Design,synthesis and biological evaluation of ambenonium derivatives as AChE inhibitors

Ambenonium (1), an old AChE inhibitor, is endowed with an outstanding affinity and a peculiar mechanism of action that, taken together, make it a very promising pharmacological tool for the treatment of Alzheimer's disease (AD). Unfortunately, the bisquaternary structure of 1 prevents its passage through the blood brain barrier. In a search of centrally active ambenonium derivatives, we planned to synthesize tertiary amines of 1, such as 2 and 3. In addition, to add new insights into the binding mechanism of the inhibitor, we designed constrained analogues of ambenonium by incorporating the diamine functions into cyclic moieties (4-12). The biological evaluation of the new compounds has been assessed in vitro against human AChE and BChE. All tertiary amine derivatives resulted more than 1000-fold less potent than 1 and, unlike prototype, did not show any selectivity between the two enzymes. This result, because of recent findings concerning the role of BChE in AD, makes our compounds, endowed with a well-balanced profile of AChE/BChE inhibition, valuable candidates for further development. To better clarify the interactions that account for the high affinity of 1, docking simulations and molecular dynamics studies on the AChE-1 complex were also carried out.     

Aminoacyl-anthraquinone conjugates as telomerase inhibitors: synthesis, biophysical and biological evaluation

The telomerase-telomere complex is a prospective anticancer target. To inhibit enzyme activity by induction of G-quadruplex in human telomeres, we have synthesized a small library of 2,6- and 2,7-amino-acyl/ peptidyl anthraquinones with diverse connecting linkers, charge, lipophilicity and bulk. The test compounds modulated G-quadruplex stability to different extents and showed clear preference for quadruplex over duplex DNA. Telomerase inhibition correlated with G-quadruplex stabilization. A SAR analysis showed that type of linkage between the linker and the anthraquinone, together with the position of the side chains and the nature of the amino acid components play a major role both in stabilizing G-quadruplex and producing telomerase inhibition. Short-term cytotoxic activity was poor. However, after prolonged exposure to effective G-quadruplex binders, cells became senescent. These results are of help in the rational design of more efficient G-quadruplex stabilizers, possibly endowed with cancer cell-selective antiproliferative effects.     

新型乙酰胆碱酯酶抑制剂5H-噻唑并[3,2-a]嘧啶类化合物的设计、合成与生物活性研究

目的 寻找作为乙酰胆碱酯酶抑制剂的具有新化学结构类型的化合物。方法 采用分子对接的虚拟筛选方法寻找新型乙酰胆碱酯酶抑制剂，设计了10个5H-噻唑并[3,2-a]嘧啶类化合物。以芳醛、硫脲等为起始原料，通过Biginelli反应生成二氢嘧啶类化合物，再与氯代苯乙酮作用经Hantzsch环合反应制得目标化合物，其结构经红外光谱、质谱、核磁共振氢谱和碳谱确证。采用Ellman方法进行体外抑制乙酰胆碱酯酶活性测试。 结果 合成了10个5H-噻唑并[3,2-a]嘧啶类化合物，体外抑制乙酰胆碱酯酶活性测试结果显示，所有目标化合物均具有乙酰胆碱酯酶抑制活性，其中3个目标化合物在10 μmol.L^-1时抑制活性均超过50%。结论5H-噻唑并[3,2-a]嘧啶类化合物是潜在的乙酰胆碱酯酶抑制剂。将计算机辅助药物分子设计、有机合成和生物活性测试相结合是发现和设计新型乙酰胆碱酯酶抑制剂的有效途径。     

Design,synthesis, and biological evaluation of new pyrazoloquinazoline derivatives as dual COX-2/5-LOX inhibitors

A new series of pyrazoloquinazoline derivatives equipped with different chalcones was designed, synthesized, and identified through ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and infrared spectroscopic techniques. Our design strategy of the quinazolinone-privileged scaffold as a new scaffold was based on merging pharmacophores previously reported to exhibit cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory activity. All the newly synthesized derivatives were biologically evaluated for COX and 5-LOX inhibitory activity and COX-2 selectivity, using celecoxib and zileuton as reference drugs, as they exhibited promising anti-inflammatory activity. Compound 3j was found to be the most promising derivative, with IC₅₀ values of 667 and 47 nM against COX-1 and COX-2, respectively, which are superior to that of celecoxib (IC₅₀ value against COX-2 = 95 nM), showing an SI of 14.2 that was much better than celecoxib. Compounds 3f and 3h exhibited COX-1 inhibition, with IC₅₀ values of 1,485 and 684 nM, respectively. The synthesized compounds showed a significant inhibitory activity against 5-LOX, with IC₅₀ values ranging from 0.6 to 4.3 µM, where compounds 3f and 3h were found to be the most potent derivatives, with IC₅₀ values of 0.6 and 1.0 µM, respectively, in comparison with that of zileuton (IC₅₀ = 0.8 µM). These promising derivatives, 3f , 3h , and 3j , were further investigated in vivo for anti-inflammatory, gastric ulcerogenic effects, and prostaglandin production (PGE2) in rat serum. The molecular docking studies concerning the binding sites of COX-2 and 5-LOX revealed similar orientation, compared with reported inhibitors, which encouraged us to design new leads targeting COX-2 and 5-LOX as dual inhibitors, as a new avenue in anti-inflammatory therapy.     

