Detection of mecA Genes in Hospital-Acquired MRSA and SOSA Strains Associated with Biofilm Formation.

Methicillin-resistant (MR) Staphylococcus aureus (SA) and others, except for Staphylococcus aureus (SOSA), are common in healthcare-associated infections. SOSA encompass largely coagulase-negative staphylococci, including coagulase-positive staphylococcal species. Biofilm formation is encoded by the icaADBC operon and is involved in virulence. mecA encodes an additional penicillin-binding protein (PBP), PBP2a, that avoids the arrival of ß-lactams at the target, found in the staphylococcal cassette chromosome mec (SCCmec). This work aims to detect mecA, the bap gene, the icaADBC operon, and types of SCCmec associated to biofilm in MRSA and SOSA strains. A total of 46% (37/80) of the strains were S. aureus, 44% (35/80) S. epidermidis, 5% (4/80) S. haemolyticus, 2.5% (2/80) S. hominis, 1.25% (1/80) S. intermedius, and 1.25% (1/80) S. saprophyticus. A total of 85% were MR, of which 95.5% showed mecA and 86.7% ß-lactamase producers; thus, Staphylococcus may have more than one resistance mechanism. Healthcare-associated infection strains codified type I-III genes of SCCmec; types IV and V were associated to community-acquired strains (CA). Type II prevailed in MRSA mecA strains and type II and III in MRSOSA (methicillin-resistant staphylococci other than Staphylococcus aureus). The operon icaADBC was found in 24% of SA and 14% of SOSA; probably the arrangement of the operon, fork formation, and mutations influenced the variation. Methicillin resistance was mainly mediated by the mecA gene; however, there may be other mechanisms that also participate, since biofilm production is related to genes of the icaADBC operon and methicillin resistance was not associated with biofilm production. Therefore, it is necessary to strengthen surveillance to prevent the spread of these outbreaks both in the nosocomial environment and in the community.

Aptamers: A Cutting-Edge Approach for Gram-Negative Bacterial Pathogen Identification.

Early and accurate diagnoses of pathogenic microorganisms is essential to correctly identify diseases, treating infections, and tracking disease outbreaks associated with microbial infections, to develop precautionary measures that allow a fast and effective response in epidemics and pandemics, thus improving public health. Aptamers are a class of synthetic nucleic acid molecules with the potential to be used for medical purposes, since they can be directed towards any target molecule. Currently, the use of aptamers has increased because they are a useful tool in the detection of specific targets. We present a brief review of the use of aptamers to detect and identify bacteria or even some toxins with clinical importance. This work describes the advances in the technology of aptamers, with the purpose of providing knowledge to develop new aptamers for diagnoses and treatment of different diseases caused by infectious microorganisms.

Bifidobacterium longum LBUX23 Isolated from Feces of a Newborn; Potential Probiotic Properties and Genomic Characterization.

