Disposable Pencil Graphite Electrode for Ciprofloxacin Determination in Pharmaceutical Formulations by Square Wave Voltammetry

In this work, a new electrochemical sensor based on pencil graphite with interesting features, such as low cost (US$ 0.01 per electrode), ease manufacture, and portability was developed. The sensor showed an adequate manufacturing reproducibility with RSD <5.3 %. Under this electrochemical platform, ciprofloxacin underwent an irreversible oxidation process at 1.03 V, characterized by the diffusion of electroactive species. A simple method by square wave voltammetry (SWV) has been optimized for the determination of ciprofloxacin in pharmaceutical formulations using a pencil graphite electrode (PGE). The method showed satisfactory analytical performance, with a wide linear range (12 to 55 μmol L⁻¹), low detection limit (5.6 μmol L⁻¹), adequate precision (RSD <3.2 %), and accuracy with an average recovery of (102±15)%. Samples of pharmaceutical formulations were evaluated, obtaining levels of ciprofloxacin close to those established by the manufacturers. In addition, the samples were analyzed by liquid chromatography and there was no significant difference between the methods at the 95 % confidence level. In this sense, the method developed proved to be reliable and promising for the quality control of pharmaceutical formulations.     

Simultaneous Production of Amyloglucosidase and Exo-Polygalacturonase by <Emphasis Type="Italic">Aspergillus niger</Emphasis> in a Rotating Drum Reactor

Simultaneous production of amyloglucosidase (AMG) and exo-polygalacturonase (exo-PG) was carried out by Aspergillus niger in substrate of defatted rice bran in a rotating drum bioreactor (RDB) and studied by a 3¹ × 2² factorial experimental design. Variables under study were A. niger strains (A. niger NRRL 3122 and A. niger t0005/007-2), types of inoculum (spore suspension and fermented bran), and types of inducer (starch, pectin, and a mix of both). Solid-state fermentation process (SSF) was conducted at 30 °C under 60-vvm aeration for 96 h in a pilot scale. Production of AMG and exo-PG was significantly affected by the fungal strain and the type of inoculum, but inducers did not trigger any significant effect, an evidence of the fact that these enzymes are constitutive. The maximum activity of exo-PG was 84 U g_dm ^?1 whereas the maximum yield of AMG was 886.25 U g_dm ^?1.     

DFT study on the complexation of anions with 1,4,7,10,13,16-hexaazacyclooctodeca-2,5,8,11,14,17-hexaene

Macrocyclic compounds have been widely used as anion carriers, as they play important functions in chemical and biological systems. This work reports a theoretical study on free 1,4,7,10,13,16-hexaazacyclooctodeca-2,5,8,11,14,17-hexaene (HAC), as well as its complex with fluoride, chloride, bromide and acetate anions, with and without the presence of the sodium counterion, in the gas phase and implicit solvents (cyclohexane and acetonitrile), at the ωB97X-D/6-311G(d,p) level. The negative ?G⁰ values indicate that the crown-anion complex is prone to be formed due to hydrogen bonds in all tested media. Nevertheless, such interactions weaken as the solvent polarity increases. The ΔG⁰ _C6H12 values decrease when the counterion is taken into account, reinforcing the formation of the Na⁺?HAC?X^? complex. However, the complexation is disfavored in polar solution, since the presence of the counterion increases the HAC-anion distance. Natural bond orbital analysis, the quantum theory of atoms in molecules and non-covalent interactions methods explored the nature and strength of the hydrogen bond interactions, while spin–spin coupling constant calculations for the fluoride-based complex (^1h J _F,H(N)) gave insight into the potential of this NMR parameter to experimentally probe the complexation of HAC with fluoride.     

Antioxidant,antibacterial and cytotoxic potential of the ripe fruits of Solanum lycocarpum A. St. Hil. (Solanaceae)

Ethanol extract (EE) and fractions obtained from the ripe fruits of Solanum lycocarpum were examined in order to determine their phenolic composition, antioxidant capacity, antibacterial activities and cytotoxic potential. High-performance liquid chromatography coupled with DAD analysis indicated that caffeic and chlorogenic acids were the main phenolic compounds present in the EE, dichloromethane (DCM) and ethyl acetate (Ac) fractions. The antioxidant activity assessed by the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radical was significantly more pronounced for DCM and Ac fractions than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). EE and fractions exhibited selective antibacterial activity against Gram-positive bacteria, especially the hexane (Hex) and DCM fractions. EE and fractions exhibited low toxicity towards the LLC-MK2 cell line, especially the Hex, DCM and Ac fractions. This work provides the knowledge of phenolic composition in the extract and fractions from the ripe fruits of S. lycocarpum and their antioxidant, antibacterial and cytotoxic activities.     

Antiviral properties from plants of the Mediterranean flora

Natural products are a successful source in drug discovery, playing a significant role in maintaining human health. We investigated the in vitro cytotoxicity and antiviral activity of extracts from 18 traditionally used Mediterranean plants. Noteworthy antiviral activity was found in the extract obtained from the branches of Daphne gnidium L. against human immunodeficiency virus type-1 (EC₅₀ = 0.08 μg/mL) and coxsackievirus B5 (EC₅₀ = 0.10 μg/mL). Other relevant activities were found against BVDV, YFV, Sb-1, RSV and HSV-1. Interestingly, extracts from Artemisia arborescens L. and Rubus ulmifolius Schott, as well as those from D. gnidium L., showed activities against two different viruses. This extensive antiviral screening allowed us to identify attractive activities, offering opportunities to develop lead compounds with a great pharmaceutical potential.     

