Secondary metabolites

Top PDF Secondary metabolites:

Evaluación de la capacidad antioxidante y metabolitos secundarios de extractos de dieciséis plantas medicinales / Evaluation of antioxidant capacity and secondary metabolites of sixteen medicinal plants extracts

Evaluación de la capacidad antioxidante y metabolitos secundarios de extractos de dieciséis plantas medicinales / Evaluation of antioxidant capacity and secondary metabolites of sixteen medicinal plants extracts

value (g/mL) (necessary amount to inhibit the formation of 50% of DPPH radical). The low value of IC50 reflects better free radical scavenging action. Although most of the samples tested showed good antioxidant capacity with this method (DPPH), tests of hydro- alcoholic extracts show that alcachofa (IC50 9.89 mg/mL), moringa (IC50 11.4 mg/mL) and borraja (IC50 14.0 mg/mL) were those with higher antioxidant capacity. Through chemical characterization tests, the presence of flavonoids, tannins, triterpenes, alkaloids and saponins were detected in most of the analyzed species (approximately 56-69%); only 20% of them showed the presence of polyphenols, cyanogenic glycosides, lactones, coumarins, anthraquinones and sterols. According to the results obtained, these plants might be considered as promising sources of secondary metabolites with antioxidant activity.

7 Lee mas

Isolation and characterizacion of enzymes involved in the biosynthesis of secondary metabolites with phytotherapeutic interest

Isolation and characterizacion of enzymes involved in the biosynthesis of secondary metabolites with phytotherapeutic interest

Nowadays, there are several strategies to identify and to analyze genes that encode interesting enzymes, such as GTs and GHs. One of these strategies is the analysis of the expressed sequence tags (ESTs) through bioinformatics tools. The use of these ESTs allows the elucidation, in several cases, of the nucleotide sequence of plant genes. ESTs are determined by single-pass sequencing of the 5’ or 3’ ends of cDNA clones. The cDNA libraries are generated from tissue, developmental stage or specific mRNA samples. Therefore, ESTs are a powerful strategy for gene identification, gene expression studies and identification of important genetic variants such as single nucleotide polymorphisms (SNP). ESTs have been used to identify GTs involved in the glycosylation of secondary metabolites in Stevia rebaudina leafs [9], in the glucosylation of flavonoids in Maclura pomifera fruits [10], to identify and to characterize GTs with in vitro activity against isoflavones, flavones and flavonols in Medicago trunculata [11], to identify a UDP-Glc: cinnamate glucosyltransferase involved in the biosynthesis of cinnamic acid, a precursor of some metabolites responsible for flavor in strawberries [12], to a GT involved in the biosynthesis of phloridzin, the most important phenolic compounds in apple [13], and 6 GTs involved in glycyrrhizin biosynthesis in Glycyrrhiza uralensis, one of the most popular medicinal plants in the world which is used in food and tobacco flavoring [14]. Recently, 454 pyrosequencing technology have been used as first step for isolation and characterization of GTs and GHs in Consolida orientalis from a ESTs library, which are involved in the benzoxazinoid biosynthesis, one of the multiple metabolites secondary involved in the defense against herbivores and pathogens attack [15].

