Pei Cai

Synthesis and pharmacological evaluation of novel chromone derivatives as balanced multifunctional agents against Alzheimer's disease

In a continuing effort to develop multitargeted compounds as potential treatment agents against Alzheimers disease (AD), a series of chromone derivatives were designed, synthesized and evaluated. In vitro assay indicated that most of the target compounds have both MAOs inhibition activities, antioxidant activity and biometal chelating ability. Especially, compound s19 exhibits good inhibitory potency for inhibition of MAOs (IC50 value of 5.12μM for hMAO-A and 0.816μM for hMAO-B), moderate inhibition of Aβ aggregation (75.1% at 20μM), metal chelation, control of ROS generation and antioxidant activity (ORAC=3.62). In addition, s19 could reduce PC12 cells death induced by oxidative stress and penetrate the blood-brain barrier (BBB). Taken together, these results suggested that s19 might be a promising multitargeted compound for AD treatment.

Novel 8-hydroxyquinoline derivatives targeting β-amyloid aggregation, metal chelation and oxidative stress against Alzheimer’s disease

A series of multitargeted 8-hydroxyquinoline derivatives were designed and synthesized for the treatment of Alzheimers disease (AD). In vitro studies indicated that most of the prepared compounds exhibited significant inhibitory effects against self-induced Aβ1-42 aggregation and potential antioxidant properties especially compound 5b (IC50 = 5.64 μM for self-induced Aβ aggregation; the oxygen radical absorbance capacity using fluorescein (ORAC-FL) value is 2.63 Trolox equivalents). Notably, 5b can chelate biometals and inhibit Cu2+/Zn2+-induced Aβ1-42 aggregation. The cell assays showed that 5b had excellent protective effects against oxidative toxin H2O2 and presented low neurotoxicity in PC12 cells. Furthermore, 5b could penetrate the blood-brain barrier (BBB) in vitro and did not show any acute toxicity in mice at doses up to 2000 mg/kg in vivo. Our findings provide a rationale for the potential application of compound 5b as a lead compound in AD therapy.

Rational Design and Multibiological Profiling of Novel Donepezil–Trolox Hybrids against Alzheimer’s Disease, with Cholinergic, Antioxidant, Neuroprotective, and Cognition Enhancing Properties

A novel series of donepezil-trolox hybrids were designed, synthesized, and evaluated as multifunctional ligands against Alzheimers disease (AD). Biological assays showed that these derivatives possessed moderate to good inhibitory activities against acetylcholinesterase (AChE) and monoamine oxidase B (MAO-B) as well as remarkable antioxidant effects. The optimal compound 6d exhibited balanced functions with good inhibition against hAChE (IC50 = 0.54 μM) and hMAO-B (IC50 = 4.3 μM), significant antioxidant activity (41.33 μM IC50 by DPPH method, 1.72 and 1.79 trolox equivalent by ABTS and ORAC methods), excellent copper chelation, and Aβ1-42 aggregation inhibition effect. Furthermore, cellular tests indicated that 6d has very low toxicity and is capable of combating oxidative toxin (H2O2, rotenone, and oligomycin-A) induced neurotoxicity. Most importantly, oral administration of 6d demonstrated notable improvements on cognition and spatial memory against scopolamine-induced acute memory deficit as well as d-galactose (d-gal) and AlCl3 induced chronic oxidative stress in a mouse model without acute toxicity and hepatotoxicity. In summary, both in vitro and in vivo results suggested that 6d is a valuable candidate for the development of a safe and effective anti-Alzheimers drug.

Neuroprotective effects of benzyloxy substituted small molecule monoamine oxidase B inhibitors in Parkinson's disease.

The benzyloxy substituted small molecules are well-known highly potent monoamine oxidase B inhibitors, but their therapeutic potential against Parkinsons disease have not been investigated in detail. In this paper, a series of representative benzyloxy substituted derivatives were synthesized and evaluated for MAO-A/B inhibition. In addition, their neuroprotective effects were investigated in 6-OHDA- and rotenone-treated PC12 cells. It was observed that most of the compounds exhibited a marked increase in survival of PC12 cells which treated with the neurotoxins. Among them, 13 exhibited remarkable and balanced neuroprotective potency. The protective effects of 13 against neurotoxins-induced apoptosis were confirmed with flow cytometry and staining methods. Furthermore, 13 also showed good BBB permeability and low toxicity according to in vitro BBB prediction and in vivo acute toxicity test. The results indicated that 13 is an effective and promising candidate to be further developed as disease-modifying drug for Parkinsons disease therapy.

