USP28 Serves as a Key Suppressor of Mitochondrial Morphofunctional Defects and Cardiac Dysfunction in the Diabetic Heart.

BACKGROUND: The majority of people with diabetes are susceptible to cardiac dysfunction and heart failure, and conventional drug therapy cannot correct diabetic cardiomyopathy progression. Herein, we assessed the potential role and therapeutic value of USP28 (ubiquitin-specific protease 28) on the metabolic vulnerability of diabetic cardiomyopathy. METHODS: The type 2 diabetes mouse model was established using db/db leptin receptor-deficient mice and high-fat diet/streptozotocin-induced mice. Cardiac-specific knockout of USP28 in the db/db background mice was generated by crossbreeding db/m and Myh6-Cre+/USP28fl/fl mice. Recombinant adeno-associated virus serotype 9 carrying USP28 under cardiac troponin T promoter was injected into db/db mice. High glucose plus palmitic acid-incubated neonatal rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes were used to imitate diabetic cardiomyopathy in vitro. The molecular mechanism was explored through RNA sequencing, immunoprecipitation and mass spectrometry analysis, protein pull-down, chromatin immunoprecipitation sequencing, and chromatin immunoprecipitation assay. RESULTS: Microarray profiling of the UPS (ubiquitin-proteasome system) on the basis of db/db mouse hearts and diabetic patients' hearts demonstrated that the diabetic ventricle presented a significant reduction in USP28 expression. Diabetic Myh6-Cre+/USP28fl/fl mice exhibited more severe progressive cardiac dysfunction, lipid accumulation, and mitochondrial disarrangement, compared with their controls. On the other hand, USP28 overexpression improved systolic and diastolic dysfunction and ameliorated cardiac hypertrophy and fibrosis in the diabetic heart. Adeno-associated virus serotype 9-USP28 diabetic mice also exhibited less lipid storage, reduced reactive oxygen species formation, and mitochondrial impairment in heart tissues than adeno-associated virus serotype 9-null diabetic mice. As a result, USP28 overexpression attenuated cardiac remodeling and dysfunction, lipid accumulation, and mitochondrial impairment in high-fat diet/streptozotocin-induced type 2 diabetes mice. These results were also confirmed in neonatal rat ventricular myocytes and human induced pluripotent stem cell-derived cardiomyocytes. RNA sequencing, immunoprecipitation and mass spectrometry analysis, chromatin immunoprecipitation assays, chromatin immunoprecipitation sequencing, and protein pull-down assay mechanistically revealed that USP28 directly interacted with PPARα (peroxisome proliferator-activated receptor α), deubiquitinating and stabilizing PPARα (Lys152) to promote Mfn2 (mitofusin 2) transcription, thereby impeding mitochondrial morphofunctional defects. However, such cardioprotective benefits of USP28 were largely abrogated in db/db mice with PPARα deletion and conditional loss-of-function of Mfn2. CONCLUSIONS: Our findings provide a USP28-modulated mitochondria homeostasis mechanism that involves the PPARα-Mfn2 axis in diabetic hearts, suggesting that USP28 activation or adeno-associated virus therapy targeting USP28 represents a potential therapeutic strategy for diabetic cardiomyopathy.

Heterobifunctional Cross-Linker with Dinitroimidazole and N-Hydroxysuccinimide Ester Motifs for Protein Functionalization and Cysteine-Lysine Peptide Stapling.

A heterobifunctional cross-linker with one sulfhydryl-reactive dinitroimidazole end and another amine-reactive N-hydroxysuccinimide (NHS) ester end was designed and synthesized. The two motifs of this cross-linker, dinitroimidazole and NHS ester, proved to react with thiol and amine, respectively, in an orthogonal way. The cross-linker was further applied to construct stapled peptides of different sizes and mono- and dual functionalization (including biotinylation, PEGylation, and fluorescence labeling) of protein.

A multi-target directed ligands strategy for the treatment of Alzheimer's disease: Dimethyl fumarate plus Tranilast modified Dithiocarbate as AChE inhibitor and Nrf2 activator.

