Insecticidal action, repellency, and toxicity mechanism of the essential oil of Lippia turbinata against the stored product pest Rhipibruchus picturatus (F.).

The use of essential oils (EOs) in the development of alternative management methods for bruchid control under storage conditions aroused great interest because they have proven to be effective, less toxic, and less persistent in the ecosystem than synthetic pesticides. In this sense, leaves of Lippia turbinata (Griseb.) Moldenke EO were studied in the present work. The monoterpene limonene and the monoterpenoid eucalyptol were its main constituents. EO showed a potent insecticidal activity, both in contact and fumigant conditions, against Rhipibruchus picturatus (F.) which is one of the main pests of Prosopis alba pods in stored conditions. Moreover, the EO produces repellency in these insects. Additionally, the toxicity mechanism of action was studied. In this regard, the EO inhibits the acetylcholinesterase enzyme in in vitro assays, alters the activity of the antioxidant enzymes superoxide dismutase and catalase, and produces an increase in the lipid peroxidation reactions. This is the first report of the use of the L. turbinata EO against R. picturatus insect pest. The data obtained demonstrate its potential for developing more efficient and natural storage pest control strategies.

Antimicrobial properties of the essential oil of Schinus areira (Aguaribay) against planktonic cells and biofilms of S. aureus.

The essential oil (EO) of Schinus areira L. (Anacardiaceae) leaves has shown antibacterial activity against Staphylococcus aureus. In this study, we aimed to unravel the mechanisms of its antibacterial action by using bacterial cells and model membranes. First, the integrity of the S. aureus membrane was evaluated by fluorescence microscopy. It was observed that there was an increase in the permeability of cells that was dependent on the EO concentration as well as the incubation time. For a deep comprension of the action of the EO on the lipids, its effect on the membrane fluidity was evaluated on DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine): DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-1'-rac-glycerol) (5:1) liposomes by dynamic light scattering and by using Laurdan doped liposomes. The results indicate that EO produces changes in lipid membrane packing, increasing the fluidity, reducing the cooperative cohesive interaction between phospholipids and increasing access of water or the insertion of some components of the EO to the interior of the membrane. In addition, the potential effect of EO on intracellular targets, such as the increase of cytosolic reactive oxygen species (ROS) and DNA damage, were analyzed. The EO was capable of increasing the production of ROS as well as inducing a partial DNA degradation. Finally, the effect of EO on S. aureus biofilm was tested. These assays showed that EO was able to inhibit the biofilm formation, and also eradicate preformed biofilms. The results show, that the EO seems to have several bacterial targets involved in its antibacterial activity, from the bacterial membrane to DNA. Furthermore, the antibacterial action affects not only planktonic cells but also biofilms; reinforcing the potential application of this EO.

Elucidating the complete oxidation mechanism of betanidin in an aqueous solution.

An important point to take advantage of the use of antioxidants in industrial applications in a more efficient way is to know in depth their oxidation mechanism. This is not always a simple task and requires an in-depth study that is often insufficient to precisely describe all the structures and processes involved. This is the case of betanidin, a natural pigment employed in the drug, food, and cosmetic industries. In the present work, we seek to unravel the complete oxidation mechanism of betanidin with the use of computational techniques, supported by experimental data. For this aim, the pKas and oxidation potentials of the reactions involved at different pHs were analyzed using density functional theory (DFT) with the B3LYP/6-31+G(d,p)/SMD approach. Moreover, the decomposition mechanism of the intermediate products (decarboxylation reactions) was studied deeply. The analysis of DFT results allowed the proposal of a tentative mechanism that was put to test using the digital simulations of cyclic voltammetry by comparing the results of these simulations with an experimental case. Based on the rigorous experimental analysis, DFT, and simulations of cyclic voltammetry, the complete mechanism of the oxidation of betanidin in an aqueous medium was proposed. The dimerization of the oxidation products was also considered to explain the voltammetric response of betanidin.

Predicting octanol/water partition coefficients and pKa for the SAMPL7 challenge using the SM12, SM8 and SMD solvation models.

