Microwave assisted synthesis of novel hybrid tacrine-sulfonamide derivatives and investigation of their antioxidant and anticholinesterase activities

A novel series of tacrine derivatives containing sulfonamide group were synthesized and their inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) were evaluated. The result showed that all the synthesized tacrine-sulfonamides (VIIIa–o) exhibited inhibitory activity on both cholinesterases. VIIIg showed the highest inhibitory activity on AChE IC₅₀ = 0.009 μM. This value is 220-fold greater than that of galantamine (IC₅₀ = 2.054 μM) and 6-fold greater than tacrine (IC₅₀ = 0.055 μM). VIIIf displayed the strongest inhibition of BuChE (IC₅₀ = 2.250 μM), which is close to donepezil (IC₅₀ = 2.680 μM) and 8-fold greater than that of galantamine (IC₅₀ = 18.130 μM) Furthermore, all of the synthesized tacrine derivatives showed higher inhibition of BuChE than that of galantamine. In addition, the cupric reducing antioxidant capacities (CUPRAC) and ABTS cation radical scavenging abilities of the synthesized compounds were investigated for the antioxidant activity. Among them, VIIIb (IC₅₀ = 94.390 ± 2.310 μM) showed significantly better ABTS cation radical scavenging ability than all of the new synthesized compounds.     

Nitric oxide inhibitory principles from Derris trifoliata stems

Nine rotenoids were isolated from the hexane and dichloromethane extracts of Derris trifoliata stems and were tested for nitric oxide (NO) inhibitory activity using RAW264.7 cells. The result indicated that 12a-hydroxyrotenone (7) possessed very potent NO inhibitory activity with an IC₅₀ value of 0.002 μM, followed by 1 (deguelin, IC₅₀=0.008 μM), 9 (12a-hydroxyelliptone, IC₅₀=0.010 μM) and 2 (α-toxicarol, IC₅₀=0.013 μM), respectively. In addition, the DPPH scavenging activity of rotenoids was also investigated. It was found that 6a,12a-dehydrodeguelin (5) possessed the highest activity against DPPH with an IC₅₀ value of 7.4 μM, followed by deguelin (1, IC₅₀=27.4 μM). All compounds did not show any cytotoxicity at their IC₅₀ values for NO inhibitory activity.Structure–activity relationships (SARs) of these rotenoids against NO release are as follows: (1) hydroxylation at C12a dramatically increased activity, (2) prenylation at furan ring increased activity markedly and (3) hydrogenation of a double bond at C6a–C12a conferred higher activity. For the DPPH radical scavenging effect, it was found that (1) introduction of a double bond at C6a–C12a increased activity and (2) hydroxylation of C11 at the D-ring decreased activity. As regards active compounds of Derris trifoliata stems, the isolated compounds are responsible for the NO inhibitory effect, especially 7, 1, 9 and 2, whereas 5 and 1 are those for the DPPH scavenging activity.     

Synthesis,in vitro ADME profiling and in vivo pharmacological evaluation of novel glycogen phosphorylase inhibitors

A small set of indole-2-carboxamide derivatives identified from a high-throughput screening campaign has been described as a novel, potent, and glucose-sensitive inhibitors of glycogen phosphorylase a (GPa). Among this series of compounds, compound 2 exhibited moderate GP inhibitory activity (IC₅₀ = 0.29 μM), good cellular efficacy (IC₅₀ = 3.24 μM for HepG2 cells and IC₅₀ = 7.15 μM for isolated rat hepatocytes), together with good absorption, distribution, metabolism, and elimination (ADME) profiles. The in vivo animal study revealed that compound 2 significantly inhibited an increase of fasting blood glucose level in adrenaline-induced diabetic mice.     