Bifidobacterium longum is considered a microorganism with probiotic potential, which has been extensively studied, but these probiotic effects are strain dependent. This work aims to characterize the probiotic potential, based on the biochemical and genomic functionality, of B. longum LBUX23, isolated from neonates' feces. B. longum LBUX23 contains one circular genome of 2,287,838 bp with a G+C content of 60.05%, no plasmids, no CRISPR-Cas operon, possesses 56 tRNAs, 9 rRNAs, 1 tmRNA and 1776 coding sequences (CDSs). It has chromosomally encoded resistance genes to ampicillin and dicloxacillin, non-hemolytic activity, and moderate inhibition of Escherichia coli ATCC 25922 and to some emergent pathogen's clinical strains. B. longum LBUX23 was able to utilize lactose, sucrose, fructooligosaccharides (FOS), and lactulose. The maximum peak of bacterial growth was observed in sucrose and FOS at 6 h; in lactose and lactulose, it was shown at 8 h. B. longum LBUX23 can survive in gastrointestinal conditions (pH 4 to 7). A decrease in survival (96.5 and 93.8%) was observed at pH 3 and 3.5 during 120 min. argC, argH, and dapA genes could be involved in this tolerance. B. longum LBUX23 can also survive under primary and secondary glyco- or tauro-conjugated bile salts, and a mixture of bile salts due to the high extracellular bile salt hydrolase (BSH) activity (67.3 %), in taurocholic acid followed by taurodeoxycholic acid (48.5%), glycocholic acid (47.1%), oxgall (44.3%), and glycodeoxycholic acid (29.7%) probably due to the presence of the cbh and gnlE genes which form an operon (start: 119573 and end: 123812). Low BSH activity was determined intracellularly (<7%), particularly in glycocholic acid; no intracellular activity was shown. B. longum LBUX23 showed antioxidant effects in DPPH radical, mainly in intact cells (27.4%). In the case of hydroxyl radical scavenging capacity, cell debris showed the highest reduction (72.5%). In the cell-free extract, superoxide anion radical scavenging capacity was higher (90.5%). The genome of B. longum LBUX23 contains PNPOx, AhpC, Bcp, trxA, and trxB genes, which could be involved in this activity. Regarding adherence, it showed adherence up to 5% to Caco-2 cells. B. longum LBUX23 showed in vitro potential probiotic properties, mainly in BSH activity and antioxidant capacity, which indicates that it could be a good candidate for antioxidant or anti-cholesterol tests using in vivo models.

Isolation and Identification of Multidrug-Resistant Klebsiella pneumoniae Clones from the Hospital Environment.

Global dispersion, hospital outbreaks, and lineage relationships between emerging antibiotic-resistant strains such as Klebsiella pneumoniae are of public health interest. This study aimed to isolate and identify K. pneumoniae clones from third-level healthcare hospitals in Mexico to establish their multidrug-resistant phenotype, phylogeny, and prevalence. Biological and abiotic surface samples were used to isolate K. pneumoniae strains and to test their antibiotic susceptibility to classify them. The housekeeping genes: gapA, InfB, mdh, pgi, phoE, ropB, and tonB were used for multilocus sequence typing (MLST). Phylogenetic networks were constructed with 48 strains. Isolated strains (93) were mainly from urine and blood, 96% were resistant to ampicillin as expected, 60% were extended-spectrum ß-lactamases (ESBL), 98% were susceptible to ertapenem and meropenem and 99% were susceptible to imipenem, 46% were multi-drug resistant (MDR), 17% were extensively-drug resistant (XDR), 1% were pan-drug resistant (PDR), and 36% were not classified. The tonB, mdh, and phoE genes were the most variable, and the InfB gene showed positive selection. The most prevalent sequence types (STs) were ST551 (six clones), ST405 (six clones), ST1088 (four clones), ST25 (four clones), ST392 (three clones), and ST36 (two clones). ST706 was PDR, and ST1088 clones were MDR; neither of these STs has been reported in Mexico. The strains analyzed were from different hospitals and locations; thus, it is important to maintain antibiotic surveillance and avoid clone dissemination to prevent outbreaks, adaptation to antibiotics, and the transmission of antibiotic resistance.

Genomic and Biochemical Characterization of Bifidobacterium pseudocatenulatum JCLA3 Isolated from Human Intestine.

Bifidobacteria have been investigated due to their mutualistic microbe-host interaction with humans throughout their life. This work aims to make a biochemical and genomic characterization of Bifidobacterium pseudocatenulatum JCLA3. By multilocus analysis, the species of B. pseudocatenulatum JCLA3 was established as pseudocatenulatum. It contains one circular genome of 2,369,863 bp with G + C content of 56.6%, no plasmids, 1937 CDSs, 54 tRNAs, 16 rRNAs, 1 tmRNA, 1 CRISPR region, and 401 operons predicted, including a CRISPR-Cas operon; it encodes an extensive number of enzymes, which allows it to utilize different carbohydrates. The ack gene was found as part of an operon formed by xfp and pta genes. Two genes of ldh were found at different positions. Chromosomally encoded resistance to ampicillin and cephalothin, non-hemolytic activity, and moderate inhibition of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 6538 were demonstrated by B. pseudocatenulatum JCLA3; it can survive 100% in simulated saliva, can tolerate primary and secondary glyco- or tauro-conjugated bile salts but not in a mix of bile; the strain did not survive at pH 1.5-5. The cbh gene coding to choloylglycine hydrolase was identified in its genome, which could be related to the ability to deconjugate secondary bile salts. Intact cells showed twice as much antioxidant activity than debris. B. pseudocatenulatum JCLA3 showed 49% of adhesion to Caco-2 cells. The genome and biochemical analysis help to elucidate further possible biotechnological applications of B. pseudocatenulatum JCLA3.

