Tackling neuroinflammation and cholinergic deficit in Alzheimer's disease: Multi-target inhibitors of cholinesterases, cyclooxygenase-2 and 15-lipoxygenase.

Neuroinflammation and cholinergic deficit are key detrimental processes involved in Alzheimer's disease. Hence, in the search for novel and effective treatment strategies, the multi-target-directed ligand paradigm was applied to the rational design of two series of new hybrids endowed with anti-inflammatory and anticholinesterase activity via triple targeting properties, namely able to simultaneously hit cholinesterases, cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX) enzymes. Among the synthesized compounds, triazoles 5b and 5d, and thiosemicarbazide hybrid 6e emerged as promising new hits, being able to effectively inhibit human butyrylcholinesterase (hBChE), COX-2 and 15-LOX enzymes with a higher inhibitory potency than the reference inhibitors tacrine (for hBChE inhibition), celecoxib (for COX-2 inhibition) and both NDGA and Zileuton (for 15-LOX inhibition). In addition, compound 6e proved to be a submicromolar mixed-type inhibitor of human acetylcholinesterase (hAChE). The anti-neuroinflammatory activity of the three most promising hybrids was confirmed in a cell-based assay using PC12 neuron cells, showing decreased expression levels of inflammatory cytokines IL-1ß and TNF-α. Importantly, despite the structural resemblance to tacrine, they showed ideal safety profiles on hepatic and murine brain cell lines and were safe up to 100 µM when assayed in PC12 cells. All three hybrids were also predicted to have superior BBB permeability than tacrine in the PAMPA assay, and good physicochemical properties, drug-likeness and ligand efficiency indices. Finally, molecular docking studies highlighted key structural elements impacting selectivity and activity toward the selected target enzymes. To the best of our knowledge, compounds 5b, 5d and 6e are the first balanced, safe and multi-target compounds hitting the disease at the three mentioned hubs.

Design and synthesis of some new 2,3'-bipyridine-5-carbonitriles as potential anti-inflammatory/antimicrobial agents.

AIM: Inflammation may cause accumulation of fluid in the injured area, which may promote bacterial growth. Other reports disclosed that non-steroidal anti-inflammatory drugs may enhance progression of bacterial infection. RESULTS: This work describes synthesis of new series of 2,3'-bipyridine-5-carbonitriles as structural analogs of etoricoxib, linked at position-6 to variously substituted thio or oxo moieties. Biological screening results revealed that compounds 2b, 4b, 7e and 8 showed significant acute and chronic AI activities and broad spectrum of antimicrobial activity. In addition, similarity ensemble approach was applied to predict potential biological targets of the tested compounds. Then, pharmacophore modeling study was employed to determine the most important structural parameters controlling bioactivity. Moreover, title compounds showed physicochemical properties within those considered adequate for drug candidates. CONCLUSION: This study explored the potential of such series of compounds as structural leads for further modification to develop a new class of dual AI-antimicrobial agents.

Photochemical hydroxylation of 1-methyl-9,10-anthraquinones: synthesis of 9'-hydroxyaloesaponarin II.

Photolysis of 1-methyl-9,10-anthraquinones in the presence of oxygen yields endoperoxides that can be reduced to produce 1-hydroxymethyl-9,10-anthraquinones. The reaction proceeds in a fashion similar to that of other o-alkylphenones which yield either a 1,4-diradical or a "photoenol" upon irradiation. Anthraquinones undergo photochemistry at a wavelength where the endoperoxide is transparent, allowing its isolation. A singlet oxygen quencher had no effect on the rate of formation of the endoperoxide. The photochemical hydroxylation has been used in a total synthesis of a naturally occurring polyketide, 9'-hydroxyaloesaponarin II.

Observation of heavy atom effects in the development of water soluble caged 4-hydroxy-trans-2-nonenal.

During the course of our study on the photochemistry of 1-alkoxy-9,10-anthraquinones, we have developed a second generation of a caged 4-hydroxy-trans-2-nonenal (4-HNE). As we optimized the anthraquinonyl chromophore to achieve water solubility, we studied the photochemistry of various substituents to understand their effect on the photochemistry. We observed a significant heavy atom effect that severely reduced the rate of oxidative cleavage of the alkoxy group. Based on the results of our substituent study, we designed a new caged 4-HNE that is soluble under physiological conditions, and that releases 4-HNE photochemically in high yield.