Novel pyrazoline derivatives as bi-inhibitor of COX-2 and B-Raf in treating cervical carcinoma

Twenty four pyrazoline derivatives modified from Celecoxib were designed and synthesized as bi-inhibitor of COX-2 and B-Raf. They were evaluated for their COX-1/COX-2/B-Raf inhibitory and anti-proliferation activities. Compound A3 displayed the most potent activity against COX-2 and HeLa cell line (IC₅₀ = 0.008 μM; GI₅₀ = 19.86 μM) and showed superb COX-1/COX-2 selectivity (>500), being more potent and selective than positive control Celecoxib or 5-fluorouracil. Compounds A5 and B5 were introduced best B-Raf inhibitory activities (IC₅₀ = 0.15 μM and 0.12 μM, respectively). Compound A4 retained superb bioactivity against COX-2 and HeLa cell line (IC₅₀ = 0.015 μM; GI₅₀ = 23.82 μM) and displayed moderate B-Raf inhibitory activity (IC₅₀ = 3.84 μM). Docking simulation was conducted to give binding patterns. QSAR models were built using bioactivity data and optimized conformations to provide a future modification of COX-2/B-Raf inhibitors.     

Synthesis and α-glucosidase inhibitory activity evaluation of N-substituted aminomethyl-β-d-glucopyranosides

A series of N-substituted 1-aminomethyl-β-d-glucopyranoside derivatives was prepared. These novel synthetic compounds were assessed in vitro for inhibitory activity against yeast α-glucosidase and both rat intestinal α-glucosidases maltase and sucrase. Most of the compounds displayed α-glucosidase inhibitory activity, with IC₅₀ values covering the wide range from 2.3 μM to 2.0 mM. Compounds 19a (IC₅₀ = 2.3 μM) and 19b (IC₅₀ = 5.6 μM) were identified as the most potent inhibitors for yeast α-glucosidase, while compounds 16 (IC₅₀ = 7.7 and 15.6 μM) and 19e (IC₅₀ = 5.1 and 10.4 μM) were the strongest inhibitors of rat intestinal maltase and sucrase. Analysis of the kinetics of enzyme inhibition indicated that 19e inhibited maltase and sucrase in a competitive manner. The results suggest that the aminomethyl-β-d-glucopyranoside moiety can mimic the substrates of α-glucosidase in the enzyme catalytic site, leading to competitive enzyme inhibition. Moreover, the nature of the N-substituent has considerable influence on inhibitory potency.     

Synthesis and pharmacological evaluation of trifluoromethyl containing 4-(2-pyrimidinylamino)benzamides as Hedgehog signaling pathway inhibitors

In present study, a series of novel containing trifluoromethyl 4-(2-pyrimidinylamino)benzamide derivatives were designed by the fluorine scan strategy. Their Hh signaling inhibitory activities were evaluated by Gli-luciferase reporter method. The comprehensive SAR was discussed and several derivatives were found to display more potent Hh signaling inhibitory activity than positive drug vismodegib. Compound 13d was the most potent compound with IC₅₀ of 1.44 nM against Hh signaling pathway and also exhibited optimal PK properties in the in vivo PK properties study, deserved as an ideal lead compound for further study in future.     

Synthesis and SAR study of 4,5-diaryl-1H-imidazole-2(3H)-thione derivatives,as potent 15-lipoxygenase inhibitors

A series of 4,5-diaryl-1H-imidazole-2(3H)-thione was synthesized and their inhibitory potency against soybean 15-lipoxygenase and free radical scavenging activities were determined. Compound 11 showed the best IC₅₀ for 15-LOX inhibition (IC₅₀ = 4.7 μM) and free radical scavenging activity (IC₅₀ = 14 μM). Methylation of SH at C₂ position of imidazole has dramatically decreased the 15-LOX inhibition and radical scavenging activity as it can be observed in the inactive compound 14 (IC₅₀ >250 μM). Structure activity similarity (SAS) showed that the most important chemical modification in this series was methylation of SH group and Docking studies revealed a proper orientation for SH group towards Fe core of the 15-LOX active site. Therefore it was concluded that iron chelating could be a possible mechanism for enzyme inhibition in this series of compounds.     