Strategies for the Identification and Assessment of Bacterial Strains with Specific Probiotic Traits.

Early in the 1900s, it was proposed that health could be improved and senility delayed by manipulating gut microbiota with the host-friendly bacteria found in yogurt. Later, in 1990, the medical community reconsidered this idea and today probiotics represent a developed area of research with a billion-dollar global industry. As a result, in recent decades, increased attention has been paid to the isolation and characterization of novel probiotic bacteria from fermented foods and dairy products. Most of the identified probiotic strains belong to the lactic acid bacteria group and the genus Bifidobacterium. However, current molecular-based knowledge has allowed the identification and culture of obligatory anaerobic commensal bacteria from the human gut, such as Akkermansia spp. and Faecalibacterium spp., among other human symbionts. We are aware that the identification of new strains of these species does not guarantee their probiotic effects and that each effect must be proved through in vitro and in vivo preclinical studies before clinical trials (before even considering it as a probiotic strain). In most cases, the identification and characterization of new probiotic strain candidates may lack the appropriate set of in vitro experiments allowing the next assessment steps. Here, we address some innovative strategies reported in the literature as alternatives to classical characterization: (i) identification of alternatives using whole-metagenome shotgun sequencing, metabolomics, and multi-omics analysis; and (ii) probiotic characterization based on molecular effectors and/or traits to target specific diseases (i.e., inflammatory bowel diseases, colorectal cancer, allergies, among others).

Ingesta alimentaria y composición corporal asociadas a síndrome metabólico en estudiantes universitarios / Dietary intake and body composition associated with metabolic syndrome in university students

Resumen El objetivo de este estudio fue conocer la relación de la ingesta alimentaria (IA) y la composición corporal (CMC) con el síndrome metabólico (SM) entre estudiantes universitarios. Participaron 50 alumnos (56% mujeres) de entre 19 y 25 años de edad (M = 20.58, DE = 1.86), quienes completaron un cuestionario dirigido a evaluar IA, además se recabaron parámetros bioquímicos y de CMC. De acuerdo con el porcentaje de grasa corporal (PG), se identificó una alta ocurrencia de sobrepeso (22%) y obesidad (38%). Además, la grasa visceral incrementó conforme aumentó el PG. En ambos sexos existió un consumo bajo de hidratos de carbono y alto en lípidos, mayormente de origen animal, así como alto consumo de grasas saturadas, pero bajo de omegas 3 y 6. El SM fue identificado en 20% de la muestra, principalmente mujeres. El criterio de riesgo más frecuente fue los bajos niveles séricos de colesterol HDL, seguido de la obesidad abdominal; en tanto que la dislipidemia más frecuente fue la hipertrigliceridemia. En este estudio, aunque no se encontró relación directa entre IA y SM, si de éste con indicadores de CMC. Resulta inminente la necesidad de implementar estrategias que permitan a los estudiantes universitarios adquirir hábitos alimentarios y de actividad física saludables.

Abstract The objective of this study was to know the relationship between dietary intake (DI) and body composition (BC) with the metabolic syndrome (MS) among university students. A total of 50 students (56% female) among 19 and 25 years of age (M = 20.58, SD = 1.86), completed a questionnaire aimed at assessing DI, in addition biochemical and BC parameters were collected. According to the percentage of body fat (BF), a high prevalence of overweight (22%) and obesity (38%) was identified. In addition, visceral fat increased as the BF increased. In both sexes, there was a low consumption of carbohydrates and high in lipids, mostly of animal fat as well as high consumption of saturated fats, but low omegas 3 y 6. The MS was identified in 20% of the sample, mainly in women. The most frequently risk criteria were low levels of HDL cholesterol, followed by abdominal obesity; whereas the most frequent dyslipidemia was hypertriglyceridemia. In this study, although no direct relationship was found between DI and MS, it was found between MS and BC indicators. It is imminent the need to implement strategies that allow university students to acquire healthy eating and physical activity habits.