Alzheimer's disease (AD) possessed intricate pathogenesis. Currently, multi-targeted drugs were considered to have the potential to against AD by simultaneously triggering molecules in functionally complementary pathways. Hence, a series of molecules based on the pharmacophoric features of Dimethyl fumarate, Tranilast, and Dithiocarbate were designed and synthesized. These compounds showed significant AChE inhibitory activity in vitro. Among them, compound 4c2 displayed the mighty inhibitory activity to hAChE (IC50 = 0.053 µM) and held the ability to cross the BBB. Kinetic study and molecular docking pointed out that 4c2 bound well into the active sites of hAChE, forming steady and sturdy interactions with key residues in hAChE. Additionally, 4c2 as an Nrf2 activator could promote the nuclear translocation of Nrf2 protein and induce the expressions of Nrf2-dependent enzymes HO-1, NQO1, and GPX4. Moreover, 4c2 rescued BV-2 cells from H2O2-induced injury and inhibited ROS accumulation. For the anti-neuroinflammatory potential of 4c2, we observed that 4c2 could lower the levels of pro-inflammatory cytokines (NO, IL-6 and TNF-α) and suppressed the expressions of iNOS and COX-2. In particular, 4c2 was well tolerated in mice (2500 mg/kg, p.o.) and efficaciously recovered the memory impairment in a Scopolamine-induced mouse model. Overall, these results highlighted that 4c2 was a promising multi-targeted agent for treating AD.

Design, Synthesis and Anti-Tumor Activity Evaluation of Novel 3,4-(Methylenedioxy)cinnamic Acid Amide-Dithiocarbamate Derivatives.

The fragments, 3,4-(methylenedioxy)cinnamic acid amide and dithiocarbamates, have received increasing attention because of their multiple pharmacological activities in recent years, especially in anti-tumor. We synthesized 17 novel 3,4-(methylenedioxy)cinnamic acid amide-dithiocarbamate derivatives based on the principle of pharmacophore assembly and discovered that compound 4a7 displayed the most potent antiproliferative activity against HeLa cells with IC50 value of 1.01 µM. Further mechanistic studies revealed that 4a7 triggered apoptosis in HeLa cells via activating mitochondria-mediated intrinsic pathways and effectively inhibited colony formation. Also, 4a7 had the ability to arrest cell cycle in the G2/M phase as well as to inhibit the migration in HeLa cells. More importantly, acute toxicity experiments showed that 4a7 had good safety in vivo. All the results suggested that compound 4a7 might serve as a promising lead compound that merited further attention in future anti-tumor drug discovery.

[Leves and health risk assessment of 10 kinds of metal/metalloid elements in drinking water in Dongcheng District of Beijing from 2018 to 2020].

OBJECTIVE: To analyze the level of metal/metalloid elements and assess the health risk in drinking water in Dongcheng District of Beijing. METHODS: From 2018 to 2020, 10 kinds of metal/metalloid elements(Fe, Mn, Cu, Zn, Al, Pb, Cd, Ni, As and Se)in drinking water were detected by inductively coupled plasma-mass spectrometry(ICP-MS). The concentration of these metals were compared with the hygiene standards of drinking water. The health risk assessment model was applied from the USEPA. RESULTS: The concentration of 10 kinds of elements met the hygiene standards in all of the drinking water samples except that the zinc concentration of one sample exceeded the limit. The concentration of Al, Fe and Zn in drinking water was tens of µg/L. The concentration of Cu, Mn, Ni and Se was 1-2 µg/L or even lower. The concentration of As, Cd and Pb was basically less than 1 µg/L. The monthly average concentration of Al in drinking water showed a trend of increasing, and then decreasing in a year. The concentration of Zn decreased year by year. The 10 kinds of elements had not shown significant difference in the two water supply modes of municipal pipe network terminal water and secondary water(P>0.05). The total carcinogenic risk of elements through drinking exposure was 3.53×10~(-5). The carcinogenic risk of As was higher than that of Cd. The total non-carcinogenic risk was 9.75×10~(-8). The order of non-carcinogenic risk was: As>Se>Ni>Zn>Al>Pb>Fe>Cu>Mn>Cd. The total health risk was 3.54×10~(-5). CONCLUSION: The 10 kinds of metal/metalloid parameters of drinking water in Dongcheng District of Beijing met the hygiene standards. According to USEPA evaluation standard, the health risk assessment of elements in drinking water was acceptable.

Design and synthesis of novel 3,4-dihydrocoumarins as potent and selective monoamine oxidase-B inhibitors with the neuroprotection against Parkinson's disease.