Chemical constituents of Mussaenda erythrophylla Schumach. & Thonn. (Rubiaceae) and their chemophenetic significance

The chemical investigation of the CH₂Cl₂/MeOH (1:1) extract from the aerial part of Mussaenda erythrophylla Schumach. & Thonn. (Rubiaceae) resulted in the isolation of sixteen known compounds (1–16) distributed in coumarins, flavonoid glucosides, quinic acid derivatives, triterpenoids, monoglycerid, steroids, tetraterpenoid and polyol. The structures of the compounds were determined by spectrometric and spectroscopic analysis including MS and NMR data followed by their comparison with reported ones in the literature. The chemophenetic significance of the isolated compounds was discussed. The crude extract and some of the isolated compounds were assessed in vitro for their antileishmanial, cytotoxic and antiplasmodial activities. The crude extract of M. erythrophylla showed moderate antileishmanial activity (IC₅₀ = 61.6 μg/mL) while the hexane soluble fraction showed good antileishmanial activity (IC₅₀ = 31.06 μg/mL) compared to the reference drug amphotericin B (IC₅₀ = 0.11 μM). Compounds 11 and 9 also exhibited potent antileishmanial activity (IC₅₀ = 53.7–52.0 μM). The crude extract as well as the ethyl acetate soluble fraction also exhibited good antiplasmodial activity (IC₅₀ = 7.43 ± 0.00 μg/mL and 14.49 ± 2.96 μg/mL respectively), while compounds 11, 15 and 16 showed weak activity with IC₅₀ > 20 μM compared to the reference drug artemisinin (IC₅₀ = 0.014 ± 0.001 μM).     

Studies on depigmenting activities of dihydroxyl benzamide derivatives containing adamantane moiety

Six diphenolic compounds containing adamantane moiety were synthesized and evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells. The inhibitory activity of 4-adamantyl resorcinol 1 was similar to that of 4-n-butyl resorcinol in both assays. However, dihydroxyl benzamide derivatives 6a–e showed different inhibitory patterns. All derivatives significantly suppressed the cellular melanin formation without tyrosinase inhibitory activities. These behaviors indicated that the introduction of amide bond changes the binding mode of dihydroxyl groups to tyrosinase. Among derivatives, 6d (3,4-dihydroxyl compound) and 6e (2,3-dihydroxyl compound) showed stronger inhibitory activities (IC₅₀ = 1.25 μM and 0.73 μM, respectively) as compared to 4-n-butyl resorcinol (IC₅₀ = 21.64 μM) and hydroquinone (IC₅₀ = 3.97 μM). This study showed that the position of dihydroxyl substituent at aromatic ring is important for the intercellular inhibition of melanin formation, and also amide linkage and adamantane moiety enhance the inhibition.     

Synthesis and biological activity of 4-substituted benzoxazolone derivatives as a new class of sEH inhibitors with high anti-inflammatory activity in vivo

A series of novel 4-substituted benzoxazolone derivatives was synthesized, characterized and evaluated as human soluble epoxide hydrolase (sEH) inhibitors and anti-inflammatory agents. Some compounds showed moderate sEH inhibitory activities in vitro, and two novel compounds, 3g and 4j, exhibited the highest activities with IC₅₀ values of 1.72 and 1.07 μM, respectively. Structure–activity relationships (SARs) revealed that introduction of a lipophilic amino acid resulted in an obvious increase in the sEH inhibitory activity, especially for derivatives containing a phenyl (3d, IC₅₀ = 2.67 μM), pyrrolidine (3g, IC₅₀ = 1.72 μM), or sulfhydryl group (3e, IC₅₀ = 3.02 μM). Several compounds (3a–3g) were tested in vivo using a xylene-induced ear edema mouse model. Three compounds (3d, 3f, and 3g) showed strong anti-inflammatory activities in vivo which were higher than that of Chlorzoxazone, a reference drug widely used in the clinic. Our investigation provided a novel type of sEH inhibitor and anti-inflammatory agent that may lead to the discovery of a potential candidate for clinical use.     

