The Natural Compound Hydrophobic Usnic Acid and Hydrophilic Potassium Usnate Derivative: Applications and Comparisons

Usnic acid is the best-studied lichen metabolite, presenting several biological activities, such as antibacterial, immunostimulating, antiviral, antifungal, anti-inflammatory, and antiparasitic agents; despite these relevant properties, it is a hydrophobic and toxic molecule. In this context, scientific research has driven the development of innovative alternatives, considering usnic acid as a source of raw material in obtaining new molecules, allowing structural modifications (syntheses) from it. The purpose is to optimize biological activities and toxicity, with less concentration and/or response time. This work presents a literature review with an analogy of the hydrophobic molecule of usnic acid with its hydrophilic derivative of potassium usnate, emphasizing the elucidation and structural characteristics, biological activities, and toxicological aspects of both molecules, and the advantages of using the promising derivative hydrophilic in different in vitro and in vivo assays when compared to usnic acid.     

Bifurcation of Nonclassical Viscous Shock Profiles from the Constant State

We determine the bifurcation from the constant solution of nonclassical transitional and overcompressive viscous shock profiles, in regions of strict hyperbolicity. Whereas classical shock waves in systems of conservation laws involve a single characteristic field, nonclassical waves involve two fields in an essential way. This feature is reflected in the viscous profile differential equation, which undergoes codimension-three bifurcation of the kind studied by Dumortier et al., as opposed to the codimension-one bifurcation occurring in the classical case. We carry out a complete bifurcation analysis for systems of two quadratic conservation laws with constant, strictly parabolic viscosity matrices by reducing to a canonical form introduced by Fiddelaers. We show that all such systems, except possibly those on a codimension-one variety in parameter space, give rise to nonclassical shock waves, and we classify the number and types of their bifurcation points. One consequence of our analysis is that weak transitional waves arise in pairs, with profiles forming a 2-cycle configuration previously shown to lead to nonuniqueness of Riemann solutions and to nontrivial asymptotic dynamics of the conservation laws. Another consequence is that appearance of weak nonclassical waves is necessarily associated with change of stability in constant solutions of the parabolic system of conservation laws, rather than with change of type in the associated hyperbolic system.     

Antifungal Activity and In Silico Studies on 2-Acylated Benzo- and Naphthohydroquinones

The high rates of morbidity and mortality due to fungal infections are associated with a limited antifungal arsenal and the high toxicity of drugs. Therefore, the identification of novel drug targets is challenging due to the several resemblances between fungal and human cells. Here, we report the in vitro antifungal evaluation of two acylphenols series, namely 2-acyl-1,4-benzo- and 2-acyl-1,4-naphthohydroquinones. The antifungal properties were assessed on diverse Candida and filamentous fungi strains through the halo of inhibition (HOI) and minimal inhibitory concentration (MIC). The antifungal activities of 2-acyl-1,4-benzohydroquinone derivatives were higher than those of the 2-acyl-1,4-naphthohydroquinone analogues. The evaluation indicates that 2-octanoylbenzohydroquinone 4 is the most active member of the 2-acylbenzohydroquinone series, with MIC values ranging from 2 to 16 μg/mL. In some fungal strains (i.e., Candida krusei and Rhizopus oryzae), such MIC values of compound 4 (2 and 4 μg/mL) were comparable to that obtained by amphotericin B (1 μg/mL). The compound 4 was evaluated for its antioxidant activity by means of FRAP, ABTS and DPPH assays, showing moderate activity as compared to standard antioxidants. Molecular docking studies of compound 4 and ADMET predictions make this compound a potential candidate for topical pharmacological use. The results obtained using the most active acylbenzohydroquinones are promising because some evaluated Candida strains are known to have decreased sensitivity to standard antifungal treatments.     

Antiangiogenic and Antioxidant In Vitro Properties of Hydroethanolic Extract from açaí (Euterpe oleracea) Dietary Powder Supplement

The Euterpe oleracea fruit (açaí) is a promising source of polyphenols with health-promoting properties. To our knowledge, few studies have focused on the influence of açaí phytochemicals on angiogenesis, with a significant impact on cancer. This study aimed at investigating the phytochemical profile of a purple açaí hydroethanolic extract (AHE) obtained from a commercial dietary powder supplement by high-performance liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry, and evaluate its in vitro effects on distinct angiogenic steps during vessel growth and on oxidative markers in human microvascular endothelial cells (HMEC-1). The phenolic profile of AHE revealed the presence of significant levels of anthocyanins, mainly cyanidin-3-O-rutinoside, and other flavonoids with promising health effects. The in vitro studies demonstrated that AHE exerts antiangiogenic activity with no cytotoxic effect. The AHE was able to decrease HMEC-1 migration and invasion potential, as well as to inhibit the formation of capillary-like structures. Additionally, AHE increased antioxidant defenses by upregulating superoxide dismutase and catalase enzymatic activities, accompanied by a reduction in the production of reactive oxygen species. These data bring new insights into the potential application of angiogenic inhibitors present in AHE on the development of novel therapeutic approaches for angiogenesis-dependent diseases.     

Sobolev homeomorphisms are dense in volume preserving automorphisms

In this paper we prove a weak version of Lusin's theorem for the space of Sobolev-$(1,p)$ volume preserving homeomorphisms on closed and connected n-dimensional manifolds, $n\ge 3$, for $p<n?1$. We also prove that if $p>n$ this result is not true. More precisely, we obtain the density of Sobolev-$(1,p)$ homeomorphisms in the space of volume preserving automorphisms, for the weak topology. Furthermore, the regularization of an automorphism in a uniform ball centered at the identity can be done in a Sobolev-$(1,p)$ ball with the same radius centered at the identity.     

Existence and asymptotic behaviour for the time‐fractional Keller–Segel model for chemotaxis

One of the most important systems for understanding chemotactic aggregation is the Keller–Segel system. We consider the time‐fractional Keller–Segel system of order . We prove an existence result with small initial data in a class of Besov–Morrey spaces. Self‐similar solutions are obtained and we also show an asymptotic behaviour result.     

Optical properties of B x N y C z monolayers

We apply first-principles methods, based on the density functional theory, to investigate the optical properties of B _x N _y C _z hybrid monolayers containing domains. It is observed that the energy structure of such compounds exhibits bound excitons in the near-infrared region. Moreover, such compounds present an extraordinary absorptive capacity in the visible spectrum, which makes them important candidates for future solar cells applications.     

Thermo-rheological behavior of model protein–polysaccharide mixtures

The use of mixtures of pea protein isolate (PPI) and κ-carrageenan (κ-C) is increasing rapidly with the aim of increasing the stability and viscosity of food products. Recent works have studied their textural and thermal properties but few have studied the influence of the temperature and concentration on the rheological behavior of model systems. In the present work, we study the thermo-rheological properties in the linear and non-linear viscoelastic regimes, in both shear and extensional flows, of mixtures of PPI and κ-C with the aim of obtaining a model for the temperature-induced gelation of complex mixtures of globular vegetable proteins under linear and non-linear deformations. We analyzed the influence of temperature and protein-to-polysaccharide ratios and showed that there are strong changes in the mechanical properties. In shear flows, small-amplitude oscillatory shear was used to study the linear regime and large-amplitude oscillatory shear was used for the non-linear regime. In extensional flows, studies were carried out via the analysis of the dynamics of capillary thinning and breakup process in a filament-thinning rheometer.