Effectiveness of a formulation based on Ocimum gratissimum essential oil and cashew gum as inhibitors of quality loss and melanosis in shrimp.

In this study, two nanoemulsions were formulated with essential oil (EO) of Ocimum gratissimum with (EON) or without (EOE) cashew gum (CG). Subsequently, inhibition of melanosis and preservation of the quality of shrimp stored for 16 days at 4 ± 0.5 °C were evaluated. A computational approach was performed to predict the system interactions. Dynamic light scattering (DLS) and atomic force microscopy (AFM) were used for nanoparticle analysis. Gas chromatography and flame ionization detector (GC-FID) determined the chemical composition of the EO constituents. Shrimps were evaluated according to melanosis's appearance, psychrotrophic bacteria's count, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances. EON exhibited a particle size three times smaller than EOE. The shrimp treated with EON showed a more pronounced sensory inhibition of melanosis, which was considered mild by the 16th day. Meanwhile, in the other groups, melanosis was moderate (EOE) or severe (untreated group). Both EON and EOE treatments exhibited inhibition of psychrotrophic bacteria and demonstrated the potential to prevent lipid oxidation, thus extending the shelf life compared to untreated fresh shrimp. EON with cashew gum, seems more promising due to its physicochemical characteristics and superior sensory performance in inhibiting melanosis during shrimp preservation.

In silico and in vitro assays suggests Congo red dye degradation by a Lentinus sp. laccase enzyme.

Laccase is a superfamily of ligninolytic enzymes known to degrade a wide variety of xenobiotics, including synthetic dyes. Congo Red (CR) has a diazo dye function, carcinogenic and mutagenic potential, and is currently applied in clinical analysis. The objective of this work was to produce and characterize the crude extract of Lentinus sp. in semi-solid fermentation (FSS) and perform in vitro and in silico studies to assess the potential of the crude extract to discolor the CR dye. Laccase activity was determined using ABTS as substrate and characterized. The in vitro discoloration was carried out using experimental design 22 at room temperature and monitored at 340 nm for 24h. Molecular docking and molecular dynamics simulations were performed between laccase and CR. The maximum laccase activity production was 29.63 U L-1 with six days of FSS. The optimal temperature and pH were 50 °C and 3.0, respectively. Discoloration of the CR dye was obtained only in tests containing CuSO4. Laccase formed stable complexes with the dye, presenting negative binding energy values ranging from -70.94 to -63.16 kcal mol-1 and the occurrence of seven hydrogen bonds. Molecular dynamics results showed the stability of the system (RMSD ranging from 1.0 to 2.5 Ä) and protein-ligand interaction along simulation. RMSF values pointed residues at the end of chains A (residues 300 to 305, 480 to 500) and B (residues 650 to 655 and 950 to 1000) as the most flexible regions of the laccase. This study highlighted the enzymatic action in the bioremediation of CR in vitro in agreement with the in silico simulations that demonstrate the enzyme potential.Communicated by Ramaswamy H. Sarma.

Evolution of supersaturation from amorphous solid dispersions in water-insoluble polymer carriers: Effects of swelling capacity and interplay between partition and diffusion.

The use of water-insoluble carriers for amorphous solid dispersions (ASDs) has attracted more recent interest as the kinetic solubility profiles (KSP) from these systems can achieve a more sustained level of supersaturation when compared with ASDs based on water-soluble polymers. However, the effect of swelling capacity of water-insoluble carriers on the resulting KSP of ASDs has not been fully explored in terms of their achievable degree and extent of drug supersaturation. Thus, the objective of this study is to compare kinetic solubility profiles of ASDs based on commercially available water-insoluble carriers in order to bridge this knowledge gap and provide fundamental information important to the design of ASDs based on water-insoluble carriers. This was achieved by comparing the KSP from non-sink dissolution studies of ASDs of two model poorly-water soluble drugs, indomethacin (IND) and posaconazole (PCZ) based on commercially available water-insoluble carriers with different equilibrium water swelling such as fully hydrolyzed (physically crosslinked) poly (vinyl alcohol) (PVA), Eudragit RS PO, as well as chemically crosslinked PHEMA hydrogels . Our results show that the higher the swelling capacity of the water-insoluble carrier, the faster the rate of supersaturation generation, and the shorter the sustained supersaturation due to drug precipitation. The interplay of particle size, total dose and the swelling capacity was also shown to be an essential aspect when tailoring the supersaturation generation from water-insoluble polymer-based ASDs. The importance of the swelling feature was confirmed using firstly different polymer carriers (PVA, Eudragit RS PO, and PHEMA) and then polymer samples of identical composition and drug loading but with different swelling capacities (e.g., PVA, physically crosslinked to different degrees). Furthermore, a large drug partitioning value between the polymer carrier and dissolution medium was found to limit the extent of drug release or supersaturation buildup from these ASDs. Finally, the existence of electrostatic polymer-drug interactions realized from our molecular dynamic simulations supports the observed impact of the large partitioning of the model drug IND between the polymer ED RS PO and the dissolution medium, thereby leading to a lower degree of supersaturation generation (or slower drug release) from this ASD.