Design,modification and 3D QSAR studies of novel naphthalin-containing pyrazoline derivatives with/without thiourea skeleton as anticancer agents

Two series of novel naphthalin-containing pyrazoline derivatives C1–C14 and D1–D14 have been synthesized and evaluated for their EGFR/HER-2 inhibitory and anti-proliferation activities. Compound D14 displayed the most potent activity against EGFR and A549 cell line (IC₅₀ = 0.05 μM and GI₅₀ = 0.11 μM), being comparable with the positive control Erlotinib (IC₅₀ = 0.03 μM and GI₅₀ = 0.03 μM) and more potent than our previous compounds C0–A (IC₅₀ = 5.31 μM and GI₅₀ = 33.47 μM) and C0–B (IC₅₀ = 0.09 μM and GI₅₀ = 0.34 μM). Meanwhile, compound C14 displayed the most potent activity against HER-2 and MCF-7 cell line (IC₅₀ = 0.88 μM and GI₅₀ = 0.35 μM), being a little less potent than Erlotinib (IC₅₀ = 0.16 μM and GI₅₀ = 0.08 μM) but far more potent than C0–A (IC₅₀ = 6.58 μM and GI₅₀ = 27.62 μM) and C0–B (IC₅₀ = 2.77 μM and GI₅₀ = 3.79 μM). The docking simulation was performed to analyze the probable binding models and the QSAR models were built for reasonable design of EGFR/HER-2 inhibitors at present and in future. The structural modification of introducing naphthalin moiety reinforced the combination of our compounds and the receptor, resulting in progress of bioactivity. Moreover, the replacement of thiourea skeleton by using benzene ring resulted in the slight diversity of the two series towards specific targets.     

Design,synthesis and primary activity assay of bi- or tri-peptide analogues with the scaffold l-arginine as amino-peptidase N/CD13 inhibitors

A series of bi- or tri-peptide analogues with the scaffold l-arginine were designed, synthesized and evaluated for their inhibitory activities against amino-peptidase N (APN) and metalloproteinase-2 (MMP-2). The primary activity assay showed that all the compounds exhibited higher inhibitory activities against APN than MMP-2. Within this series, compounds C6 and C7 (IC₅₀ = 4.2 and 4.3 μM) showed comparable APN inhibitory activities with the positive control bestatin (IC₅₀ = 3.8 μM).     

Synthesis,biological evaluation,and molecular docking studies of novel 2-styryl-5-nitroimidazole derivatives containing 1,4-benzodioxan moiety as FAK inhibitors with anticancer activity

A series of 2-styryl-5-nitroimidazole derivatives containing 1,4-benzodioxan moiety (3a–3r) has been designed, synthesized and their biological activities were also evaluated as potential antiproliferation and focal adhesion kinase (FAK) inhibitors. Among all the compounds, 3p showed the most potent activity in vitro which inhibited the growth of A549 with IC₅₀ value of 3.11 μM and Hela with IC₅₀ value of 2.54 μM respectively. Compound 3p also exhibited significant FAK inhibitory activity (IC₅₀ = 0.45 μM). Docking simulation was performed for compound 3p into the FAK structure active site to determine the probable binding model.     

Discovery of small molecules that inhibit melanogenesis via regulation of tyrosinase expression

5,6,7,8-Tetrahydro-4H-cyclohepta[d]isoxazole derivatives were synthesized and evaluated as a novel class of inhibitors for α-melanocyte-stimulating hormone (α-MSH) induced melanogenesis in a mouse melanoma B16F10 cell line. Compound 8e (IC₅₀ = 0.67 μM), 8h (IC₅₀ = 1.01 μM) and 9b (IC₅₀ = 0.99 μM) exhibited a potent inhibitory activity approximately 85- to 126-fold greater than kojic acid, a well-known potent inhibitor. A biochemical study indicates that the activity of this series should be displayed via down-regulation of the expression of tyrosinase.     

