Phenotypic and Target-Directed Screening Yields New Acaricidal Alternatives for the Control of Ticks.

Rhipicephalus microplus, the "common cattle tick", is the most important ectoparasite in livestock worldwide due to the economic and health losses it produces. This tick is a vector for pathogens of several tick-borne diseases. In Latin American countries, damages reach approximately USD 500 million annually due to tick infections, as well as tick-borne diseases. Currently, resistant populations for every chemical group of acaricides have been reported, posing a serious problem for tick control. This study aims to find new alternatives for controlling resistant ticks with compounds derived from small synthetic organic molecules and natural origins. Using BME26 embryonic cells, we performed phenotypic screening of 44 natural extracts from 10 Mexican plants used in traditional medicine, and 33 compounds selected from our chemical collection. We found 10 extracts and 13 compounds that inhibited cell growth by 50% at 50 µg/mL and 100 µM, respectively; the dose-response profile of two of them was characterized, and these compounds were assayed in vitro against different life stages of Rhipicephalus microplus. We also performed a target-directed screening of the activity of triosephosphate isomerase, using 86 compounds selected from our chemical collection. In this collection, we found the most potent and selective inhibitor of tick triosephosphate isomerase reported until now. Two other compounds had a potent acaricidal effect in vitro using adults and larvae when compared with other acaricides such as ivermectin and Amitraz. Those compounds were also selective to the ticks compared with the cytotoxicity in mammalian cells like macrophages or bovine spermatozoids. They also had a good toxicological profile, resulting in promising acaricidal compounds for tick control in cattle raising.

Pre-Germinative Treatments and Morphophysiological Traits in Enterolobium cyclocarpum and Piscidia piscipula (Fabaceae) from the Yucatan Peninsula, Mexico.

Enterolobium cyclocarpum and Piscidia piscipula are two important tree Fabaceae species distributed from the Yucatan Peninsula, Mexico. Our aims were focused on the E. cyclocarpum and P. piscipula seeds for: (1) to examine the seed permeability and imbibition rate, (2) to evaluate the effect of seed pre-germinative treatments, and (3) to characterize the structures involved on the presence of physical dormancy (PY). We used fresh seeds to determine seed permeability and imbibition rate, seed viability by means of tetrazolium test, furthermore, we applied mechanical scarification and boiler shocks for 5 s, 10 s and 15 s treatments. Morphological characterization of the seed coat was by Scanning Electron Microscope (SEM). Seed viability in E. cyclocarpum and P. piscipula were 100% and 96%, respectively. Seed permeability and imbibition rate in E. cyclocarpum were low. The highest germination in E. cyclocarpum was in the mechanical scarification (92%), while in P. piscipula, this parameter was in the 10 s boiling water treatment (76.0%). The presence of PY was confirmed in both species because they showed low seed permeability, and imbibition rate; furthermore, exhibited macrosclereids cells. The present research seeks to promote the sustainable use of E. cyclocarpum and P. piscipula.

The Influence of Drying Temperatures on the Metabolic Profiles and Antioxidant Activity of Manilkara zapota Leaves.

In the present study, the leaves of Manilkara zapota (L.) P. Royen (Sapotaceae), an evergreen tree recognized for its medicinal properties in Southern Mexico, were used as a model to study the effect of different drying temperatures on its metabolic profile and therefore, its antioxidant potential. For this purpose, a methanol extraction of leaves dried at room temperature (25 °C) or by heat convection (50, 75 and 100 °C) were compared in terms of drying efficiency, yield of extraction, total phenol content, 1H-NMR metabolic profile, and DPPH antioxidant activity. The drying curves enabled the fact to be uncovered that drying efficiency improves with increase of temperature, as does the level of total phenols and antioxidant activity. A metabolomics approach using principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) of the corresponding 1H-NMR profiles allowed the impact of the drying temperature on their metabolic profile to be documented and also, caffeic acid and epicatechin as main secondary metabolites contributing to the antioxidant activity of M. zapota to be identified.