Anthropometric measure and adipokine levels of a young undergraduate population with a usual diet.

INTRODUCTION: Background: the aim of this study was to evaluate the intake of nutrients, anthropometric parameters, health indicators, adipokines and insulin levels in a population of young undergraduates. Method: in this study, 378 young undergraduates were invited to participate. Due to the inclusion criteria and their own decision of participating, 90 attended the anthropometric, health indicators: waist circumference (WC), waist to hip ratio (WHR), waist to height ratio (WHtR), and homeostatic model assessment-insulin resistance index (HOMA-IR) studies and completed the questionnaire of frequency of food intake; and 34 participants were selected to perform the determination of biochemical parameters, insulin and adipokines levels: leptin, IL-6, IL-8, tumor necrosis factor alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and hepatocyte growth factor (HGF). Results: according to WC, WHR and WHtR, obese population showed health, cardiovascular and metabolic risk. Overweight population showed cardiometabolic risk. In general, lipid intake was higher than 30%, being animal fat the most consumed. The levels of leptin (women: 17.2 ± 9.2, 28 ± 11.3, 36.8 ± 17.8; men: 4.3 ± 3.6, 9.5 ± 3.1, 24.6 ± 16.4 to lean overweight and obese, respectively) and insulin (women: 408 ± 182, 438 ± 187, 768 ± 167; men: 244 ± 88, 520 ± 256, 853 ± 590) increased along with body mass index (BMI), body fat percentage (BFP), visceral fat area (VFA), WC, WHR and WHtR. Lean (2.4 ± 1.3), overweight (2.2 ± 0.9) and obese (4.3 ± 1.1) women and overweight (2.8 ± 1.2) and obese (5.0 ± 3.1) men showed insulin resistance according to HOMA-IR. Significant correlation between leptin and HOMA-IR was found (p = 0.41). BMI, BFP, VFA, WC, and WHtR positively correlated with leptin (p = 0.67, 0.75, 0.66, 0.60, 0.67, respectively) and insulin (p = 0.37, 0.40, 0.48, 0.49, 0.42, respectively), while WHR only with insulin (p = 0.43). No significant differences were found in the other adipokines. Conclusion: the use of health indicators such VFA, WC, WHR, WHtR and HOMA-IR are useful tools in the determination of health, cardio vascular and metabolic risk and are correlated with levels of leptin and insulin in the studied population.

