestinal smooth muscle. The most active extract was that of D. viscosa. These findings tend to support the ethnomedical use of the selected species as spasmolytic agents in Mexican traditional medicine. Additionally, the potential antimicrobial activity of the extracts against pathogenic enterobacteria was investigated. Seven of the nine plants evaluated displayed antibacterial effects.

Vasoactive effects of aqueous extracts from five Mexican medicinal plants on isolated rat aorta.

The present investigation describes the effects of aqueous extracts from Chiranthodendron pentadactylon flowers, Galphimia glauca leaves and flowers, Ipomoea stans roots, Juglans regia leaves and Taxodium mucronatum aerial parts on isolated rat thoracic aorta precontracted by noradrenaline (NA). In all cases, the aqueous extracts (0.5-12 mg/ml) significantly inhibited, in a concentration-dependent manner, the maximal contractile response induced by NA in rat aorta. The most active extract was that of G. glauca flowers. These findings indicate that the active principle(s) present in the crude extracts can exert a vasorelaxant effect.