Sargassum natans I Algae: An Alternative for a Greener Approach for the Synthesis of ZnO Nanostructures with Biological and Environmental Applications.

In this work, the influence of the Sargassum natans I alga extract on the morphological characteristics of synthesized ZnO nanostructures, with potential biological and environmental applications, was evaluated. For this purpose, different ZnO geometries were synthesized by the co-precipitation method, using Sargassum natans I alga extract as stabilizing agent. Four extract volumes (5, 10, 20, and 50 mL) were evaluated to obtain the different nanostructures. Moreover, a sample by chemical synthesis, without the addition of extract, was prepared. The characterization of the ZnO samples was carried out by UV-Vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, and scanning electron microscopy. The results showed that the Sargassum alga extract has a fundamental role in the stabilization process of the ZnO nanoparticles. In addition, it was shown that the increase in the Sargassum alga extract leads to preferential growth and arrangement, obtaining well-defined shaped particles. ZnO nanostructures demonstrated significant anti-inflammatory response by the in vitro egg albumin protein denaturation for biological purposes. Additionally, quantitative antibacterial analysis (AA) showed that the ZnO nanostructures synthesized with 10 and 20 mL of extract demonstrated high AA against Gram (+) S. aureus and moderate AA behavior against Gram (-) P. aeruginosa, depending on the ZnO arrangement induced by the Sargassum natans I alga extract and the nanoparticles' concentration (ca. 3200 µg/mL). Additionally, ZnO samples were evaluated as photocatalytic materials through the degradation of organic dyes. Complete degradation of both methyl violet and malachite green were achieved using the ZnO sample synthesized with 50 mL of extract. In all cases, the well-defined morphology of ZnO induced by the Sargassum natans I alga extract played a key role in the combined biological/environmental performance.

Antibacterial and Anti-Inflammatory Properties of ZnO Nanoparticles Synthesized by a Green Method Using Sargassum Extracts.

The present work shows the synthesis of ZnO nanoparticles through a green method, using sargassum extracts, which provide the reducing and stabilizing compounds. The conditions of the medium in which the reaction was carried out was evaluated, that is, magnetic stirring, ultrasound assisted, and resting condition. UV-Vis, FTIR spectroscopy, and X-ray diffraction results confirmed the synthesis of ZnO with nanometric crystal size. The scanning electron microscopy analysis showed that the morphology and size of the particles depends on the synthesis condition used. It obtained particles between 20 and 200 nm in the sample without agitation, while the samples with stirring and ultrasound were 80 nm and 100 nm, respectively. ZnO nanoparticles showed antibacterial activity against Gram-positive S. aureus and Gram-negative P. aeruginosa. A quantitative analysis was performed by varying the concentration of ZnO nanoparticles. In all cases, the antibacterial activity against Gram-positives was greater than against Gram-negatives. Ultrasound-assisted ZnO nanoparticles showed the highest activity, around 99% and 80% for S. aureus and P. aeruginosa, respectively. Similar results were obtained in the study of the anti-inflammatory activity of ZnO nanoparticles; the ultrasound-assisted sample exhibited the highest percentage (93%), even above that shown by diclofenac, which was used as a reference. Therefore, the ZnO nanoparticles synthesized with sargassum extracts have properties that can be used safely and efficiently in the field of biomedicine.

Shock wave-assisted extraction of phenolic acids and flavonoids from Eysenhardtia polystachya heartwood: A novel method and its comparison with conventional methodologies.

Phenolic compounds, obtained from plants are important in the food, biomaterial and pharmaceutical industries; however current extraction methods, such as Soxhlet (solid-liquid) extraction, liquid-liquid extraction, microwave-assisted extraction, and ultrasonic extraction (USE), have the disadvantages of large processing times, contamination by solvents, and degradation of analytes. This study demonstrates that shock wave-assisted extraction can be used as a more efficient, eco-friendly and rapid method. Extraction of powdered samples of Eysenhardtia polystachia heartwood, a plant with high concentration of phenolic compounds, exposed to different doses of underwater shock waves, was compared with the conventional methods. Our results revealed that shock wave-assisted extraction (1500 shock waves with a peak positive pressure of approximately 88 MPa) produced 34.54% and 31.95% higher contents than Soxhlet and USE, respectively. Extraction times using shock waves were much shorter than with all other methods tested, proving that it is an attractive method to obtain both phenolic acids and flavonoids without the need for organic solvents. Furthermore, shock waves produced a significantly higher content of total reducing sugars than Soxhlet extraction and less phenolic acids which gives the insight of a more selective extraction of components.

Fluorescence decay rate of selected compounds from Eysenhardtia polystachya extracts and their viability as biosensors.