INTRODUCCIÓN: Introducción: el objetivo de este estudio fue evaluar la ingesta de nutrientes, parámetros antropométricos, indicadores de salud, adipocinas y niveles de insulina en una población de jóvenes universitarios con una dieta habitual. Método: en este estudio se invitó a participar a 378 jóvenes universitarios. Debido a los criterios de inclusión y su propia decisión de participar, 90 asistieron a los estudios antropométricos y de indicadores de salud: circunferencia de cintura (WC), índice de cadera cintura (WHR), índice de cintura-talla (WHtR) y modelo homeostático de evaluación-índice de resistencia a la insulina (HOMA-IR) y completaron el cuestionario de frecuencia de ingesta de alimentos. Treinta y cuatro participantes fueron seleccionados para realizar la determinación de los parámetros bioquímicos, niveles de insulina y adipocinas (leptina, IL-6, IL-8, factor de necrosis tumoral alfa [TNF-α], proteína quimioatractante de monocitos-1 [MCP-1] y factor de crecimiento hepático [HGF]). Resultados: de acuerdo con WC, WHR y WHtR, la población obesa mostró riesgo cardiovascular, metabólico y para la salud. La población con sobrepeso mostró riesgo cardiometabólico. En general, la ingesta de lípidos fue superior al 30% y la grasa animal fue la más consumida. Los niveles de leptina (mujeres: 17,2 ± 9,2, 28 ± 11,3, 36,8 ± 17,8; hombres: 4,3 ± 3,6, 9,5 ± 3,1, 24,6 ± 16,4 para delgados, sobrepeso y obesos, respectivamente) e insulina (mujeres: 408 ± 182, 438 ± 187, 768 ± 167; hombres: 244 ± 88, 520 ± 256, 853 ± 590) aumentaron junto con el índice de masa corporal (BMI), porcentaje de grasa corporal (BFP), área de grasa visceral (VFA), WC, WHR y WHtR. Las mujeres delgadas (2,4 ± 1,3), con sobrepeso (2,2 ± 0,9) y obesas (4,3 ± 1,1) y los hombres con sobrepeso (2,8 ± 1,2) y obesos (5,0 ± 3,1) mostraron resistencia a la insulina de acuerdo con HOMA-IR. Se encontró una correlación significativa entre leptina y HOMA-IR (p = 0,41). BMI, BFP, VFA, WC y WHtR correlacionaron positivamente con leptina (p = 0,67, 0,75, 0,66, 0,60 y 0,67, respectivamente) e insulina (p = 0,37, 0,40, 0,48, 0,49 y 0,42, respectivamente), mientras que el WHR solo con insulina (p = 0,43). No se encontraron diferencias significativas en las otras adipocinas. Conclusión: el uso de indicadores de salud como VFA, WC, WHR, WHtR y HOMA-IR es una herramienta útil en la determinación del riesgo metabólico, cardiovascular y de salud, y dichos indicadores correlacionaron con los niveles de leptina e insulina en la población estudiada.

Anthropometric measure and adipokine levels of a young undergraduate population with a usual diet / Medidas antropométricas y niveles de adipocinas de una población joven de pregrado con dieta habitual

Background: obesity is the excessive accumulation of adipose tissue related to food intake and other factors. The aim of this study was to evaluate the intake of nutrients, anthropometric parameters, health indicators, adipokines and insulin levels in a population of young undergraduates. Method: in this study, 378 young undergraduates were invited to participate. Due to the inclusion criteria and their own decision of participating, 90 attended the anthropometric, health indicators: waist circumference (WC), waist to hip ratio (WHR), waist to height ratio (WHtR), and homeostatic model assessment-insulin resistance index (HOMA-IR) studies and completed the questionnaire of frequency of food intake; and 34 participants were selected to perform the determination of biochemical parameters, insulin and adipokines levels: leptin, IL-6, IL-8, tumor necrosis factor alpha (TNF- α), monocyte chemoattractant protein-1 (MCP-1) and hepatocyte growth factor (HGF). Results: according to WC, WHR and WHtR (women: 104 ± 20, 0.87 ± 0.08, 0.6 ± 0.13; men: 112 ± 10, 0.95 ± 0.09, 0.64 ± 0.06, respectively), obese population showed health, cardiovascular and metabolic risk. Overweight population showed cardiometabolic risk. In general, lipid intake was higher than 30%, being animal fat the most consumed. The levels of leptin (women: 17.2 ± 9.2, 28 ± 11.3, 36.8 ± 17.8; men: 4.3 ± 3.6, 9.5 ± 3.1, 24.6 ± 16.4 to lean overweight and obese, respectively) and insulin (women: 408 ± 182, 438 ± 187, 768 ± 167; men: 244 ± 88, 520 ± 256, 853 ± 590) increased along with body mass index (BMI), body fat percentage (BFP), visceral fat area (VFA), WC, WHR and WHtR. Lean (2.4 ± 1.3), overweight (2.2 ± 0.9) and obese (4.3 ± 1.1) women and overweight (2.8 ± 1.2) and obese (5.0 ± 3.1) men showed insulin resistance according to HOMA-IR. Significant correlation between leptin and HOMA-IR was found (p = 0.41). BMI, BFP, VFA, WC, and WHtR positively correlated with leptin (p = 0.67, 0.75, 0.66, 0.60, 0.67, respectively) and insulin (p = 0.37, 0.40, 0.48, 0.49, 0.42, respectively), while WHR only with insulin (p = 0.43). No significant differences were found in the other adipokines. Conclusion: the use of health indicators such VFA, WC, WHR, WHtR and HOMA-IR are useful tools in the determination of health, cardio vascular and metabolic risk and are correlated with levels of leptin and insulin in the studied population

