J.Med.Chem.2008,51,2027-2036 Bis-()-nor-meptazinols as Novel Nanomolar Cholinesterase Inhibitors with High Inhibitory Potency on Amyloid-B Aggregation Qiong Xie, "Hao Wang, t* Zheng Xia, Meiyan Lu, t Weiwei Zhang. Xinghai Wang, t Wei Fu, t Yun Tang, Wei Sheng, Wei Li, Wei Zhou, Xu Zhu, Zhuibai Qiu, *f and Hongzhuan Chen*+ Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 138 Yixueyuan Road, Shanghai 200032, P. R. China, Departmen of Pharmacology, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, 280 South Chongqing Road, 30 Meilong Road, Shanghai 200237, P. R. China Received February 9. 2007 Bis-(-)-nor-meptazinols(bis-()-nor-MEPs)5 were designed and synthesized by connecting two MEP monomers with alkylene linkers of different lengths via the secondary amino groups acetylcholinesterase(AChE) inhibitory activities were more greatly influenced by the length of the Alkylene exhibited low-nanomolar ICso values for both ChEs, having a 10 000-fold and 1500-fold increase in inhibitic of AChE and BChE compared with(-)-MEP. Molecular docking elucidated that 5h simultaneously bound to the catalytic and peripheral sites in AChE via hydrophobic interactions with Trp86 and Trp286. In comparison, it folded in the large aliphatic cavity of BChE because of the absence of peripheral site and the enlargement of the active site. Furthermore, 5h and 5i markedly prevented the AChE-induced AB aggregation with ICso values of 16.6 and 5.8 uM, similar to that of propidium (IC50= 12. 8 uM), which suggests promising disease-modifying agents for the treatment of AD patients Introduction Alzheimer's disease(AD), which is characterized by progres- sive loss of memory and impairment in cognition, is becoming a serious threat to life expectancy for elderly people. The main pathological changes in the Ad brain are the abnormal formation Linked of extracellular senile plaques consisting of aggregated amyloid B-peptide(Ap)deposits and intracellular neurofibrillary tangles (NTFs) consisting of abnormally phosphorylated microtubule- associated protein T Current clinical therapy for Ad patients is mainly palliative = atalytic site treatment targeting acetylcholinesterase(AChE). On the basis of the cholinergic hypothesis, inhibition of AChE effectively ncreases the available acetylcholine(ACh) within cholinergic synapses, resulting in modest improvement in cognitive symp- Figure 1. Catalytic and peripheral sites of AChE active site gorge oms. Mounting evidence has indicated that AChE may be involved in several noncholinergic functions. AChE colocalizes cognitive deficit of AD patients by elevating ACh levels but with AB in senile plaques, promoting the assembly of AB into also act as disease-modifying agents delaying amyloid plaque fibrils'and accelerating AB peptide deposition. Structural formation. 9a, 13 models of the interaction between AChE and AB have recently Recently, bivalent ligand strategy has been utilized in the been explored. It has been speculated that AChE achieves design of dual binding site ache inhibitors 9-13 homobivalent aggregation-promoting action through direct binding with A or heterobivalent ligands are obtained by connecting two via the specific region of the enzyme that involves a peripheral identical or distinct moieties through a linker of suitable length binding site. Inhibition of the peripheral site might prevent A, to make contact with both the catalytic and peripheral sites. A peptide deposition induced by AChE. This enzyme has a narrow spatial 12 A distance was determined by X-ray crystal diffraction 20 A deep active site gorge, the bottom and opening regions of from Trp86(mammalian numbering), the catalytic anionic site which are known as catalytic and peripheral sites, respectively center, to Trp286(mammalian numbering), core of the periph (Figure 1). AChE inhibitors simultaneously blocking both the eral site(Figure 1). In many cases of homobivalent ligands catalytic and peripheral sites might not only alleviate the (bis-ligands ), AChE inhibitory potency and selectivity improved relative to the monomer and additional inhibition of ache- 21地0m1 hE inhibitor reported g aoli@shamu.edu.cn strategy, presenting a more than 1000-fold increase in AChE Fudan inhibiting potency and a 10000-fold increase in AChE/butyryl These authors contributed equally to this work cholinesterase (BChE) selectivity compared with tacrine Shanghai Jiao Tong University. Bis-galanthamine 2(Figure 2, n=8), bis-5-amino-5,6,7, 8- East China University of Science and Technology 10 or 12) 10. 1021/jm070154q CCC: $.75 C 2008 American Chemical Society Published on web 03/12/2008Bis-(-)-nor-meptazinols as Novel Nanomolar Cholinesterase Inhibitors with High Inhibitory Potency on Amyloid-
