New and selective ryanodine receptor activators for insect control

Diamide insecticides have emerged as one of the most promising new classes of insecticide chemistry owing to their excellent insecticidal efficacy and high margins of mammalian safety. Chlorantraniliprole and flubendiamide, the first two insecticides from this class, demonstrate exceptional activity across a broad range of pests in the order Lepidoptera. This chemistry has been confirmed to control insects via activation of ryanodine receptors which leads to uncontrolled calcium release in muscle. The high levels of mammalian safety are attributed to a strong selectivity for insect over mammalian receptors.     

A bis-[N-3-(1-hydroxy-1-methyl-ethyl)-benzyl)-cyclic urea as a HIV protease inhibitor

Synthetic efforts to overcome the metabolic oxidative degradation of the HIV protease inhibitory cyclic urea DMP323, a benzyl alcohol, have led to the discovery of a tertiary carbinol with superior affinity for the viral protease and more potent inhibitory activity against viral replication. Synthetic approaches to this new carbinol and comparative analysis of its pharmacology and pharmacokinetics are presented.     

Antioxidant properties of violacein: possible relation on its biological function

Violacein, a violet pigment produced by Chromobacterium violaceum, has attracted much attention in recent literature due to its pharmacological properties. In this work, the antioxidant properties of violacein were investigated. The reactivity with oxygen and nitrogen reactive species and 1,1-diphenyl-2-picryl-hydrazyl (DPPH), a stable free radical, was evaluated. EPR studies were carried out to evaluate the reactivity with the hydroxyl radical. The action of violacein against lipid peroxidation in three models of lipid membranes, including rat liver microsomes, Egg and Soy bean phosphathidylcholine liposomes were also evaluated. The compound reacted with DPPH (IC₅₀ = 30 μM), nitric oxide (IC₅₀ = 21 μM), superoxide radicals (IC₅₀ = 125 μM) and decreased the hydroxyl radical EPR signal. The compound protected the studied membranes against peroxidation induced by reactive species in the micromolar range. The reconstitution of violacein into the membranes increased its antioxidant effect. These results indicate that the compound has strong antioxidant potential. Based on these results we suggest violacein plays an important role with the microorganism membrane in defense against oxidative stress.     

Cryotherapy and ankle bracing effects on peroneus longus response during sudden inversion

Cryotherapy and ankle bracing are often used in conjunction as a treatment for ankle injury. No studies have evaluated the combined effect of these treatments on reflex responses during inversion perturbation. This study examined the combined influence of ankle bracing and joint cooling on peroneus longus (PL) muscle response during ankle inversion. A 2 × 2 RM factorial design guided this study; the independent variables were: ankle brace condition (lace-up brace, control), and treatment (ice, control), and the dependent variables studied were PL stretch reflex latency (ms), and PL stretch reflex amplitude (% of max). Twenty-four healthy participants completed 5 trials of a sudden inversion perturbation to the ankle/foot complex under each ankle brace and cryotherapy treatment condition. No two-way interaction was observed between ankle brace and treatment conditions on PL latency (P = 0.283) and amplitude (P = 0.884). The ankle brace condition did not differ from control on PL latency and amplitude. Cooling the ankle joint did not alter PL latency or amplitude compared to the no-ice treatment. Ankle bracing combined with joint cooling does not have a deleterious effect on dynamic ankle joint stabilization during an inversion perturbation in normal subjects.     

Multiple bacterial infection ofAlexandrium catenella (Dinophyceae)

Chilean clones of Alexandrium catenella are shown to be infectedwith bacteria. The endocyto-plasmic bacteria have been isolatedand grown in culture. Using biochemical characterization, theywere tentatively identified as Aeromonas salmonicida, Flavobacteriumbreve, Pseudomonas diminuta, Pasteurella haemolytica, Proteusvulgaris, Pseudomonas putida, Pseudomonas versicularis and Moraxellasp.-like. In several instances, the analysis showed that A.catenella clones are simultaneously infected by different speciesof bacteria. Intracellular bacterial localization was demonstratedby confocal and electron microscope observations. Viabilityof intracellular bacteria was confirmed by using a specificdye that becomes fluorescent when it is reduced by electronsgenerated by respiration of live organisms. Thus, the bacteriaare alive and appear to be dividing inside the cells. Antibiotictreatment of A. catenella did not generate bacteria-free cells,leading instead to the killing of the host cells. Of all bacterialstrains isolated, only Moraxella sp.-like and P. diminuta arecapable of producing small amounts of saxitoxin, as detectedby HPLC. Toxic Moraxella sp.-like bacterium was isolated onlyfrom one A. catenella clone and confirmed by western blot analysis,suggesting that bacterial infection might be clone specific.     

Composition,Antibiofilm, and Antibacterial Potential of Volatile Oils from Geopropolis of Different Stingless Bees’ Species**

We aimed to characterize and investigate the antibacterial potential of the native stingless bees geopropolis volatile oils (VO) for the search of potentially new bioactive compounds. Geopropolis samples from Melipona bicolor schencki, M. compressipes manaosensis, M. fasciculata, M. quadrifasciata, M. marginata and M. seminigra merrillae were collected from hives in South Brazil. VO were obtained by hydrodistillation and characterised by gas chromatography coupled to mass spectrometry (GC/MS). Antimicrobial activity was assessed by microplate dilution method. The lowest MIC against cell walled bacteria was 219±0 μg mL⁻¹ from M. quadrifasciata geopropolis VO with Staphylococcus aureus. The M. b. schencki geopropolis VO minimal inhibition concentration (MIC) was 424±0 μg mL⁻¹ against all the mycoplasma strains evaluated. Fractionation resulted in the reduction of 50 % of the MIC value from the original oil. However, its compounds’ synergism seems to be essential to this activity. Antibiofilm assays demonstrated 15.25 % eradication activity and 13.20 % inhibition of biofilm formation after 24 h for one subfraction at 2× its MIC as the best results found. This may be one of the essential mechanisms by which geopropolis VOs perform their antimicrobial activity.