Optimization of Pramipexole-Loaded In Situ Thermosensitive Intranasal Gel for Parkinson's Disease.

The objective of the present work was to develop and optimize an intranasal in situ gel of Pramipexole dihydrochloride for enhanced drug delivery, better patient acceptability, and possible proper treatment of Parkinson's disease. Preliminary studies were performed to select formulation components and identify key variables affecting the formulation. The optimization of the in situ gelling system of Pramipexole dihydrochloride was achieved by applying 32 full factorial design using Design-Expert® software (Stat-Ease 9.0.6 version) and taking concentrations of Poloxamer 407 (X1) and HPMC K4M (X2) as independent variables. The gelling temperature, gel strength, and percentage of drug diffused after 8 h were taken as dependent variables. The software provided an optimized formulation, with 16.50% of X1 and 0.2% of X2 with the highest desirability. An in vivo drug retention time study was performed for the optimized formulation in Wistar rats. The results of the optimization process demonstrated that the selected gel formulation exhibited desirable characteristics, including gelation near body temperature, good gel strength, suitable viscosity, and sustained drug release. The optimized formulation displayed significantly higher drug retention, lasting about 5 h, versus the plain poloxamer gel formulation. Hence, it was concluded that the optimized formulation will remain affixed at the site of application for a significant time after intranasal administration and consequently sustain the release of the drug. The optimized formulation was found to be stable during the stability studies. The developed dosage form may improve patient compliance, enhance nasal drug residence, and offer sustained drug release. However, further clinical studies are necessary to validate these findings.

Activation of the SNF2 family ATPase ALC1 by poly(ADP-ribose) in a stable ALC1·PARP1·nucleosome intermediate.

The human ALC1/CHD1L oncogene encodes an SNF2 family ATPase with a macrodomain that binds poly(ADP-ribose) (PAR). We and others previously showed that ALC1 possesses a cryptic ATP-dependent nucleosome remodeling activity that is potently activated in the presence of PARP1 and NAD(+), its substrate for PAR synthesis. In this work, we dissected the mechanism by which PARP1 and NAD(+) activate ALC1 nucleosome remodeling. We demonstrate that ALC1 activation depends on the formation of a stable ALC1·PARylated PARP1·nucleosome intermediate. In addition, by exploiting a novel PAR footprinting assay, we obtained evidence that the ALC1 macrodomain remains stably associated with PAR on autoPARylated PARP1 during the course of nucleosome remodeling reactions. Taken together, our findings are consistent with the model that PAR present on PARylated PARP1 acts as an allosteric effector of ALC1 nucleosome remodeling activity.

Regioselective iron-catalyzed decarboxylative allylic etherification.

An anionic iron complex catalyzes the decarboxylative allylation of phenols to form allylic ethers in high yield. The allylation is regioselective rather than regiospecific. This suggests that the allylation proceeds through pi-allyl iron intermediates in contrast to related allylations of carbon nucleophiles that have been proposed to proceed via sigma-allyl complexes. Ultimately, iron catalysts have the potential to replace more expensive palladium catalysts that are typically utilized for decarboxylative couplings.

Mild decarboxylative allylation of coumarins.

Allyl esters of 3-carboxylcoumarins undergo facile decarboxylative coupling at just 25-50 degrees C. This represents the first extension of decarboxylative C-C bond-forming reactions to the coupling of aromatics with sp(3)-hybridized electrophiles. Finally, the same concept can be applied to the sp(2)-sp(3) couplings of pyrones and flavones. Thus, a variety of biologically important heteroaromatics can be readily functionalized without the need for strong bases or stoichiometric organometallics that are typically required for more standard cross-coupling reactions.