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ETHNOPHARMACOLOGICAL RELEVANCE: Plants have been used in folk medicine by Mayan ancient people from the Yucatan Peninsula, Mexico, to treat some diseases considered as cancer diseases such as chronic wounds or tumors. AIM OF THE STUDY: We collected a selection of nine plants in order to investigate their cytotoxic activity against cancer cell lines. MATERIALS AND METHODS: Methanolic extracts were tested for their cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay on four cancer cell lines; nasopharynx carcinoma (KB), laryngeal carcinoma (Hep-2), cervix adenocarcinoma (HeLa), and cervix squamous carcinoma cells (SiHa) and one normal cell line; canine kidney (MDCK). RESULTS: All species exhibited some degree of cytotoxic activity. The root bark extract of Hamelia patens exhibited the highest cytotoxic activity on HeLa cells with a CC50 of 13 microg/mL and selectivity index of 13.3, higher than docetaxel. Gossypium schottii and Dioon spinulosum showed similar good cytotoxic activity and selectivity index on HeLa and Hep-2 cells, respectively. CONCLUSIONS: Hamelia patens, Dioon spinulosum and Gossypium schottii demonstrated promising cytotoxic activity and have been selected for future bio-guided fractionation and isolation of active cytotoxic compounds.

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Two new additional A-type proanthocyanidins have been isolated from Geranium niveum. Their structures were determined by spectroscopic, chemical and chiroptical methods as epi-afzelechin-(4beta-->8,2beta-->O-->7)-gallocatechin (1) and epi-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin-(4beta-->8,2beta-->O-->7)-afzelechin (2). Proanthocyanidins 1 and 2 were given the trivial names of geranins C and D, respectively. Compound 2 showed moderate antiprotozoal activity against Entamoeba histolytica and Giardia lamblia, whereas 1 exhibited weak activity toward E. histolytica.

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In this work we analyzed by RT-PCR, the mRNA changes for IL-4, IL-10, TNF and IFN (induced by TSL-1 antigens in a rat mast cell line (HRMC) with mucosal characteristics. The data obtained showed an increase of 65 and 52% in mRNA expression for IL-4 and TNF respectively and a decrease of 59 and 55% in mRNAs for IFN gamma and IL-10. Our results suggest that TSL-1 antigens induce the release from MC of regulatory molecules, such as IL-4 by an IgE independent mechanism. Our data also provides important information related to the ability of MC to participate not only in the effector phase against the infectious agents, but also in the orchestration of the immune response by the host against parasites.

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No information about the levels of pro-inflammatory interleukins has been described in children with neurocysticercosis (NCC). The levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-5, IL-6, and IL-12 in the cerebrospinal fluid from children with NCC were determined by enzyme-linked immunosorbent assay (ELISA). Twelve children with NCC, six with active and six with inactive disease, and six children without NCC were studied. TNF-alpha was undetectable in CSF from controls and five children with inactive NCC, whereas the levels were significantly higher (median 22.1 pg/ml; P = 0.008) in all children with active NCC. Levels of IL-6 were low in active and inactive NCC patients but two subjects with active subarachnoid disease had high levels. IL-5 and IL-12 were not detected. This study shows that high levels of TNF-alpha are present in CSF from children with active NCC. IL-6 levels are higher when infection occurs in the subarachnoid space.

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Bioassay-guided fractionation of the antiprotozoal extract of Conyza filaginoides led to the isolation of three new flavonol caffeoyl glycosides, namely, kaempferol 3-O-(6' '-O-E-caffeoyl)-beta-D-galactopyranoside (1), isorhamnetin 3-O-(6' '-O-E-caffeoyl)-beta-D-galactopyranoside (2), and quercetin 3-O-(6' '-O-E-caffeoyl)-beta-D-glucopyranoside (3). In addition, seven known compounds, erythrodiol (4), beta-caryophyllene-4,5-alpha-oxide (5), astragalin (6), isoquercitrin (7), nicotiflorin (8), narcissin (9), and rutin (10), were obtained. The structures of the new isolates were elucidated by spectroscopic and chemical methods. Compounds were also assessed for antiamoebic and antigiardial activities, but none was significantly active compared to the standard drugs evaluated.

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The crude ethanol extract from the leaves of Zanthoxylum liebmannianum exhibited inhibitory effect on the reproduction of trophozoites of Entamoeba histolytica (IC(50)=3.48 microg/ml) and Giardia lamblia (IC(50)=58.00 microg/ml). From this extract, asarinin, hyperin, beta-sitosterol, and beta-sitosterol glucoside were isolated. Among them, asarinin was the most active with IC(50) values of 19.86 microg/ml for E. histolytica and 35.45 microg/ml for G. lamblia. The remaining compounds showed moderate activity against both parasites.

