Intravesical
therapy, already used to treat bladder cancer, is a potential treatment
option for urinary tract infections. However, short dwelling time
and washout proved to be challenging obstacles. To circumvent these
issues, PLGA 503H and PLGA 2300 nanoparticles were prepared and surface
modified with wheat germ agglutinin (WGA). Nanoparticles of both poly(
d
,
l
-lactic-
co
-glycolic acid) (PLGA)
types exhibited high inherent adhesion to human uroepithelial cells.
Although surface-bound WGA could be easily increased, adhesion did
not. Loading the nanoparticles with trimethoprim did not counteract
cell adhesion. Varying the medium for instillation revealed highest
adhesion in sodium bicarbonate buffer (pH 5). To evaluate dwelling
time, nanoparticles were incubated with the cell monolayer for increasing
time intervals. A contact time of 15 min seems to be too short for
adhesion to the cells as less than 50% particles remained bound after
washing. However, after 30 min 70% of the particles added were bound,
and afterward, no further increase was observed. WGA only slightly
increased the adhesion of the PLGA nanoparticles, but this approach
might not be economically viable. However, PLGA nanoparticles displayed
a high inherent adhesion to cells that might substantially foster
intravesical therapy.
We report a modular synthetic approach towards novel derivatives of the naturally occurring arylated benzophenone selagibenzophenone A. The initial strategy for the construction of the carbon framework of the derivatives relied on the Suzuki reaction of 2,4,6-tribromobenzonitrile, and the addition of the aryl lithium species to nitrile to generate imine. However, the formed imines showed remarkable stability toward hydrolysis. Therefore, Suzuki cross-coupling was carried out with 2,4,6-tribromobenzaldehyde and the subsequent addition of organometallic species to the aldehyde. Oxidation of the resulting alcohol ensured the access to desired ketones. The importance of the developed modular strategy is underlined by the discovery of several derivatives with selective cytotoxic effects and potential anti-inflammatory activity superior to the effect of the natural product.
The steroid sapogenin diosgenin is a well-known natural product with a plethora of described pharmacological activities including the amelioration of T helper 17 (Th17)-driven pathologies. However, the exact underlying mode of action of diosgenin leading to a dampened Th17 response is still largely unknown and specific molecular targets have yet to be identified. Here, we show that diosgenin acts as a direct ligand and inverse agonist of the nuclear receptor retinoic acid receptor (RAR)-related orphan receptor (ROR)α and RORγ, which are key transcription factors involved in Th17 cell differentiation and metabolism. IC50 values determined by luciferase reporter gene assays, employing constructs for either RORγ-Gal4 fusion proteins or full length receptors, were in the low micromolar range at around 2 µM. To highlight the functional consequences of this RORα/γ inverse agonism, we determined gene expression levels of important ROR target genes, i.e., IL-17A and glucose-6-phosphatase, in relevant cellular in vitro models of Jurkat T and HepG2 cells, respectively, by RT-qPCR (reverse transcription quantitative PCR). Thereby, it was shown that diosgenin leads to a dose-dependent decrease in target gene expressions consistent with its potent cellular ROR inverse agonistic activity. Additionally, in silico dockings of diosgenin to the ROR ligand-binding domain were performed to determine the underlying binding mode. Taken together, our results establish diosgenin as a novel, direct and dual-selective RORα/γ inverse agonist. This finding establishes a direct molecular target for diosgenin for the first time, which can further explain reported amendments in Th17-driven diseases by this compound.
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