The monoamine oxidase-B (MAO-B) inhibitors with neuroprotective effects are better for Parkinson's disease (PD) treatment, due to the complicated pathogenesis of PD. To develop new hMAO-B inhibitors with neuroprotection, a novel series of 3,4-dihydrocoumarins was designed as selective and reversible hMAO-B inhibitors to treat PD. Most compounds showed potent and selective inhibition for hMAO-B over hMAO-A with IC50 values ranging from nanomolar to sub-nanomolar. Among them, compound 4d was the most potent hMAO-B inhibitor (IC50 = 0.37 nM) being about 20783-fold more active than iproniazid, and exhibited the highest selectivity for hMAO-B (SI > 270,270). Kinetic studies revealed that compound 4d was a reversible and competitive inhibitor of hMAO-B. Neuroprotective studies indicated that compound 4d could protect PC12 cells from the damage induced by 6-OHDA and rotenone. Besides, compound 4d did not exhibit acute toxicity at a dose up to 2500 mg/kg (po), and could cross the BBB in parallel artificial membrane permeability assay. More importantly, compound 4d was able to significantly prevent the motor deficits in the MPTP-induced PD model. These results indicate that compound 4d is an effective and promising candidate against PD.

Design, synthesis and biological evaluation of coumarin-based N-hydroxycinnamamide derivatives as novel histone deacetylase inhibitors with anticancer activities.

A series of novel coumarin-based N-hydroxycinnamamide derivatives were designed and synthesized as histone deacetylase (HDAC) inhibitors. Most of the synthesized compounds showed potent HDAC inhibitory activity and significant antiproliferative activity against human cancer cell lines MCF-7, HepG2, HeLa and HCT-116. Among them, compound 14f displayed the most potent HDAC inhibition, especially against HDAC1 with IC50 value of 0.19 µM, which was better than that of SAHA (IC50 = 0.23 µM). It also showed the strongest antiproliferative activity towards HeLa cells and more than 26-fold selectivity for HDAC1 compared with HDAC6. Molecular docking studies revealed the possible binding modes of compound 14f into the two isoforms and provided a reasonable explanation for the selectivity. In addition, compound 14f could inhibit colony formation, upregulate the acetylation level of histone H3, and induce apoptosis and cell cycle arrest at G2/M phase in HeLa cells. Taken together, these results highlighted that compound 14f might be a promising HDAC inhibitor for cancer therapy.

Design, synthesis and biological evaluation of rasagiline-clorgyline hybrids as novel dual inhibitors of monoamine oxidase-B and amyloid-ß aggregation against Alzheimer's disease.

A series of rasagiline-clorgyline hybrids was designed, synthesized and investigated in vitro for their inhibition of monoamine oxidase and amyloid-ß aggregation. Most of compounds were found to be selective and highly potent hMAO-B inhibitors showing IC50 values in the nanomolar, and exhibited a moderate inhibition of amyloid-ß aggregation. 7-((5-(methyl(prop-2-yn-1-yl)amino) pentyl)oxy)chroman-4-one (6j) was the most interesting compound identified in this research, endowed with higher hMAO-B potency (IC50 = 4 nM) and selectivity (SI > 25000) compared to the reference selective inhibitor rasagiline (IC50 = 141 nM, SI > 355), and exhibited good inhibitory activity against Aß1-42 aggregation (40.78%, 25 µM). Kinetic and molecular modeling studies revealed that 6j was a competitive reversible inhibitor for hMAO-B. Moreover, compound 6j displayed low toxicity and good neuroprotective effects in SH-SY5Y cell assay, and could penetrate the blood-brain barrier according to the parallel artificial membrane permeability assay. Pharmacokinetics assay revealed that compound 6j possessed good pharmacokinetic profiles after intravenous and oral administrations. Overall, these results highlighted that compound 6j was an effective and promising multitarget agent against Alzheimer's disease.

Design, synthesis and evaluation of quinolinone derivatives containing dithiocarbamate moiety as multifunctional AChE inhibitors for the treatment of Alzheimer's disease.

A series of novel quinolinone derivatives bearing dithiocarbamate moiety were designed and synthesised as multifunctional AChE inhibitors for the treatment of AD. Most of these compounds exhibited strong and clearly selective inhibition to eeAChE. Among them, compound 4c was identified as the most potent inhibitor to both eeAChE and hAChE (IC50 = 0.22 µM for eeAChE; IC50 = 0.16 µM for hAChE), and it was also the best inhibitor to AChE-induced Aß aggregation (29.02% at 100 µM) and an efficient inhibitor to self-induced Aß aggregation (30.67% at 25 µM). Kinetic and molecular modelling studies indicated that compound 4c was a mixed-type inhibitor, which could interact simultaneously with the catalytic anionic site (CAS) and the peripheral anionic site (PAS) of AChE. In addition, 4c had good ability to cross the BBB, showed no toxicity on SH-SY5Y neuroblastoma cells and was well tolerated in mice at doses up to 2500 mg/kg (po).