221 Lee mas

2020.05.03.3

2020.05.03.3

DOI. 10.21931/RB/2020.05.03.3 Abstract: The shitake mushroom (Lentinula edodes) is the second most-consumed mushroom in the world; in Colombia, it is cultivated and commercialized on a small scale in some supermarkets. Little is known about the procedence, nutritional and medicinal properties of Shiitake produced in Colombia. In this study, four shiitake isolates grown in Colombia (LEUCO1, LEUCO2, LEUCO3, and LEUCO4) were sequenced in their ITS genes and evaluated for the production of three medicinal metabolites, eritadenine, ergotioneine and β-glucans (1,3-1, 6), using submerged culture. Genetic analysis revealed that all the isolates were close and related to the Japanese strain Cr62. LEUCO1 and LEUCO2 showed a distance of 0.000, as well as LEUCO3 and LEUCO4. All four isolates produced erythadenine in a range of 26.3-8.6 mg / L, with the best performance of LEUCO1 at 26.3 mg / L (p <0.05). Ergotioneine was produced with similar statistical yields in all the isolates with an average of 0.7 mg / g of dry weight biomass (DW). Β-glucans (1.3-1.6) were produced with yields of 5.6 - 3.8% of DW biomass, with the best values for LEUCO2 and the lowest for LEUCO4 (p <0.05). In conclusion, we identified low genetic diversity in the four isolates, corresponding to two haplotypes with minimal genetic difference between them, related to the Japanese strain Cr62, indicating that Colombian farmers cultivate almost the same strains of shitake. Secondary metabolites, eritadenine, β-glucans and ergotioneine were found in promising yields useful for the pharmaceutical and food industries. More studies should be conducted to improve the yield of shitake metabolites through new growing conditions for industrial production and to find metabolic pathways and related genes.

6 Lee mas

Bioprospeccin de frutos de Lacmellea standleyi (lechemiel)

Bioprospeccin de frutos de Lacmellea standleyi (lechemiel)

The contribution of this work was to determine the nutritional value, the chemical nature of the main nuclei of secondary metabolites, the antioxidant potentiality against radicals DPPH and ABTS, total phenolic content, the total soluble antioxidant capacity and the acute toxicity of the harvested fruits of Lacmellea standleyi in three stages of ripening (green, intermediate and mature), aiming to have scientific bases to be able to argue the traditional knowledge of the settlers of the Colombian

19 Lee mas

Análisis genómico y funcional de las singularidades de dos cepas de Bacillus amyloliquefaciens con capacidad de biocontrol

Análisis genómico y funcional de las singularidades de dos cepas de Bacillus amyloliquefaciens con capacidad de biocontrol

the way around, the fact that the chemical analysis of the other molecules correlate to their genetic analysis between fractions is supportive of the second hypothesis. In addition to this, we observed how surfactin and iturin, two lipopeptides essential in the biocontrol activity of this strain, behaved differentially depending on the temperature. Surfactin was expressed and accumulated mostly in pellicles at 37ºC, while iturin was mostly expressed and accumulated in cells of the spent medium in all conditions. It was previously reported the influence of medium in the robustness of pellicles and surfactin production (Chollet- Imbert et al., 2009), which might be influenced in this case by temperature conditions in the medium M; the characterization of pellicles structure at both situations is an aspect that should be considered in future analyses. The production of the lipopeptides should be also correlated to physiological stage of cells in the pellicle, being the sporulation rate a determinant of metabolites production. Surfactin synthesis and sporulation are controlled by pheromones of the quorum sensing system, which are probably promoted in pellicles (Chollet-Imbert et al., 2009). It seems that the expression of the lantibiotic structural genes might be influenced in such a way by regulatory pathways connected to pellicle but not the final mature peptides, which might follow a different regulatory network than other relevant secondary metabolites. Thus, the more research in this direction will help elucidating the interconnection of these secondary metabolites and how they coordinate the efficient performance of this strain.

235 Lee mas

Acrylamide content in tortilla chips prepared from pigmented maize kernels

Acrylamide content in tortilla chips prepared from pigmented maize kernels

Mexico has the largest diversity of genetic resources of maize in the world. Many of them are pigmented genotypes as purple, red, black and yellow and they have been identified as appropriate for the masa and tortilla industry (Sanchez et al., 2000; V´azquez- Carrillo et al., 2011). Pigmented maize kernels and nixtamalized corn flour prepared from them contain many secondary metabolites, such as phenolic compounds, anthocyanins among others. Strong evidence of high content of anthocyanins, phenolic compounds and antioxidant capacity has been reported for pigmented maize genotypes (Adom & Liu, 2002; Mora-Rochin et al., 2010; L´opez Martinez et al., 2009). These compounds have attracted the consumer attention due to their potential health benefits (Liu, 2004). Phenolic acids and flavonoids represent the most common form of phenolic compounds found in whole maize kernel, with a number of types that exist as soluble free and conjugated or insoluble bound forms ( ˘ Zili´c et al., 2012). Furthermore, since anthocyanins are flavonoids, they are water- soluble glycosides of polyhydroxyl and polymethoxy derivates of 2-phenylbenzopyrylium or flavylium salts. They are found in the pericarp and aleurones. Anthocyanins determine the color of pigment maize and these water-soluble compounds are potent natural antioxidants due to their ability to trap free radicals (Stavric, 1994).