Aggregation Qiong Xie,†,# Hao Wang,‡,# Zheng Xia,‡ Meiyan Lu,† Weiwei Zhang,‡ Xinghai Wang,† Wei Fu,† Yun Tang,§ Wei Sheng,† Wei Li,† Wei Zhou,‡ Xu Zhu,‡ Zhuibai Qiu,*,† and Hongzhuan Chen*,‡ Department of Medicinal Chemistry, School of Pharmacy, Fudan UniVersity, 138 Yixueyuan Road, Shanghai 200032, P. R. China, Department of Pharmacology, Institute of Medical Sciences, Shanghai JiaoTong UniVersity School of Medicine, 280 South Chongqing Road, Shanghai 200025, P. R. China, and School of Pharmacy, East China UniVersity of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. China ReceiVed February 9, 2007 Bis-(-)-nor-meptazinols (bis-(-)-nor-MEPs) 5 were designed and synthesized by connecting two (-)-nor￾MEP monomers with alkylene linkers of different lengths via the secondary amino groups. Their acetylcholinesterase (AChE) inhibitory activities were more greatly influenced by the length of the alkylene chain than butyrylcholinesterase (BChE) inhibition. The most potent nonamethylene-tethered dimer 5h exhibited low-nanomolar IC50 values for both ChEs, having a 10 000-fold and 1500-fold increase in inhibition of AChE and BChE compared with (-)-MEP. Molecular docking elucidated that 5h simultaneously bound to the catalytic and peripheral sites in AChE via hydrophobic interactions with Trp86 and Trp286. In comparison, it folded in the large aliphatic cavity of BChE because of the absence of peripheral site and the enlargement of the active site. Furthermore, 5h and 5i markedly prevented the AChE-induced A
aggregation with IC50 values of 16.6 and 5.8 µM, similar to that of propidium (IC50 ) 12.8 µM), which suggests promising disease-modifying agents for the treatment of AD patients. Introduction Alzheimer’s disease (AD), which is characterized by progres￾sive loss of memory and impairment in cognition,1 is becoming a serious threat to life expectancy for elderly people. The main pathological changes in the AD brain are the abnormal formation of extracellular senile plaques consisting of aggregated amyloid-
-peptide (A
) deposits and intracellular neurofibrillary tangles (NTFs) consisting of abnormally phosphorylated microtubule￾associated protein τ. 2 Current clinical therapy for AD patients is mainly palliative treatment targeting acetylcholinesterase (AChE). On the basis of the cholinergic hypothesis,3 inhibition of AChE effectively increases the available acetylcholine (ACh) within cholinergic synapses, resulting in modest improvement in cognitive symp￾toms. Mounting evidence has indicated that AChE may be involved in several noncholinergic functions.4 AChE colocalizes with A
in senile plaques, promoting the assembly of A
into fibrils5 and accelerating A
peptide deposition.6 Structural models of the interaction between AChE and A
have recently been explored.7 It has been speculated that AChE achieves its aggregation-promoting action through direct binding with A
via the specific region of the enzyme that involves a peripheral binding site.8 Inhibition of the peripheral site might prevent A
peptide deposition induced by AChE. This enzyme has a narrow 20 Å deep active site gorge, the bottom and opening regions of which are known as catalytic and peripheral sites, respectively (Figure 1). AChE inhibitors simultaneously blocking both the catalytic and peripheral sites might not only alleviate the cognitive deficit of AD patients by elevating ACh levels but also act as disease-modifying agents delaying amyloid plaque formation.9a,13 Recently, bivalent ligand strategy has been utilized in the design of dual binding site AChE inhibitors.9–13 Homobivalent or heterobivalent ligands are obtained by connecting two identical or distinct moieties through a linker of suitable length to make contact with both the catalytic and peripheral sites. A spatial 12 Å distance was determined by X-ray crystal diffraction from Trp86 (mammalian numbering), the catalytic anionic site center, to Trp286 (mammalian numbering), core of the periph￾eral site (Figure 1).14 In many cases of homobivalent ligands (bis-ligands), AChE inhibitory potency and selectivity improved relative to the monomer and additional inhibition of AChE￾induced A
aggregation was observed. Bis-tacrine 1 (Figure 2, n ) 7)9 was the first bivalent AChE inhibitor reported on this strategy, presenting a more than 1000-fold increase in AChE inhibiting potency and a 10000-fold increase in AChE/butyryl￾cholinesterase (BChE) selectivity compared with tacrine. Bis-galanthamine 2 (Figure 2, n ) 8),10 bis-5-amino-5,6,7,8- tetrahydroquinolinone 3 (Figure 2, n ) 10 or 12),11 and bis- * To whom correspondence should be addressed. For Z.Q.: phone, 86- 21-54237595; fax, 86-21-54237264; e-mail, zbqiu@shmu.edu.cn. For H.C.: phone, 86-21-63846590, extension 776450; fax, 86-21-64674721; e-mail, yaoli@shsmu.edu.cn. † Fudan University. # These authors contributed equally to this work. ‡ Shanghai JiaoTong University. § East China University of Science and Technology. Figure 1. Catalytic and peripheral sites of AChE active site gorge. J. Med. Chem. 2008, 51, 2027–2036 2027 10.1021/jm070154q CCC: $40.75  2008 American Chemical Society Published on Web 03/12/2008