Isolation and Structural Characterization of Bioactive Molecules on Prostate Cancer from Mayan Traditional Medicinal Plants.

Prostate cancer is the most common cancer in men around the world. It is a complex and heterogeneous disease in which androgens and their receptors play a crucial role in the progression and development. The current treatment for prostate cancer is a combination of surgery, hormone therapy, radiation and chemotherapy. Therapeutic agents commonly used in the clinic include steroidal and non-steroidal anti-androgens, such as cyproterone acetate, bicalutamide and enzalutamide. These few agents have multiple adverse effects and are not 100% effective. Several plant compounds and mixtures, including grape seed polyphenol extracts, lycopene and tomato preparations, soy isoflavones, and green tea extracts, have been shown to be effective against prostate cancer cell growth. In vivo activity of some isolated compounds like capsaicin and curcumin was reported in prostate cancer murine models. We prepared a library of plant extracts from traditional Mayan medicine. These plants were selected for their use in the contemporaneous Mayan communities for the treatment of different diseases. The extracts were assessed in a phenotypic screening using LNCaP prostate cancer androgen sensitive cell line, with a fixed dose of 25 µg/mL. MTT assay identified seven out of ten plants with interesting anti-neoplastic activity. Extracts from these plants were subjected to a bioguided fractionation to study their major components. We identified three compounds with anti-neoplastic effects against LNCaP cells, one of which shows selectivity for neoplastic compared to benign cells.

Review of Theoretical Models to Study Natural Products with Antiprotozoal Activity.

In nature, pathogenic parasite species with different susceptibility patterns of antiparasitic drugs abound. In this sense, natural products derived from plants are a potency for drugs with potential antiparasitic activity. Unfortunately, there are many metabolites and studying all of them would be costly in terms of money and resources. To this end, theoretical studies such as QSAR models could be useful. These, for the most part, predict the biological activity of the drugs against a single species of parasite. Consequently, foretell the probability with which a drug is active against many different species with a single QSAR model is an important achievement. This review consists of three parts: the first part is a review of metabolites found in nature that have antiparasitic activity, in particular the antiprotozoal (Leishmania and Trypanosoma); the second part includes a review of theoretical studies looking for a model that predicts the antiprotozoal activity of natural products; the third and final part concerns the study of theoretical models focused on the interaction between drug and receptor, analyzing new metabolites with antiprotozoal activity.

Review of Theoretical Prediction Models for Organic Extract Metabolites, Effect of Drying Temperature on Smooth Muscle Relaxing Activity Induced by Organic Extracts Specially Cecropia Obtusifolia Portal and Web Server Predictors of Drug-Protein Interaction.

Cecropia obtusifolia bertol is medicinal specie used in the treatment of diabetes mellitus and hypertension and it has scientific studies that support the traditional use. However, it is required to understand the influence of drying temperature on the yield and pharmacological activity. Drying rate, extraction efficiency, changes in the UV-Vis spectrum and estimating chlorophylls were stimulated with the increasing temperature. Finally, relaxant activity of vascular smooth muscle is increased by 70ºC and reducing ability by the method of CARF increases with temperature. Analytical studies are required to identify changes in the metabolic content and those that ensure the safety and efficacy for human consumption. In this sense, bioinformatic studies may be helpful. Studies such as QSAR can help us to study these metabolites derived from natural products. MIND-BETS model and NL MIND-BETS model to predict DPIs was introduced using MARCH-INSIDE (MI) software to calculate structural parameters for drugs and enzymes respectively. We firstly revised the state-of-art on the design with review of previous works with hypertension activity based on theoretical studies. A study, evaluating the effect of drying temperature of leaves of C. obtusifolia on the relaxing of vascular smooth muscle, antioxidant activity and the presence of chlorophylls, with a focus on Cecropia metabolites. Last, we carried out QSAR studies using MIND-BEST and NL MIND-BEST web servers in order to understand the essential metabolites structural requirement for binding with receptors for FDA proteins.