Blind predictions of octanol/water partition coefficients and pKa at 298.15 K for 22 drug-like compounds were made for the SAMPL7 challenge. Octanol/water partition coefficients were predicted from solvation free energies computed using electronic structure calculations with the SM12, SM8 and SMD solvation models. Within these calculations we compared the use of gas- and solution-phase optimized geometries of the solute. Based on these calculations we found that in general the use of solution phase-optimized geometries increases the affinity of the solutes for water as compared to octanol, with the use of gas-phase optimized geometries resulting in the better agreement with experiment. The pKa is computed using the direct approach, scaled solvent-accessible surface model, and the inclusion of an explicit water molecule, where the latter two methods have previously been shown to offer improved predictions as compared to the direct approach. We find that the use of an explicit water molecule provides superior predictions, and that the predicted macroscopic pKa is sensitive to the employed microstates.

Study of the electrochemical betanidin oxidation path using computational methods.

Betalains can be used in the food, drug, and cosmetic industries and have shown their bioactive potential. For these reasons, unraveling their oxidation mechanism is of high importance and demands a systematic and multidisciplinary study. Moreover, the properties mentioned above are drastically influenced by pH and other physicochemical conditions. Betanidin (1) is a relevant molecule of this family and is crucial to elucidating the oxidation mechanism in which its pigment is involved. In the present study, the pKas and oxidation potential values for all protic groups of 1 were analyzed using B3LYP/6-31+G(d,p)/SMD as the computational methodology. Moreover, six explicit water molecules were added to improve the solvation-free energy values. The oxidation mechanism at each pH was constructed and analyzed in depth. On the other hand, cyclic voltammetry simulations allowed obtaining electrochemical data from experiments and support the proposed mechanism. In the present work, the main oxidation path of 1 is described and consists of a concerted electron-proton transfer followed by a sequential electron and proton transfer to obtain the o-quinone product or a quinone methide molecule.

Insecticidal activity of the essential oil of Schinus areira against Rhipibruchus picturatus (F.) (Coleoptera: Bruchinae), and its inhibitory effects on acetylcholinesterase.

During the storage of Prosopis alba pods, substantial quantitative and qualitative losses were observed. One of the main factors is the seed beetle Rhipibruchus picturatus. A key strategy to develop new pest control management is the use of essential oils (EOs) due they are efficient, less toxic, and less persistent in the environment compared to synthetic pesticides. In this context, seeds and leaves of Schinus areira L. (Anacardiaceae) EOs and Citrus spp. EO were studied in the present work. In the leaves of S. areira EO, 1-epi-cadinol, sesquiterpenoid alcohol, was the major compound. On the other hand, the main compounds of the EO extracted from S. areira seeds are the monoterpenes sabinene, and α-pinene. Finally, in the Citrus EO, limonene is the principal component. The three EOs obtained exhibited insecticidal activity against R. picturatus, being the first report of the use of EOs against this insect pest. The best insecticidal results were obtained with the leaves of S. areira EO. Moreover, this EO inhibits the acetylcholinesterase enzyme in vitro assays. Molecular docking studies on acetylcholinesterase (AChE) suggest that the main components of the leaves of S, areira EOs, bind to the active site of the enzyme, in good agreement with in vitro competitive inhibition against AChE observed for this EO. The data obtained demonstrate the potential use of Schinus areira EOs in the development of new storage pest control strategies.

Rapid optimization of processes for the integrated purification of biopharmaceuticals.

Straight-through chromatography, wherein the eluate from one column passes directly onto another column without adjustment, is one strategy to integrate and intensify manufacturing processes for biologics. Development and optimization of such straight-through chromatographic processes is a challenge, however. Conventional high-throughput screening methods optimize each chromatographic step independently, with limited consideration for the connectivity of steps. Here, we demonstrate a method for the development and optimization of fully integrated, multi-column processes for straight-through purification. Selection of resins was performed using an in silico tool for the prediction of processes for straight-through purification based on a one-time characterization of host-cell proteins combined with the chromatographic behavior of the product. A two-step optimization was then conducted to determine the buffer conditions that maximized yield while minimizing process- and product-related impurities. This optimization of buffer conditions included a series of range-finding experiments on each individual column, similar to conventional screening, followed by the development of a statistical model for the fully integrated, multi-column process using design of experiments. We used this methodology to develop and optimize integrated purification processes for a single-domain antibody and a cytokine, obtaining yields of 88% and 86%, respectively, with process- and product-related variants reduced to phase-appropriate levels for nonclinical material.

