Please login first

List of accepted submissions

 
 
Show results per page
Find papers
 
  • Open access
  • 66 Reads
Potent antioxidant activity of Kigelia africana flower fractions on cell-free systems.

The aim of this work is to explore the antioxidant properties of three organic fractions obtained from Kigelia africana flowers on several cell-free systems. The vegetal material was subject to extraction with ethanol (90%) by soxhlet apparatus. Ethanolic (EF), ethylacetate (EAF) and buthanolic (BF) fractions were obtained from crude ethanolic solution by liquid-liquid extraction procedures. Total Phenolic content (TPC) and Total Flavonoids content (TFC) were determined by Folin-Ciocalteu and AlCl3 spectrophotometric methods respectively. The antioxidant and radical scavenging profile was assessed through 2, 2 – diphenyl – 1 – picrylhydrazyl (DPPH), Reducting power, Total antioxidant activity and Metal Chelating tests. Quercetin, rutin, gallic acid, hesperidin, ascorbic acid and Na2EDTA were used as references. The antioxidant potency was strongly related with TPC and TFIC values. This study reveals for the first time the antioxidant properties of K. africana flower fractions on cell-free systems. 

  • Open access
  • 105 Reads
4,6,6-trimethylbicyclo [3.1.1] hept-3-ene: Analysis of the Inhibitory Effect of Monoterpere on Pseudomonas aeruginosa Strain

Pseudomonas aeruginosa is a ubiquitous gram-negative non-fermentative bacterial species that exhibits natural resistance to some antibiotics and antiseptics, in addition to having a high expression of virulence factors, being responsible for causing, mainly, opportunistic infections in the hospital environment. It affects the respiratory tract causing about 80% of hospital pneumonias, being able to reach skin, soft tissues, eyes, ears, bones and the urinary tract. The treatment of nosocomial infections caused by P. aeruginosa is based on several classes of drugs, such as: Cephalosporins, Carbapenems, Aminoglycosides, among others. However, studies point to the existence of multiresistant species, including reserve drugs, such as imipenem, thus generating a public health problem. In addition, this year the World Health Organization has released a list of ten challenging multi-resistant microorganisms that require new antibiotics, and secondly the species Pseudomonas aeruginosa carbapenem-resistant. Given this panorama of bacteria resistant to multiple commercially available antibiotics, it is necessary to study new compounds with antibacterial activity. As a possibility to combat bacterial infections, the action of a natural product, the positive enantiomer of 4,6,6-trimethylbicyclo [3.1.1] hept-3-ene, also known as (+) - α-pinene, before the Pseudomonas aeruginosa strain ATCC 27853, using methodologies standardized by the Manual Clinical and Laboratory Standards Institute. Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration, and Nature Classification of Compound Effect were determined according to CBM/MIC ratio. The (+) - α-pinene was dissolved in 1% Tween 80, 5% DMSO and distilled water. In broth microdilution, the MIC was determined for the P. aeruginosa strain, at a concentration of 40 μL/mL, being characterized as bacteriostatic and the concentration 4 times higher than MIC was demonstrated to be bactericidal. This experiment made it possible to observe the action of the phytoconstituent on the species of Pseudomonas aeruginosa, emphasizing the need for permanent studies to determine the mechanism of action and toxicity of (+) - a - pinene allowing its future use against opportunistic infections caused by Pseudomonas aeruginosa.

  • Open access
  • 71 Reads
Uses of Black tea

INTRODUCTION

According to popular Chinese legend, the discovery of the tea attributed to the Chinese emperor Shen Nung occurred by chance when the leaves of a certain plant were deposited on a glass of boiling water. Tea is a traditional infusion made from the leaves of the Camellia sinensis plant, however, black tea is obtained by the fermentation of the leaves of the same plant.

As a consequence of the fermentation process, black tea presents a darker color together with a different flavor and appearance. From the nutritional point of view, black tea contains a higher content of caffeine and is richer in minerals such as zinc, calcium, chromium, magnesium, manganese, iron, potassium, phosphorus, fluoride and aluminum with respect to green tea (1 ).

The presence of flavonoids and polyphenols in its composition, suggests that it may have beneficial effects on health. However, regardless of whether these beneficial effects can be demonstrated, globally, black tea is the most consumed, and this will remain as consumers drink black tea for its peculiar aroma and flavor.

OBJECTIVES

Identify the main benefits associated with a consumption maintained over time of black tea and, on the other hand, check based on other research if these effects have been demonstrated in humans.

MATERIAL AND METHODS

A bibliographical search was carried out in Pubmed, using the keywords "black tea"

RESULTS

The main effects of tea are due to its antioxidant properties. It is thought that the major polyphenols in black tea are theaflavins and catechins that are also the most active components. These compounds act by inhibiting and eliminating free radicals and acting as chelating agents for metal ions. In addition, black tea theaflavins may influence the activation of transcription factors such as NF-kB (nuclear factor enhancer of the kappa light chains of activated B cells). Finally, tea theaflavins can act as inhibitors of oxidative enzymes such as xanthine oxidase or the enzyme nitric oxide synthase (2, 3).

