Francisco J. Wong-Corral

Isolation and partial characterization of three isoamylases of Rhyzopertha dominica F. (Coleoptera: Bostrichidae)

Three isoamylases of Rhyzopertha dominica (termed RdA70, RdA79, and RdA90 according to their relative mobility in gel electrophoresis) were isolated by ammonium sulfate fractionation and hydrophobic interaction chromatography. RdA70 and RdA79 showed an optimal pH of 7.0, whereas for RdA90 the optimal pH was 6.5. The three isoamylases remained stable at 50 degrees C for 1 h, but at 60 degrees C, all lost 50% of their activity in 20 min and were completely inactivated in 1 h. RdA70 and RdA79 were inhibited by albumin extracts from wheat samples varying widely in amylase inhibitory activity; however, RdA90 was highly resistant to inhibition. beta-Mercaptoethanol up to 30 mM increased the activity of the three isoamylases by 2.5-fold. The action pattern of the three isoamylases was typical of endoamylases; however, differences were observed on the hydrolytic efficiency rates measured as V(max)/K(m) ratio on starch, amylopectin, and amylose. The hydrolyzing action of RdA90 on starch and amylopectin (V(max)/K(m)=90.4+/-2.3 and 78.9+/-6.6, respectively) was less efficient than that on amylose (V(max)/K(m)=214+/-23.2). RdA79 efficiently hydrolyzed both amylopectin and amylose (V(max)/K(m)=260.6+/-12.9 and 326.5+/-9.4, respectively). RdA70 hydrolyzed starch and amylose at similar rates (V(max)/K(m)=202.9+/-5.5 and 215.9+/-6.2, respectively), but amylopectin was a poor substrate (V(max)/K(m)=124.2+/-7.4). The overall results suggest that RdA70 and RdA79 appear to belong to a group of saccharifying isoamylases that breaks down long fragments of oligosaccharide chains produced by the hydrolytic action of RdA90. The simultaneous action of the three isoamylases on starch, aside from the high resistance of RdA90 to wheat amylase inhibitors, might allow R. dominica to feed and reproduce successfully on the wheat kernel.

Insecticide Residues in Stored Grains in Sonora, Mexico: Quantification and Toxicity Testing

Food safety has acquired great attention by food importer and exporters. Food rejection or acceptance across international borders is based on the compliance with international food regulations. Due to the lack of recent data on pesticide residues in Mexican grains, this study focused on detecting and quantifying insecticide residues in stored wheat, corn, chickpeas, and beans, as well as to determine their mutagenic potential. Grains were sampled from primary storage sites in Sonora, Mexico. Malathion, chlorpyrifos, deltamethrin, cypermethrin, 4,4-DDE, 4,4-DDD and 4,4-DDT were analyzed in 135 samples. Grain samples were not mutagenic and most pesticide levels were within regulation limits.

Starch Debranching Enzyme Activity and Its Effects on Some Starch Physicochemical Characteristics in Developing Substituted and Complete Triticales (X Triticosecale Wittmack)

The present work was carried out to make a comparison between the starch debranching enzyme activity and the synthesis of total carbohydrates, starch, amylose, and amylopectin in developing kernels of two sets of triticales differing in genome composition (complete and substituted triticales). The results showed that the carbohydrate and starch accumulation observed in both genotypes of triticales increased rapidly at the early stage, reaching the maximum at the medium stage and decreasing slightly or remaining relatively constant at the last stage of kernel development. At the end of the development stage, the mature grains of complete and substituted triticales accumulated 62.5 and 54.6% starch, respectively. Both sets of triticales showed the same amylose accumulation profile as well as degree of polymerization; however, at the maturity stage there was a small but significant difference between the two sets. The final polymerization values of amylose chains in mature seeds of complete and substituted t...

Physicochemical characterization of starch from hexaploid triticale (X Triticosecale Wittmack) genotypes

The starch granules of complete and substituted triticale genotypes were analyzed for morphology and size distribution using scanning electron microscopy (SEM) and laser diffraction, respectively. A quantitative comparison of total carbohydrate, starch, and amylose contents was also performed. The results showed that the complete triticales contained 8.8% more total carbohydrate content and 13.8% more starch content than the substituted ones. No significant differences in the average amylose content (22.8%) were observed between the two sets of triticales. However, the A- and B-type starch granules of the substituted triticales showed significant differences in amylose content. Starch granule distribution profiles showed that the sizes of the A- and B-type starch granules of complete triticales were larger (in the range of 18–41 μm and 2–13 μm, respectively) than those of substituted triticales (in the range of 8–38 μm and 0.5–6 μm, respectively). This study demonstrated that the starch in triticale genotypes differs in physicochemical properties.