Development of a platform process for the production and purification of single-domain antibodies.

Single-domain antibodies (sdAbs) offer the affinity and therapeutic value of conventional antibodies, with increased stability and solubility. Unlike conventional antibodies, however, sdAbs do not benefit from a platform manufacturing process. While successful production of a variety of sdAbs has been shown in numerous hosts, purification methods are often molecule specific or require affinity tags, which generally cannot be used in clinical manufacturing due to regulatory concerns. Here, we have developed a broadly applicable production and purification process for sdAbs in Komagataella phaffii (Pichia pastoris) and demonstrated the production of eight different sdAbs at a quality appropriate for nonclinical studies. We developed a two-step, integrated purification process without the use of affinity resins and showed that modification of a single process parameter, pH of the bridging buffer, was required for the successful purification of a variety of sdAbs. Further, we determined that this parameter can be predicted based only on the biophysical characteristics of the target molecule. Using these methods, we produced nonclinical quality sdAbs as few as 5 weeks after identifying the product sequence. Nonclinical studies of three different sdAbs showed that molecules produced using our platform process conferred protection against viral shedding of rotavirus or H1N1 influenza and were equivalent to similar molecules produced in Escherichia coli and purified using affinity tags.

Mass transfer in aerated culture media combining mixed electrolytes and glucose.

The combined effects of mixed electrolyte species and glucose on oxygen transfer were studied in a bubble column with aqueous solutions. Of particular interest was the presence of electrolytes containing ions which are prone to present solute-solute interactions or to crystallize. Without and at low concentration of glucose (≤ 5 g/L), the increasing concentration of electrolytes (nominal ionic strength: 0-0.43 M), up to a critical value, enhanced the volumetric mass transfer coefficient (kLa) and the availability of specific interfacial area (a), due to the inhibition of bubble coalescence. As the glucose concentration increased (10-40 g/L), the enhancing effects of electrolytes were gradually lost. The glucose interacted with electrolytes, reducing their ability to inhibit coalescence and to enhance the kLa. Salt crystallization occurred independently of the addition of glucose; however, it did not have significant effect on mass transfer. Finally, the changes in physicochemical properties were highly collinear with composition variables.

Comparative analysis of volatile compound profiles of propolis from different provenances.

BACKGROUND: Propolis is a complex mixture that honey bees produce from the exudates of various plants and presents many medicinal properties. Its chemical composition varies according to the phytogeography characteristics of each region, among others. The aim of this study was to identify and characterize the volatile organic compounds (VOCs) present in Venezuelan propolis and compare with reference samples such as Brazilian and Argentinian propolis. RESULTS: A total of 90 VOCs were identified in a series of propolis samples using both solid-phase microextraction and dynamic headspace (DHS), both coupled to a gas chromatograph-electron ionization mass spectrometer. In the case of Venezuelan propolis, sesquiterpenes, esters, aromatic compounds, and aliphatic hydrocarbons were identified. Limonene was found only in Venezuelan samples, this being the first time it has been identified in samples from this country. In the case of green propolis, ß-caryophyllene and nerolidol were the major compounds. As for the Argentinian samples, prenyl acetate, benzyl acetate, and 2-phenylethyl acetate were detected only in these samples. CONCLUSIONS: Possible chemical markers of natural sources such as limonene were detected using DHS extraction. Several compounds have also been identified for the first time in Venezuelan propolis. Cluster analysis allowed the relating of the propolis VOCs profile to their provenance. © 2017 Society of Chemical Industry.