Vasorelaxant effect of Valeriana edulis ssp. procera (Valerianaceae) and its mode of action as calcium channel blocker.

OBJECTIVES: The aim was to evaluate the relaxant effect of extracts from Valeriana edulis and determine the possible mechanism of action of the hexanic extract as vasorelaxant agent. METHODS: Extracts from rhizomes obtained by maceration (hexanic (HEVe), dichloromethanic (DEVe), methanolic (MEVe) and hydroalcoholic (HAEVe) (3.03-500 microg/ml)) were evaluated on aortic rat rings with and without endothelium. KEY FINDINGS: Extracts induced a significant concentration-dependent and endothelium-independent relaxation on isolated rat aorta pre-contracted with noradrenaline (0.1 microM). HEVe, the most potent extract (0.15-50 microg/ml), induced relaxation in aortic rings pre-contracted with KCl (80 mM), with an IC50 value of 34.61 +/- 1.41 microg/ml and E(max) value of 85.0 +/- 4.38%. Pretreatment with HEVe (30 microg/ml) also inhibited contractile responses to noradrenaline and CaCl(2). HEVe (9.98 +/- 2.0 microg/ml) reduced noradrenaline-induced transient contraction in Ca(2+)-free solution, and inhibited contraction induced by KCl (80 mM). In endothelium-denuded rings, the vasorelaxant effect of HEVe was not modified by 1-H-[1,2,4]-oxadiazolo-[4,3a]-quinoxalin-1-one (1 microM), tetraethylammonium (5 mM), glibenclamide (10 microM) or 2-aminopyridine (100 microM). CONCLUSIONS: Our results suggest that HEVe induces relaxation through an endothelium-independent pathway, involving blockade of Ca(2+) channels, and this effect could be related to the presence of valepotriates.

Spasmolytic effect of Mentha pulegium L. involves ionic flux regulation in rat ileum strips.

Mentha pulegium is common known as "poleo" and used for the treatment of diarrhea, headache and cough in Mexican traditional medicine. Organic extracts from aerial parts were evaluated to determine their spasmolytic action on rat isolated ileum test. Hexanic (HEMp), dichloromethanic (DEMp) and methanolic (MEMp) extracts induced a concentration-dependent (0.97 to 1000 microg/mL) antispasmodic effect on spontaneous contractions. DEMp was the most active extract; therefore, spasmolytic mechanism was investigated. This extract (200 microg/mL) induced a significant depression on cumulative concentration-response curve for carbachol and serotonin (P<0.05). Besides, extract decreased and shifted to the right KCl- and CaCl2-induced contraction curves. Moreover, pre-incubation with chlorpromazine (0.001 mM) shifted to the left the relaxant curve. Pre-treatment with L-NAME (1 mM), papaverine (0.01 mM), teophylline (0.01 mM), TEA (1 mM) and glybenclamide (0.1 mM) did not produced any changed of the relaxant curves of DEMp. Findings indicate that dichloromethanic extract of M. pulegium induced its spasmolytic effect through Ca2+-influx blockade, which may explain its traditional use against diarrhea.

Micropropagation and vasorelaxant activity of Laelia autumnalis (Orchidaceae).