Zingerone attenuates aortic banding-induced cardiac remodelling via activating the eNOS/Nrf2 pathway.

Cardiac remodelling refers to a series of changes in the size, shape, wall thickness and tissue structure of the ventricle because of myocardial injury or increased pressure load. Studies have shown that cardiac remodelling plays a significant role in the development of heart failure. Zingerone, a monomer component extracted from ginger, has been proven to possess various properties including antioxidant, anti-inflammatory, anticancer and antidiabetic properties. As oxidative stress and inflammation contribute to acute and chronic myocardial injury, we explored the role of zingerone in cardiac remodelling. Mice were subjected to aortic banding (AB) or sham surgery and then received intragastric administration of zingerone or saline for 25 days. In vitro, neonatal rat cardiomyocytes (NRCMs) were treated with zingerone (50 and 250 µmol/L) when challenged with phenylephrine (PE). We observed that zingerone effectively suppressed cardiac hypertrophy, fibrosis, oxidative stress and inflammation. Mechanistically, Zingerone enhanced the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/antioxidant response element (ARE) activation via increasing the phosphorylation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) production. Additionally, we used Nrf2-knockout (KO) and eNOS-KO mice and found that Nrf2 or eNOS deficiency counteracts these cardioprotective effects of zingerone in vivo. Together, we concluded that zingerone may be a potent treatment for cardiac remodelling that suppresses oxidative stress via the eNOS/Nrf2 pathway.

Novel chromanone-dithiocarbamate hybrids as multifunctional AChE inhibitors with ß-amyloid anti-aggregation properties for the treatment of Alzheimer's disease.

By connecting chromanone with dithiocarbamate moieties through flexible linkers, a series of hybrids as novel multifunctional AChE inhibitors have been designed and synthesized. Most of these compounds displayed strong and excellently selective inhibition to eeAChE as well as potent inhibition to self- and AChE-induced Aß aggregation. Among them, compound 6c showed the best activity to inhibit eeAChE (IC50 = 0.10 µM) and AChE-induced Aß aggregation (33.02% at 100 µM), and could effectively inhibit self-induced Aß aggregation (38.25% at 25 µM). Kinetic analysis and docking study indicated that compound 6c could target both the CAS and PAS, suggesting that it was a dual binding site inhibitor for AChE. Besides, it exhibited good ability to penetrate the BBB and low neurotoxicity in SH-SY5Y cells. More importantly, compound 6c was well tolerated in mice (2500 mg/kg, po) and could attenuate the memory impairment in a scopolamine-induced mouse model. Overall, these results highlight 6c as a promising multifunctional agent for treating AD and also demonstrate that the dithiocarbamate is a valid scaffold for design of multifunctional AChE inhibitors.

A near-infrared Nile red fluorescent probe for the discrimination of biothiols by dual-channel response and its bioimaging applications in living cells and animals.

Biothiols, including cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and H2S, play important roles in human physiological processes. However, it is a great difficulty to distinguish biothiols from each other because of their similar chemical properties. Based on Nile red, we have designed and synthesized a near-infrared fluorescent probe for discriminating Cys/Hcy from GSH/H2S by a dual-channel detection method. Using an ether bond, near-infrared Nile red was attached to 7-nitrobenzofurazan to construct the probe. Due to the photo-induced electron transfer, the probe showed almost no fluorescence from the green to red emission band. But upon the addition of Cys (0-150 µM) or Hcy (0-200 µM), the probe exhibited a noteworthy fluorescence "turn-on" signal in two unique emission bands (Green and Red) with a fast response (within 30 min). In contrast, the probe displayed an increase in fluorescence only in the red channel when encountering GSH (0-70 µM) or H2S (0-50 µM), and GSH/H2S could be tested respectively by different response time. The limit of detection was calculated to be 0.09 µM (Cys), 0.30 µM (Hcy), 0.24 µM (GSH), and 0.04 µM (H2S), respectively (based on S/N = 3). The desirable dual-channel detection could be achieved in serum samples and living cells. Moreover, the probe could be applied for bioimaging in mice, which indicated its potential application in the clinic.

Coumarin-dithiocarbamate hybrids as novel multitarget AChE and MAO-B inhibitors against Alzheimer's disease: Design, synthesis and biological evaluation.