Comparison of Chemical Composition, Physicochemical Parameters, and Antioxidant and Antibacterial Activity of the Essential Oil of Cultivated and Wild Mexican Oregano Poliomintha longiflora Gray.

Mexican oregano Poliomintha longiflora Gray located in the municipality of Higueras, Nuevo Leon, Mexico was collected during the autumn (September, OCO), winter (January, OCI) and summer (June, OCV) seasons, under cultivation conditions. It was also collected in wild conditions during the autumn (OSO). Essential oil (EO) was extracted from leaves and the color, refractive index and density were reported. The EO yield, antioxidant activity by ORAC assay, thymol and carvacrol concentration and antibacterial activity were statistically compared (p-value = 0.05). Among the various harvests, the highest EO yield, antioxidant activity, thymol and carvacrol content and antibacterial activity against Salmonella Typhi were observed in leaves harvested in autumn. In order to compare wild oregano with cultivated oregano, analyses were performed in the season with the highest essential oil yield and antioxidant activity, recorded in autumn. The main difference found was the ratio of thymol:carvacrol in wild oregano oil, which was 1:8.6, while in cultivated oregano, it was approximately 1:2, which was maintained in all three seasons. The EO on wild conditions showed the best antibacterial activity in Salmonella Typhi. On the other hand, wild and cultivated oregano showed similar antioxidant activity. One advantage of the use of cultivated oregano is that its supply is guaranteed, in contrast to that of wild oregano.

Production and Characterization of Biocomposite Films of Bacterial Cellulose from Kombucha and Coated with Chitosan.

The purpose of this research is to produce and characterize bacterial cellulose (BC) films coated with chitosan (BC-CH). BC films were produced in a fermentation medium based on Camellia sinensis tea and dextrose (12 days at 25 °C) and subsequently treated with coating-forming solutions (CFSs) based on chitosan (BC-CH 0.5%, BC-CH 1.0%, and BC-CH 1.5%). As a result, the FTIR spectra of BC and BC-CH 1.5% showed the main characteristic bands of cellulose and chitosan. In the physicochemical characterization of the films, it was found that the incorporation of the chitosan coatings did not affect the thickness; however, it decreased the luminosity (L*) and increased redness (a*), yellowness (b*), and opacity (75.24%). Additionally, the light absorption properties in the UV-Vis range were improved. Furthermore, the application of the CFSs increased: the solubility (64.91%), the antimicrobial activity against S. aureus (6.55 mm) and E. coli (8.25 mm), as well as the antioxidant activity (57.71% and 24.57% free radical scavenging activity), and the content of total phenols (2.45 mg GAE/g). Finally, our results suggest that the BC-CH films developed in the present study show a potential application as active packaging material for food.

Effect of different C3-aryl substituents on the antioxidant activity of 4-hydroxycoumarin derivatives.

The antioxidant activity of 4-hydroxycoumarin synthetic derivatives and 4-methylumbelliferone were determined taking 4-hydroxycoumarin as the reference compound. Six 3-aryl-4-hydroxycoumarin derivatives were synthesized from 4-hydroxycoumarin as precursor in order to evaluate changes in their antioxidant properties due to C3-aryl substituent nature. Free radical scavenging capacities of these compounds against two different species DPPH(·) and ABTS(·+) and the protecting ability towards the ß-carotene-linoleic acid co-oxidation enzymatically induced by lipoxygenase were measured. In addition, the relationship between the activities of these molecules against DPPH radical and the bond dissociation energy of O-H (BDE) calculated using methods of computational chemistry was evaluated.

Chemical composition of Schinus areira essential oil and antimicrobial action against Staphylococcus aureus.