A simple and efficient protocol has been developed in order to obtain healthy seedlings by asymbiotic germination of seeds from Laelia autumnalis. Seeds from mature capsules were germinated asymbiotically after being cultured on full- or half-strength Murashige and Skoog's (MS) medium, without plant growth regulators and with 3.0% or 1.5% of sucrose. The percentage of germinated seeds (% GS) was recorded during 6 weeks using three different conditions of incubation: light (80% GS, p < 0.05), darkness (30% GS) and white light photoperiod (100% GS, p < 0.05). The best seed germination percentages were found on the light and white light photoperiod conditions. Moreover, we also investigated the vasorelaxant action of the methanolic extracts from wild L. autumnalis (roots, pseudobulbs and leaves) and plantlets generated in vitro. Results showed that the methanolic extract of roots and pseudobulbs produced a significant vasodilator effect, in a concentration-dependent and endothelium-independent manner on norepinephrine (NE) and potassium chloride (KCl)-induced contractions in rat aortic thoracic rings. Nevertheless, the methanolic extract of leaves and plantlets showed no relevant vasorelaxant activity. Therefore, the results suggest that pseudobulbs and roots were the main tissues of the plant where vasorelaxant compounds are stored.

Glycolipid ester-type heterodimers from Ipomoea tyrianthina and their pharmacological activity.

Tyrianthins A (1) and B (2), two new partially acylated glycolipid ester-type heterodimers were isolated from Ipomoea tyrianthina. Scammonic acid A was determined as the glycosidic acid in both monomeric units. Tyrianthin A (1) (IC(50) 0.24+/-0.09 microM and E(max) 81.80+/-0.98%), and tyrianthin B (2) (IC(50) 0.14+/-0.08 microM and E(max) 87.68+/-0.72%) showed significant in vitro relaxant effect on aortic rat rings, in endothelium- and concentration-dependent manners. Also, these compounds were able to increase the release of GABA and glutamic acid in brain cortex, and displayed weak antimycobacterial activity.

Spasmolytic action of Lepechinia caulescens is through calcium channel blockade and NO release.

The present study was undertaken to elucidate the mode of action of methanol extract from aerial parts of L. caulescens (TC-MELc) as spasmolytic agent on in vitro rat ileum test, and investigate the possible antibacterial activity of different extracts from the plant. TC-MELc induced a concentration-dependent (0.001 to 100microg/mL) antispasmodic effect on spontaneous contractions. TC-MELc also (IC50 11.2microg/mL) induced a marked depression on cumulative concentration-response curve for carbachol (Emax=2.3+/-0.3g vs. 0.66+/-0.1g) and serotonin (Emax=1.1+/-0.3g vs. -0.01+/-0.09g). Besides, extract decreased and displaced to the right KCl and CaCl2 concentration-response curves. Moreover, TC-MELc (11.2microg/mL) provoked a total relaxation when ileum strips were contracted with carbachol (1microM) in calcium-free Krebs solution. Pre-treatment with l-NAME (10microM) produced a significant change of the relaxant response and activity was markedly inhibited. Additionally, hexanic (HELc), dichloromethanic (DELc) and methanolic (MELc) extracts from aerial parts were studied to determine their antibacterial activity. DELc showed antibacterial activity on all bacterial strains assayed (

Resin glycosides from the roots of Ipomoea tyrianthina and their biological activity.

Seven new tetrasaccharide glycosides, tyrianthins 1-7 (1-7), along with six known glycolipids were isolated from the roots of Ipomoea tyrianthina, and their structures were elucidated by spectroscopic and chemical methods. The content of resin glycosides in samples collected in three different regions was analyzed and compared, and the results showed that the flowering or dry season did not have any effect on the chemical composition for the same locality, but the growing location itself did affect the chemical composition of resin glycosides. Intraperitoneal administration to mice of tyrianthin 6 (6) resulted in antidepressant activity. Tyrianthin 6 (6), scammonin 1 (8), and scammonin 2 (9) exhibited dose-dependent protective effects against pentylenetetrazole-induced seizures. Also, tyrianthin 6 (6) and scammonin 2 (9) produced relaxant effects on spontaneous contractions in the isolated rat ileum.

Design, microwave-assisted synthesis, and spasmolytic activity of 2-(alkyloxyaryl)-1H-benzimidazole derivatives as constrained stilbene bioisosteres.

