Antibacterial,antioxidant and hypoglycaemic effects of Thymus capitatus (L.) Hoffmanns. et Link leaves' fractions

Abstract

The aim of this study was to examine the bioactivity of the methanol fraction (MF) and n-hexane fraction (HF) of Thymus capitatus leaves in relation to their constituents analysed by gas chromatography and gas chromatography-mass spectrometry. The effects of T. capitatus on the growth of pathogenic bacteria associated with respiratory diseases (13 gram-positive and 4 gram-negative) were determined using a microdilution method. The MF was particularly effective on Streptococcus pneumoniae and Moraxella catarrhalis. The antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), ferric-reducing antioxidant power and β-carotene bleaching assays. A strong activity using β-carotene bleaching test was observed with the MF (IC₅₀ of 0.7?μg/mL after 30?min of incubation). In the hypoglycaemic test, a selective α-amylase inhibitory activity was detected with the HF begging the most active (IC₅₀ of 422.5?μg/mL). T. capitatus may represent a source of natural bioactive compounds.     

Biochemical characterization of the δ-carbonic anhydrase from the marine diatom Thalassiosira weissflogii,TweCA

Abstract

Diatom genome sequences clearly reveal the presence of different systems for HCO₃^? uptake. Carbon-concentrating mechanisms (CCM) based on HCO₃^? transport and a plastid-localized carbonic anhydrase (CA, EC 4.2.1.1) appear to be more probable than the others because CAs have been identified in the genome of many diatoms. CAs are key enzymes involved in the acquisition of inorganic carbon for photosynthesis in phytoplankton, as they catalyze efficiently the interconversion between carbon dioxide and bicarbonate. Five genetically distinct classes of CAs exist, α-, β-, γ-, δ- and ζ and all of them are metalloenzymes. Recently we investigated for the first time the catalytic activity and inhibition of the δ-class CA from the marine diatom Thalassiosira weissflogii, named TweCA. This enzyme is an efficient catalyst for the CO₂ hydration and its inhibition profile with sulfonamide/sulfamate and anions have also been investigated. Here, we report the detailed biochemical characterization and chemico-physical properties of the δ-CA of T. weissflogii. The δ-CA encoding gene was cloned and expressed in Artic Express cells and the recombinant protein purified to homogeneity. Interesting to note that TweCA has no intrinsic esterase activity with 4-nitrophenyl acetate (pNpA) as substrate although the phylogenetic analysis showed that δ-CAs are closer to the α-CAs than to the other classes of such enzymes.     

Quantitative structure-activity relationship study of novel rhinacanthins and related naphthoquinone esters as anticancer agents

Abstract

GPR119 is a promising target for discovery of anti-type 2 diabetes mellitus agents. We described the optimisation of a novel series of pyrimido[5,4-b][1,4]oxazine derivatives as GPR119 agonists. Most designed compounds exhibited good agonistic activities. Among them, compound 10 and 15 demonstrated the potent EC₅₀ values (13 and 12?nM, respectively) and strong inherent activities. Moreover, significant hypoglycaemic effect of compound 15 was observed by reducing the blood glucose AUC_0–2h at the dose of 30?mg/kg, which is stronger than Vildagliptin (23.4% reduction vs. 17.9% reduction).     

Identification of a single and non-essential cysteine residue in dextransucrase of Leuconostoc mesenteroides NRRL B-512F

Amino acid analysis of purified dextransucrase (sucrose: 1,6-α-D-glucan 6-α-D-glucosyltransferase EC 2.4.1.5) from Leuconostoc mesenteroides NRRL B-512F was carried out. The enzyme is virtually devoid of cysteine residue there being only one cysteine residue in the whole enzyme molecule comprising over 1500 amino acid residues. The enzyme is rich in acidic amino acid residues. The number of amino acid residues was calculated based on the molecular weight of 188,000 (Goyal and Katiyar 1994). Amino sugars were not found, implying that the enzyme is not a glycoprotein. It has been shown earlier that the cysteine residue in dextransucrase is not essential for enzyme activity (Goyal and Katiyar 1998). The presence of only one cysteine residue per enzyme molecule illustrates that its tertiary structure is solely dependent on other types of non-covalent interactions such as hydrogen bonding, ionic and nonpolar hydrophobic interactions.     

Molecular identity,morphology and taxonomy of the Rhynchospio glutaea complex with a key to Rhynchospio species (Annelida,Spionidae)