Design, synthesis and biological evaluation of new 5,5-diarylhydantoin derivatives as selective cyclooxygenase-2 inhibitors

A new group of 5,5-diarylhydantoin derivatives bearing a methylsulfonyl COX-2 pharmacophore at the para position of the C-5 phenyl ring were designed and synthesized as selective COX-2 inhibitors. In vitro COX-1/COX-2 inhibition structure-activity relationships identified 5-[4-(methylsulfonyl)phenyl]-5-phenyl-hydantoin (4) as a highly potent and selective COX-2 inhibitor (COX-2 IC(50) = 0.077 μM; selectivity index > 1298). It was more selective than the reference drug celecoxib (COX-2 IC(50) = 0.060 μM; selectivity index = 405). A molecular modeling study where 4 was docked in the binding site of COX-2 indicated that the p-MeSO(2) COX-2 pharmacophore group on the C-5 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket. The results of this study showed that the type of substituent on the N-3 hydantoin ring substituent is important for COX-2 inhibitory activity.     

Design, synthesis, and biological evaluation of 3,4-diarylmaleimides as angiogenesis inhibitors

The new analogue 2 of combretastatin A-4 was discovered to be an inhibitor of tubulin polymerization with an IC50 of 7.6 microM and reduced angiogenesis in the in vivo chick embryo model. Interestingly, in a series of 2,3-diarylmaleimides closely related to this lead, no other compound was found to be active in the tubulin polymerization assay. However, by screening in the in vivo chick embryo assay 10 was identified as a potent angiogenesis inhibitor indicating an alternative target. Indeed, molecular modeling studies suggest a reasonable binding mode of 10 at the ATP-binding site of the model kinase CDK2. Motivated by these results, analogues of 10 were screened for inhibitory activity in a panel of 12 selected protein kinases and a high affinity of 10 to VEGF-R2 was found showing an IC50 of 2.5 nM. Structure-activity relationships (SAR) for this compound series with the isolated enzyme and equivalent antiangiogenic activity in the chick embryo assay are presented herein.     

Structure-activity relationships of new A,D-ring modified steroids as aromatase inhibitors: design, synthesis, and biological activity evaluation

Inhibition of aromatase is an efficient approach for the prevention and treatment of breast cancer. New A,D-ring modified steroid analogues of formestane and testolactone were designed and synthesized and their biochemical activity was investigated in vitro in an attempt to find new aromatase inhibitors and to gain insight into their structure-activity relationships (SAR). All compounds tested were less active than formestane. However, the 3-deoxy steroidal olefin 3a and its epoxide derivative 4a proved to be strong competitive aromatase inhibitors (K(i) = 50 and 38 nM and IC50 = 225 and 145 nM, respectively). According to our findings, the C-3 carbonyl group is not essential for anti-aromatase activity, but 5alpha-stereochemistry and some planarity in the steroidal framework is required. Furthermore, modification of the steroidal cyclopentanone D-ring, by construction of a delta-lactone six-membered ring, decreases the inhibitory potency. From the results obtained, it may be concluded that the binding pocket of the active site of aromatase requires planarity in the region of the steroid A,B-rings and the D-ring structure is critical for the binding.     

Design,synthesis and biological evaluation of novel quinoline [4,3-b]chromene derivatives as AChE inhibitors through an efficient one-pot,four-component microwave-mediated reaction

An efficient synthesis of chromeno[4,3-b]quinoline derivatives via one-pot, four-component reaction of 4-hydroxycoumarin, formaldehyde, cyclohexanedione, ammonium ceric nitrate under microwave irradiation was accomplished. The structures of these compounds were unambiguously confirmed by single crystal X-ray diffraction. Furthermore, the anti-AChE activities of these compounds in vitro were investigated at concentrations of 20 μM and 50 μM by using a standard Ellman’s method. The relationship of inhibitory activities and structures of these chromeno [4,3-b]quinolines was also systematically studied. Of all the compounds investigated, 4ag emerged as the most potent AChE inhibitor with IC₅₀ values of 5.63 µM, and it might be used as potent lead for the development anti-AChE agents. Moreover, molecular modelling was conducted to understand the optimal interaction of AChE with these types of compounds.     