A simple, fast, and efficient method for the preparation of several 2-(alkyloxyaryl)-1H-benzimidazole derivatives is reported. Compounds were synthesized through a rapid one-pot three component reaction via microwave irradiation, starting from commercially available aldehydes and o-phenylenediamine, in the presence of Na(2)S(2)O(5) and solvent-free conditions. The design of these compounds explore the hypothesis that the stilbene framework could be mimicked with an appropriate 2-(Alkyloxyphenyl)benzimidazole scaffold. This framework has a similar structural motif as the 6-phenylnaphthalene and behaves like stilbene bioisosteres. The spasmolytic activity of these compounds was recorded using isolated rat ileum test. Compound 12 was the most active of the series, showing an IC(50) of 1.19 microM.

Ursolic acid mediates the vasorelaxant activity of Lepechinia caulescens via NO release in isolated rat thoracic aorta.

We have determined that the methanolic extract of L. caulescens (MELc) produced a significant vasodilator effect in a concentration-dependent and endothelium-dependent manner. This relaxation was blocked by N(omega)-nitro-L-arginine methylester (L-NAME), indicating that MELc vasodilator properties are endothelium mediated due to liberation of nitric oxide (NO). In this paper we aimed to corroborate its mode of action. MELc effects on noradrenaline (NA)-induced contraction in isolated rat aortic thoracic rings with endothelium (+E), in the presence of atropine (0.1 microM) and 1-H-[1,2,4]-oxadiazolo-[4,3a]-quinoxalin-1-one (ODQ, 1 microM) were conducted. MELc relaxation curve was significantly shifted to the right in the presence of ODQ and atropine, thus confirming that its mode of action is related with activation of nitric oxide synthase (NOS) and the consequent increment in NO formation. Bio-guided study of MELc allowed the isolation of ursolic acid (UA, 50 mg) and ursolic-oleanolic acids mixture [UA/OA (7:3), 450 mg]. The relaxant effect of UA (0.038-110 microM) was evaluated in functional experiments. UA induced a significant relaxation in a concentration- and endothelium-dependent manner (IC(50)=44.15 microM) and did not produce a vasorelaxant effect on contraction evoked by KCl (80 mM). In addition, NA-induced contraction was significantly displaced to the right by UA (30 microM). In order to determine its mode of action, UA-induced relaxant effect was evaluated in the presence of atropine (0.1 microM), indomethacin (10 microM), L-NAME (100 microM) and ODQ (1 microM). Relaxation was blocked by L-NAME and ODQ. On the other hand, UA (3 microM) provoked a significant displacement to the left in the relaxation curve induced by sodium nitroprusside (SNP, 0.32 nM to 0.1 microM), but it was not significant in the presence of Carbamoyl choline (carbachol, 1 nM to 10 microM). These results indicate that UA-mediated relaxation is endothelium dependent, probably due to NO release, and the consequent activation of vascular smooth muscle soluble guanylate cyclase (sGC), a signal transduction enzyme that forms the second messenger cGMP.

Relaxant activity of 2-(substituted phenyl)-1H-benzimidazoles on isolated rat aortic rings: design and synthesis of 5-nitro derivatives.

The relaxant activity of 2-(o, p-substituted phenyl)-1H-benzimidazole derivatives with various 5- and 6-position substituents (-H, -CH3, -NO2, -CF3), namely 1-7, was recorded using the in vitro rat aorta ring test. Compounds 3 and 6 [2-(5-nitro-1H-benzimidazol-2-yl)phenol and 2-(4-methoxyphenyl)-5-nitro-1H-benzimidazole] were prepared using a short route, and were the most potent compounds of the series, showing IC50 value of 0.95 and 1.41 (with endothelium) and 2.01 and 3.61 microM (without endothelium), respectively. Studying further structure-activity relationships through the use of bioisosteric substitution in these benzimidazole derivatives should provide novel vasorelaxant leads and possibly against hypertensive diseases.