Rhynchospio glutaea (Ehlers, 1897 Ehlers, E. 1897. Polychaeten. Ergebnisse der Hamburger Magalhaensischen Sammelreise 1892/93. L. Friederichsen & Co., Hamburg, Germany. [Google Scholar]), Rhynchospio arenincola Hartman, 1936 Hartman, O. 1936. New species of Spionidae (Annelida Polychaeta) from the coast of California. University of California Publications in Zoology 41, 45–52. [Google Scholar] and Rhynchospio arenincola asiatica Chlebovitsch, 1959 Chlebovitsch, V.V. 1959. Species of Polychaeta worms from the Kurile Islands, which are new or recorded for the first time in the USSR fauna. Zoologichesky Zhurnal 38, 167–181. [Google Scholar], originally described from Strait of Magellan, California, and South Kurile Islands respectively, appear similar to each other in adult morphology. These species and subspecies have been considered by some authors as subjective synonyms and are here referred to as members of the R. glutaea complex. Sequence data of four gene fragments (2465 bp in total) of the mitochondrial 16S rDNA, nuclear 18S and 28S rDNA, and Histone 3 have shown that R. glutaea complex individuals from the South West Atlantic (Argentina), North East Pacific (British Columbia and Oregon) and North West Pacific (South Korea) were genetically distant and not conspecific. These data also indicate that R. arenincola from North America and R. aff. asiatica from South Korea are more closely related to each other, and both are closer to R. glutaea from South America than to R. nhatrangi from Vietnam: nhatrangi (glutaea (arenincola-aff. asiatica)). Adults of the R. glutaea complex are hermaphrodites and the arrangement of gametes is suggested to be a crucial reproductive character for distinguishing these species. Based on this character, two species of the complex are apparent in the North West Pacific: R. asiatica Chlebovitsch, 1959 Chlebovitsch, V.V. 1959. Species of Polychaeta worms from the Kurile Islands, which are new or recorded for the first time in the USSR fauna. Zoologichesky Zhurnal 38, 167–181. [Google Scholar] stat. nov. from the Kurile Islands (not analysed here) and an unnamed species from the mainland coast of Asia (here referred to as R. aff. asiatica). Adult morphology of R. asiatica stat. nov. is briefly described and illustrated. The lectotype and the type locality of the species on Iturup Is. are established for the first time. An identification key is provided to the 10 currently recognized Rhynchospio species.     

The language of systematics,and the philosophy of ‘total evidence’

This contribution analyses the primacy of classification over generalization, and the philosophy of total evidence that emerges from the relation of homology to character statements. Primary conjectures of homology are basic character statements, i.e. statements that predicate properties of organisms, properties that are instantiated by those organisms and/or their parts. Secondary conjectures of homology are embedded in a second‐level (metalinguistic) discourse that turns on the coherence or incoherence of those basic character statements relative to a hierarchy. The coherence or incoherence of character statements is a logical relation between statements, not a causal (historical) relation between organisms. The choice of the hypothesis of relationships that is supported by the largest set of coherent basic character statements is based on the empirical presupposition that the properties referred to by the set of coherent character statements are grounded in causally efficacious relations of inheritance and ontogeny, and co‐instantiated because they are inherited through common ancestry (Hennig's auxiliary principle). Unless that empirical presupposition is causally grounded, phylogeny reconstruction is of an inherently probabilistic nature, whether under parsimony or other models of analysis. The causal grounding of a coherent set of character statements typically seeks a link between character statements and causally efficacious generative mechanisms for morphological characters (as is defeasibly indicated by topology and connectivity), or secondary structure information for molecular characters.     

Systematics of naviculoid diatoms (Bacillariophyta): A preliminary analysis of protoplast and frustule characters for family and order level classification

The relationships between 49 naviculoid diatoms, currently arranged in 14 families and four orders were investigated using cladistic analysis in order to test the types of characters used in diatom systematics and to assess how well the current classification reflects possible phylogenetic relationships in this group. Some of the families and orders comprise taxa with different protoplast characters, or taxa with similar protoplast arrangements are placed in separate families or orders. Therefore as both cell wall and protoplast characters were used, three analyses were undertaken; total data, protoplast data and frustule data. The analyses support the recognition of the Mastogloiales (unequivocally) and the Cymbellales (largely) but indicate that some of the familial groupings are more ambiguous. The members of the Berkeleyaceae, Berkeleya, Parlibellus and Climaconeis, were never grouped together and Achnanthes brevipes never grouped with the other monoraphid diatoms, but usually with members of the Mastogloiales (total and protoplast data). Similarly, Round et al.’s familial groupings within the Cymbellales do not emerge from our analyses. Our results support the hypothesis that monoraphid genera have arisen independently from different naviculoid diatoms, and that Achnanthes sensu stricto should be transferred to the Mastogloiales. Some of the problems associated with incomplete information and inaccurate terminology are discussed briefly.     

Proteomics in translational cancer research: biomarker discovery for clinical applications

This special focus issue of Expert Review of Proteomics invites key opinion leaders to report their recent findings and views on the important topic of translating potential proteomic biomarkers to clinically useful, regulator-approved biomarkers: a challenging journey. The issue also highlights the difficulties associated with and the way forward in the discovery of proteomic cancer biomarkers for clinical applications, as well as presenting recent original research in the field.     

Optimization and validation of spectrofluorimetric method for determination of cefadroxile and cefuroxime sodium in pharmaceutical formulations

A simple, accurate, precise and validated spectrofluorimetric method is proposed for the determination of two cephalosporins, namely, cefadroxile (cefa) and cefuroxime sodium (cefu) in pharmaceutical formulations. The method is based on a reaction between cephalosporins with 1,2‐naphthoquinone‐4‐sulfonate in alkaline medium, to form fluorescent derivatives that are extracted with chloroform and subsequently measured at 610 and 605 nm after excitation at 470 and 460 nm for cefa and cefu respectively. The optimum experimental conditions have been studied. Beer's law is obeyed over the concentrations of 20–70 ng/mL and 15–40 ng/mL for cefa and cefu, respectively. The detection limits were 4.46 ng/mL and 3.02 ng/mL with a linear regression correlation coefficient of 0.9984 and 0.998, and recoveries ranging 97.50–109.96% and 95.73–98.89% for cefa and cefu, respectively. The effects of pH, temperature, reaction time, 1,2‐naphthoquinone‐4‐sulfonic concentration and extraction solvent on the determination of cefa and cefu, have been examined. The proposed method can be applied for the determination of cefa and cefu in pharmaceutical formulations in quality control laboratories. Copyright © 2013 John Wiley & Sons, Ltd.