Synthesis of Active Pharmaceutical Ingredients using Electrochemical Methods: Keys to Improve Sustainability

Organic electrochemistry is receiving renewed attention as a green and cost-efficient synthetic technology. Electrochemical methods promote redox transformations by electron exchange between electrodes and species in solution, thus avoiding the...

Creating enzymes and self-sufficient cells for biosynthesis of the non-natural cofactor nicotinamide cytosine dinucleotide

Nicotinamide adenine dinucleotide (NAD) and its reduced form are indispensable cofactors in life. Diverse NAD mimics have been developed for applications in chemical and biological sciences. Nicotinamide cytosine dinucleotide (NCD) has emerged as a non-natural cofactor to mediate redox transformations, while cells are fed with chemically synthesized NCD. Here, we create NCD synthetase (NcdS) by reprograming the substrate binding pockets of nicotinic acid mononucleotide (NaMN) adenylyltransferase to favor cytidine triphosphate and nicotinamide mononucleotide over their regular substrates ATP and NaMN, respectively. Overexpression of NcdS alone in the model host Escherichia coli facilitated intracellular production of NCD, and higher NCD levels up to 5.0 mM were achieved upon further pathway regulation. Finally, the non-natural cofactor self-sufficiency was confirmed by mediating an NCD-linked metabolic circuit to convert L-malate into D-lactate. NcdS together with NCD-linked enzymes offer unique tools and opportunities for intriguing studies in chemical biology and synthetic biology.

Recent Applications of Heteropolyacids and Related Compounds in Heterocycle Synthesis. Contributions between 2010 and 2020

Over the past two decades, polyoxometalates (POM) have received considerable attention as solid catalysts, due to their unique physicochemical characteristics, since, first, they have very strong Bronsted acidity, approaching the region of a superacid, and second, they are efficient oxidizers that exhibit rapid redox transformations under fairly mild conditions. Their structural mobility is also highlighted, since they are complex molecules that can be modified by changing their structure or the elements that compose them to model their size, charge density, redox potentials, acidity, and solubility. Finally, they can be used in substoichiometric amounts and reused without an appreciable loss of catalytic activity, all of which postulate them as versatile, economic and ecological catalysts. Therefore, in 2009, we wrote a review article highlighting the great variety of organic reactions, mainly in the area of the synthesis of bioactive heterocycles in which they can be used, and this new review completes that article with the contributions made in the same area for the period 2010 to 2020. The synthesized heterocycles to be covered include pyrimidines, pyridines, pyrroles, indoles, chromenes, xanthenes, pyrans, azlactones, azoles, diazines, azepines, flavones, and formylchromones, among others.

Probing pollutants reactions at the iron surface: A case study of selenite reactions with nanoscale zero-valent iron

Nanoscale zero-valent iron (nZVI) has shown a high efficacy for removing selenite (Se(IV)) from water, yet the reaction mechanism in solid phase, especially the redox transformations of selenite in the...

Nanotechnology and Its Applications in Environmental Remediation

Decontamination of pollutants from soil, air, and water is a challenging quest in contemporary society due to the recalcitrant, bioaccumulative, and bio-resistant nature of such contaminants. Remediation processes of these environmental contaminants relies on a number of processes including adsorption, photocatalysis, redox transformations, and filtration among other chemical reactions. The use of nanotechnology to enhance the performance of remediation processes has developed research interest in modern day due to the high reactivity and environmental friendliness associated with nanoparticles. This chapter explores the science behind the application of nanotechnology in environmental remediation, the processes used in decontaminating environmental media, and the various categories of nanomaterials. Various examples based on literature are used to enhance insight on the subject.

Using nature’s blueprint to expand catalysis with Earth-abundant metals

Numerous redox transformations that are essential to life are catalyzed by metalloenzymes that feature Earth-abundant metals. In contrast, platinum-group metals have been the cornerstone of many industrial catalytic reactions for decades, providing high activity, thermal stability, and tolerance to chemical poisons. We assert that nature’s blueprint provides the fundamental principles for vastly expanding the use of abundant metals in catalysis. We highlight the key physical properties of abundant metals that distinguish them from precious metals, and we look to nature to understand how the inherent attributes of abundant metals can be embraced to produce highly efficient catalysts for reactions crucial to the sustainable production and transformation of fuels and chemicals.