Design and synthesis of l- and d-phenylalanine derived rhodanines with novel C5-arylidenes as inhibitors of HCV NS5B polymerase

Hepatitis C virus (HCV) NS5B polymerase is a key target for anti-HCV therapeutics development. Herein, we report the synthesis and in vitro evaluation of anti-NS5B polymerase activity of a molecular hybrid of our previously reported lead compounds 1 (IC₅₀ = 7.7 μM) and 2 (IC₅₀ = 10.6 μM) as represented by hybrid compound 27 (IC₅₀ = 6.7 μM). We have explored the optimal substituents on the terminal phenyl ring of the 3-phenoxybenzylidene moiety in 27, by generating a set of six analogs. This resulted in the identification of compound 34 with an IC₅₀ of 2.6 μM. To probe the role of stereochemistry towards the observed biological activity, we synthesized and evaluated the d-isomers 41 (IC₅₀ = 19.3 μM) and 45 (IC₅₀ = 5.4 μM) as enantiomers of the l-isomers 27 and 34, respectively. The binding site of compounds 32 and 34 was mapped to palm pocket-I (PP-I) of NS5B. The docking models of 34 and 45 within the PP-I of NS5B were investigated to envisage the molecular mechanism of inhibition.     

Design,synthesis and biological evaluation of heterocyclic azoles derivatives containing pyrazine moiety as potential telomerase inhibitors

Three series of novel heterocyclic azoles derivatives containing pyrazine (5a–5k, 8a–8k and 11a–11k) have been designed, synthesized, structurally determined, and their biological activities were evaluated as potential telomerase inhibitors. Among the oxadiazole derivatives, compound 5c showed the most potent biological activity against SW1116 cancer cell line (IC₅₀ = 2.46 μM against SW1116 and IC₅₀ = 3.55 μM for telomerase). Compound 8h performed the best in the thiadiazole derivatives (IC₅₀ = 0.78 μM against HEPG2 and IC₅₀ = 1.24 μM for telomerase), which was comparable to the positive control. While compound 11f showed the most potent biological activity (IC₅₀ = 4.12 μM against SW1116 and IC₅₀ = 15.03 μM for telomerase) among the triazole derivatives. Docking simulation by positioning compounds 5c, 8h and 11f into the telomerase structure active site was performed to explore the possible binding model. The results of apoptosis demonstrated that compound 8h possessed good antitumor activity against HEPG2 cancer cell line. Therefore, compound 8h with potent inhibitory activity in tumor growth inhibition may be a potential antitumor agent against HEPG2 cancer cell. Therefore, the introduction of oxadiazole, thiadiazole and triazole structures reinforced the combination of our compounds and the receptor, resulting in progress of bioactivity.     

α-Glucosidase inhibitory and nitric oxide production inhibitory activities of alkaloids isolated from a twig extract of Polyalthia cinnamomea

The first phytochemical investigation of Polyalthia cinnamomea led to the isolation and identification of two new oxoprotoberberine alkaloids, (−)-(13aS)-polyalthiacinnamines A and B, together with eleven known compounds. The structures of the new compounds were elucidated by extensive spectroscopic methods. The absolute configuration of miliusacunine E and consanguine B was established by X-ray diffraction analysis using Cu Kα radiation and ECD spectra, whereas the absolute configurations of polyalthiacinnamines A and B were established by comparison of their ECD spectra and specific rotations with those of miliusacunine E and consanguine B. Compounds 1–4, 6, and 8 exhibited α-glucosidase inhibitory activities (IC₅₀ values ranging from 11.3 to 57.9 µM) better than a positive control (acarbose, IC₅₀ 83.5 μM). Compound 2 also exhibited NO production inhibitory activity with an IC₅₀ value of 24.4 μM (indomethacin, a positive control, IC₅₀ = 32.2 μM).     