Comparison of Protein and Starch Content of Substituted and Complete Triticales (X Triticosecale Wittmack): Contribution to Functional Properties

The starch and protein content of substituted and complete triticales were quantitated and evaluated for their contribution to the functional properties of flours by means of the amylograph, farinograph, and the breadmaking test. Although no clear differences were observed in the starch and protein contents of the two triticale genotypes, a detailed analysis of their components revealed compositional differences between them. The amylose content was lower in the substituted triticales Duron S and Alamos 83 than in the complete types Tarasca 87 and Brumby II (P ≤ 0.05). Among the protein fractions, only the albumin and the total polymeric protein, although with an opposite effect, significantly contributed to the rheological properties of triticale doughs evaluated with the farinograph and in the breadmaking test. The SDS-PAGE test showed that the substituted triticales contained an additional HMW-GS band that was not observed in the complete triticales. Amylograph peak temperatures and maximum viscosities, farinograph development times, and loaf volumes of triticale doughs were higher in substituted triticale flours than those of the complete ones. This study demonstrated that the triticale genotypes can be differentiated not only by quantitating their starch and protein composition, but also by testing their functional dough properties.

Relationship between Chemical and Physical Parameters of Maize Varieties and Susceptibility to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

Abstract. Fourteen varieties of maize were analyzed for physical and chemical characteristics to study their relationship with susceptibility to maize weevil, Sitophilus zeamais (Motschulsky). Free-choice and no-choice tests were carried out at 27°C and 70% relative humidity. The susceptibility of maize varieties to attack by maize weevil was not related to grain hardness nor chemical composition. Insects selected softer and harder varieties for oviposition. The number of damaged grains was positively correlated with insect emergence. Germination was less in varieties susceptible to the insect. No &agr;-amylase inhibitors were detected in the maize varieties.

Zein-polysaccharide nanoparticles as matrices for antioxidant compounds: A strategy for prevention of chronic degenerative diseases

Oxidative Stress (OS) produces the formation of free radicals and other reactive oxygen and nitrogen species that are intimately involved in many diseases, especially Chronic Degenerative Diseases (CDD) such as cancer, diabetes, cardiovascular diseases, and obesity, among others. Thus, reactive compounds need to be quenched by antioxidants. The problems of these compounds include that they are susceptible to degradation, have low bioavailability, and can lose their bioactivity in the gastroIntestinal tract. Therefore, an alternative is encapsulation. Zein is a protein used in nanotechnology as a polymer matrix because it can encapsulate different compounds such as antioxidants to provide stability and control of the release. The disadvantage of zein as a delivery vehicle is that it is limited by the low stability of aggregation when suspended in water, in addition to the conditions of acid pH or that higher ionic strength tends to destabilize. To reduce these limitations, the incorporation of polysaccharides as a second polymer matrix can provide stability in zein nanoparticles. In this review, we discuss OS as a source of CDD, the role of antioxidants in the prevention of these diseases, and the preparation, characterization, and application of antioxidant-zein-polysaccharide particles as delivery systems as well as possible mechanisms to control CDD.

Características de la germinación de Lippiapalmeri (Wats) proveniente de regiones silvestres del desierto de Altar, Sonora, México