Introducción: la obesidad es la acumulación excesiva de tejido adiposo relacionada con la ingesta de alimentos y otros factores. El objetivo de este estudio fue evaluar la ingesta de nutrientes, parámetros antropométricos, indicadores de salud, adipocinas y niveles de insulina en una población de jóvenes universitarios con una dieta habitual. Método: en este estudio se invitó a participar a 378 jóvenes universitarios. Debido a los criterios de inclusión y su propia decisión de participar, 90 asistieron a los estudios antropométricos y de indicadores de salud: circunferencia de cintura (WC), índice de cadera cintura (WHR), índice de cintura-talla (WHtR) y modelo homeostático de evaluación-índice de resistencia a la insulina (HOMA-IR) y completaron el cuestionario de frecuencia de ingesta de alimentos. Treinta y cuatro participantes fueron seleccionados para realizar la determinación de los parámetros bioquímicos, niveles de insulina y adipocinas (leptina, IL-6, IL-8, factor de necrosis tumoral alfa [TNF- α], proteína quimioatractante de monocitos-1 [MCP-1] y factor de crecimiento hepático [HGF]). Resultados: de acuerdo con WC, WHR y WHtR (mujeres: 104 ± 20, 0,87 ± 0,08, 0,6 ± 0,13; hombres: 112 ± 10, 0,95 ± 0,09, 0,64 ± 0,06, respectivamente), la población obesa mostró riesgo cardiovascular, metabólico y para la salud. La población con sobrepeso mostró riesgo cardiometabólico. En general, la ingesta de lípidos fue superior al 30% y la grasa animal fue la más consumida. Los niveles de leptina (mujeres: 17,2 ± 9,2, 28 ± 11,3, 36,8 ± 17,8; hombres: 4,3 ± 3,6, 9,5 ± 3,1, 24,6 ± 16,4 para delgados, sobrepeso y obesos, respectivamente) e insulina (mujeres: 408 ± 182, 438 ± 187, 768 ± 167; hombres: 244 ± 88, 520 ± 256, 853 ± 590) aumentaron junto con el índice de masa corporal (BMI), porcentaje de grasa corporal (BFP), área de grasa visceral (VFA), WC, WHR y WHtR. Las mujeres delgadas (2,4 ± 1,3), con sobrepeso (2,2 ± 0,9) y obesas (4,3 ± 1,1) y los hombres con sobrepeso (2,8 ± 1,2) y obesos (5,0 ± 3,1) mostraron resistencia a la insulina de acuerdo con HOMA-IR. Se encontró una correlación significativa entre leptina y HOMA-IR (p = 0,41). BMI, BFP, VFA, WC y WHtR correlacionaron positivamente con leptina (p = 0,67, 0,75, 0,66, 0,60 y 0,67, respectivamente) e insulina (p = 0,37, 0,40, 0,48, 0,49 y 0,42, respectivamente), mientras que el WHR solo con insulina (p = 0,43). No se encontraron diferencias signifi cativas en las otras adipocinas. Conclusión: el uso de indicadores de salud como VFA, WC, WHR, WHtR y HOMA-IR es una herramienta útil en la determinación del riesgo metabólico, cardiovascular y de salud, y dichos indicadores correlacionaron con los niveles de leptina e insulina en la población estudiada

Antibiotic resistance and tolerance to simulated gastrointestinal conditions of eight hemolytic Bacillus pumilus isolated from pulque, a traditional Mexican beverage.

