Kaurenoic acid extracted from Sphagneticola trilobata reduces acetaminophen-induced hepatotoxicity through inhibition of oxidative stress and pro-inflammatory cytokine production in mice

Acetaminophen (paracetamol) is a widely used analgesic and antipyretic drug that is safe at therapeutic doses. However, acetaminophen overdose can be fatal. Currently, the only treatment available is the N-acetyl cysteine. The diterpene kaurenoic acid (ent-kaur-16-en-19-oic acid, KA) is the major constituent of Sphagneticola trilobata (L.) Pruski. KA presents anti-inflammatory, anti-nociceptive and antioxidant properties. In this study, we evaluated the efficacy of KA in a model of acetaminophen-induced hepatotoxicity. KA increased, in a dose-dependent manner, the survival rate after acetaminophen overdose. KA reduced acetaminophen-induced hepatic necrosis and ALT and AST levels. KA decreased acetaminophen-induced neutrophil and macrophage recruitment, oxidative stress and the production of IL-33, TNF-α and IL-1β, alongside with normalisation of IL-10 levels in the liver. Therefore, KA showed preclinical efficacy in acetaminophen-induced hepatotoxicity and lethality.     

Cytotoxic flavonoids from two Lonchocarpus species

A new isoflavone, 4′-prenyloxyvigvexin A (1) and a new pterocarpan, (6aR,11aR)-3,8-dimethoxybitucarpin B (2) were isolated from the leaves of Lonchocarpus bussei and the stem bark of Lonchocarpus eriocalyx, respectively. The extract of L. bussei also gave four known isoflavones, maximaisoflavone H, 7,2′-dimethoxy-3′,4′-methylenedioxyisoflavone, 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone, durmillone; a chalcone, 4-hydroxylonchocarpin; a geranylated phenylpropanol, colenemol; and two known pterocarpans, (6aR,11aR)-maackiain and (6aR,11aR)-edunol. (6aR,11aR)-Edunol was also isolated from the stem bark of L. eriocalyx. The structures of the isolated compounds were elucidated by spectroscopy. The cytotoxicity of the compounds was tested by resazurin assay using drug-sensitive and multidrug-resistant cancer cell lines. Significant antiproliferative effects with IC₅₀ values below 10 μM were observed for the isoflavones 6,7,3′-trimethoxy-4′,5′-methylenedioxyisoflavone and durmillone against leukemia CCRF-CEM cells; for the chalcone, 4-hydroxylonchocarpin and durmillone against its resistant counterpart CEM/ADR5000 cells; as well as for durmillone against the resistant breast adenocarcinoma MDA-MB231/BCRP cells and resistant gliobastoma U87MG.ΔEGFR cells.     

Universal critical exponent in class D superconductors

We study a physical system consisting of noninteracting quasiparticles in disordered superconductors that have neither time-reversal nor spin-rotation invariance. This system belongs to class D within the recent classification scheme of random matrix ensembles, and its phase diagram contains three different phases: metallic and two distinct localized phases with different quantized thermal Hall conductances. We find that critical exponents describing different transitions (insulator-to-insulator and insulator-to-metal) are identical within the error of numerical calculations and also find that critical disorder of the insulator-to-metal transition is energy-independent.     

Nonlinear surface acoustic waves: silicon strength in phonon-focusing directions

The anisotropy of the elastic properties of single-crystal silicon manifests itself in features of both the linear and nonlinear surface acoustic wave (SAW) propagation. Directions showing the phonon-focusing effect and strong nonlinearity were employed in contact-free and notch-free laser-based fracture experiments, yielding the intrinsic strength of silicon. The critical tensile stress values vary between 2.5 GPa and 7 GPa for the different crystallographic planes and directions of SAW propagation investigated.     

Highly asymmetric soliton complexes in parabolic optical lattices

We introduce multipole soliton complexes in optical lattices induced by nondiffracting parabolic beams. Despite the symmetry breaking dictated by the curvature of the lattice channels, we find that complex, asymmetric higher-order states can be stable. The unique topology of parabolic lattices affords new types of soliton motion: single solitons launched into the lattice with nonzero transverse momentum perform periodic oscillations along parabolic paths.     

Power-dependent shaping of vortex solitons in optical lattices with spatially modulated nonlinear refractive index

We address vortex solitons supported by optical lattices featuring modulation of both the linear and nonlinear refractive indices. We find that when the modulation is out of phase the competition between both effects results in remarkable shape transformations of the solitons that profoundly affect their properties and stability. Nonlinear refractive index modulation is found to impose restrictions on the maximal power of off-site solitons, which are shown to be stable only below a maximum nonlinearity modulation depth.     

Random vortex-street model for a self-similar plane turbulent jet

We ask what determines the (small) angle of turbulent jets. To answer this question we first construct a deterministic vortex-street model representing the large-scale structure in a self-similar plane turbulent jet. Without adjustable parameters the model reproduces the mean velocity profiles and the transverse positions of the large-scale structures, including their mean sweeping velocities, in a quantitative agreement with experiments. Nevertheless, the exact self-similar arrangement of the vortices (or any other deterministic model) necessarily leads to a collapse of the jet angle. The observed (small) angle results from a competition between vortex sweeping tending to strongly collapse the jet and randomness in the vortex structure, with the latter resulting in a weak spreading of the jet.     

Universal mechanism for breaking the hc/2e periodicity of flux-induced oscillations in small superconducting rings

A universal mechanism of restoration of minimal hc/e periodicity in the response of small superconducting rings or cylinders to the magnetic flux is proposed. The mechanism is based on the dependence of the Cooper pair's internal energy on its motion as a whole and does not rely on the presence of quasiparticles in the system. The thermal equilibrium hc/2e periodicity is broken by an offset of the transition between different current-carrying states. The magnitude of the offset is calculated for an s-wave superconducting cylinder of radius R in the limit R>xi_{0}, where xi_{0} is the BCS coherence length and turns out to be exponentially small. A possible enhancement of the effect for nodal superconductors is suggested. Similar conclusions should also apply to the response of charged or neutral superfluids to rotation.