7 research outputs found
Synthesis of Phidianidines A and B
Reaction of a substituted indole-3-acetyl chloride with <i>N</i>-5-azidopentyl-<i>N</i>′-hydroxyguanidine
generated a substituted 3-(5-azidopentylamino)-5-((indol-3-yl)methyl)-1,2,4-oxadiazole.
Reduction of the azide with zinc and ammonium formate afforded the
amine, which was elaborated to the guanidine, completing short and
efficient syntheses of the cytotoxic natural products phidianidines
A and B in 19% overall yield by a convergent route that will make
analogues readily available for biological evaluation. Initial screening
in the NCI 60 cell line at 10<sup>–5</sup> M indicated that
the bromine on the indole is necessary for activity and that the amine
precursor to phidianidine A is more potent than phidianidine A
Synthesis of (±)-7-Hydroxylycopodine
A seven-step synthesis of (±)-7-hydroxylycopodine that proceeds
in 5% overall yield has been achieved. The key step is a Prins reaction
in 60% sulfuric acid that gave the key tricyclic intermediate with
complete control of the ring fusion stereochemistry. A one-pot procedure
orthogonally protected the primary alcohol as an acetate and the tertiary
alcohol as a methylthiomethyl ether. The resulting product was converted
to 7-hydroxydehydrolycopodine by heating with KO-<i>t</i>-Bu and benzophenone in benzene followed by acidic workup. During
unsuccessful attempts to make optically pure starting material, we
observed the selective Pt-catalyzed hydrogenation of the 5-phenyl
group of a 4,5-diphenyloxazolidine under acidic conditions and the
Pt-catalyzed isomerization of the oxazolidine to an amide under neutral
conditions. In attempts to hydroxylate the starting material so that
we could adapt this synthesis to the preparation of (±)-7,8-dihydroxylycopodine
(sauroine) we observed the novel oxidation of a bicyclic vinylogous
amide to a keto pyridine with Mn(OAc)<sub>3</sub> and to an amino
phenol with KHMDS and oxygen
A Generalizable Platform for Interrogating Target- and Signal-Specific Consequences of Electrophilic Modifications in Redox-Dependent Cell Signaling
Despite the known propensity of small-molecule
electrophiles to
react with numerous cysteine-active proteins, biological actions of
individual signal inducers have emerged to be chemotype-specific.
To pinpoint and quantify the impacts of modifying one target out of
the whole proteome, we develop a target-protein-personalized “electrophile
toolbox” with which specific intracellular targets can be selectively
modified at a precise time by specific reactive signals. This general
methodology, T-REX (<u>t</u>argetable <u>r</u>eactive <u>e</u>lectrophiles and o<u>x</u>idants), is established by (1) constructing a platform that can deliver
a range of electronic and sterically different bioactive lipid-derived
signaling electrophiles to specific proteins in cells; (2) probing
the kinetics of targeted delivery concept, which revealed that targeting
efficiency in cells is largely driven by initial on-rate of alkylation;
and (3) evaluating the consequences of protein-target- and small-molecule-signal-specific
modifications on the strength of downstream signaling. These data
show that T-REX allows quantitative interrogations into the extent
to which the Nrf2 transcription factor-dependent antioxidant response
element (ARE) signaling is activated by selective electrophilic modifications
on Keap1 protein, one of several redox-sensitive regulators of the
Nrf2–ARE axis. The results document Keap1 as a promiscuous
electrophile-responsive sensor able to respond with similar efficiencies
to discrete electrophilic signals, promoting comparable strength of
Nrf2–ARE induction. T-REX is also able to elicit cell activation
in cases in which whole-cell electrophile flooding fails to stimulate
ARE induction prior to causing cytotoxicity. The platform presents
a previously unavailable opportunity to elucidate the functional consequences
of small-molecule-signal- and protein-target-specific electrophilic
modifications in an otherwise unaffected cellular background
Arene–Arene Coupled Disulfamethazines (or Sulfadiazine)-Phenanthroline-Metal(II) Complexes were Synthesized by In Situ Reactions and Inhibited the Growth and Development of Triple-Negative Breast Cancer through the Synergistic Effect of Antiangiogenesis, Anti-Inflammation, Pro-Apoptosis, and Cuproptosis
The novel metal(II)-based complexes HA-Cu, HA-Co, and
HA-Ni with
phenanthroline, sulfamethazine, and aromatic–aromatic coupled
disulfamethazines as ligands were synthesized and characterized. HA-Cu,
HA-Co, and HA-Ni all showed a broad spectrum of cytotoxicity and antiangiogenesis.
