6 research outputs found
Hünlich Base: (Re)Discovery, Synthesis, and Structure Elucidation after a Century
After almost 100 years, the structure of the product of the reaction between 2,4-diaminotoluene and formaldehyde was elucidated: derivative <b>3</b>, which we call the Hünlich base, was synthesized on a multigram scale and its enantiomers were easily separated in preparative amounts. Furthermore, transformation of the NH<sub>2</sub> groups to the corresponding bis-iodides and bis-azides is presented. The latter was also used for desymmetrization by click chemistry
Hünlich Base: (Re)Discovery, Synthesis, and Structure Elucidation after a Century
After almost 100 years, the structure of the product of the reaction between 2,4-diaminotoluene and formaldehyde was elucidated: derivative <b>3</b>, which we call the Hünlich base, was synthesized on a multigram scale and its enantiomers were easily separated in preparative amounts. Furthermore, transformation of the NH<sub>2</sub> groups to the corresponding bis-iodides and bis-azides is presented. The latter was also used for desymmetrization by click chemistry
Experimental Evolution of Diverse Strains as a Method for the Determination of Biochemical Mechanisms of Action for Novel Pyrrolizidinone Antibiotics
The continuing rise
of multidrug resistant pathogens has made it
clear that in the absence of new antibiotics we are moving toward
a “postantibiotic” world, in which even routine infections
will become increasingly untreatable. There is a clear need for the
development of new antibiotics with truly novel mechanisms of action
to combat multidrug resistant pathogens. Experimental evolution to
resistance can be a useful tactic for the characterization of the
biochemical mechanism of action for antibiotics of interest. Herein,
we demonstrate that the use of a diverse panel of strains with well-annotated
reference genomes improves the success of using experimental evolution
to characterize the mechanism of action of a novel pyrrolizidinone
antibiotic analog. Importantly, we used experimental evolution under
conditions that favor strongly polymorphic populations to adapt a
panel of three substantially different Gram-positive species (lab
strain <i>Bacillus subtilis</i> and clinical strains methicillin-resistant <i>Staphylococcus aureus</i> MRSA131 and <i>Enterococcus faecalis</i> S613) to produce a sufficiently diverse set of evolutionary outcomes.
Comparative whole genome sequencing (WGS) between the susceptible
starting strain and the resistant strains was then used to identify
the genetic changes within each species in response to the pyrrolizidinone.
Taken together, the adaptive response across a range of organisms
allowed us to develop a readily testable hypothesis for the mechanism
of action of the CJ-16 264 analog. In conjunction with mitochondrial
inhibition studies, we were able to elucidate that this novel pyrrolizidinone
antibiotic is an electron transport chain (ETC) inhibitor. By studying
evolution to resistance in a panel of different species of bacteria,
we have developed an enhanced method for the characterization of new
lead compounds for the discovery of new mechanisms of action
Enantioselective Total Synthesis of Antibiotic CJ-16,264, Synthesis and Biological Evaluation of Designed Analogues, and Discovery of Highly Potent and Simpler Antibacterial Agents
An
improved and enantioselective total synthesis of antibiotic
CJ-16,264 through a practical kinetic resolution and an iodolactonization
reaction to form the iodo pyrrolizidinone fragment of the molecule
is described. A series of racemic and enantiopure analogues of CJ-16,264
was designed and synthesized through the developed synthetic technologies
and tested against drug-resistant bacterial strains. These studies
led to interesting structure–activity relationships and the
identification of a number of simpler, and yet equipotent, or even
more potent, antibacterial agents than the natural product, thereby
setting the foundation for further investigations in the quest for
new anti-infective drugs
Streamlined Total Synthesis of Trioxacarcins and Its Application to the Design, Synthesis, and Biological Evaluation of Analogues Thereof. Discovery of Simpler Designed and Potent Trioxacarcin Analogues
A streamlined total synthesis of
the naturally occurring antitumor
agents trioxacarcins is described, along with its application
to the construction of a series of designed analogues of these complex
natural products. Biological evaluation of the synthesized compounds
revealed a number of highly potent, and yet structurally simpler,
compounds that are effective against certain cancer cell lines, including
a drug-resistant line. A novel one-step synthesis of anthraquinones
and chloro anthraquinones from simple ketone precursors and
phenylselenyl chloride is also described. The reported work,
featuring novel chemistry and cascade reactions, has potential applications
in cancer therapy, including targeted approaches as in antibody–drug
conjugates
Synthesis and Biological Investigation of Δ<sup>12</sup>-Prostaglandin J<sub>3</sub> (Δ<sup>12</sup>-PGJ<sub>3</sub>) Analogues and Related Compounds
A series of Δ<sup>12</sup>-prostaglandin
J<sub>3</sub> (Δ<sup>12</sup>-PGJ<sub>3</sub>) analogues and
derivatives were synthesized
employing an array of synthetic strategies developed specifically
to render them readily available for biological investigations. The
synthesized compounds were evaluated for their cytotoxicity against
a number of cancer cell lines, revealing nanomolar potencies for a
number of them against certain cancer cell lines. Four analogues (<b>2</b>, <b>11</b>, <b>21</b>, and <b>27</b>)
demonstrated inhibition of nuclear export through a covalent addition
at Cys528 of the export receptor Crm1. One of these compounds (i.e., <b>11</b>) is currently under evaluation as a potential drug candidate
for the treatment of certain types of cancer. These studies culminated
in useful and path-pointing structure–activity relationships
(SARs) that provide guidance for further improvements in the biological/pharmacological
profiles of compounds within this class