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BACKGROUND: Two albendazole (ABZ) prodrugs, N-methoxycarbonyl-N'-[(2-nitro-4-propylthio) phenyl] thiourea (compound 2), and N-methoxycarbonyl-N'-[(2-nitro-5-propylthio) phenyl] thiourea (compound 3) have recently been synthesized. These compounds showed greater solubility than ABZ itself. METHODS: In order to evaluate the biotransformation of compounds 2 and 3 to ABZ and/or ABZ-sulphoxide (ABZ-SO), plasma samples taken from mice treated with the prodrugs were analyzed by HPLC. Also, the anthelmintic activity of compounds 2 and 3 against Trichinella spiralis was evaluated in the mice experimentally infected with the parasite. RESULTS: The presence of ABZ and/or ABZ-SO was demonstrated in plasma samples taken at different time intervals after prodrug administration, although their levels were low compared to those reached in mice treated with ABZ. Additionally, prodrugs 2 and 3 were also detected in these samples. In regard to the anthelmintic activity of ABZ prodrugs, it was shown that compound 3 was more active than compound 2. Additionally, it was as effective as ABZ against T. spiralis pre-adult, adult, and female fecundity. However, compound 3 was not as active as ABZ against the muscle stage of the parasite. CONCLUSIONS: Compound 3 had better anthelmintic activity against T. spiralis than compound 2. The bioconversion of compounds 2 and 3 to ABZ and/or ABZ-SO was demonstrated by HPLC, but they did not reach equivalent concentrations to that of ABZ. Prodrugs 2 and 3 were also present in plasma samples, suggesting that prodrugs were not efficiently reduced in the intestine of mice.

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Bioassay-guided fractionation of the antiprotozoal extract of Geranium niveum led to the isolation of two new A-type proanthocyanidins, epi-afzelechin-(4beta-->8, 2beta-->O-->7)-afzelechin (1) and epi-catechin-(4beta-->8, 2beta-->O-->7)-afzelechin (2). Compounds 1 and 2 were given the trivial names of geranins A and B, respectively. In addition, five known compounds, mahuannin B (3), reynoutrin (4), hyperin (5), methyl gallate (6), and 3-beta-caffeoyl-12-oleanen-28-oic acid (7), were obtained. The structures of the new proanthocyanidins were elucidated by spectroscopic and chemical methods as well as CD measurements. Compounds 1, 2, and 4-7 were tested against axenically grown trophozoites of Giardia lamblia and Entamoeba histolytica.

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Structure characterization and biological evaluation of the compounds isolated from Helianthemum glomeratum, particularly that of the polyphenols, has been the aim of a series of studies carried out to define the further potential use of this plant in the treatment of infectious diarrhoea in children. The flavan-3-ols, (-)-epigallocatechin and (-)-epigallocatechin gallate, isolated from Helianthemum glomeratum roots were tested for their antiamoebic and antigiardial effects in vitro. Compared with the activity determined with the leaf and the root methanol extracts, the effect of (-)-epigallocatechin against Entamoeba histolytica was of a similar potency, nevertheless, it also suppressed the growth of Giardia lamblia in axenic cultures, a parasite that proved to be resistant to the crude extracts. It might be assumed that determined biological properties are due to the presence of (-)-epigallocatechin in the plant, although the flavonoids, kaempferol and tiliroside isolated from the leaves, could account for the antiprotozoal properties of this herbal resource, used in Mayan traditional medicine for the treatment of bloody diarrhoea.

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The in vitro antiprotozoal activity of 18 natural flavonoids has been determined against Entamoeba histolytica and Giardia lamblia. (-)-Epicatechin, (-)-epigallocatechin and kaempferol were the most active flavonoids against both protozoa.

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BACKGROUND: Lyme disease is the most common vector-borne human disease in Europe and the United States. In Mexico, clinical cases suggestive of Lyme borreliosis have been reported; however, infection was not confirmed by serologic or microbiologic tests. METHODS: To study the prevalence of IgG antibodies against Borrelia burgdorferi among Mexican persons, a community-based sero-survey including all states of Mexico was done. A sample of 2,890 sera representing individuals of all ages and all socioeconomic levels was studied. Antibodies anti-B. burgdorferi were determined by enzyme-linked immunosorbent assay (ELISA) using a whole-cell sonicated extract of B. burgdorferi strain B31. Serum specimens positive for ELISA were further studied by Western blot (WB). A serum sample was considered positive by WB if at least three of the following protein bands were recognized: 18, 24, 28, 29, 31, 34, 39, 41, 45, 58, 62, 66, and 93 kDa. Some WB positive specimens were further confirmed with an immunodot-blot (IDB) test using recombinant and purified B. burgdorferi proteins. RESULTS: Of the 2,890 specimens, 34 were positive for ELISA; nine of these 34 were confirmed as positive by WB. Four of the nine WB positive sera were tested by IDB and all four were positive. The prevalence of WB confirmed cases in the sample studied was 0.3%. Positive specimens were from residents of the northeastern and central areas of Mexico. CONCLUSIONS: The serological evidences of this study suggest that Borrelia burgdorferi infection is present in the Mexican population. This finding should be confirmed by documenting the infection in clinical cases and in tick vectors.