Ascorbic acid in cosmetic formulations: Stability,in vitro release,and permeation using a rapid,inexpensive, and simple method

Ascorbic acid (AA) is involved in important metabolic processes in the human body. However, its chemical instability requires the assessment of products containing AA. The aim of this study was to develop systems that improve AA stability and to evaluate its release profile, permeation, and skin retention in vitro. For this purpose, we prepared binary systems consisting of propylene glycol and water, microemulsions, liquid crystalline systems, and an emulsion. The AA content in these systems was evaluated over time by measuring the inhibition of 1,1-diphenyl-2-picrylhydrazyl (DPPH). Our results demonstrated that the binary systems and molecular aggregates were less stable and effective than the emulsion. Thus, in vitro AA release, skin permeation, and retention were evaluated using the emulsion. Our results indicate that AA exhibits low release and permeation levels and a high retention rate in the skin, characteristics desirable in cosmetic products.     

Synthesis and anti‐HIV‐1 activity of 1,3‐phenylene bis‐uracil analogues of MKC‐442

Reaction of 1,3‐phenylenediacetonitrile with the zinc organometallic reagent of ethyl 2‐bromobutyrate afforded the 1,3‐phenylene‐bis(acetoacetate) 2 which was used as the starting material for the synthesis of 1,3‐phenylene‐bis[6‐(2‐thiouracil)] 4 . Desulphurization of 4 gave the corresponding bis‐uracil 6 , which after silylation was N‐1 alkylated with bis(allyoxy)methane using TMS‐triflate as the catalyst or with chloromethyl ethyl ether to give the MKC‐442 analogues 7 and 9 . The amino‐DABO and S‐DABO derivatives 11, 12a,b and 14 were also synthesized. The anti‐HIV‐1 activity test showed that when MKC‐442 analogues were constructed with 1,3‐phenylene in all cases they were detrimental to have activity against HIV‐1.     

T cell response in rheumatic fever: crossreactivity between streptococcal M protein peptides and heart tissue proteins

Molecular mimicry between streptococcal and human proteins has been proposed as the triggering factor leading to autoimmunity in rheumatic fever (RF) and rheumatic heart disease (RHD). In this review we focus on the studies on genetic susceptibility markers involved in the development of RF/RHD and molecular mimicry mediated by T cell responses of RHD patients against streptococcal antigens and human tissue proteins. We identified several M protein epitopes recognized by peripheral T cells of RF/RHD patients and by heart tissue infiltrating T cell clones of severe RHD patients. The regions of the M protein preferentially recognized by human T cells were also recognized by murine T cells. By analyzing the T cell receptor (TCR) we observed that some Vbeta families detected on the periphery were oligoclonal expanded in the heart lesions. These results allowed us to confirm the major role of T cells in the development of RHD lesions.     

Long-Term Evaluation of Poly(lactic acid) (PLA) Implants in a Horse: An Experimental Pilot Study

In horses, there is an increasing interest in developing long-lasting drug formulations, with biopolymers as viable carrier alternatives in addition to their use as scaffolds, suture threads, screws, pins, and plates for orthopedic surgeries. This communication focuses on the prolonged biocompatibility and biodegradation of PLA, prepared by hot pressing at 180 °C. Six samples were implanted subcutaneously on the lateral surface of the neck of one horse. The polymers remained implanted for 24 to 57 weeks. Physical examination, plasma fibrinogen, and the mechanical nociceptive threshold (MNT) were performed. After 24, 28, 34, 38, and 57 weeks, the materials were removed for histochemical analysis using hematoxylin-eosin and scanning electron microscopy (SEM). There were no essential clinical changes. MNT decreased after the implantation procedure, returning to normal after 48 h. A foreign body response was observed by histopathologic evaluation up to 38 weeks. At 57 weeks, no polymer or fibrotic capsules were identified. SEM showed surface roughness suggesting a biodegradation process, with an increase in the median pore diameter. As in the histopathological evaluation, it was not possible to detect the polymer 57 weeks after implantation. PLA showed biocompatible degradation and these findings may contribute to future research in the biomedical area.     

Effect of Biologically Oriented Preparation Technique on the Stress Concentration of Endodontically Treated Upper Central Incisor Restored with Zirconia Crown: 3D-FEA

The aim of this study was to evaluate the effect of biologically oriented preparation technique on the stress concentration of endodontically treated upper central incisors restored with zirconia crown (yttria-stabilized zirconia polycrystalline ceramic) through finite element analysis (FEA). Four models of maxillary central incisors containing enamel, dentin, periodontal ligament, cortical and medullary bone were created in CAD. Each model received a polymeric core-build up with nanofilled dental resin composite. The evaluated models were SM—preparation in shoulder 90°; CM—chamfer preparation; BOPT—biologically oriented preparation technique and BOPTB—BOPT preparation 1 mm below the cement-enamel junction. All models received zirconia crowns (5Y-TZP), fiberglass post and 1 mm ferrule. The models were imported into the analysis software with parameters for mechanical structural testing using the maximum principal stress and the tensile strength as the analysis criteria. Then, load of 150 N was applied at the cingulum with 45° slope to the long axis of the tooth, with the fixed base for each model. The type of marginal preparation affected the stresses concentration in endodontically treated teeth and in the zirconia crown margin. Considering the stress magnitude only, BOPT is a viable option for anterior monolithic zirconia crowns; however, with the highest stress magnitude at the restoration margin.