Antimicrobial activities of indole alkaloids from Tabernaemontana catharinensis

Tabernaemontana catharinensis root bark ethanol extract, EB2 fraction and the MMV alkaloid (12-methoxy-4-methylvoachalotine) were evaluated for their antimicrobial activities. T. catharinensis ethanol extract was effective against both strains of the dermatophyte Trichophyton rubrum at concentrations of 2.5 mg/mL (wild strain) and 1.25 mg/mL (mutant strain), while the EB2 fraction and MMV alkaloid showed a strong antifungal activity against wild and mutant strains with MIC values of <0.02 and 0.16 mg/mL, respectively. The EB2 fraction showed a strong antibacterial activity against ATCC strains of S. aureus, S. epidermidis, E. coli and P. aeruginosa with MICs from <0.02 to 0.04 mg/mL, as well as against resistant clinical isolates species of Enterococcus sp, Klebsiella oxytoca, Citrobacter, K. pneumoniae, P. mirabilis, S. aureus, S. epidermidis, E. coli and P. aeruginosa with MIC values ranging from 0.04 to 0.08 mg/mL. The MMV alkaloid presented a MIC of 0.16 mg/mL against the strains of S. aureus and E. coli ATCC. For the resistant clinical isolates Enterococcus sp, Citrobacter, S. aureus, S. epidermidis, E. coli and P. aeruginosa the MIC of MMV ranged from 0.08 to 0.31 mg/mL. The chromatography analysis of the EB2 fraction revealed the presence of indole alkaloids, including MMV, possibly responsible for the observed antimicrobial activity.     

Computing the Automorphic Chromatic Index of Certain Snarks

The automorphic G-chromatic index of a graph Γ is the minimum integer m for which Γ has a proper edge-coloring with m colors which is preserved by the full automorphism group G of Γ. We determine the automorphic G-chromatic index of each member of four infinite classes of snarks: type I Blanu?a snarks, type II Blanu?a snarks, Flower snarks and Goldberg snarks.     

Linear parameter varying control design for rotating systems supported by journal bearings

Linear parameter varying (LPV) control is a model-based control technique that takes into account time-varying parameters of the plant. In the case of rotating systems supported by lubricated bearings, the dynamic characteristics of the bearings change in time as a function of the rotating speed. Hence, LPV control can tackle the problem of run-up and run-down operational conditions when dynamic characteristics of the rotating system change significantly in time due to the bearings and high vibration levels occur. In this work, the LPV control design for a flexible shaft supported by plain journal bearings is presented. The model used in the LPV control design is updated from unbalance response experimental results and dynamic coefficients for the entire range of rotating speeds are obtained by numerical optimization. Experimental implementation of the designed LPV control resulted in strong reduction of vibration amplitudes when crossing the critical speed, without affecting system behavior in sub- or super-critical speeds.     

Weakly Regular and Regular sets in Minkowski planes

A Regular (respectively Weakly Regular) set for an incidence structure Q is a set of points such that the identity is the only automorphism of Q which maps onto itself (respectively which fixes pointwise). In this work Weakly Regular and Regular sets in Minkowski planes are investigated.Work done within the activity of G.N.S.A.G.A. of C.N.R. and supported by 40 % grants of M.U.R.S.T.G.Rinaldi thanks Fondazione Francesco Severi and Banca Popolare dell'Etruria e del Lazio for the prize which allowed this research.     

Gyroscopic signal smoothness assessment by geometric jolt estimation

The present contribution focuses on the estimation of the geometric acceleration and of the geometric jolt (namely, the derivative of the acceleration) of a multidimensional, structured gyroscopic signal. A gyroscopic signal encodes the instantaneous orientation of a rigid body during a full three‐dimensional rotation that is regarded as a trajectory in the curved space SO(3) of the special orthogonal matrices. The geometric acceleration and jolt associated to a gyroscopic signal are evaluated through the rules of calculus prescribed by differential geometry. Such an endeavor is motivated by recent studies on the smoothness of human body movement in biomechanical engineering, sports science, and rehabilitation neuroengineering. Two indexes of smoothness are compared, namely, a normalized proper geometric acceleration index and a normalized proper geometric jolt index. Our investigation concludes that, in the considered experiments with measured signals, for relatively low values of the acceleration and of the jolt indexes, such indexes are strongly positively correlated. Copyright © 2017 John Wiley & Sons, Ltd.     

HS–SPME–GC–MS for the Quantitation and Chiral Characterization of Camphor and Menthol in Creams

A GC–MS method is proposed for the analysis of camphor and menthol in “over-the-counter” (OTC) products. Sample preparation was achieved by head-space solid phase microextraction using a polydimethylsiloxane fibre. GC analysis was performed using a Phenomenex ZB-5 column and a temperature program was adopted. The method was validated by studying linearity (range 0.1–15.0% w/w), accuracy, reproducibility and sensitivity. Applications were directed to the determination of the active ingredients in four different OTC-products; the mean recoveries were in the ranges 91.30–99.74% and 94.34–102.89% for camphor and menthol, respectively and the LOD was in the order of 0.005% (w/w). Other important terpenoids (α- and β-pinene, 1,8-cineole, menthone, isomenthone, α-terpineole, t-cinnamaldehyde, eugenole) were identified by mass spectra and Kovats retention indices and quantified by peak area normalization to 100%. Further information for a comprehensive characterization of the OTC-products was achieved by the GC chiral analysis on a Cyclosil B capillary column.     

Novel iminium ion equivalents prepared through C-H oxidation for the stereocontrolled synthesis of functionalized propargylic amine derivatives

Access to stereochemically complex, polyfunctionalized amine derivatives is made possible using novel oxathiazinane N,O-acetal starting materials. These heterocycles are prepared through intramolecular sulfamate ester C-H insertion with a Rh(2+)-carboxylate catalyst and PhI(OAc)(2) as the terminal oxidant. Such compounds function as unique iminium ion equivalents to which nucleophilic alkynylzinc reagents add smoothly in the presence of BF(3).OEt(2). The coupled products are isolated in high yield (63-92%) and with good levels of diastereoinduction (6 --> 20:1). The alkyne-substituted oxathiazinanes serve as versatile building blocks and may be further manipulated through nucleophilic ring-opening reactions of the sulfamate core. The efficient construction of 1,7,8-trihydroxyindolizidine in six steps and in 34% overall yield highlights the power of these combined methods for synthesis.     

Aspidosperma Alkaloids. A New Didehydrodimerization Mode of β-Anilinoacrylic Alkaloids by Anodic Oxidation

A regio- and stereoselective didehydrodimerization procedure, whose key step involves the anodic oxidation, allows the conversion of β-anilinoacrylic alkaloids belonging to the Aspidosperma class, typified by tabersonine ( 1 ) and its 3-oxo derivative 2 , into the hitherto unknown 16,10′-didehydro dimers 3 and 7 , respectively.     

Iron in olive tree leaves in the Mediterranean area

In this paper we used the technique of X-ray fluorescence by dispersionin energy in order to study a phytopathology named sooty mouldin olive tree leaves in the Mediterranean area. Samples studied included leaveswhich were infected and non-infected by sooty mould. Energy depressive X-rayfluorescence showed a significant increase in the amount of Fe in the affectedleaves when compared to leaves that don't have this pattern of blackmaterial. We suggest here that a treatment for this condition may be basedon a method that deprives these organisms of the Fe that they apparently needto survive. The average Fe concentration obtained for the infected olive treeleaves was 80 ppm, while the non-infected ones showed no measurable Fe presence.