10 Lee mas

Fast separation of terbinafine and eight of its metabolites by capillary electrophoresis

Fast separation of terbinafine and eight of its metabolites by capillary electrophoresis

Most drugs undergo extensive chemical changes known as metabolism when they reach the organism and before they are excreted. This process involves a series of com- plex events, which modulate the effectiveness of the ad- ministered drug in the treatment of the disease and deter- mine its pharmacological and toxicological effects. There- fore, the subsequent isolation and structural characteriza- tion of the resulting plethora of metabolites is vitally impor- tant to understand the physical and biological effects of the parent drug [1, 2]. The enzymatic reactions involved in drug metabolism pathways are often classified into three groups: phase I, phase II, and phase III [3, 4]. Phase I me- tabolism consists of a variety of functionalization reac- tions, including oxidation, reduction, and hydrolysis, which generally produce more polar compounds that are subse- quently susceptible to further modification. These reac- tions often result in only minor structural modifications of

6 Lee mas

Standard English Varieties in a Secondary EFL Classroom

Standard English Varieties in a Secondary EFL Classroom

As part of our empirical study, we will develop a questionnaire to test the knowledge and attitudes of six groups of students in a Secondary school in Palma, one group per academic year, related to the distinction between Standard British and American English accents in a listening exercise, and their ability to identify BrE and AmE spelling and vocabulary. This will be followed by a brief survey intended to collect the students’ perceived difficulties and their own preferences about the two accents, their attitudes towards them, and whether their English variety of choice may or may not be motivated by social or cultural factors and their exposure to these English varieties through American or British entertainment media, such as films, series or Internet content.

66 Lee mas

Fisiopatologa de la lesin cerebral traumtica severa

Fisiopatologa de la lesin cerebral traumtica severa

TBI is divided in two events, primary and secondary injuries. Primary injury results from the trauma event itself caused by physical mechanisms like a direct collision of the brain tissue against the skull base and or vault at a tangible speed submitting brain tissue into different kinds of deformation: compressive, tensile (tissue stretching) and shear (tissue distortion produced as a result of sliding over other tissue). These lesions lead to neurons, glial cells and vessels damage, giving rise to hematoma, brain swelling and also traumatic axonal lesions.

5 Lee mas

Secondary sclerosing cholangitis following major burn

Secondary sclerosing cholangitis following major burn

Background and aims. Secondary sclerosing cholangitis in critically ill patients (SSC-CIP) is a relatively new previously unrecognized entity which may lead to severe biliary disease with rapid progression to cirrhosis. We present for the first time a case series of patients with rapidly progressive SSC-CIP requiring aggressive intensive care treatment following major burn injury. Results. SSC-CIP was diagnosed in 4 consecutive pa- tients hospitalized due to major burn injuries at our Intensive Care Unit (ICU). SSC-CIP was diagnosed when ERCP (n = 1) or MRCP (n = 3) demonstrated irregular intrahepatic bile ducts with multiple strictures and dilatations and, when a liver biopsy (n = 3) demonstrated severe cholestasis and bile duct damage. All pa- tients were males; none of whom had pre-existing liver disease. Ages: 18-56 y. All patients suffered from severe (grade 2-3) burn injuries with total burn surface area ranging from 35 to 95%. Mean length of ICU hospitalization was 129.2 ± 53.0 days. All patients required mechanical ventilation (with a mean PEEP of 8.4 ± 2.1 cm H 2 O) and the administration of catecholamines for hemodynamic stabilization. All patients demon- strated severe cholestasis. Blood cultures and cultures from drained liver abscesses grew hospital ac- quired multiple resistant bacteria. Liver cirrhosis developed within 12 months. One patient underwent orthotopic liver transplantation. Two patients (50%) died. In conclusion, SSC-CIP following major burn inju- ry is a rapidly progressive disease with a poor outcome. Liver cirrhosis developed rapidly. Awareness of this grave complication is needed for prompt diagnosis and considerations of a liver transplantation.