Human studies have been conducted to evaluate the consumption of black tea on cardiovascular risk factors, although these have been limited to a few months (4).

The conclusions of this study have not been positive or conclusive since no significant statistical effects were found in the evaluated biomarkers (lipids, hemoglobin, inflammatory markers and oxidability of lipoproteins).

Human studies are currently underway to evaluate the properties of black tea in reducing body weight. This study has enormous potential because obesity is one of the most prevalent diseases worldwide and continues to increase over the years. The effect on obesity would be in the polyphenols of black tea, since they would inhibit the digestion and absorption of lipids and saccharides, while in green tea its anti-obesity properties would be due to an effect on the gut microbiota (5).

CONCLUSIONS

Most of the studies that have been carried out to date to evaluate the biological potential of the polyphenolic compounds present in black tea have been carried out in vitro or in very limited human trials. Therefore, long-term studies are required to establish a safe dose of black tea before giving a conclusive recommendation to the population.

REFERENCES

    Sang S, Lambert JD, Ho CT, Yang CS. The chemistry and biotransformation of tea constituents. Pharmacol Res. 2011; 64 (2): 87-99.
    Łuczaj W, Skrzydlewska E. Antioxidative properties of black tea. Prev Med.2005; 40 (6): 910-8.
    Frei B, Higdon JV. Antioxidant activity of tea polyphenols in vivo: evidence from animal studies. J Nutr. 2003; 133 (10): 3275S-84S.
    Mukamal KJ, MacDermott K, Vinson JA, Oyama N, Manning WJ, Mittleman MA. 6-month randomized pilot study of black tea and cardiovascular risk factors. Am Heart J. 2007; 154 (4): 724.e1-6. 3.
    Pan H, Gao Y, Tu Y. Mechanisms of Body Weight Reduction by Black Tea Polyphenols. Molecules. 2016; 21 (12).

  • Open access
  • 62 Reads
Exploring different strategies to improve the magnetic response of cobalt doped ferrite nanoparticles

With the aim of studying the structural and magnetic properties of cobalt doped magnetite nanoparticles         (Fe3-xCoxO4), several samples were synthetized by thermal decomposition method using different cobalt concentrations (0 – 5%) at different condition reflux time (30 – 120 min). In this work, we demonstrate that the synthetic parameters highly influence. Both, the morphology and the cobalt concentration, obtaining higher saturation magnetization values for 2 hours reflux. An exhaustive magnetic characterization by means of magnetization and electronic magnetic resonance have established conditions to improve the magnetic response of doped nanoparticles.

  • Open access
  • 74 Reads
Comparison of Base Distributions in Dengue, Zika and Other Flavivirus Envelope and NS5 Genes

Among the nucleotide sequences of flaviviruses that include Zika virus, Dengue virus, yellow fever virus, Japanese encephalitis virus and West Nile virus, those of the Zika virus and Dengue type 2 virus are believed to share a high degree of similarity as can be commonly shown by BLAST pairwise analysis. Our study of the nucleotide sequences of the envelope and NS5 genes shows that the sequences of the Dengue type 2 virus are sharply different compared to other aforementioned human infecting flaviviruses. This is emphatically seen in a 2D graphical representation where each axis represents a nucleotide base and distinctly discriminated in terms of relevant RNA descriptors. The descriptors indicate the quantitative spread of nucleotide sequence graphs.  In this report, we demonstrate this difference in terms of base distribution in the gene sequences through various parameters and consider possible reasons for such variations that seem to have been largely neglected in the literature.

 

 

  • Open access
  • 98 Reads
Some Comments on Mathematical Descriptors of Biomolecular Sequences and their Characteristics

The advent of techniques of graphical representation and mathematical characterization of biomolecular sequences has seen the growth of a genre of non-alignment methods for analyses of their similarities/dissimilarities. The new descriptors are important and convenient to provide a  quantitative measure of the composition and distribution of the basic units, allow discrimination amongst members of a family of similar sequences with a low computational overhead and hold promise for discovery of new systematics. These opportunities led to a plethora of models for graphical representation and numerical characterisations, but the question is how far the various sequence descriptors derived by these different mathematical approaches encode non-redundant information. We briefly consider the issues that when comparative studies of biomolecular sequences are undertaken, it is important to consider which properties are being considered and choose models that allow for computational closure and non-redundancy. We believe graphical representation and numerical characterization models have a significant role to play in non-alignment similarity/dissimilarity analysis of bio-molecular sequences, but the issues have to be approached with an eye to specific properties being investigated.