Traditional fermented sap beverages from two provinces of Mexico were studied for the isolation of pathogenic bacteria from these beverages. Eight strains of hemolytic Gram positive bacteria, identified as Bacillus pumilus (B. pumilus), were isolated. They showed different antibiotic resistance profiles and tolerances to the simulated gastrointestinal conditions. All the B. pumilus isolated were resistant to at least one antibiotic tested. Regarding the simulated gastrointestinal conditions, strains S1 and S3 were able to tolerate all the conditions. Hemolytic activity has been associated with a health risk and is often considered as a virulence determinant associated with pathogenicity. Therefore, the hemolytic activity along with the ability to tolerate gastrointestinal conditions and the resistance to antibiotics exhibited by B. pumilus strains S1 and S3 could be associated with a health risk for pulque consumers.

Correlation between diet and gut bacteria in a population of young adults.

Dietary habits strongly influence gut microbiota. The aim of this study was to compare and correlated the abundance of Firmicutes and Bacteroidetes phyla, some representative bacteria of these phyla such as Bacteroides thetaiotaomicron, Prevotella, Faecalibacterium prausnitzii, Clostridium leptum and Bifidobacterium longum as a member of Actinobacteria phylum in young adults with their food intake. Faecal samples used came from lean subjects (BMI = 19.83 ± 0.94 kg/m(2)), overweight (BMI = 27.17 ± 0.51 kg/m(2)) and obese (BMI = 41.33 ± 5.25 kg/m(2)). There were significant differences in total studied gut microbiota between the overweight and lean groups. Members of the Firmicutes phylum, and Bifidobacterium longum, were more abundant in the lean group. The results suggest that diet rich in unsaturated fatty acids and fibre promote an abundant population of beneficial bacteria such as B. longum and Bacteroidetes. However, it has been considered that the results may be biased due to the size of the individuals studied; therefore the results could be only valid for the studied population.

Siderin from Toona ciliata (Meliaceae) as photosystem II inhibitor on spinach thylakoids.

Four natural products were isolated from plants of the Rutaceae and Meliaceae families and their effect on photosynthesis was tested. Siderin (1) inhibited both ATP synthesis and electron flow (basal, phosphorylating, and uncoupled) from water to methylviologen (MV); therefore, it acts as Hill reaction inhibitor in freshly lysed spinach thylakoids. Natural products 2-4 were inactive. Secondary metabolite 1 did not inhibit PSI electron transport. It inhibits partial reactions of PSII electron flow from water to 2,6-dichlorophenol indophenol (DCPIP), from water to sodium silicomolybdate, and partially inhibits electron flow from diphenylcarbazid (DPC) to DCPIP. These results established that the site of inhibition of 1 was at the donor and acceptor sides of PSII, between P(680) and Q(A). Chlorophyll a fluorescence measurements confirmed the behavior of the Toona ciliate coumarin 1 as P(680) to Q(A) inhibitor by the creation of silent centers. May be this is the mechanisms of action of 1 and is the way in which it develops a phytotoxic activity against photosynthesis.

Pachypodol from Croton ciliatoglanduliferus Ort. as water-splitting enzyme inhibitor on thylakoids.

A bioactivity-guided chemical study of aerial parts of Croton ciliatoglanduliferus Ort. led to the isolation for the first time of the flavonoids retusin (5-hydroxy-3,7,3',4'-tetramethoxyflavone) (1) and pachypodol (5,4'-dihydroxy-3,7,3'-trimethoxyflavone) (2) from the n-hexane extract. Compounds 1 and 2 were separated by preparative thin-layer chromatography. Compound 2 was the most active compound on ATP synthesis inhibition. The I50 value was 51 microM. Pachypodol behaves as a Hill reaction inhibitor. It inhibited the uncoupled electron flow on photosystem II partial reaction from water to dichlorophenol indophenol (DCPIP) and from water to sodium silicomolybdate. However, the uncoupled partial reaction from diphenylcarbazide to DCPIP and the uncoupled photosystem I from DCPIPred to MV were not inhibited by 2. These results were corroborated by fluorescence decay data. Therefore, pachypodol inhibits the water-splitting enzyme activity. Compound 1 with a 4'-methoxy group was a weak inhibitor, indicating that the 4' free -OH group is important for strong inhibition.