The antimicrobial activities of plant extracts have formed the basis of many alternative medicines. In this context, the genus Schinus L. (Anacardiaceae), exhibits many traditional uses in medicine. However, a few studies on the antimicrobial properties of Schinus areira essential oils were conducted. The essential oil from S. areira leaves from Santiago del Estero was obtained by hydrodistillation and twenty-eight compounds were identified using CG-MS-EI spectrometry. The sesquiterpenoid alcohol 1-epi-cadinol was the major compound, followed by δ-cadinene, alloaromadendrene, ß-pinene, ß-caryophyllene, and γ-cadinene. The essential oil obtained exhibited antimicrobial activity against Staphylococcus aureus, showing a bacteriostatic activity at 64 µg/mL and bacteriolytic activity at 256 µg/mL; in contrast, non antibacterial effect was observed in Escherichia coli in the assayed conditions. The antibacterial activity was accompanied by significant changes in Zeta potential on the S. aureus surface. The data obtained suggest that the essential oil of S.areira leaves presents potential use in pharmaceutical industries.

Betanidin pK a Prediction Using DFT Methods.

Betalains can be used in food, drugs, and cosmetic industries and have shown their bioactive potential. These properties are strongly influenced by pH and other physicochemical conditions. The pK a values for the polyprotic Betanidin (Bd) molecule are unknown, and they are crucial to elucidate the oxidation mechanism in which its pigment is involved. In the present study, the values of pK a for all protic groups of Bd were analyzed using five hybrid density functionals (B3LYP, B3PW91, ωB97XD, PBE0, and M06-2X), five basis sets (6-31+G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d,p), and 6-311++G(d,p)) and the solvation model based on density (SMD) implicit solvation model. Moreover, one and three explicit water molecules were added to improve the solvation free energy values. Furthermore, the values of pK a of betanin, betalamic acid, and cyclo-dihydroxyphenylalanine (DOPA) were studied. Based on these analyses, we propose the acid-base behavior of Bd in water and develop new tools to understand their chemical reactivity.

Studied of Defatted Flour and Protein Concentrate of Prunus serotine and Applications.

Prunus serotine seed, was processed to produce a defatted flour (71.07 ± 2.10% yield) without hydrocyanic acid. The total protein was 50.94 ± 0.64%. According to sensory evaluation of cookies with P. serotine flour, the highest score in overall impression (6.31) was at 50% flour substitution. Its nutritional composition stood out for its protein and fiber contents 12.50% and 0.93%, respectively. Protein concentrate (PsPC) was elaborated (81.44 ± 7.74% protein) from defatted flour. Emulsifying properties of PsPC were studied in emulsions at different mass fractions; ϕ = 0.002, 0.02, 0.1, 0.2, and 0.4 through physicochemical analysis and compared with whey protein concentrate (WPC). Particle size in emulsions increased, as did oil content, and results were reflected in microscope photographs. PsPC at ϕ 0.02 showed positive results along the study, reflected in the microphotograph and emulsifying stability index (ESI) test (117.50 min). At ϕ 0.4, the lowest ESI (29.34 min), but the maximum emulsifying activity index (EAI) value (0.029 m2/g) was reached. WPC had an EAI value higher than PsPC at ϕ ≥ 0.2, but its ESI were always lower in all mass fraction values. PsPC can compete with emulsifiers as WPC and help stabilize emulsions.

Application of a Multisystem Coating Based on Polymeric Nanocapsules Containing Essential Oil of Thymus Vulgaris L. to Increase the Shelf Life of Table Grapes (Vitis Vinifera L.).

In developing countries, the incidence of postharvest losses reduces the quantity and quality of food for human consumption and causes an economical damage along the food chain, especially, for primary producers. In this study, a multisystem coating (NC-EOt-C) based on pullulan and polymeric nanocapsules containing EO of Thymus vulgaris L. (EOt) was applied to increase the shelf life of table grapes (Vitis vinifera L.). The major components of EOt, chemically characterized by GC-MS, were o-cymene (32.68%), thymol (31.90%), and γ -terpinene (15.69%). The NC-EOt were prepared by nanoprecipitation and showed a particle mean size of 153.9 nm, a polydispersity index of 0.186, a zeta potential of -4.11 mV, and an encapsulation efficiency of 52.81%. The antioxidant capacity (DPPH and ABTS+ methods) of EOt was maintained, or even improved, after its incorporation into NC. The shelf life study showed that grapes having the NC-EOt-C multisystem maintained their characteristics of color, firmness, TA, and SSC for longer time than those without the multisystem. NC-EOt-C multisystem acted as a barrier which reduced the metabolism of fruits. In addition, the compounds of EOt with antimicrobial activity avoided microorganism growth, while those with antioxidant activity reduced the oxidative stress induced during postharvest of grapes. Additionally, the polymeric structure of NC prevented the rapid evaporation of volatile compounds of EOt, increasing then their residence time on the fruit. Our study demonstrated that NC-EOt-C multisystem can be a viable alternative to preserve horticultural products for longer storage periods.

