Eduardo M. Sánchez

Extracts of Edible and Medicinal Plants Damage Membranes of Vibrio cholerae

ABSTRACT The use of natural compounds from plants can provide an alternative approach against food-borne pathogens. The mechanisms of action of most plant extracts with antimicrobial activity have been poorly studied. In this work, changes in membrane integrity, membrane potential, internal pH (pHin), and ATP synthesis were measured in Vibriocholerae cells after exposure to extracts of edible and medicinal plants. A preliminary screen of methanolic, ethanolic, and aqueous extracts of medicinal and edible plants was performed. Minimal bactericidal concentrations (MBCs) were measured for extracts showing high antimicrobial activity. Our results indicate that methanolic extracts of basil (Ocimum basilicum L.), nopal cactus (Opuntia ficus-indica var. Villanueva L.), sweet acacia (Acacia farnesiana L.), and white sagebrush (Artemisia ludoviciana Nutt.) are the most active against V. cholera, with MBCs ranging from 0.5 to 3.0 mg/ml. Using four fluorogenic techniques, we studied the membrane integrity of V. cholerae cells after exposure to these four extracts. Extracts from these plants were able to disrupt the cell membranes of V. cholerae cells, causing increased membrane permeability, a clear decrease in cytoplasmic pH, cell membrane hyperpolarization, and a decrease in cellular ATP concentration in all strains tested. These four plant extracts could be studied as future alternatives to control V. cholerae contamination in foods and the diseases associated with this microorganism.

Electrochemical Aspects of Asymmetric Phosphonium Ionic Liquids

Abstract Print abstract Electrochemical Aspects of Asymmetric Phosphonium Ionic Liquids J. Electrochem. Soc., Volume 154, Issue 2, pp. B229-B233 (2007) Rosa E. Ramirez, Luis C. Torres-Gonzalez, and Eduardo M. SanchezLaboratorio de Investigacion del Vidrio, Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, NL Mexico 66450 (Revised 28 September 2006; published 26 December 2006) Asymmetric aliphatic tetraalkyl phosphonium cations form room-temperature ionic liquids with iodide as an anion. Isobutyl-trihexyl phosphonium iodide shows the highest ionic conductivity at room temperature and it is enhanced by 3-methoxypropionitrile addition. A cyclovoltammetric study shows adequate redox behavior for nanocrystalline solar cells devices. ©2006 The Electrochemical Society doi:10.1149/1.2404789 Additional Information View ISIs Web of Science data for this article: [ Source Abstract | Related Articles ] View Cart Full Text: HTML |Sectioned HTML| PDF |GZipped PS

Reduction of Campylobacter jejuni and Campylobacter coli in Poultry Skin by Fruit Extracts

Campylobacter spp. are a major cause of foodborne bacterial gastroenteritis in humans, and current methods to control Campylobacter contamination in foods are not completely successful. Plants are a promising source of antimicrobial agents, particularly given the growing interest in all natural foods. In this study, the antimicrobial activity of extracts from 28 edible plants against Campylobacter jejuni and Campylobacter coli was evaluated in vitro and in a poultry skin model. Nine of 28 extracts exhibited antimicrobial activity in a diffusion assay, and MBCs were determined for the three most active extracts, i.e., lime, plum, and sour orange peel (MBCs of 2 to 3 mg/ml). Mixtures of the lime, plum, and sour orange peel extracts were applied to chicken skin inoculated with 10(5) CFU of Campylobacter to test for synergistic or antagonist effects. After incubation (48 h at 4 degrees C) with any extract mixture, no Campylobacter CFUs were detectable. A panel of tasters determined that the mixture of lime and plum gave the best flavor to chicken wings. These active extracts from edible fruits are simple to prepare and are alternatives to reduce or eliminate Campylobacter contamination of chicken products.

Isolation, characterization and mode of antimicrobial action against Vibrio cholerae of methyl gallate isolated from Acacia farnesiana

The antimicrobial activity of Acacia farnesiana against Vibrio cholerae has been demonstrated; however, no information regarding its active compound or its mechanism of action has been documented.

Antibacterial and Antioxidant Activities in Extracts of Fully Grown Cladodes of 8 Cultivars of Cactus Pear

The antimicrobial and antioxidant activities of some cultivars of the nopal cactus have not been determined. In this study, 8 cultivars of nopal cacti from Mexico were assayed for phenolic content, antioxidant activities, and antimicrobial activities against Campylobacter Jejuni, Vibrio cholera, and Clostridium Perfringens. Plant material was washed, dried, and macerated in methanol. Minimum bactericidal concentrations (MBCs) were determined using the broth microdilution method. Antioxidant activities were quantitatively determined using spectrophotometric methods. The MCBs of the nopal cacti ranged from 1.1 to 12.5 mg/mL for c. jejuni, 4.4 to 30 mg/mL for V. cholera, and 0.8 to 16 mg/mL for C. perfringens in the cultivars Cardon Blanco, Real de Catorce, and Jalpa, respectively. High quantities of total phenols and total flavonoids were found in the Jalpa cacti (3.80 mg of gallic acid equivalent GAE/g dry weight [DW] and 36.64 mg of quercetin equivalents [QE]/g DW, respectively). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities (RSA) were correlated to bioactive compound contents. The Villanueva cacti had the highest %RSA at 42.31%, and the lowest activity was recorded in Copena V1 at 19.98%. In conclusion, we found that some of the 8 cactus pear cultivars studied may be used for their antioxidant compounds or antimicrobials to control or prevent the contamination of foods.