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A nationwide community-based survey for Helicobacter pylori infection had not been done. This study sought to determine the seroprevalence of infection in Mexico, and the socioeconomic and demographic variables that are risk factors for infection. The survey assessed 11,605 sera from a sample population representing persons ages 1-90 years from all socioeconomic and demographic levels and from all regions of Mexico. Antibodies against H. pylori were studied by ELISA using whole cell antigen. Among the findings were that 66% of the population was infected and that age was the strongest risk factor for infection. By age 1 year, 20% were infected and by age 10 years, 50% were infected. Crowding (odds ratio [OR], 1.4), low educational level (OR, 2.42), and low socioeconomic level (OR, 1.43) were risk factors for infection. Prevalence was similar in urban and in rural communities (OR, 0.95). This study is the largest community-based seroepidemiologic study of H. pylori to date.

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OBJECTIVE: To evaluate two staining procedures used in the detection of P. carinii. MATERIAL AND METHODS: Bronchoalveolar lavage samples were obtained from 20 immunosupressed rats. The samples were stained by three procedures: o-toluidine blue (OTB), Diff Quik (DQ), and a silver stain as the gold standard. The microscopic search for P. carinii was made independently by two observers. RESULTS: Fifteen of the 20 samples were positive to P. carinii with the silver stain. The sensitivity with DQ was 27% and the specificity 100%. With OTB the sensitivity was 93% and the specificity was 80%. The inter-raters' agreement by kappa was 0.11 for DQ and 0.53 for OTB. CONCLUSION: Our results suggest that the silver stain should be used for an adequate diagnosis of pneumonia caused by P. carinii.

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The variable clinical course of human giardiasis may be due in part to differences in the virulence of various strains of Giardia lamblia. To address this issue, the in vitro cytopathic effect of isolates obtained from human symptomatic or asymptomatic infections was assessed by ultrastructural and electrophysiological methods. Axenic trophozoites of 10 strains of G. lamblia isolated from children with infections in Mexico City were cultured for 12 to 24 hr on live MDCK epithelial cells. No decrease in transepithelial resistance of MDCK monolayers mounted in Ussing chambers was detected with any of the isolates analyzed. On the contrary, trophozoites or media in which the isolates grew produced up to a twofold increase in transepithelial resistance. Transmission and scanning electron microscopy revealed that all isolates of G. lamblia, irrespective of their origin, gave rise to focal regions of microvilli depletion. These modifications were induced by the close attachment of the ventrolateral flange of the parasite adhesive disk to the apical surface of MDCK cells. The circular imprints evolved progressively to larger areas devoid of microvilli. In conclusion, under in vitro conditions, isolates of G. lamblia trophozoites derived from symptomatic or asymptomatic human infections damage epithelial cultured cells mainly by depleting their microvilli. None of the isolates showed evidence of an invasive effect.

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The susceptibility of a strain of Giardia lamblia to benzimidazole carbamates, 5-nitroimidazoles, nitrofurans and other drugs was studied in vitro. Albendazole was the most active compound, with a 50% inhibitory concentration (IC50) of 0.01 mg/L and a minimal lethal concentration (MLC) of less than 0.04 mg/L; the IC50 of mebendazole was 0.06 mg/L and the MLC less than 0.5 mg/L. Among the 5-nitroimidazoles tested, ornidazole was the most effective (IC50 0.12 mg/L); tinidazole, metronidazole, secnidazole and hemezole were less active. Nifuroxazide, etofamide and nalidixic acid exhibited modest anti-giardial activity; quinfamide did not inhibit the growth of the parasite at a concentration of 200 mg/L. Albendazole and mebendazole are promising candidates for clinical use and should be further evaluated.

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Axenically grown Giardia lamblia trophozoites treated with low concentrations of the benzimidazole carbamates albendazole and mebendazole detach from glass culture tubes and lose viability. Scanning electron microscopic observations revealed that these drugs produce grotesque modifications of the cell shape of the parasite and disassembly of the adhesive disc. Transmission electron microscopy showed several stages of the fragmentation of adhesive discs with dispersion of microtubules and microribbons in the cytoplasm. Flagella appeared undamaged. In drug-treated trophozoites electron-dense precipitates were selectively deposited on microtubules and microribbons. The results indicate that the antigiardial effect of benzimidazoles is the result of binding to microtubules and subsequent alterations of the cytoskeleton. The electron microscopic observations also suggest that the drugs may bind to microribbon components of the adhesive disc, possibly giardin proteins.

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