With the rapid development of modern society, many chronic diseases are increasing including diabetes, obesity, cardiovascular diseases, etc., which further cause an increased death rate worldwide. A high caloric diet with reduced natural polysaccharides, typically indigestible polysaccharides, is considered a health risk factor. With solid evidence accumulating that indigestible polysaccharides can effectively prevent and/or ameliorate symptoms of many chronic diseases, we give a narrative review of many natural polysaccharides extracted from various food resources which mainly contribute their health beneficial functions via intestinal fermentation.
An efficient method for the diastereo- and enantioselective construction of vicinal all-carbon quaternary stereocenters through palladium-catalyzed decarboxylative cycloaddition of vinylethylene carbonates with activated Michael acceptors was developed. By using a palladium complex generated in situ from [Pd2(dab)3]⋅CHCl3 and a phosphoramidite ligand as a catalyst under mild reaction conditions, the process provides multifunctionalized tetrahydrofurans bearing vicinal all-carbon quaternary stereocenters in high yields with a high level of absolute and relative stereocontrol.
The selective generation of covalent bonds between and within proteins would provide new avenues for studying protein function and engineering proteins with new properties. New covalent bonds were genetically introduced into proteins by enabling an unnatural amino acid (Uaa) to selectively react with a proximal natural residue. This proximity-enabled bioreactivity was expanded to a series of haloalkane Uaas. Orthogonal tRNA/synthetase pairs were evolved to incorporate these Uaas, which only form a covalent thioether bond with cysteine when positioned in close proximity. By using the Uaa and cysteine, spontaneous covalent bond formation was demonstrated between an affibody and its substrate Z protein, thereby leading to irreversible binding, and within the affibody to increase its thermostability. This strategy of proximity-enabled protein crosslinking (PEPC) may be generally expanded to target different natural amino acids, thus providing diversity and flexibility in covalent bond formation for protein research and protein engineering.
Neurodegenerative diseases and spinal cord injury affect approximately 50 million people worldwide, bringing the total healthcare cost to over 600 billion dollars per year. Nervous system growth factors, that is, neurotrophins, are a potential solution to these disorders, since they could promote nerve regeneration. An average of 500 publications per year attests to the significance of neurotrophins in biomedical sciences and underlines their potential for therapeutic applications. Nonetheless, the poor pharmacokinetic profile of neurotrophins severely restricts their clinical use. On the other hand, small molecules that modulate neurotrophic activity offer a promising therapeutic approach against neurological disorders. Nature has provided an impressive array of natural products that have potent neurotrophic activities. This Review highlights the current synthetic strategies toward these compounds and summarizes their ability to induce neuronal growth and rehabilitation. It is anticipated that neurotrophic natural products could be used not only as starting points in drug design but also as tools to study the next frontier in biomedical sciences: the brain activity map project.
A concise, protecting group-free total synthesis of (−)-fusarisetin A (1) was efficiently achieved in 9 steps from commercially available (S)-(−)-citronellal. The synthetic approach was inspired by our proposed biosynthesis of 1. Key transformations of our strategy include a facile construction of the decalin moiety that sets the stage for a stereoselective IMDA reaction and a one-pot TEMPO induced radical cyclization/aminolysis that forms the C ring of 1. Our route is amenable to analogue synthesis for biological evaluation.
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