7 Lee mas

List of Clustered Permutations in Secondary Memory

List of Clustered Permutations in Secondary Memory

For general metric spaces, there exist a number of methods to preprocess the database in order to reduce the number of distance evaluations [3, 14, 13]. In general metric spaces, the (black-box) distance function is the only way to distinguish between ob- jects, and usually, the function of distance is expensive to calculate (in time and/or resources), compared to the CPU time to traverse the index and decide which elements are relevant. However, when the index is located in secondary memory the I/O opera- tions are also very significant [12]. Therefore, the goal of similarity search algorithms for metric spaces in secondary memory is to solve queries using the minimum number of distances computations and I/O operations.

10 Lee mas

Intergenerational mobility, middle sectors and entrepreneurship in Uruguay

Intergenerational mobility, middle sectors and entrepreneurship in Uruguay

We also computed an index of social mobility, which reflects how much of children’s educational outcome, or SG, is explained by the parents’ schooling and income. We found that while there were no changes in the index for mandatory education, there was a decrease, or lower mobility for non-mandatory education, i.e., the last three years of high school and university attendance. Therefore, the evidence suggests that inter-generational social mobility in Uruguay has lowered and there are risks of increased social segmentation. The overall picture suggests that during the mandatory education years, the Uruguayan public education system been an equalizing device. Beyond the mandatory years, the educational system evolved to produce a worsening in inter- generational mobility since the 1990s. This evidence, together with the transition matrices, suggests that the larger enrollment and retention problems are at the secondary education level.

38 Lee mas

Estimation of caffeine intake from analysis of caffeine metabolites in wastewater

Estimation of caffeine intake from analysis of caffeine metabolites in wastewater

Caffeine metabolites in wastewater were investigated as potential biomarkers for assessing caffeine intake in a population. The main human urinary metabolites of caffeine were measured in the urban wastewater of ten European cities and the metabolic profiles in wastewater were compared with the human urinary excretion profile. A good match was found for 1,7-dimethyluric acid, an exclusive caffeine metabolite, suggesting that might be a suitable biomarker in wastewater for assessing population-level caffeine consumption. A correction factor was developed considering the percentage of excretion of this metabolite in humans, according to published pharmacokinetic studies. Daily caffeine intake estimated from wastewater analysis was compared with the average daily intake calculated from the average amount of coffee consumed by country per capita. Good agreement was found in some cities but further information is needed to standardize this approach. Wastewater analysis proved useful to providing additional local information on caffeine use.

39 Lee mas

Gender Equality Action Plan in EFL: Secondary Education and Upper Secondary Level

Gender Equality Action Plan in EFL: Secondary Education and Upper Secondary Level

Nevertheless, within the core competences that are established in the Common European Framework of Reference for Languages, none of them highlight gender equality as a specific competence. In this case, it can be encompassed within the sociocultural knowledge competence, since it mentions interpersonal relations such as “relations between sexes (gender, intimacy)” (CEFR, 2001, p. 111). However, it may also be included as an implicit factor of the existential competence (savoir-être), since it mentions values and beliefs, among other selfhood factors. This evidence may be understood as another proof that corroborates how gender equality is not as visualized as it may resemble. Frequently, it is presented as a secondary implicit value of a subject rather than as a key competence to be acquired. In particular, when teaching English foreign language, the focus of attention is set in terms of linguistic competences such as grammar or vocabulary. For this reason, it is necessary to analyze the management tools of education in order to determine whether or not they are inclusive toward incorporating transversal values such as gender equality or not.