  • Open access
  • 59 Reads
Antioxidant activity of 5-FU and new fluorinated uracil derivates

The intake of antioxidants has increased in the last years in order to treat some pathologies associated with oxidative stress such as cancer, diabetes mellitus, atherosclerosis, myocardial infarction, acute pancreatitis, Parkinson's and Alzheimer's disease among others. In colorectal cancer, a widely antineoplastic drug used is the fluorinated uracil molecule 5-Fluorouracile (5-FU). The aim of this study is to assess the antioxidant capacity observed by the inhibition of lipid peroxidation by 5-FU and other fluorinated uracil derivates: 6-[Difluoro(phenyl)methyl]-3-(2,4,6-trifluorophenyl)pyrimidine-2,4(1H,3H)-dione (S-81), 3-[2-Chloroethyl]-6-[difluoro(phenyl)methyl]pyrimidine-2,4(1H,3H)-dione (S-86), 6-[Difluoro(phenyl)methyl]-3-(4-trifluoromethoxyphenyl)pyrimidine-2,4(1H,3H)-dione (S-123). The results showed a significant decrease in MDA production of 58.12% in S-86, 44.61% in S-123, 24.11% in 5-FU and 10.83% in S-81 in the sample with highest concentration (10µM). 5-FU also showed a Total Antioxidant Capacity of 0.68 Trolox Equivalent Antioxidant Capacity.

  • Open access
  • 82 Reads
Inhibition of Secretory Aspartyl Protease of Candida albicans by metabolites of Streptomyces chrestomyceticus strain ADP4

Candida albicans is a commensal but a significant opportunistic pathogen. Various pathogenic attributes and virulence factors are found to be responsible for devastating Candida infections. Secretory aspartic proteases (Saps) enable hyphae formation, adhesion and phenotypic switching; digestion of the host cell membranes and evading host immune response by degrading and inactivating the central human complement components. Therefore, an agent capable of inhibiting production of C. albicans Saps will be useful in the treatment of such infections. The partially purified fractions of Streptomyces chrestomyceticus strain ADP4 displayed strong anti-Candida activity, hence were investigated further for their ability to inhibit production of Saps. Strong inhibition of production of Saps was observed when tested against the ATCC strain of C. albicans. Docking studies of the GCMS-predicted molecules of the metabolite extract and of the various fractions with a Sap of C. albicans were performed using VLife MDS4.6. These studies revealed the significant affinity of GCMS-predicted molecules when compared with the standard Sap inhibitor, Pepstatin A. 

  • Open access
  • 48 Reads
Criminalistics and its role in prevention

 Addressing the study of the problem of the Prevention of Crime and Infractions of the Law from the Criminalistic point of view is the fundamental objective of this work; It is true that theoretically several concepts have been formulated that have explained the scope of prevention as a criminological category, using as synonyms of prevention, terms such as: avoidance, precaution, control, prediction of delinquency, etc .; nowadays it is synonymous with: suppression, precaution, prophylaxis. Some authors criticize the term prophylaxis because the expression contains a hygienic medical meaning due to the equality between "crime-disease" and "delinquent-sick", as well as the cure of the offender that was the end of Criminal Law in the beginning of Criminology. For others, these terms do not differ, while the concept of crime prevention is used to designate both the objective premises of the liquidation of the crime and the subjective factors of the fight against it. For us, the prophylaxis concept of crime only expresses a special activity of criminal prevention, considering prophylactic activity as an integral part of criminal prevention, so we understand that both terms can be used interchangeably. Ref: Brito Febles, O. “La Profilaxis de los delitos como tarea de la Ciencia Criminalística”. Tesis de Doctorado. La Habana. Cuba. 1997.

  • Open access
  • 49 Reads
Influence of Carbon Nanotubes in Nano-carboapatite

One of the characteristics to be achieved by biomaterials is to have similarity to the host material. Carbonated hydroxyapatite (HAC) has both considerable composition and order of magnitude in relation to human bone. For the application in cases of bone substitution, HAC would be a good candidate, but it is shown with low mechanical resistance, which would make it difficult to apply it in areas that perform high mechanical stress. However, carbon nanotubes (CNTs) have low density and strong covalent bonding between their atoms, which confers high mechanical resistance to the material. For this reason, the influence of CNTs on the structure and properties of HAC was studied. Pure CNTs (pristines) and functionalized with CNT-COOH carboxyl were inserted for the study. The results of Elemental Analysis (CHN-O) indicated the amount of carbon present in the samples in each case. The results of XRD, TG / DTA and IR showed that pristine CNTs apparently did not significantly influence the structure of HAC. However, XRD results suggested that CNTs functionalized with COOH clusters may have interacted with HAC. In this case, the displacement of some peaks was observed in the sample (HAC + CNT_COOH), showing a decrease in the c axis of the sample. The refinement of the diffractograms also revealed samples of the nanometric order, with crystallite size in the order 25 Å. The results of the thermal analysis showed a peak close to 600 ° C, associated to the decomposition of the carbonate; Indicating the presence of these ions in the A site of HAC. The IR spectra showed the vibrational modes corresponding to the carbonate ion, confirming the presence of these ions in sites A and B.

Top