Phenolic content and antibacterial activity of extracts of Hamelia patens obtained by different extraction methods

Abstract Hamelia patens, is a plant traditionally used to treat a variety of conditions among the Huastec people of Mexico. The objective of this study is to characterize the phenolic content and critically examine the antimicrobial activity of leaf extracts H. patens, obtained by maceration, Soxhlet and percolation, using ethanol as 70% solvent. Phenolic compounds are characterized by liquid chromatography, coupled to a High Resolution Mass Spectrometry, and the antimicrobial activity was studied from the inhibitory effect of each extract for Escherichia coli, Staphylococcus aureus, Salmonella typhi and S. paratyphi, and by the Minimum Bactericidal Concentration, the percentage of activity and the Index of Bacterial Susceptibility of each extract. The phenolic compound identified in different concentrations in the three extracts was epicatechin. The extracts obtained by the three methods had antimicrobial activity, however, there was no significant difference (p < 0.05) between the Minimum Bactericidal Concentration of the extracts obtained by maceration, percolation and Soxhlet. The results of this study contribute to the body of knowledge on the use of extracts in controlling microorganisms with natural antimicrobials.

Efecto de las diferentes fuentes de polifenoles sobre la eficiencia de liberación de ácido elágico por Aspergillus niger / Effect of different polyphenol sources on the efficiency of ellagic acid release by Aspergillus niger

Fungal hydrolysis of ellagitannins produces hexahydroxydiphenic acid, which is considered an intermediate molecule in ellagic acid release. Ellagic acid has important and desirable beneficial health properties. The aim of this work was to identify the effect of different sources of ellagitannins on the efficiency of ellagic acid release by Aspergillus niger. Three strains of A. niger (GH1, PSH and HT4) were assessed for ellagic acid release from different polyphenol sources: cranberry, creosote bush, and pomegranate used as substrate. Polyurethane foam was used as support for solid-state culture in column reactors. Ellagitannase activity was measured for each of the treatments. Ellagic acid was quantified by high performance liquid chromatography. When pomegranate polyphenols were used, a maximum value of ellagic acid (350.21 mg/g) was reached with A. niger HT4 in solid-state culture. The highest amount of ellagitannase (5176.81 U/l) was obtained at 8 h of culture when cranberry polyphenols and strain A. niger PSH were used. Results demonstrated the effect of different polyphenol sources and A. niger strains on ellagic acid release. It was observed that the best source for releasing ellagic acid was pomegranate polyphenols and A. niger HT4 strain, which has the ability to degrade these compounds for obtaining a potent bioactive molecule such as ellagic acid.

La hidrólisis fúngica de los elagitaninos produce ácido hexahidroxidifénico, considerado como una molécula intermedia en la liberación de ácido elágico. El ácido elágico tiene importantes y deseables propiedades benéficas para la salud humana. El objetivo de este trabajo fue identificar el efecto de la fuente de elagitaninos sobre la eficiente liberación de ácido elágico por Aspergillus niger. La liberación de ácido elágico se realizó con tres cepas de A. niger (GH1, PSH y HT4) en presencia de diferentes fuentes de polifenoles (arándano, gobernadora y granada), usadas como sustrato. Se empleó espuma de poliuretano como soporte para el cultivo en estado sólido en reactores en columna. Se midió la actividad elagitanasa a cada uno de los tratamientos. El ácido elágico liberado se cuantificó por cromatografía líquida de alta resolución. Cuando se utilizaron los polifenoles de granada, se alcanzó un valor máximo de 350,21 mg/g de ácido elágico con A. niger HT4 en cultivo en estado sólido. La mayor actividad elagitanasa (5176.81 U/l) se obtuvo a 8 h de cultivo cuando se usaron los polifenoles de arándano como sustrato y A. niger PSH. Los resultados demostraron el efecto que tiene la fuente de polifenoles y la cepa de A. niger en la liberación de ácido elágico. Se observó que la mejor fuente para la liberación de ácido elágico fueron los polifenoles de granada y que la cepa A. niger HT4 posee la habilidad de degradar estos compuestos para la obtención de potentes moléculas bioactivas, como el ácido elágico.