Possible Metsulfuron Herbicide Detoxification by a Oryza sativa L. Glutathione S-transferase Enzyme

Abstract Rice (Oryza sativa L.) is one of the most important crops in the world, and it is considered the primary source of nutritional layout in developing countries in Asia. The glutathione S-transferases (GSTs) superfamily confers to rice protection against biotic and abiotic stress, and herbicide resistance. However, the three-dimensional structure of a GST Tau class, is unsolved. The objectives of this work were to develop a reliable comparative model for the s-transferase glutathione class Tau 4 from rice, and simulate docking interactions, against herbicides bentazon and metsulfuron. Results showed that the predicted model is reliable and has structural quality. Ramachandran plot set 91.9% of the residues in the most favored regions. All complexes showed negative binding energies values; and metsulfuron docked to the glutathione tripeptide, and it represents a possible insilico evidence of glutathione conjugation with this herbicide.

Solvent-free production of phthalated cashew gum for green synthesis of antimicrobial silver nanoparticles.

This work describes a solvent-free method for the chemical modification of cashew gum (Anacardium occidentale L.) using phthalic anhydride in different proportions with different reaction times. Four biopolymers were synthesized and characterized by FTIR, NMR, and elemental analysis. A computational chemistry study was conducted to understand better the reaction. Phthalated cashew gum was used in preparation of silver nanoparticles (AgNPs) by a conventional route, using sodium borohydride (NaBH4) as reducing agent, and for green route. AgNPs were evaluated for antimicrobial activity and characterized by UV-Vis spectroscopy, FTIR, nanoparticle tracking analysis, Zeta Potential analysis, and atomic force microscopy. AgNPs produced by the green route had an average size of 51.9 nm and Zeta Potential of -55.8 mV, and AgNPs produced by the conventional method had an average size of 47.7 nm and Zeta Potential of -39.3 mV. AgNPs synthesized using phthalated cashew gum showed antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Enhanced delivery of fixed-dose combination of synergistic antichagasic agents posaconazole-benznidazole based on amorphous solid dispersions.

Posaconazole (PCZ) and benznidazole (BNZ) are known to show synergetic effect in treating the acute and chronic phases of Chagas disease, a neglected parasitic disease. However, as both compounds are poorly water soluble, the development of amorphous solid dispersions (ASDs) of a PCZ/BNZ fixed-dose combination in a water-soluble polymer becomes an attractive option to increase their apparent solubility and dissolution rate, potentially improving their oral bioavailability. The initial approach was to explore solvent evaporated solid dispertion (SD) systems for a PCZ/BNZ 50:50 (wt%) combination at several total drug loading levels (from SD with 10% to 50% drug loading) in water-soluble carriers, including polyvinylpyrrolidone (PVP K-30) and vinylpyrrolidone-vinyl acetate copolymer (PVPVA 64). Based on comparison of non-sink in vitro dissolution performance, ASD systems based on PVPVA was identified as the most effective carrier for a 50:50 (w/w %) fixed-dose combination of PCZ/BNZ to increase their apparent solubility and dissolution rate, mainly at 10% drug loading, which shows more expressive values of area under the curve (AUC) (7336.04 ±â€¯3.77 min.µL/mL for PCZ and 15,795.02 ±â€¯7.29 min.µL/mL for BNZ). Further characterization with polarized microscopy, powder X-ray diffraction, and thermal analysis reveals that there exists a threshold drug loading level at about 30% PCZ/BNZ, below which ASDs are obtained and above which a certain degree of crystallinity tends to result. Moreover, infrared spectroscopic analysis reveals the lack of hydrogen bonding interactions between the drugs (PCZ and BNZ) and the polymer (PVPVA) in the ASD, this is also confirmed through molecular dynamics simulations. The molecular modeling results further show that even in the absence of meaningful hydrogen bonding interactions, there is a greater tendency for PVPVA to interact preferentially with PCZ and BNZ through electrostatic interactions thereby contributing to the stability of the system. Thus, the present SD system has the advantage of presenting a fixed-dese combination of two synergistic antichagasic agents PCZ and BNZ together in amorphous form stabilized in the PVPVA matrix with enhanced dissolution, potentially improving their bioavailability and therapeutic activity in treating Chagas disease.