Metal ion-improved complexation countercurrent chromatography for enantioseparation of dihydroflavone enantiomers

Cu(II) ion was selected as an additive to improve the enantioseparation efficiency of three dihydroflavone enantiomers in high-speed counter-current chromatography (HSCCC), using hydroxypropyl-β-cyclodextrin (HP-β-CyD) as the chiral selector. The influences of important parameters, including the metal ion, the concentrations of HP-β-CyD and the Cu(II) ion, and the sample size were investigated. Under optimal conditions, three dihydroflavone enantiomers, including (±)-hesperetin, (±)-naringenin, and (±)-farrerol, were successfully enantioseparated. The chiral recognition mechanism was investigated. The enantioseparation was attributed to the different thermodynamic stabilities of the binary complexes of HP-β-CyD and (±)-hesperetin, and Cu(II) ion could enhance this difference by forming ternary complexes with the binary complexes. This Cu(II) ion-improved complexation HSCCC system exhibited improved performance for chiral separation, and therefore it has great application potential in the preparative enantioseparation of other compounds with similar skeletons.

Design, synthesis, and evaluation of salicyladimine derivatives as multitarget-directed ligands against Alzheimer’s disease

A series of salicyladimine derivatives were designed, synthesized and evaluated as multi-target-directed ligands for the treatment of Alzheimers disease (AD). Biological activity results demonstrated that some derivatives possessed significant inhibitory activities against amyloid-β (Aβ) aggregation and human monoamine oxidase B (hMAO-B) as well as remarkable antioxidant effects and low cell toxicity. The optimal compound, 5, exhibited excellent potency for inhibition of self-induced Aβ1-42 aggregation (91.3±2.1%, 25μM), inhibition of hMAO-B (IC50, 1.73±0.39μM), antioxidant effects (43.4±2.6μM of IC50 by DPPH method, 0.67±0.06 trolox equivalent by ABTS method), metal chelation and BBB penetration. Furthermore, compound 5 had neuroprotective effects against ROS generation, H2O2-induced apoptosis, 6-OHDA-induced cell injury, and a significant in vitro anti-inflammatory activity. Collectively, these findings highlighted that compound 5 was a potential balanced multifunctional neuroprotective agent for the development of anti-AD drugs.

Donepezil-butylated hydroxytoluene (BHT) hybrids as Anti-Alzheimer's disease agents with cholinergic, antioxidant, and neuroprotective properties

The multifactorial nature of Alzheimers disease (AD) calls for the development of multitarget agents addressing key pathogenic processes. A novel family of donepezil-butylated hydroxytoluene (BHT) hybrids were designed, synthesized and evaluated as multifunctional ligands against AD. The optimal compound 7d displayed a balanced multifunctional profile covering an intriguing acetylcholinesterase (AChE) inhibition (IC50, 0.075 μM for eeAChE and 0.75 μM for hAChE) and Monoamine oxidase B (MAO-B) inhibition (IC50, 7.4 μM for hMAO-B), excellent antioxidant activity (71.7 μM of IC50 by DPPH method, 0.82 and 1.62 trolox equivalent by ABTS method and ORAC method respectively), and inhibitory effects on self-induced, hAChE-induced Aβ aggregation. Moreover, 7d possessed neuroprotective potency against H2O2-induced oxidative damage on PC12 cells and Lipopolysaccharides (LPS)-stimulated inflammation on BV2 cells. Compound 7d was capable of penetrating BBB and presented good liver microsomal metabolic stability. Importantly, compound 7d could dose-dependently reverse scopolamine-induced memory deficit in mice without acute toxicity. Taken together, those outstanding results highlight the donepezil-BHT hybrid 7d as a promising prototype in the research of innovative compound for AD.