Most small molecules are unable to rapidly traverse the outer membrane of Gram-negative bacteria and accumulate inside these cells, making the discovery of much-needed drugs for these pathogens very challenging. Current understanding of the physicochemical properties that dictate small-molecule accumulation in Gram-negatives is largely based on retrospective analyses of antibacterials that suggest polarity and molecular weight as key factors. Here we assess the ability of over 180 diverse compounds to accumulate in Escherichia coli. Computational analysis of the results reveals major differences from the retrospective studies, namely that the small molecules that are most likely to accumulate contain an amine, are amphiphilic and rigid, and have low globularity. These guidelines were then applied to convert deoxynybomycin, a natural product that is active only against Gram-positive organisms, into an antibiotic with activity against a diverse panel of multi-drug-resistant Gram-negative pathogens. We anticipate these findings will aid in the discovery and development of antibiotics effective against Gram-negative bacteria.
Enantioselective total syntheses of the anticancer isocarbostyril alkaloids (+)-7-deoxypancratistatin, (+)-pancratistatin, (+)-lycoricidine, and (+)-narciclasine are described. Our strategy for accessing this unique class of natural products is based on the development of a Nicatalyzed dearomative trans-1,2-carboamination of benzene. The effectiveness of this dearomatization approach is notable, as only two additional olefin functionalizations are needed to construct the fully decorated aminocyclitol cores of these alkaloids. Installation of the lactam ring has been achieved through several pathways and a direct interconversion between natural products was established via a late-stage C-7 cupration. Using this synthetic blueprint, we were able to produce natural products on a gram scale and provide tailored analogs with improved activity, solubility, and metabolic stability.
Even in the era of personalized medicine and immunotherapy, temozolomide (TMZ), a small molecule DNA alkylating agent, remains the standard-of-care for glioblastoma (GBM). TMZ has an unusual mode-of-action, spontaneously converting to its active component via hydrolysis in vivo. While TMZ has been FDA approved for two decades, it provides little benefit to patients whose tumors express the resistance enzyme MGMT and gives rise to systemic toxicity through myelosuppression. TMZ was first synthesized in 1984, but certain key derivatives have been inaccessible due to the chemical sensitivity of TMZ, precluding broad exploration of the link between imidazotetrazine structure and biological activity. Here, we sought to discern the relationship between the hydrolytic stability and anticancer activity of imidazotetrazines, with the objectives of identifying optimal timing for prodrug activation and developing suitable compounds with enhanced efficacy via increased blood-brain barrier penetrance. This work necessitated the development of new synthetic methods to provide access to previously unexplored functionality (such as aliphatic, ketone, halogen, and aryl groups) at the C8 position of imidazotetrazines. Through synthesis and evaluation of a suite of compounds with a range of aqueous stabilities (from 0.5 to 40 h), we derive a predictive model for imidazotetrazine hydrolytic stability based on the Hammett constant of the C8 substituent. Promising compounds were identified that possess activity against a panel of GBM cell lines, appropriate hydrolytic and metabolic stability, and brain-to-serum ratios dramatically elevated relative to TMZ, leading to lower hematological toxicity profiles and superior activity to TMZ in a mouse model of GBM. This work points a clear path forward for the development of novel and effective anticancer imidazotetrazines.
Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal‐catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non‐explosive and non‐toxic, and should find broad utility as a replacement for diazomethane.
A synthetic study on the creation of a bivalent, ROMP capable monomer has the ability to be polymerized into the corresponding neo-glycopolymer mimetic of the surface glycans on gp120 envelope spike of the HIV virus. In our approach, we have developed a new strategy for orthogonally attaching both the terminal Manα1-2Man disaccharide unit of the D1 arm of Man9GlcNAc2 of HIV gp120 and the terminal Manα1-2 unit of its D2 arm to a bivalent scaffold to produce the corresponding polymerizable monomer. The Manα1-2 saccharide moieties were assembled using a nickel catalyst, Ni(4-F-PhCN) 4 (OTf) 2 , to activate trihaloacetimidate donors under mild and operationally simple procedure. KeywordsHIV; Glycopolymer; Carbohydrate Synthesis; Nickel Catalyzed Human immunodeficiency virus (HIV) has evolved into one of the most threatening global viruses since its first isolation in 1983. Despite extensive research efforts in more than two decades, the conception of a synthetic HIV vaccine capable of eliciting broadly-neutralizing antibodies, has thus far proven elusive. 1 A principal explanation for this phenomenon focuses on the heavily glycosylated viral envelope, comprised of oligosaccharide fragments, which may disguise the virion from immune responses if they are recognized as "self", 2 the virus also utilizes its "glycan shield" to prevent protein-specific antibodies from binding to the inner protein core. 3 The isolation of carbohydrate-specific broadly-neutralizing antibody 2G12, capable of binding to HIV gp120's surface oligosaccharides, 4,5 suggests that the carbohydrate shield of HIV could be considered as a potential target for neutralization. 6 This elucidation inspired the use of glycan antigens towards the development of potential vaccines. Along with the 2G12 antibody, several other carbohydrate-specific broadly- hien-nguyen@uiowa.edu Phone: 319-384-1887 Fax: 319-335-1270. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Supplementary dataSupplementary data associated with this article can be found in the online version, at http:// Figure 1) of gp120. The crystal structure of 2G12 in particular revealed that approximately 85% of the contact with gp120 was through this terminal disaccharide unit, 6,[8][9] and that its unusual Fab domain-swapped structure provided for additional multivalent binding sites. 6,10 This discovery suggests that a majority of the binding event may be conserved upon utilization of only a fraction of the Man 9 GlcNAc 2 epitope. Our objective is to develop a glycan mimetic of HIV gp120 that potentially binds to glycan-specific bnAbs; this synthe...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.