Enhancement of dissolution rate through eutectic mixture and solid solution of posaconazole and benznidazole.

Benznidazole (BNZ), the only commercialized antichagasic drug, and the antifungal compound posaconazole (PCZ) have shown synergistic action in the therapy of Chagas disease, however both active pharmaceutical ingredients (APIs) exhibit low aqueous solubility potentially limiting their bioavailability and therapeutic efficacy. In this paper, we report for the first time the formation of a eutectic mixture as well as an amorphous solid solution of PCZ and BNZ (at the same characteristic ratio of 80:20wt%), which provided enhanced solubility and dissolution rate for both APIs. This eutectic system was characterized by DSC and the melting points obtained were used for the construction of a phase diagram. The preservation of the characteristic PXRD patterns and the IR spectra of the parent APIs, and the visualization of a characteristic eutectic lamellar crystalline microstructure using Confocal Raman Microscopy confirm this system as a true eutectic mixture. The PXRD result also confirms the amorphous nature of the prepared solid solution. Theoretical chemical analyses indicate the predominance of π-stacking interactions in the amorphous solid solution, whereas an electrostatic interaction between the APIs is responsible for maintaining the alternating lamellar crystalline microstructure in the eutectic mixture. Both the eutectic mixture and the amorphous solid solution happen to have a characteristic PCZ to BNZ ratio similar to that of their pharmacological doses for treating Chagas disease, thus providing a unique therapeutic combination dose with enhanced apparent solubility and dissolution rate.

Theoretical and experimental studies of the stability of drug-drug interact.

Several factors can intervene in the molecular properties and consequently in the stability of drugs. The molecular complexes formation often occur due to favor the formation of hydrogen bonds, leading the system to configuration more energy stable. This work we aim to investigate through theoretical and experimental methods the relation between stability and properties of molecular complexes the molecular complex formed between the drugs, efavirenz (EFV), lamivudine (3TC) and zidovudine (AZT). With this study was possible determining the most stable complex formed between the compounds evaluated. In addition the energy and structural properties of the complex formed in relation to its individual components allowed us to evaluate the stability of the same.

Gums' based delivery systems: Review on cashew gum and its derivatives.

The development of delivery systems using natural polymers such as gums offers distinct advantages, such as, biocompatibility, biodegradability, and cost effectiveness. Cashew gum (CG) has rheological and mucoadhesive properties that can find many applications, among which the design of delivery systems for drugs and other actives such as larvicide compounds. In this review CG is characterized from its source through to the process of purification and chemical modification highlighting its physicochemical properties and discussing its potential either for micro and nanoparticulate delivery systems. Chemical modifications of CG increase its reactivity towards the design of delivery systems, which provide a sustained release effect for larvicide compounds. The purification and, the consequent characterization of CG either original or modified are of utmost importance and is still a continuing challenge when selecting the suitable CG derivative for the delivery of larvicide compounds.

Molecular docking of Anopheles gambiae and Aedes aegypti glutathione S-transferases epsilon 2 (GSTE2) against usnic acid: an evidence of glutathione conjugation

The aim of this study was to develop a theoretical model using Anopheles gambiae GSTE2 structure as template for Aedes aegypti GSTE2 by homology modeling Docking simulations were performed for both the enzymes against usnic acid in neutral and anionic forms. Ramachandran plot revealed that 93.9% of the GSTE2 model residues were located on most favored regions. Model evaluation was made by the ANOLEA and GROMOS analysis. Docking results indicated that the enzymes were able to form glutathione-conjugate with usnic acid in both the forms (anionic and neutral).

Anionic form of usnic acid promotes lamellar to nonlamellar transition in DPPC and DOPC membranes.

Usnic acid is a secondary metabolite found in several species of lichens, organisms resulting from the symbiosis between fungi and algae. This compound has been extensively studied because of its pharmacological properties. Despite its potential medicinal importance, it exhibits a high degree of toxicity. The confinement of the usnic acid within liposomes has been investigated as a possibility to reduce its toxicity. In this work, we characterize the interaction of usnic acid in its neutral and anionic states (usniate) with DPPC and DOPC by means of molecular dynamics simulations. A lamellar to nonlamellar transition is observed for both membranes upon contact with usniate within 100 ns time scale. The transition suggests the formation of a liposome-like structure encapsulating the metabolyte. Furthermore, such process occurs at a significantly shorter time frame for DOPC.