Compuestos prebióticos: de las moléculas al ser humano / Prebiotic compounds: from molecules to human beings

Según la definición otorgada por la Organización de las Naciones Unidas para la Agricultura y la Alimentación (FAO), los prebióticos son componentes no vivos de los alimentos que confieren un beneficio saludable al huésped, asociado con la modulación de la microbiota. Los compuestos prebióticos incluyen oligosacáridos (fructooligosácaridos, galactooligosacáridos, xylooligosacáridos, pecticoligosacáridos), lactosacarosa, azúcares-alcoholes, glucooligosacáridos, levanos o fructanos, almidón resistente, xylosacáridos, entre otros. Los procesos de recuperación, síntesis y/o purificación son específicos para cada grupo. El metabolismo de la microflora produce la formación de gases como H2, CO2 y CH4, y compuestos orgánicos (ácidos grasos de cadena corta y etanol) como producto de la fermentación de prebióticos. Los efectos observados por acción de los prebióticos impactan en la salud del consumidor y pueden manifestarse de forma localizada como aumento de la masa fecal, de la absorción colónica de algunos minerales y de la síntesis de ácido fólico. También, pueden observarse de forma sistémica con la disminución de colesterol, triglicéridos, amonio, urea, entre otras actividades. Una de las aplicaciones con mayor potencial de los estudios de pre y probióticos, es la formulación de alimentos simbióticos; así mismo, los prebióticos prometen cumplir con las necesidades actuales de los consumidores, quienes demandan alimentos funcionales.

According to the definition given by the United Nations Food and Agriculture Organization (FAO), prebiotics are non live components of food that grant a health benefit to the host, associated with the modulation the intestinal microbiota. Prebiotic compounds include, among others, oligosaccharides (fructooligosaccharides, galactooligosaccharides, xylooligosaccharides, pecticooligosaccharides), lactosaccharose, sugar-alcohols, glucooligosccharides, levans or fructans, resistant starch, and xylosaccharides. The recovery, synthesis and/or purification processes are specific for each group. Microflora metabolism produces formation of gases such as H2, CO2 and CH4, and organic compounds (short chain fatty acids and ethanol) as products of prebiotic fermentation. The effects on the health of the consumer produced by the action of the prebiotics can be manifested locally, as by an increase of fecal mass, colon absorption of some minerals, and folic acid synthesis. They can also be observed systemically, as by a decrease of cholesterol, triglycerides, ammonium, and urea, among other activities. One of the applications with the greatest potential in the study of pre and probiotics is the formulation of symbiotic food; probiotics also promise to fulfill the present needs of comsumers, who demand functional food.

Purification and some properties of pectinesterase from potato (Solanum tuberosum L.) alpha cultivar

Pectinesterase was extracted from potato alpha cultivar, purified and partially characterized The used protocol resulted in a 58.8-fold purification (51 850.2 units/mg protein) with 15.5 percent recovery of pectinesterase activity. The purified enzyme had a molecular weight of 27 kDa and its isoelectric point was around 4.5 with pH and temperature optima of 8.0 and 60°C, respectively. The purified enzyme had a single symmetric peak of specific activity after chromatographic steps. The homogeneity of the purified pectinesterase was confirmed by gel filtration and polyacrylamide electrophoresis gel.

A pectinesterase foi extraída da batata (cultivar do alfa), purificada e parcialmente caracterizada. O protocolo usado levou a uma proteína purificada 58,8 vezes (51 850,2 units/mg da proteína) com uma recuperação de 15,5 por cento da atividade da proteína. A enzima purificada apresentou um peso molecular de 27 kDa e seu ponto isoelétrico foi ao redor 4,5. A pectinesterase exibiu pH e temperatura ótimos de respectivamente 8,0 e 60°C. A enzima purificada apresentou um único pico simétrico de atividade específica após as etapas de cromatografia. A homogeneidade da pectinesterase purificada foi confirmada por filtração em gel e por eletroforese em gel de poliacrilamida.