Anti-inflammatory and antimicrobial activity of bioactive hydroxyapatite/silver nanocomposites.

Biomaterials are often used in orthopedic surgery like cavity fillings. However, related complications often require long-term systemic antibiotics, device removal, and extended rehabilitation. Hydroxyapatite/silver (HA/Ag) composites have been proposed as implantation biomaterials owing to the osteogenic properties of hydroxyapatite and to the antimicrobial efficiency of silver. Nevertheless, higher silver concentrations induce cytotoxic effects. The aim of this study was to synthesize and characterize HA/Ag nanocomposites that will allow us to use lower concentrations of silver nanoparticles with better antimicrobial efficiency and anti-inflammatory properties. The characterization of HA/Ag was performed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, and laser diffraction. Bioactivity was evaluated under a simulated body fluid. The viability of osteoblast like-cells (MG-63) was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) and the antimicrobial activity was evaluated by the standard McFarland method. The detection of nitric oxide was measured by a colorimetric assay and the inflammatory cytokines by flow cytometry. We obtained particulate composites of calcium phosphates identified as hydroxyapatite and silver nanoparticles. The bioactivity of the HA/Ag nanocomposites on SFB was confirmed by apatite formations. The viability of MG-63 cells was not affected. We also found antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans owing to the presence of silver nanoparticles at non-cytotoxic concentrations. HA/Ag reduced the release of nitric oxide and decreased the secretion of IL-1 and TNF-α in cells stimulated with Lipopolysaccharide (LPS). In conclusion, the inflammatory and antimicrobial capacity of the HA/Ag nanocomposites, as well as its bioactivity and low cytotoxicity make it a candidate as an implantation biomaterial for bone tissues engineering and clinical practices in orthopedic, oral and maxillofacial surgery.

Interaction of semiochemicals with model lipid membranes: A biophysical approach.

Unravelling the chemical language of insects has been the subject of intense research in the field of chemical ecology for the past five decades. Insect communication is mainly based on chemosensation due to the small body size of insects, which limits their ability to produce or perceive auditory and visual signals, especially over large distances. Chemicals involved in insect communication are called semiochemicals. These volatiles and semivolatiles compounds allow to Insects to find a mate, besides the oviposition site in reproduction and food sources. Actually, insect olfaction mechanism is subject to study, but systematic analyses of the role of neural membranes are scarce. In the present work we evaluated the interactions of α-pinene, benzaldehyde, eugenol, and grandlure, among others, with a lipid membrane model using surface pressure experiments and Monte Carlo computational analysis. This allowed us to propose a plausible membranotropic mechanism of interaction between semiochemicals and insect neural membrane.

In vitro and in vivo Methods for the Evaluation of Natural Products against Dermatophytes.

Dermatomycoses are infections caused by fungi called dermatophytes; these affect 20-25% of the world population and the incidence continues to grow each year. Recently, an alternative for the treatment of these diseases is the use of natural products, thanks to the fact that they possess great chemical diversity and thus biological activity. However, to understand the therapeutic potential of natural products, their microbiological assessment presents certain limitations. Currently, there is no established reference method to determine the antifungal capacity in vitro and in vivo of natural products (i.e., essential oils). This review focuses on describing the various microbiological methods as well as the many adaptations used to evaluate the antifungal activity of natural products both in vitro and in vivo. In addition, the antifungal evaluation of natural products formulated in creams, gels, nanoemulsions, nanocapsules and solid lipid nanoparticles is included.