A series of new coumarin-dithiocarbamate hybrids were designed and synthesized as multitarget agents for the treatment of Alzheimer's disease. Most of them showed potent and clearly selective inhibition towards AChE and MAO-B. Among these compounds, compound 8f demonstrated the most potent inhibition to AChE with IC50 values of 0.0068 µM and 0.0089 µM for eeAChE and hAChE, respectively. Compound 8g was identified as the most potent inhibitor to hMAO-B, and it is also a good and balanced inhibitor to both hAChE and hMAO-B (0.114 µM for hAChE; 0.101 µM for hMAO-B). Kinetic and molecular modeling studies revealed that 8g was a dual binding site inhibitor for AChE and a competitive inhibitor for MAO-B. Further studies indicated that 8g could penetrate the BBB and exhibit no toxicity on SH-SY5Y neuroblastoma cells. More importantly, 8g did not display any acute toxicity in mice at doses up to 2500 mg/kg and could reverse the cognitive dysfunction of scopolamine-induced AD mice. Overall, these results highlighted 8g as a potential multitarget agent for AD treatment and offered a starting point for design of new multitarget AChE/MAO-B inhibitors based on dithiocarbamate scaffold.

Design, synthesis and biological evaluation of new coumarin-dithiocarbamate hybrids as multifunctional agents for the treatment of Alzheimer's disease.

A series of new coumarin-dithiocarbamate hybrids were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer's Disease (AD). The biological assays indicated that most of them showed potent inhibition and excellent selectivity towards acetylcholinesterase (AChE), and could inhibit self-induced ß-amyloid (Aß) aggregation. Especially, compound 4n presented the highest ability to inhibit AChE (IC50, 0.027 µM for hAChE) and good inhibition of Aß aggregation (40.19% at 25 µM). Kinetic and molecular modeling studies revealed that 4n was a mixed-type inhibitor, which could interact simultaneously with the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE. In addition, it also possessed specific metal-chelating ability, good BBB permeability and low toxicity on SH-SY5Y neuroblastoma cells. Moreover, compound 4n did not exhibit any acute toxicity in mice at doses up to 1000 mg/kg, and could reverse the cognitive dysfunction of scopolamine-induced AD mice. As far as we know, 4n was the first reported dithiocarbamate derivative with multifunctional activity. Its excellent profiles in vitro and effectivity in vivo highlight this structurally distinct compound as a potential lead compound in the research of innovative multifunctional drugs for AD.

Design, synthesis and biological evaluation of novel coumarin-N-benzyl pyridinium hybrids as multi-target agents for the treatment of Alzheimer's disease.

Combining N-benzyl pyridinium moiety and coumarin into in a single molecule, novel hybrids with ChE and MAO-B inhibitory activities were designed and synthesized. The biological screening results indicated that most of compounds displayed potent inhibitory activity for ChE and Aß (1-42) self-aggregation, and clearly selective inhibition to MAO-B over MAO-A. Of these compounds, compound 7f was the most potent inhibitor for hMAO-B, and it was also a good and balanced inhibitor to ChEs and hMAO-B (0.0373 µM for eeAChE; 2.32 µM for eqBuChE; 1.57 µM for hMAO-B). Molecular modeling and kinetic studies revealed that compound 7f was a mixed-type inhibitor, which bond simultaneously to CAS and PAS of AChE, and it was also a competitive inhibitor, which occupied the active site of MAO-B. In addition, compound 7f with no toxicity on PC12 neuroblastoma cells, showed good ability to inhibit Aß (1-42) self-aggregation and cross the BBB. Collectively, all these results suggested that compound 7f might be a promising multi-target lead candidate worthy of further pursuit.

Design, synthesis and biological activity of novel donepezil derivatives bearing N-benzyl pyridinium moiety as potent and dual binding site acetylcholinesterase inhibitors.

A series of new donepezil derivatives were designed synthesized and evaluated as multifunctional cholinesterase inhibitors against Alzheimer's disease (AD). In vitro studies showed that most of them exhibited significant potency to inhibit acetylcholinesterase and self-induced ß-amyloid (Aß) aggregation, and moderate antioxidant activity. Especially, compound 5b presented the greatest ability to inhibit cholinesterase (IC50, 1.9 nM for eeAChE and 0.8 nM for hAChE), good inhibition of Aß aggregation (53.7% at 20 µM) and good antioxidant activity (0.54 trolox equivalents). Kinetic and molecular modeling studies indicated that compound 5b was a mixed-type inhibitor, binding simultaneously to the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. In addition, compound 5b could reduce PC12 cells death induced by oxidative stress and Aß (1-42). Moreover, in vivo experiments showed that compound 5b was nontoxic and tolerated at doses up to 2000 mg/kg. These results suggested that compound 5b might be an excellent multifunctional agent for AD treatment.

