Chemical composition of essential oil from the leaves of Premna coriacea Clarke

In this study, the chemical composition of the essential oil of Premna coriacea leaves was investigated. Extraction by hydrodistillation followed by gas chromatography and mass spectrometry (GC-MS) yielded 27 compounds representing 99.89% of the oil. The major volatile components of the oil were aromadendrene (23.51), caryophyllene (19.27), tetracontane (11.90), 17-pentatriacontene (6.61), 3',8,8'-trimethoxy-3-piperidyl-2,2'- binaphthalene-1,1',4,4'-tetrone (4.68), cis-α-bisabolene (4.65), octadecane, 3-ethyl-5-(2-ethylbutyl)- (4.21), 2-mercaptobenzothiazole (3.17) and tetratetracontane (2.38).Keywords: Premna coriacea, essential oil, aromadendrene, caryophylleneAfrican Journal of Biotechnology Vol. 12(20), pp. 2914-291

STUDY OF ENDOPHYTIC FUNGAL COMMUNITY FROM BARK OF VENTILAGO MADRASAPATNA GAERTN.

Endophytic fungi were isolated from the inner bark of Ventilago madrasapatna, a wellknown medicinal plant of India. It was investigated for endophytic mycoflora as a possible source of bioactive secondary metabolites. A total 66 isolates of 14 species belongs to 5 classes, were studied adopting a standard isolation protocol. The colonization frequency of the endophytic fungi was reported as 87.84%. Fungus composition included 6.25 % Eurotiomycetes, 9.3 % Dothideomycetes, 14.26% Soradariomycetes, 11.08 % Ascomycetes, 2.6 % Leotiomycetes and 1.3 % isolates were classified under Mycelia sterilia. The sterile endophytic fungi presently reported are expected to add to the list of new fungal species. Among the endophytic flora, Fusarium oxysporum was found to be the core-group fungus with a colonization frequency of 34.22%.Cladosporium cladosporiodes and Botrytis sp. are present only in bark of plant collected in Belur forest region. These results indicated that distribution of endophytic fungi is mainly influenced by environment factors

Simultaneous electrochemical determination of acetaminophen and metoclopramide at electrochemically pre-treated disposable graphite pencil electrode

A sensitive and economic voltammetric method was developed for the simultaneous determination of acetaminophen (AMP) and metoclopramide (MCP) using pre-treated graphite pencil electrode (PTGPE). Compared to a graphite pencil electrode, the pre-treated electrode showed an apparent shift of the oxidation potentials in the positive direction and a notable enhancement in the current responses for both AMP and MCP. Cyclic voltammetry (CV) was used to study the voltammetric behavior of the drugs, while differential pulse voltammetry (DPV) was used to determine AMP and MCP simulta-neously. The dependence of the current on scan rate, pH and concentration was investi-gated to boost the experimental conditions for simultaneous determination. The calibra-tion curves were obtained over the range of 0.1×10-7 to 1.1×10-7 M, the concentration of each of both the drugs was varied by keeping the other constant, and achieved lower detection limit of 3.25 nM for AMP and 1.16 nM for MCP. The developed method was found to be selective, and rapid for the simultaneous determination of AMP and MCP. The proposed method was applied simultaneously in real samples and pharmaceutical samples, with satisfactory results

Square wave and differential pulse voltammetric methods for the analysis of olivetol at gold electrode

Few electrochemical techniques have been employed for the determination of the powerful antitumor agent olivetol (OLV) in real samples at gold electrode. An intense and well pronounced oxidation peak was obtained at 1.04 V in the phosphate buffer pH 5.0 as the supporting electrolyte. The effects of pH and scan rate on the oxidation peak were studied. The electrochemical behavior of OLV was investigated using cyclic voltammetric (CV), square wave voltammetric (SWV) and differential pulse voltammetric (DPV) techniques. In DPV and SWV, the gold electrode showed a good sensitivity for OLV in a linear range of 0.1-1.5 μM and 0.1-1.3 μM and detection limits of 1.936×10-9 M and 4.754×10-9 M, respectively. A plausible mechanism involving an adsorption controlled oxidation reaction was deduced. The effect of various excipients was also studied and the method was successfully applied for the determination of OLV in human biological samples

Mechanism of Oxidation of L-Histidine by Heptavalent Manganese in Alkaline Medium

The kinetics of oxidation of L-histidine by manganese(VII) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm-3 was studied spectrophotometrically. The reaction between permanganate and L-histidine in alkaline medium exhibits 2:1 stoichiometry (KMnO4: L-histidine). The reaction is of first order in [KMnO4], less than unit order in [L-histidine] and [alkali]. Decrease in the dielectric constant of the medium decreases the rate of reaction. Effect of added products and ionic strength of the reaction medium have been investigated. The main products were identified by spot test and I.R. A mechanism involving the free radical has been proposed. In composite equilibrium step L-histidine binds to MnO4- species to form a complex(C). The reaction constants involved in the different steps of mechanism are evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed and thermodynamic quantities are also determined

Algebraic Approaches to Space-Time Code Construction for Multiple-Antenna Communication

A major challenge in wireless communications is overcoming the deleterious effects of fading, a phenomenon largely responsible for the seemingly inevitable dropped call. Multiple-antennas communication systems, commonly referred to as MIMO systems, employ multiple antennas at both transmitter and receiver, thereby creating a multitude of signalling pathways between transmitter and receiver. These multiple pathways give the signal a diversity advantage with which to combat fading. Apart from helping overcome the effects of fading, MIMO systems can also be shown to provide a manyfold increase in the amount of information that can be transmitted from transmitter to receiver. Not surprisingly,MIMO has played, and continues to play, a key role in the advancement of wireless communication.Space-time codes are a reference to a signalling format in which information about the message is dispersed across both the spatial (or antenna) and time dimension. Algebraic techniques drawing from algebraic structures such as rings, fields and algebras, have been extensively employed in the construction of optimal space-time codes that enable the potential of MIMO communication to be realized, some of which have found their way into the IEEE wireless communication standards. In this tutorial article, reflecting the authors’interests in this area, we survey some of these techniques

Square Wave Voltammetric Determination of 2-Thiouracil in Pharmaceuticals and Real Samples Using Glassy Carbon Electrode

A simple and rapid method was developed using cyclic and square wave voltammetric techniques for the determination of trace-level sulfur containing compound, 2-thiouracil, at a glassy carbon electrode. 2-thiouracil produced two anodic peaks at 0.334 V and 1.421 V and a cathodic peak at −0.534 V. The square wave voltammetry of 2-thiouracil gave a good linear response in the range of 1–20 μM with a detection limit of 0.16 μM and quantification limit of 0.53 μM (0.0679 μg/g), which is in good agreement as per IUPAC definition of trace component analysis (100 μg/g). The obtained recoveries range from 98.10% to 102.1%. The proposed method was used successfully for its quantitative determination in pharmaceutical formulations and urine as real samples