Phthalimide analogs as probable 15-lipoxygenase-1 inhibitors: synthesis,biological evaluation and docking studies

Background

Recent studies have been explained the role of lipoxygenases (LOX) in the origin of cancer. Among the lipoxygenases, the 5-LOX, 12-LOX and 15-LOX are more important in the cause of neoplastic disorders. In the present investigation, a new series of anticancer agents with 1,3,4-thiadiazole and phthalimide substructures were synthesized and their in vitro cytotoxicity was evaluated by MTT assay. Moreover, enzyme inhibitory potency was also assessed by enzymatic protocol towards 15-LOX-1. Molecular docking was performed to explore in silico binding mode of the target compounds.

Results

Tested compounds showed a better cytotoxic activity against HT29 cell line (colorectal cancer) in comparison with other cell lines (PC3: prostate carcinoma; SKNMC: neuroblastoma). Unfortunately, all of the tested derivatives rendered lower inhibitory potency than quercetin towards 15-LOX-1. Four hydrogen bonds were detected in docking studies for compound 4d as the most potent derivative in enzymatic assay.

Conclusions

The biological results of reported compounds in this research were not so satisfactory. But, further structural modifications are necessary to improve the bioactivity of these derivatives.     

Design,synthesis, and biological evaluation of chrysin derivatives as potential FabH inhibitors

New series of chrysin derivatives ( 4a – 4t ) were designed and synthesized by introducing different substituted piperazines at C‐7 position. Their inhibitory effects on FabH were evaluated using two Gram‐negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa, and two Gram‐positive bacterial strains, Bacillus subtilis and Staphylococcus aureus. To our delight, most of these compounds exhibited a dramatic increase in inhibitory potency, compared with the control positive drugs. Among them, compound 4s exhibited the most potent inhibitory activity with IC₅₀ values of 5.78 ± 0.24 μm inhibiting E. coli FabH and potent antibacterial activity against S. aureus and E. coli with MIC of 1.25 ± 0.01, 1.15 ± 0.12 μg/mL, respectively, comparing to the control positive drugs penicillin G (7.56 ± 0.30 μm ). Docking simulation was performed to position compound 4s into the FabH active site, and the result showed that compound 4s could bind well with the FabH as potent FabH inhibitor.     

Design, synthesis and biological evaluation of new 2-benzoxazolinone derivatives as potential cholinesterase inhibitors for therapy of alzheimer's disease

Currently acetylcholinesterase inhibitor (AChEI) therapy is one of the most frequently used methods in the treatment of Alzheimer's disease; tacrine, donepezil, rivastygmine and galantamine are applied in different stages of AD. In the present study, we propose a new series of 2-benzoxazolinone derivatives as potential cholinesterase inhibitors. These compounds were synthesized by condensation of 6-chloro acetyl-2-benzoxa zolinone with the corresponding amine and evaluated as acetylcholinesterase inhibitors using the colorimetric Ellman's method. Selectivity and the IC50 values were determined for the received derivatives. All tested compounds exhibited the inhibitory activity towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Compound 3e showed stronger activity than the standard tacrine, and compound 3a showed activity similar to that of tacrine for AChE. Compounds 3a, 3b, 3c, and 3e showed stronger activity than the standard donepezil towards the inhibition of BChE, and the compound 3e showed stronger activity than donepezil towards AChE.     

Bis-isatin derivatives: design,synthesis, and biological activity evaluation as potent dimeric DJ-1 inhibitors

The PARK7 gene (encode DJ-1 protein) was first discovered as an oncogene and later found to be a causative gene for autosomal recessive early onset Parkinson’s disease. DJ-1 has been proposed as a potential therapeutic anticancer target due to its pivotal role in tumorigenesis and cancer progression. Based on the homodimer structure of DJ-1, a series of bis-isatin derivatives with different length linkers were designed, synthesized, and evaluated as dimeric inhibitors targeting DJ-1 homodimer. Among them, DM10 with alkylene chain of C10 displayed the most potent inhibitory activity against DJ-1 deglycase. We further demonstrated that DM10 bound covalently to the homodimer of DJ-1. In human cancer cell lines H1299, MDA-MB-231, BEL7402, and 786-O, DM10 (2.5–20 μM) inhibited the cell growth in a concentration-dependent manner showing better anticancer effects compared with the positive control drug STK793590. In nude mice bearing H1299 cell xenograft, intratumor injection of DM10 (15 mg/kg) produced significantly potent tumor growth inhibition when compared with that caused by STK793590 (30 mg/kg). Moreover, we found that DM10 could significantly enhance N-(4-hydroxyphenyl)retinamide-based apoptosis and erastin-based ferroptosis in H1299 cells. In conclusion, DM10 is identified as a potent inhibitor targeting DJ-1 homodimer with the potential as sensitizing agent for other anticancer drugs, which might provide synergistical therapeutic option for cancer treatment.     