Synthesis and pharmacological evaluation of donepezil-based agents as new cholinesterase/monoamine oxidase inhibitors for the potential application against Alzheimer's disease.

In a continuing effort to develop multitargeted compounds as potential treatment agents against Alzheimer's disease (AD), a series of donepezil-like compounds were designed, synthesized and evaluated. In vitro studies showed that most of the designed compounds displayed potent inhibitory activities toward AChE, BuChE, MAO-B and MAO-A. Among them, w18 was a promising agent with balanced activities, which exhibited a moderate cholinesterase inhibition (IC50, 0.220 µM for eeAChE; 1.23 µM for eqBuChE; 0.454 µM for hAChE) and an acceptable inhibitory activity against monoamine oxidases (IC50, 3.14 µM for MAO-B; 13.4 µM for MAO-A). Moreover, w18 could also be a metal-chelator, and able to cross the blood-brain barrier with low cell toxicity on PC12 cells. Taken together, these results suggested that w18 might be a promising multitargeted compound for AD treatment.

Design, synthesis and biological evaluation of novel donepezil-coumarin hybrids as multi-target agents for the treatment of Alzheimer's disease.

Combining N-benzylpiperidine moiety of donepezil and coumarin into in a single molecule, novel hybrids with ChE and MAO-B inhibitory activity were designed and synthesized. The biological screening results indicated that most of compounds displayed potent inhibitory activity for AChE and BuChE, and clearly selective inhibition to MAO-B. Of these compounds, 5m was the most potent inhibitor for eeAChE and eqBuChE (0.87 µM and 0.93 µM, respectively), and it was also a good and balanced inhibitor to hChEs and hMAO-B (1.37 µM for hAChE; 1.98 µM for hBuChE; 2.62 µM for hMAO-B). Molecular modeling and kinetic studies revealed that 5m was a mixed-type inhibitor, which bond simultaneously to CAS, PAS and mid-gorge site of AChE, and it was also a competitive inhibitor, which occupied the active site of MAO-B. In addition, 5m showed good ability to cross the BBB and had no toxicity on SH-SY5Y neuroblastoma cells. Collectively, all these results suggested that 5m might be a promising multi-target lead candidate worthy of further pursuit.

Multi-target tacrine-coumarin hybrids: cholinesterase and monoamine oxidase B inhibition properties against Alzheimer's disease.

A series of novel tacrine-coumarin hybrids were designed, synthesized and evaluated as multi-target agents against Alzheimer's disease. The biological assays indicated that most of compounds displayed potent inhibitory activity toward AChE and BuChE, and clearly selective inhibition for MAO-B. Among these compounds, 14c exhibited strong inhibitory activity for AChE (IC50 values of 33.63 nM for eeAChE and 16.11 nM for hAChE) and BuChE (IC50 values of 80.72 nM for eqBuChE and 112.72 nM for hBuChE), and the highest inhibitory activity against hMAO-B (IC50 value of 0.24 µM). Kinetic and molecular modeling studies revealed that 14c was a mixed-type inhibitor, binding simultaneously to catalytic, peripheral and mid-gorge sites of AChE. It was also a competitive inhibitor, which covered the substrate and entrance cavities of MAO-B. Moreover, 14c could penetrate the CNS and show low cell toxicity. Overall, these results suggested that 14c might be an excellent multi-target agent for AD treatment.

Multifunctional tacrine-trolox hybrids for the treatment of Alzheimer's disease with cholinergic, antioxidant, neuroprotective and hepatoprotective properties.

Combining tacrine with trolox in a single molecule, novel multifunctional hybrids have been designed and synthesized. All these hybrids showed ChE inhibitory activity in nanomolar range and strong antioxidant activity close to the parent compound trolox. Among them, compound 6d was the most potent inhibitor against AChE (IC50 value of 9.8 nM for eeAChE and 23.5 nM for hAChE), and it was also a strong inhibitor to BuChE (IC50 value of 22.2 nM for eqBuChE and 20.5 nM for hBuChE). Molecular modeling and kinetic studies suggested that 6d was a mixed-type inhibitor, binding simultaneously to CAS and PAS of AChE. In vivo hepatotoxicity assays indicated that 6d was much less toxic than tacrine. In addition, it showed neuroprotective effect and good ability to penetrate the BBB. Overall, all these results highlighted 6d a promising multifunctional agent for AD treatment.