Eysenhardtia polystachya (EP) is an endemic Mexican plant that has been widely studied for its antidiabetic, antibacterial, and antioxidant properties. Several studies had reported the main components of EP, but their fluorescence properties had not been broadly studied. In a previous study we obtained extracts with different composition from this plant and they presented florescence. In this work we study fluorescent compounds from EP and evaluate their fluorescence properties. EP extracts were obtained by Soxhlet extraction with ethanol, samples were dried, and compounds were separated by column chromatography. Fluorescent fractions were classified apart from other fractions and characterized by Scanning electron microscopy (SEM), UV-Vis, Raman, FTIR and 1H NMR spectra. Additionally, we obtained functional nanomaterials (using silica nanoparticles). TD-DFT molecular calculations of the fluorescent components were carried out to compare their theoretical UV-Vis spectra to experimental results. Nine fractions were obtained by chromatography and five of them showed fluorescence. Fluorescence of extracts from Eysenhardtia polystachya is due to more than one component and we suggest that could be other hydrochalcones for which we present possible structures. This finding would help to dissipate questions about which component is responsible for fluorescence in extracts from the plant and in this way determinate the appropriate use for these fluorophores. Finally, the application and viability as a biosensor using pulmonary epithelium fibroblast cell culture IMR-90 was proved, and in the concentration used are non-toxic materials.

Green synthesis of Ag nanoflowers using Kalanchoe Daigremontiana extract for enhanced photocatalytic and antibacterial activities.

The synthesis and applications of anisotropic nanostructures have attracted much attention in the last decade. The nanoflower-type structures are one of the nanomaterials with anisotropic structures most investigated because of owing to high densities of edges, corners, and stepped atoms present on their nano-petals. Here, silver nanoparticles obtained by a one-step green synthesis method using extract from Kalanchoe Daigremontiana´s leaves are reported. To identify the compounds responsible for reduction of silver ions, the functional groups present in plant extract were investigated by UV-vis and FTIR. Ag nanoparticles were characterized by UV-vis, XPS, ζ-potential, XRD, and SEM-EDS. Different solvents were used to eliminate agglomeration of the silver nanoparticles. These solvents produced nanoflower-like morphology with abundant nano-petals. This is the first report of the synthesis of Ag nanoflowers formed by green synthesis method using Kalanchoe Daigremontiana extract. The synthesized Ag nanoflowers are faced center cubic structure in nature with a petal thickness approximately of 25 nm. Photocatalytic activity of the different Ag nanostructures was evaluated through the degradation of methylene blue, where the degradation time as low as 1 min is reported. Furthermore these green synthesized Ag nanoflowers were found to show high antibacterial activity against Gram-negative bacteria Escherichia coli and Gram-positive Staphylococcus aureus.

Stability Analysis of Anthocyanins Using Alcoholic Extracts from Black Carrot (Daucus Carota ssp. Sativus Var. Atrorubens Alef.).

Anthocyanins are used for food coloring due their low toxicity and health benefits. They are extracted from different sources, but black carrot has higher anthocyanin content compared with common fruits and vegetables. Here, we study alcoholic anthocyanin extracts from black carrot to enhance their stability. The objective of our research is to determine if microencapsulation with tetraethyl orthosilicate (TEOS) is a feasible option for preventing black carrot anthocyanin degradation. Extraction solvents were solutions of (1) ethanol/acetic acid and (2) ethanol/citric acid. Samples were purified through a resin column and microencapsulated using TEOS. Fourier Transformed Infrared Spectroscopy (FTIR) spectra of samples were obtained, and degradation studies were performed under different conditions of UV radiation, pH and temperature. Antioxidant activity was evaluated with radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and electrochemical cupric reducing antioxidant capacity (CUPRAC). Color evaluation on food models were performed with CIE Lab at the beginning of experiments and after 25 days of storage. Results indicate that the more stable extracts against pH media changes are samples obtained with ethanol/acetic acid solution as extraction solvent. Extract purification through resin and TEOS microencapsulation had no significant effect on extract stability. In conclusion, although TEOS microencapsulation has proven to be effective for some dried materials from natural extracts in our previous research, we do not recommend its use for black carrot extracts considering our results in this particular case.

Effects of tetraethyl orthosilicate (TEOS) on the light and temperature stability of a pigment from Beta vulgaris and its potential food industry applications.

A novel, simple and inexpensive modification method using TEOS to increase the UV light, pH and temperature stability of a red-beet-pigment extracted from Beta vulgaris has been proposed. The effects on the molecular structure of betalains were studied by FTIR spectroscopy. The presence of betacyanin was verified by UV-Vis spectroscopy and its degradation in modified red-beet-pigment was evaluated and compared to the unmodified red-beet-pigment; performance improvements of 88.33%, 16.84% and 20.90% for UV light, pH and temperature stability were obtained, respectively,. Measurements of reducing sugars, phenol, and antioxidant contents were performed on unmodified and modified red-beet-pigment and losses of close to 21%, 54% and 36%, respectively, were found to be caused by the addition of TEOS. Polar diagrams of color by unmodified and modified red-beet-pigment in models of a beverage and of a yogurt were obtained and the color is preserved, although here is a small loss in the chromaticity parameter of the modified red-beet-pigment.