Design and synthesis of novel 1,4-benzodiazepine derivatives and their biological evaluation as cholinesterase inhibitors

A new series of 1,4-benzodiazepine-2,5-dione structurally related to cyclopenin has been synthesized. The new compounds were assayed in vivo and in vitro for their ability to inhibit acetylcholinesterase enzyme and were found to have potent reversible anticholinesterase activity when tested in vitro for isolated frog rectus abdominis and guinea pig ileum in addition to increasing brain cholinesterase level in rats when percentage inhibition were tested in vivo, moreover compounds 5a, 5b, 5c and 5g were the most active. LD(50) was performed for these derivatives and they displayed high safety margin.     

alpha-Functionalized phosphonylphosphinates: synthesis and evaluation as transcarbamoylase inhibitors.

Diverse alpha-methyl-substituted phosphonylphosphinates (P-C-P-C-X) are accessible from a protected, pentafluorophenylsulfonated phosphonylphosphinate via nucleophilic displacement. The utility of this route is demonstrated with several nitrogen nucleophiles. The resulting amine and amino acid phosphonylphosphinate derivatives were evaluated as inhibitors of Streptococcus faecalis ornithine transcarbamoylase (OTC). Compared with the structurally related phosphonoacetyl-L-ornithine (L-PALO), a known inhibitor of OTCs from various sources, the phosphonylphosphinates are surprisingly poor inhibitors, binding several orders of magnitude less tightly to the enzyme. These results suggest that the tetrahedral intermediate formed in the normal transcarbamoylase reaction is poorly mimicked by a tetrahedral and anionic phosphonate, either because of directly unfavorable interactions with a hydrogen-bond acceptor within the active site or because transition-state analogues are unable to induce the protein conformation changes that normally accompany reaction.     

Design, synthesis, and biological evaluation of novel carbohydrate-based sulfamates as carbonic anhydrase inhibitors

Carbonic anhydrases (CAs) IX and XII are enzymes with newly validated potential for the development of personalized, first-in-class cancer chemotherapies. Here we present the design and synthesis of novel carbohydrate-based CA inhibitors, several of which were very efficient inhibitors (K(i)<10 nM) with good selectivity for cancer-associated CA isozymes over off-target CA isozymes. All inhibitors comprised a carbohydrate core with one hydroxyl group derivatized as a sulfamate. Five different carbohydrates were chosen to present a selection of molecular shapes with subtle stereochemical differences to the CA enzymes active site. Variable modifications of the remaining sugar hydroxyl groups were incorporated to provide an incremental coverage of chemical property parameters that are associated with biopharmaceutical performance. All sulfamate inhibitors displayed ligand efficiencies that are consistent with those reported for good drug lead candidates.     

含吡嗪环的苯甲酰胺类HDAC抑制剂的合成及其抗肿瘤活性

目的设计合成具有抗肿瘤活性的新型苯甲酰胺类组蛋白去乙酰化酶抑制剂。方法 4-氨甲基苯甲酸酯化后与2,6-二氯吡嗪反应得到中间体,再经过Suzuki反应后与相应的取代苯硼酸偶联,在CDI的作用下与相应的苯胺反应得到目标化合物。结果与结论合成了12个未见文献报道的新化合物,其结构经MS、1H-NMR谱确证。化合物4a、4b、4d、4i和4k对人急性白血病细胞(HL60)和人乳腺癌细胞(M CF-7)的抑制活性与阳性对照物MS-275相比,活性相当或有较为显著的提高,可进行进一步研究。     

Design, synthesis, and biological evaluation of 14-substituted aromathecins as topoisomerase I inhibitors

The aromathecin or "rosettacin" class of topoisomerase I (top1) inhibitors is effectively a "composite" of the natural products camptothecin and luotonin A and the synthetic indenoisoquinolines. The aromathecins have aroused considerable interest following the isolation and total synthesis of 22-hydroxyacuminatine, a rare cytotoxic natural product containing the 12 H-5,11a-diazadibenzo[ b, h]fluoren-11-one system. We have developed two novel syntheses of this system and prepared a series of 14-substituted aromathecins as novel antiproliferative topoisomerase I poisons. These inhibitors are proposed to act via an intercalation and "poisoning" mechanism identical to camptothecin and the indenoisoquinolines. Many of these compounds possess greater antiproliferative activity and anti-top1 activity than the parent unsubstituted compound (rosettacin) and previously synthesized aromathecins, as well as greater top1 inhibitory activity than 22-hydroxyacuminatine. In addition to potentially aiding solubility and localization to the DNA-enzyme complex, nitrogenous substituents located at the 14-position of the aromathecin system have been proposed to project into the major groove of the top1-DNA complex and hydrogen-bond to major-groove amino acids, thereby stabilizing the ternary complex.