65 Lee mas

Empirical studies on human capital and natural resources

Empirical studies on human capital and natural resources

education they choose and their probability to continue with post-secondary education. This points at the existence of heterogeneity in the returns to post-secondary education. Separate regressions for each secondary school group reveal that imposing equal returns to vocational training among the three secondary school groups overestimates the returns to vocational training for Hauptschule and understates returns to vocational training for Realschule and Gymnasium graduates. Returns to university are underestimated. These new results indicate that vocational training raises monthly earnings of Hauptschule and Realschule graduates on average by 16 to 27%, ceteris paribus. Moreover, monthly earn- ings of Gymnasium increase on average 43%. Annual returns of vocational training thus amount to 5.2%, 9.1% and 21.3% for Hauptschule, Realschule and Gymnasium graduates. A university degree raises earnings by nearly 70% which corresponds to an annual return to university of about 14% which is signi…cantly lower than annual returns to vocational training. However, it is very likely that the true returns to vocational training are not as high as our estimates suggest due to the fact that participants of a vocational training pro- gram gain actual labor market experience during its completion, which is not necessarily the case for university graduates. 5

138 Lee mas

Actividad antimicrobiana in vitro de extractos de hoja de Guazuma ulmifolia Lam. contra fitopatógenos

Actividad antimicrobiana in vitro de extractos de hoja de Guazuma ulmifolia Lam. contra fitopatógenos

Currently it is looking for a biological control of pathogens microorganisms, with plant-derived substances. The (Guazuma ulmifolia) is a tree with pesticide properties and healing effects. Yield, antifungal and antibacterial activity of extracts obtained with buffering solutions (peptides) and organic solvents (metabolites) from guacima leaves were evaluated. The peptides were extracted with buffers: B1 (pH 7.0) KCl, EDTA; B2 (pH 5.2) KCl, CH3COONa, β-mercaptoethanol; and B3 (pH 7.0) KCl, EDTA, phenylmethylsulfonyl fluoride (PMSF), polyvinylpyrrolidone, thiourea, while metabolites were extracted with hexane, methanol and dichloromethane. Protein concentration was made by the Bradford method and the molecular weight by polyacrylamide gel electrophoresis. Thin layer chromatography (TLC)-Packed column, were sequentially applied to separate the compounds and bio-testing them later. In parallel fungus Sclerotium cepivorum of onion and Fusarium oxysporum of melon, as well as the bacteria Xanthomonas campestris of tomato were isolated, and Pseudomonas aeruginosa was inoculated (registry number 0693-P). Antifungal activity was measured by inhibition of in vitro mycelial growth of microorganisms while the antibacterial activity was evaluated by inhibition of colony formation (CFUmL-1). Relative to extracts yields, buffer 2 (B2) showed the highest value (15.7 %), while extracts in hexane (3.9 %), methanol (3.0 %) and dichloromethane (2.2 %) were lower in this parameter. Furthermore the approximate molecular protein weight was of 24.9 kDa. Also, dichloromethane extract showed the greatest inhibition over Sclerotium (88.4 %), B2 over Fusarium (86.5 %) and hexane extracts also on Xantomonas (84.0 %).

12 Lee mas

Descargar
			
			
				Descargar PDF

Descargar Descargar PDF

The “San Pedro Macho” cacti (Echinopsis peruviana or also known as Trichocereus peruviana) owes its name and importance, in part, to its taxonomical and alkaloid composition similarity to the well-known “San Pedro Hembra” cacti (Echinopsis pachanoi) or commonly referred as “San Pedro”, which is the most important species among the plants used in Traditional Medicine (TM) in Northern Perú. This phytochemical report of an Echinopsis peruviana species cultivated in Perú involves the qualitative analysis of its secondary metabolites, the quantification of the total alkaloid content and the isolation of the alkaloid mescaline, as its sulphate dihydrate salt, of the chlorenchyma in the green outer cortex of the stems of E. peruviana. ESI-MS; 1 H, 13 C NMR; IR; UV; elemental analysis and TLC techniques were used to characterize this compound.

9 Lee mas

Show all 584 documents...