Surface Characterization and CO2 Reduction Using Electrodeposited Silver Particles over TiO2 Thin Film

TiO2 thin films supported on transparent conductive glass plates were modified by silver particles (250 nm diameter) deposited by electrochemical double pulse from an aqueous solution of silver nitrate. Selective formation of Ag particles on TiO2 surface could be seen from SEM and AFM images and topography. Rugosity and particle size analyses were performed on the modified surface. Benefits of silver particle modification are discussed based on the enhanced electrochemical reduction of carbon dioxide in aqueous solution.

Fabrication and characterization of a nanostructured TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber (eta) solar cell

In this work we report the successful assembly and characterization of a TiO2/In2S3-Sb2S3/CuSCN extremely thin absorber solar cell. Nanostructured TiO2 deposited by screen printing on an ITO substrate was used as an n-type electrode. An ~80 nm extremely thin layer of the system In2S3-Sb2S3 deposited by successive ionic layer adsorption and a reaction (silar) method was used as an absorber. The voids were filled with p-type CuSCN and the entire assembly was completed with a gold contact. The solar cell fabricated with this heterostructure showed an energy conversion efficiency of 4.9%, which is a promising result in the development of low cost and simple fabrication of solar cells.

The Extrusion Process as an Alternative for Improving the Biological Potential of Sorghum Bran: Phenolic Compounds and Antiradical and Anti-Inflammatory Capacity

Approximately 80% of sorghum phenolic compounds are linked to arabinoxylans by ester bonds, which are capable of resisting the digestion process in the upper gastrointestinal tract, compromising their bioaccessibility and biological potential. The aim of this study was to evaluate the effect of the extrusion process on the content of phenolic compounds in sorghum bran and its impact on phenolic compounds and antiradical and anti-inflammatory capacity. Results revealed that the extrusion process increased total phenol content in sorghum bran compared to nonextruded sorghum, particularly for extrusion at 180°C with 20% moisture content (2.0222 ± 0.0157 versus 3.0729 ± 0.0187u2009mgu2009GAE/g +52%), which positively affected antiradical capacity measured by the DPPH and TEAC assays. The percentage of inhibition of nitric oxide (NO) production by RAW cells due to the presence of extruded sorghum bran extract was significantly higher than that of nonextruded sorghum bran extract (90.2 ± 1.9% versus 76.2 ± 1.3%). The results suggest that extruded sorghum bran could be used as a functional ingredient and provide advantages to consumers by reducing diseases related to oxidative stress and inflammation.

Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus

Toxigenic fungi invade crops prior to harvest as well as during storage and produce harmful, even carcinogenic toxins such as aflatoxins. Since consumers demand safe commodities, and due to enhanced public awareness of the dangers of many synthetic fungicides, the importance of investigating alternative, natural products to control these toxigenic fungi is clear. This study investigated the effect of aqueous extracts of Agave americana on growth, conidia and aflatoxin production. Aspergillus parasiticus strains SRRC 148, SRRC 143 (Su-1), and A. parasiticus SRRC 162, a mutant (nor-) that accumulates norsolorinic acid (NOR, an orange-coloured intermediate of the aflatoxin pathway), were first inoculated into Adye and Mateles liquid medium, then plant extracts were added, and incubated at 28 °C for 7 days. Aflatoxin and norsolorinic acid were assayed by HPLC and spectrophotometry, respectively. While the extract of A. americana stimulated growth of the studied fungi, conidiogenesis, norsolorinic acid accumul...

Ultrasonic irradiation-assisted synthesis of Bi2S3 nanoparticles in aqueous ionic liquid at ambient condition

In this work, an easy, fast and environmentally friendly method to obtain Bi2S3 nanostructures with sphere-like morphology is introduced. The promising material was successfully synthesized by a sonochemical route in 20% 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM][EtSO4] ionic liquid solution (IL). Morphological studies by electron microscopy (SEM and TEM) show that the use of IL in the synthesis of Bi2S3 favors the formation of nanocrystals non-agglomerated. Micro Raman and energy dispersive X-ray spectroscopy (EDXS) were used to determine the composition and purity of the synthesized material. X-ray powder diffraction (XRD) and selective area electron diffraction (SAED) revealed that ultrasonic radiation accelerated the crystallization of Bi2S3 into orthorhombic bismuthinite structure. The band gap calculated from the diffuse reflectance spectra (DRS) was found to be 1.5eV.