HA-Cu was superior to HA-Co and HA-Ni, and even superior to DDP, showing
significant inhibitory effect on the growth and development of tripe-negative
breast cancer in vivo and in vitro. HA-Cu exhibited observable synergistic
effects of antiproliferation, antiangiogenesis, anti-inflammatory,
pro-apoptosis, and cuproptosis to effectively inhibited tumor survival
and development. The molecular mechanism was confirmed that HA-Cu
could downregulate the expression of key proteins in the VEGF/VEGFR2
signaling pathway and the expression of inflammatory cytokines, enhance
the advantage of pro-apoptotic protein Bax, and enforce cuproptosis
by weakening the expression of FDX1 and enhancing the expression of
HSP70. Our research will provide a theoretical and practical reference
for the development of metal-sulfamethazine and its derivatives as
chemotherapy drugs for cancer treatment
Arene–Arene Coupled Disulfamethazines (or Sulfadiazine)-Phenanthroline-Metal(II) Complexes were Synthesized by In Situ Reactions and Inhibited the Growth and Development of Triple-Negative Breast Cancer through the Synergistic Effect of Antiangiogenesis, Anti-Inflammation, Pro-Apoptosis, and Cuproptosis
The novel metal(II)-based complexes HA-Cu, HA-Co, and
HA-Ni with
phenanthroline, sulfamethazine, and aromatic–aromatic coupled
disulfamethazines as ligands were synthesized and characterized. HA-Cu,
HA-Co, and HA-Ni all showed a broad spectrum of cytotoxicity and antiangiogenesis.
HA-Cu was superior to HA-Co and HA-Ni, and even superior to DDP, showing
significant inhibitory effect on the growth and development of tripe-negative
breast cancer in vivo and in vitro. HA-Cu exhibited observable synergistic
effects of antiproliferation, antiangiogenesis, anti-inflammatory,
pro-apoptosis, and cuproptosis to effectively inhibited tumor survival
and development. The molecular mechanism was confirmed that HA-Cu
could downregulate the expression of key proteins in the VEGF/VEGFR2
signaling pathway and the expression of inflammatory cytokines, enhance
the advantage of pro-apoptotic protein Bax, and enforce cuproptosis
by weakening the expression of FDX1 and enhancing the expression of
HSP70. Our research will provide a theoretical and practical reference
for the development of metal-sulfamethazine and its derivatives as
chemotherapy drugs for cancer treatment
Substoichiometric Hydroxynonenylation of a Single Protein Recapitulates Whole-Cell-Stimulated Antioxidant Response
Lipid-derived
electrophiles (LDEs) that can directly modify proteins
have emerged as important small-molecule cues in cellular decision-making.
However, because these diffusible LDEs can modify many targets [e.g.,
>700 cysteines are modified by the well-known LDE 4-hydroxynonenal
(HNE)], establishing the functional consequences of LDE modification
on individual targets remains devilishly difficult. Whether LDE modifications
on a single protein are biologically sufficient to activate discrete
redox signaling response downstream also remains untested. Herein,
using T-REX (targetable reactive electrophiles and oxidants), an approach
aimed at selectively flipping a single redox switch in cells at a
precise time, we show that a modest level (∼34%) of HNEylation
on a single target is sufficient to elicit the pharmaceutically important
antioxidant response element (ARE) activation, and the resultant strength
of ARE induction recapitulates that observed from whole-cell electrophilic
perturbation. These data provide the first evidence that single-target
LDE modifications are important individual events in mammalian physiology
Precision Electrophile Tagging in <i>Caenorhabditis elegans</i>
Adduction of an electrophile to privileged
sensor proteins and
the resulting phenotypically dominant responses are increasingly appreciated
as being essential for metazoan health. Functional similarities between
the biological electrophiles and electrophilic pharmacophores commonly
found in covalent drugs further fortify the translational relevance
of these small-molecule signals. Genetically encodable or small-molecule-based
fluorescent reporters and redox proteomics have revolutionized the
observation and profiling of cellular redox states and electrophile–sensor
proteins, respectively. However, precision mapping between specific
redox-modified targets and specific responses has only recently begun
to be addressed, and systems tractable to both genetic manipulation
and on-target redox signaling in vivo remain largely limited. Here
we engineer transgenic <i>Caenorhabditis elegans</i> expressing
functional HaloTagged fusion proteins and use this system to develop
a generalizable light-controlled approach to tagging a prototypical
electrophile–sensor protein with native electrophiles in vivo.
The method circumvents issues associated with low uptake/distribution
and toxicity/promiscuity. Given the validated success of <i>C.
elegans</i> in aging studies, this optimized platform offers
a new lens with which to scrutinize how on-target electrophile signaling
influences redox-dependent life span regulation