Quercetin, a dietary flavonoid found in fruits and vegetables, has been described as a substance with many anti-cancer properties in a variety of preclinical investigations. In the present study, we demonstrate that 2D and 3D melanoma models exhibit not only different sensitivities to quercetin, but also opposite, cancer-promoting effects when metastatic melanoma spheroids are treated with quercetin. Higher concentrations of quercetin reduce melanoma growth in three tested cell lines, whereas low concentrations induce the opposite effect in metastatic melanoma spheroids but not in the non-metastatic cell line. High (>12.5 µM) or low (<6.3 µM) quercetin concentrations decrease or enhance cell viability, spheroid size, and cell proliferation, respectively. Additionally, melanoma cells cultivated in 2D already show significant caspase 3 activity at very low concentrations (>0.4 µM), whereas in 3D spheroids apoptotic cells, caspase 3 activity can only be detected in concentrations ≥12.5 µM. Further, we show that the tumor promoting or repressing effect in the 3D metastatic melanoma spheroids are likely to be elicited by a precisely controlled regulation of Nrf2/ARE-mediated cytoprotective genes, as well as ERK and NF-κB phosphorylation. According to the results obtained here, further studies are needed to better characterize the mechanisms of action underlying the pro- and anti-carcinogenic effects of quercetin on human melanomas.

In recent decades, a shift has been seen in the use of light-emitting diodes over incandescent lights and compact fluorescent lamps (CFL), which eventually led to an increase in wastes of electrical equipment (WEE), especially fluorescent lamps (FLs) and CFL light bulbs. These widely used CFL lights, and their wastes are good sources of rare earth elements (REEs), which are desirable in almost every modern technology. Increased demand for REEs and their irregular supply have exerted pressure on us to seek alternative sources that may fulfill this demand in an eco-friendly manner. Bio-removal of wastes containing REEs, and their recycling may be a solution to this problem and could balance environmental and economic benefits. To address this problem, the current study focuses on the use of the extremophilic red alga, Galdieria sulphuraria, for bioaccumulation/removal of REEs from hazardous industrial wastes of CFL bulbs and the physiological response of a synchronized culture of G. sulphuraria. A CFL acid extract significantly affected growth, photosynthetic pigments, quantum yield, and cell cycle progression of this alga. A synchronous culture was able to efficiently accumulate REEs from a CFL acid extract and efficiency was increased by including two phytohormones, i.e., 6-Benzylaminopurine (BAP - Cytokinin family) and 1-Naphthaleneacetic acid (NAA - Auxin family).

Coniferyl alcohol is considered to be a potent antioxidant and a precursor of several bioactive products. In addition, it is a frequently used as a model compound in lignin chemistry. Coniferyl thiol is used analogously to study the sulfur chemistry in technical lignins. Coniferyl alcohol was synthesized in a large scale from commercially available ferulic acid by a mixed anhydride reduction method which affords high yields (84%) under very mild conditions and allows using sodium borohydride. The nucleophilic substitution of 4-O-acetylated coniferyl alcohol (3) with thioacetic acid in the presence of dimethylformamide (DMF) dineopentylacetal afforded 4-O-acetylated coniferyl thioacetate (5) in a 70% yield, which, in a 72% yield, was deprotected to the respective thiol (6). Both coniferyl alcohol and coniferyl thiol were comprehensively analytically characterized [one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy]. The presented approach renders the two model substances readily available on a gram scale and according to low-risk, environmentally compatible protocols.

Modern society is heavily dependent on critical raw materials, such as rare earth elements (REEs), for use in electronic devices. The increasing demand for these materials has led to the need for environmentally friendly methods of processing non-recycled materials from e-waste and wastewater, as well as waste streams from cleaning and manufacturing facilities. Modern society’s dependence on such materials is growing by the day, and with it, the need for environmentally friendly processing of non-recycled materials from e-waste and wastewater in the form of “end-of-life” products, as well as waste streams from cleaning and manufacturing facilities, also increases. As these are problematic indications for modern isolation methods in the industry, these sources may be more suitable for new techniques as they have low concentration and high throughput for bioaccumulation. Chemical methods using nanomaterials are already being tested for their possibilities but still depend on acids and harsh chemicals. Microorganisms, on the other hand, can adsorb/absorb REEs in a more ecological way. Previous studies could already show that it is possible to accumulate REEs in the precipitates of bacterial cultures spiked with REEs to a value of over 50%. However, the question arose whether rare earths were spun into the pellets by centrifugation, adsorbed, or really incorporated in the cells. Therefore, we established a new easy-to-use experimental design in which the microorganisms were spiked with an REE standard and washed to minimize the falsification of measurements by peripheral binding of ions before being analyzed for REE contents by ICP-OES. The bioaccumulation of rare earths in microorganisms was monitored, yielding an uptake rate of up to 53.12% of the overall present ionic REE concentration. In this manuscript, we present the different concentration measurements that were taken during the process, before and after washing of the cells, to create a full picture of the localization, binding, incorporation, and occurrence of the ions of interest. The setup also showed a correlation between the introduction method of rare earths and the uptake of certain elements that might be correlated with the differentiation between light and heavy rare earth elements, while Y and Sc often seem to represent outliers.

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