5 research outputs found
Three Homology Models of PAR2 Derived from Different Templates: Application to Antagonist Discovery
Protease
activated receptor 2 (PAR2) is an unusual G-protein coupled receptor
(GPCR) involved in inflammation and metabolism. It is activated through
cleavage of its N-terminus by proteases. The new N-terminus functions
as a tethered ligand that folds back and intramolecularly activates
PAR2, initiating multiple downstream signaling pathways. The only
compounds reported to date to inhibit PAR2 activation are of moderate
potency. Three structural models for PAR2 have been constructed based
on sequence homology with known crystal structures for bovine rhodopsin,
human ORL-1 (also called nociceptin/orphanin FQ receptor), and human
PAR1. The three PAR2 model structures were compared and used to predict
potential interactions with ligands. Virtual screening for ligands
using the Chembridge database, and either ORL-1 or PAR1 derived PAR2
models led to identification of eight new small molecule PAR2 antagonists
(IC<sub>50</sub> 10–100 μM). Notably, the most potent
compound <b>1</b> (IC<sub>50</sub> 11 μM) was derived
from the less homologous template protein, human ORL-1. The results
suggest that virtual screening against multiple homology models of
the same GPCR can produce structurally diverse antagonists and that
this may be desirable even when some models have less sequence homology
with the target protein
Hyaluronic Acid-Functionalized Gold Nanorods with pH/NIR Dual-Responsive Drug Release for Synergetic Targeted Photothermal Chemotherapy of Breast Cancer
Tumor-targeted
delivery of photothermal agent and controlled release of concomitant
chemotherapeutic drug are two key factors for combined photothermal
chemotherapy. Herein, we developed a pH/near-infrared (NIR) dual-triggered
drug release nanoplatform based on hyaluronic acid (HA)-functionalized
gold nanorods (GNRs) for actively targeted synergetic photothermal
chemotherapy of breast cancer. Targeting folate (FA), dopamine, and
adipic acid dihydrazide triconjugated HA was first synthesized and
used to decorate GNRs via Au–catechol bonds, and then an anticarcinogen
doxorubicin (DOX) was conjugated onto HA moieties via an acid-labile
hydrazone linkage, resulting in multifunctional nanoparticles GNRs-HA-FA-DOX.
The nanoparticles exhibited excellent stability and had a pH and NIR
dual-responsive drug release behavior. In vitro studies showed that
the nanoparticles could be efficiently internalized into breast cancer
MCF-7 cells and kill them under NIR irradiation in a synergistic fashion
via inducing cell apoptosis. Pharmacokinetics and biodistribution
studies in tumor-bearing mice indicated that the nanoparticles had
a long blood circulation with a half-life of 2.4 h and exhibited a
high accumulation of 11.3% in tumor site. The tumors of mice treated
with combined chemotherapy and photothermal therapy were completely
suppressed without obvious systemic toxicity after 20 d of treatment.
These results demonstrated a great potential of GNRs-HA-FA-DOX nanoparticles
for targeted synergistic therapy of breast cancer
Il bilancio pluriennale nel nuovo ordinamento finanziario e contabile degli enti locali
Virtual screening of a drug database
identified Carvedilol, Loratadine,
Nefazodone and Astemizole as PAR2 antagonists, after ligand docking
and molecular dynamics simulations using a PAR2 homology model and
a putative binding mode of a known PAR2 ligand. The drugs demonstrated
competitive binding and antagonism of calcium mobilization and ERK1/2
phosphorylation in CHO-hPAR2 transfected cells, while inhibiting IL-6
secretion in PAR2 expressing MDA-MB-231 breast cancer cells. This
research highlights opportunities for GPCR hit-finding from FDA-approved
drugs
Discovery of Novel Small Molecule Inhibitors of Dengue Viral NS2B-NS3 Protease Using Virtual Screening and Scaffold Hopping
By virtual screening, compound <b>1</b> was found
to be active
against NS2B-NS3 protease (IC<sub>50</sub> = 13.12 ± 1.03 μM).
Fourteen derivatives (<b>22</b>) of compound <b>1</b> were
synthesized, leading to the discovery of four new inhibitors with
biological activity. In order to expand the chemical diversity of
the inhibitors, small-molecule-based scaffold hopping was performed
on the basis of the common scaffold of compounds <b>1</b> and <b>22</b>. Twenty-one new compounds (<b>23</b>, <b>24</b>) containing quinoline (new scaffold) were designed and synthesized.
Protease inhibition assays revealed that 12 compounds with the new
scaffold are inhibitors of NS2B-NS3 protease. Taken together, 17 new
compounds were discovered as NS2B-NS3 protease inhibitors with IC<sub>50</sub> values of 7.46 ± 1.15 to 48.59 ± 3.46 μM,
and 8 compounds belonging to two different scaffolds are active to
some extent against DENV based on luciferase reporter replicon-based
assays. These novel chemical entities could serve as lead structures
for discovering therapies against DENV
Crystal Structures of SgcE6 and SgcC, the Two-Component Monooxygenase That Catalyzes Hydroxylation of a Carrier Protein-Tethered Substrate during the Biosynthesis of the Enediyne Antitumor Antibiotic C‑1027 in <i>Streptomyces globisporus</i>
C-1027
is a chromoprotein enediyne antitumor antibiotic produced
by <i>Streptomyces globisporus</i>. In the last step of
biosynthesis of the (<i>S</i>)-3-chloro-5-hydroxy-β-tyrosine
moiety of the C-1027 enediyne chromophore, SgcE6 and SgcC compose
a two-component monooxygenase that hydroxylates the C-5 position of
(<i>S</i>)-3-chloro-β-tyrosine. This two-component
monooxygenase is remarkable for two reasons. (i) SgcE6 specifically
reacts with FAD and NADH, and (ii) SgcC is active with only the peptidyl
carrier protein (PCP)-tethered substrate. To address the molecular
details of substrate specificity, we determined the crystal structures
of SgcE6 and SgcC at 1.66 and 2.63 Ã… resolution, respectively.
SgcE6 shares a similar β-barrel fold with the class I HpaC-like
flavin reductases. A flexible loop near the active site of SgcE6 plays
a role in FAD binding, likely by providing sufficient space to accommodate
the AMP moiety of FAD, when compared to that of FMN-utilizing homologues.
SgcC shows structural similarity to a few other known FADH<sub>2</sub>-dependent monooxygenases and sheds light on some biochemically but
not structurally characterized homologues. The crystal structures
reported here provide insights into substrate specificity, and comparison
with homologues provides a catalytic mechanism of the two-component,
FADH<sub>2</sub>-dependent monooxygenase (SgcE6 and SgcC) that catalyzes
the hydroxylation of a PCP-tethered substrate