Anthemis wiedemanniana essential oil prevents LPS-induced production of NO in RAW 264.7 macrophages and exerts antiproliferative and antibacterial activities in vitro

Anthemis wiedemanniana is known in folk medicine for the treatment of microbial infections, cancer and also urinary and pulmonary problems. In this study, the chemical composition of the essential oil from A. wiedemanniana was evaluated and its antibacterial activity was tested against 10 bacterial strains. The oil was also tested for its potentiality to inhibit nitric oxide production in RAW 264.7 macrophages and for its cytotoxicity against four human cancer cell lines. A. wiedemanniana oil, rich of oxygenated monoterpenes (25.4%), showed a good antibacterial activity against Gram-positive bacteria and a good activity against the two Gram-negative bacteria, Escherichia coli and Proteus vulgaris. Besides that, it exhibited a high inhibitory effect on the LPS-induced nitrite production and a strong cytotoxic activity, especially against amelanotic melanoma (C32) and large lung cell carcinoma (COR-L23) cell lines.     

Real-Time Analysis of Polyphenol–Protein Interactions by Surface Plasmon Resonance Using Surface-Bound Polyphenols

A selection of bioactive polyphenols of different structural classes, such as the ellagitannins vescalagin and vescalin, the flavanoids catechin, epicatechin, epigallocatechin gallate (EGCG), and procyanidin B2, and the stilbenoids resveratrol and piceatannol, were chemically modified to bear a biotin unit for enabling their immobilization on streptavidin-coated sensor chips. These sensor chips were used to evaluate in real time by surface plasmon resonance (SPR) the interactions of three different surface-bound polyphenolic ligands per sensor chip with various protein analytes, including human DNA topoisomerase IIα, flavonoid leucoanthocyanidin dioxygenase, B-cell lymphoma 2 apoptosis regulator protein, and bovine serum albumin. The types and levels of SPR responses unveiled major differences in the association, or lack thereof, and dissociation between a given protein analyte and different polyphenolic ligands. Thus, this multi-analysis SPR technique is a valuable methodology to rapidly screen and qualitatively compare various polyphenol–protein interactions.     

Validation of two analytical methods for the determination of ochratoxin A by reversed-phased high-performance liquid chromatography coupled to fluorescence detection in musts and sweet wines from Andalusia

Some Spanish sweet wines are made from raisins, grapes dried by direct exposure to the sun after picking. This drying process can encourage ochratoxin A (OTA) formation. OTA is a mycotoxin formed by several fungi. It has been linked to nephropathy in humans, and may have a long half-life in humans. The aim of this study is to develop and to apply two procedures for the analysis of OTA in grape musts (during the raisining process) and sweet wines, respectively. Reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to fluorescence detection (FLD) was employed in both analytical methods. In grape must, the method involves the direct injection of the sample in a HPLC-FLD system without any kind of prior clean-up procedure. The complexity of the sweet wine samples requires a solid-phase extraction (SPE) clean-up on a C18 column which enables the OTA to be isolated from the matrix. The methods used were statistically validated. The validation also included the comparison of the slopes of the curve obtained with standards and the regression curves obtained by the addition of a standard. Two different studies of standard additions were conducted. One method was validated without sample preparation and it was applied to must samples. The other method was validated with SPE extraction and it was applied to sweet wine samples. Recovery was always better than 89.69%. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) were established at 0.22 and 0.77 μg l⁻¹, respectively. In general, the analytical data obtained provided good results at the sub-μg l⁻¹ concentration level.     

Pore size distribution analysis of selected hexagonal mesoporous silicas by grand canonical Monte Carlo simulations

We combine here a regularization procedure with individual adsorption isotherms obtained from grand canonical Monte Carlo simulations in order to obtain reliable pore size distributions. The methodology is applied to two hexagonal high-ordered silica materials: SBA-15 and PHTS, synthesized in our laboratory. Feasible pore size distributions are calculated through an adaptable procedure of deconvolution over the adsorption integral equation, with two necessary inputs: the experimental adsorption data and individual adsorption isotherms, assuming the validity of the independent pore model. The application of the deconvolution procedure implies an adequate grid size evaluation (i.e., numbers of pores and relative pressures to be considered for the inversion, or kernel size), the fulfillment of the discret Picard condition, and the appropriate choice of the regularization parameter (L-curve criteria). Assuming cylindrical geometry for both porous materials, the same set of individual adsorption isotherms generated from molecular simulations can be used to construct the kernel to obtain the PSD of SBA-15 and PHTS. The PSD robustness is measured imposing random errors over the experimental data. Excellent agreement is found between the calculated and the experimental global adsorption isotherms for both materials. Molecular simulations provide new insights into the studied systems, pointing out the need of high-resolution isotherms to describe the presence of complementary microporosity in these materials.     

Solid-phase extraction of soy isoflavones

An automated method using solid-phase extraction (SPE) for the concentration and clean-up of soy isoflavone extracts is proposed in this work. Using a standardized sample (0.1 g of a freeze dried soybean extract/25 mL of water); eight SPE cartridges with a wide range of sorbents (C18, divinylbenzene and modified divinylbenzene) from different suppliers were evaluated and compared. A large variation on SPE cartridges performance was observed, especially regarding retention and breakthrough volume of isoflavones during sample load and washing steps. The most effective cartridges were the divinylbenzene based cartridges, especially Strata X (from Phenomenex) and HLB oasis (from Waters). Using Strata X cartridges, several extraction parameters, such as sample loading flow (5-15 mL min(-1)), extracting solvent volume (2-6 mL of methanol), pH of the extracting solvent and the necessity of drying the sorbent before elution, were evaluated to provide a fast, specific, quantitative and reproducible SPE method. The optimized method consists of conditioning the cartridge with 10 mL of methanol and 10 mL of water (10 mL min(-1)), loading 25 mL of the standardized extract onto the cartridges (5 mL min(-1)), washing the cartridge with 10 mL of water (10 mL min(-1)) and finally eluting with 4 mL of methanol (10 mL min(-1)). Mean isoflavones recovery was 99.37% and mean intra- and inter-day reproducibility was higher than 98%. The developed sample clean-up/concentration (6.25:1) method takes less than 10 min and can be used in the analysis of isoflavones from soy extracts.     

Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications

A highly sustainable prototype of a flow system based on gold nanoparticles (4.2 nm) supported on thiol‐functionalized halloysite nanotubes (HNTs) was developed for catalytic applications. The catalytic performances were evaluated using the reduction of 4‐nitrophenol to 4‐aminophenol as a model system. Under the best experimental conditions (0.0001 mol%, 1.97 × 10^?8 mg of Au nanoparticles), an impressive apparent turnover frequency value up to 2 204 530 h^?1 was achieved and the halloysite‐based catalyst showed full recyclability even after ten cycles. The high catalytic activity confirms the importance of the use of HNTs as support for Au nanoparticles that can exert a synergistic effect both as medium for transfer of electrons from borohydride ions to 4‐nitrophenol and by modulating interfacial electron transfer dynamics. With the application of flow technology, the obtained heterogeneous HNT@Au catalyst was fully recovered and reused for at least one month.