espanolExisten varias especies del genero de Lippia nativas e introducidas, que son de gran potencial en zonas aridas del noroeste de Mexico; estas especies presentan bajo porcentaje de germinacion debido a la dureza y/o dormancia de la semilla. El objetivo del presente estudio consistio en dilucidar el efecto del acido giberelico sobre la germinacion de la semillas silvestre de Lippia palmeri. Para ello se recolecto la semilla en dos regiones nativas (Puerto del Oregano y Santa Ana, Sonora). Se probaron tres concentraciones con acido giberelico (GA3) (100, 200 y 300 ppm, sometidas a tres tiempos de remojo de la semilla (30, 60 y 120 min.) y como control agua destilada. Para cada tratamiento se utilizaron 100 semillas por caja Petri por triplicado siendo un total de 72 cajas Petri colocadas a una temperatura ambiente de 27 °C y 80% de humedad relativa. Para la concentracion de 100 ppm en los tres tratamientos de remojo la semilla de Puerto del Oregano, mostro un alto porcentaje de germinacion (90, 100 y 100%), para los tratamientos de 200 y 300 ppm el porcentaje de semilla germinada fue menor (80%). La semilla de Santa Ana mostro el porcentaje mas alto de germinacion con (80%) obtenido a 300 ppm y 120 minutos en remojo, el resto de los tratamientos no supero el 70% de germinacion. Se concluye que Lippia palmeri requieren ser estimuladas por la giberelina a fin de promover la accion enzimatica que induce la ruptura de las sustancias de reserva de la semilla. EnglishThere are several species of native and introduced Lippia, which are of great potential in arid areas of Northwest Mexico; these species have low germination percentage due to the hardness and / or seed dormancy. The aim of this study was to elucidate the effect of gibberellic acid on germination of seeds of wild Lippia palmeri. To do this, the seed was collected in two native sites (Puerto del Oregano and Santa Ana, Sonora). Three concentrations with gibberellic acid (GA3) (100, 200 and 300ppm), subjected to three times of soaking the seed (30, 60 and 120 min.) were tested and as a control distilled water. For each treatment 100 seeds were used by Petri dish in triplicate with a total of 72 Petri plates placed in an ambient of 27 °C and 80% relative humidity. For the concentration of 100 ppm in the three treatments soaking seed port oregano, showed a high percentage of germination (90, 100 and 100%); for treatments of 200 and 300 ppm the percentage of germinated seed was lower (80%). The seed of Santa Ana showed the highest percentage of germination (80%) obtained 300 ppm and 120 minute soak; the other treatments did not exceed 70% germination. It is concluded that Lippia palmeri require stimulated by giberalina to promote the enzymatic action inducing breakdown of reserve substances seed.

Insecticidal Efficacy and Repellency of Oregano (Lippia palmeri) Essential Oil for Control of Sitophilus zeamais and Prostephanus truncatus in Stored Maize

Abstract. Maize, Zea mays L., is the most important crop in Mexico. The maize weevil, Sitophilus zeamais Motschulsky, and larger grain borer, Prostephanus truncatus (Horn), cause significant loss to stored maize. The insects are controlled by insecticides that are toxic to humans and pollute the environment. An alternative to control insect damage is essential oil from plants. The aim of this research was to evaluate the effect of oregano (Lippia palmeri S. Watson) oil at different concentrations on repellence, emergence, and mortality of maize weevil and larger grain borer. All maize weevils died at 48 hours, while most (92%) larger grain borer died at 72 hours with 1,000 µl/liter of oregano oil. Emergence of treated insects was significantly (p < 0.05) less than the check. The repellency index at 24 hours for larger grain borer was 0.15 at a concentration of 20 µl/liter of oregano oil. The repellency index for maize weevil was zero, indicating total repellence at 24 hours. Components of the oil were determined by gas chromatography-mass spectrometry to be thymol (58.9%) and p-cymene (21.8%). Oregano oil concentration and time were important in controlling both insect species.

Anti-Inflammatory Activity and Changes in Antioxidant Properties of Leaf and Stem Extracts from Vitex mollis Kunth during In Vitro Digestion

Vitex mollis is used in traditional Mexican medicine for the treatment of some ailments. However, there are no studies on what happens to the anti-inflammatory activity or antioxidant properties and total phenolic content of leaves and stem extracts of Vitex mollis during the digestion process; hence, this is the aim of this work. Methanolic, acetonic, and hexanic extracts were obtained from both parts of the plant. Extract yields and anti-inflammatory activity (elastase inhibition) were measured. Additionally, changes in antioxidant activity (DPPH and ABTS) and total phenols content of plant extracts before and after in vitro digestion were determined. The highest elastase inhibition to prevent inflammation was presented by hexanic extracts (leaf = 94.63% and stem = 98.30%). On the other hand, the major extract yield (16.14%), antioxidant properties (ABTS = 98.51% and DPPH = 94.47% of inhibition), and total phenols (33.70 mg GAE/g of dried sample) were showed by leaf methanolic extract. Finally, leaf and stem methanolic extracts presented an antioxidant activity increase of 35.25% and 27.22%, respectively, in comparison to their initial values after in vitro digestion process. All samples showed a decrease in total phenols at the end of the digestion. These results could be the basis to search for new therapeutic agents from Vitex mollis.