Novel piperazine derivative PMS1339 exhibits tri-functional properties and cognitive improvement in mice.

Amyloid-beta-induced neuroinflammation plays a central role in the extensive loss of cholinergic neurons and cognitive decline in Alzheimer's disease. The acetylcholinesterase (AChE) inhibitors are the first class of drugs used to enhance surviving cholinergic activities. However, their limited effectiveness following long-term treatment raises a need for new multi-target therapies. We report herein a novel piperazine derivative compound PMS1339 possesses multifunctional properties including anti-platelet-activating factor, AChE inhibition, Abeta aggregation inhibition and cognitive improvement. PMS1339 could significantly inhibit both mice brain AChE (IC50=4.41+/-0.63 microM) and sera butyrylcholinesterase (BuChE, IC50=1.09+/-0.20 microM). PMS1339 was also found to inhibit neuronal AChE secreted by SH-SY5Y cell line (IC50=17.95+/-2.31 microM). Enzyme kinetics experiments performed on electric eel AChE indicated that PMS1339 acts as a mixed type competitive AChE inhibitor. Molecular docking studies using the X-ray crystal structure of AChE from Torpedo californica elucidated the interactions between PMS1339 and AChE: PMS1339 is well buried inside the active-site gorge of AChE interacting with Trp84 at the bottom, Tyr121 halfway down and Trp279 at the peripheral anionic site (PAS). Thioflavin T-based fluorimetric assay revealed the ability of PMS1339 to inhibit AChE-induced Abeta aggregation. In-vivo study indicated PMS1339 (1 mg/kg i.p.) reversed scopolamine-induced memory impairment in mice. Overall, these findings indicated that PMS1339 exhibits tri-functional properties in vitro and cognitive improvement in vivo, and revealed the emergence of a multi-target-directed ligand to tackle the determinants of Alzheimer's disease.

PMS777, a bis-interacting ligand for PAF receptor antagonism and AChE inhibition, attenuates PAF-induced neurocytotoxicity in SH-SY5Y cells.

(1) HIV-1 and viral proteins-evoked chronic brain inflammation, which is characterized by microglial activation, is the pivotal neuropathogenesis of HIV-1-associated dementia (HAD). Platelet-activating factor (PAF), mainly released from activated microglia and acts as a high potent inflammatory mediator and a neurotoxin, is indicated to be a principle initiator of neuroinflammation, neuronal dysfunction, and apoptosis related to HAD. Thus, bis-interacting ligands of acetylcholinesterase (AChE) inhibition and PAF receptor antagonism would be of great interest in the therapeutic potential of HAD not only for improvement of cognitive performance, but also for disease-modifying. (2). We have previously reported that a novel tetrahydrofuran-derived bis-interacting ligand PMS777 had satisfying potencies for PAF receptor blockade and AChE inhibition, and markedly improved cholinergic dysfunction-induced cognitive impairment in mice. Continuing with our research, we further investigated the neuroprotective activities of PMS777 on PAF-triggered neuronal injury in human neuroblastoma SH-SY5Y cells. (3) The bis-interacting ligand PMS777 (10 muM) obviously alleviated PAF-induced cell apoptosis in SH-SY5Y cells. Pretreatment with PMS777 also markedly inhibited intracellular Ca(2+) overload, down-regulation of anti-apoptotic bcl-2 mRNA, stimulation of pro-apoptotic bax mRNA expression and activation of caspase-3 pathway. Also, PMS777 could fine-tune pro-inflammatory cyclooxygenase-2 (cox-2) mRNA expression in PAF-treated cells. (4) These results suggest that PMS777 possesses a neuroprotective profile via anti-apoptotic/inflammatory signaling and warrant further investigations in connection with the potential value of this compound in HAD treatment.

Pharmacological profile of PMS777, a new AChE inhibitor with PAF antagonistic activity.

The key pathophysiological mechanisms in Alzheimer's disease involve the selective loss of cholinergic neurons and pro-inflammatory mediator-related chronic inflammatory responses in the brain, therefore interventions of these processes are crucial to the treatment of this disease. In the present study, the pharmacological profile of PMS777, a new acetylcholinesterase (AChE) inhibitor with platelet-activating factor (PAF) antagonistic activity, has been evaluated in vitro and in vivo. PMS777 (1-100 microM) dose-dependently inhibited PAF-induced rabbit platelet aggregation by competing with [3H]PAF for its receptor on platelets, and protected a human neuroblastoma cell line SH-SY5Y against PAF-induced neurotoxicity. Moreover, it markedly inhibited brain AChE activity in mice and showed a modest selectivity for AChE (AChE: IC50=2.48+/-0.12 microM; butyrylcholinesterase: IC50=4.47+/-0.15 microM). Ex vivo, PMS777 (5, 10, 20 or 40 mg/kg i.p.) reduced brain AChE activity in a dose-dependent manner. In-vivo studies revealed that PMS777 (0.25, 0.5, 1, 2.5 or 5 mg/kg i.p.) could reverse scopolamine-induced memory retrieval deficits in mice, and displayed a typical bell-shaped dose-response relationship. Taken together, these results demonstrate that PMS777 possesses dual activities for PAF receptor antagonism and AChE inhibition, suggesting that this compound may be a promising lead compound for further investigation related to the treatment for Alzheimer's disease.