Pyrazole-hydrazone derivatives as anti-inflammatory agents: Design,synthesis, biological evaluation,COX-1,2/5-LOX inhibition and docking study

A new series of pyrazole-hydrazone derivatives 4a-i were designed and synthesized, their chemical structures were confirmed by IR, ¹H NMR, ¹³C NMR, MS spectral data and elemental analysis. IC₅₀ values for all prepared compounds to inhibit COX-1, COX-2 and 5-LOX enzymes were determined in vitro. Compounds 4a (IC₅₀ = 0.67 μM) and 4b (IC₅₀ = 0.58 μM) showed better COX-2 inhibitory activity than celecoxib (IC₅₀ = 0.87 μM) with selectivity index (SI = 8.41, 10.55 in sequent) relative to celecoxib (SI = 8.85). Also, compound 4a and 4b exhibited superior inhibitory activity against 5-LOX (IC₅₀ = 1.92, 2.31 μM) higher than zileuton (IC₅₀ = 2.43 μM). All target pyrazoles were screened for their ability to reduce nitric oxide production in LPS stimulated peritoneal macrophages. Compounds 4a, 4b, 4f and 4i displayed concentration dependent reduction and were screened for in vivo anti-inflammatory activity using carrageenan-induced rat paw edema assay. Compound 4f showed the highest anti-inflammatory activity (% edema inhibition = 15–20%) at all doses when compared to reference drug celecoxib (% edema inhibition = 15.7–17.5%). Docking studies were carried out to investigate the interaction of target compounds with COX-2 enzyme active site.     

Rational design,synthesis and biological evaluation of 1,3,4-oxadiazole pyrimidine derivatives as novel pyruvate dehydrogenase complex E1 inhibitors

On the basis of previous study on 2-methylpyrimidine-4-ylamine derivatives I, further synthetic optimization was done to find potent PDHc-E1 inhibitors with antibacterial activity. Three series of novel pyrimidine derivatives 6, 11 and 14 were designed and synthesized as potential Escherichia coli PDHc-E1 inhibitors by introducing 1,3,4-oxadiazole-thioether, 2,4-disubstituted-1,3-thiazole or 1,2,4-triazol-4-amine-thioether moiety into lead structure I, respectively. Most of 6, 11 and 14 exhibited good inhibitory activity against E. coli PHDc-E1 (IC₅₀ 0.97–19.21 μM) and obvious inhibitory activity against cyanobacteria (EC₅₀ 0.83–9.86 μM). Their inhibitory activities were much higher than that of lead structure I. 11 showed more potent inhibitory activity against both E. coli PDHc-E1 (IC₅₀ < 6.62 μM) and cyanobacteria (EC₅₀ < 1.63 μM) than that of 6, 14 or lead compound I. The most effective compound 11d with good enzyme-selectivity exhibited most powerful inhibitory potency against E. coli PDHc-E1 (IC₅₀ = 0.97 μM) and cyanobacteria (EC₅₀ = 0.83 μM). The possible interactions of the important residues of PDHc-E1 with title compounds were studied by molecular docking, site-directed mutagenesis, and enzymatic assays. The results indicated that 11d had more potent inhibitory activity than that of 14d or I due to its 1,3,4-oxadiazole moiety with more binding position and stronger interaction with Lsy392 and His106 at active site of E. coli PDHc-E1.     

Design,synthesis and preliminary activity assay of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives as novel Histone deacetylases (HDACs) inhibitors

Histone deacetylases (HDACs) are enzymes involved in tumor genesis and development. Herein, we report a novel series of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives as HDACs inhibitors. The preliminary biological screening showed that most of our compounds exhibited potent inhibitory activity against HDACs. Within this series, five compounds, 13a (IC₅₀ = 0.58 ± 0.10 μM), 7d (IC₅₀ = 1.00 ± 0.16 μM), 8l (IC₅₀ = 1.06 ± 0.14 μM), 7i (IC₅₀ = 1.17 ± 0.19 μM) and 7a (IC₅₀ = 1.29 ± 0.15 μM) possessed better HDACs inhibitory activity than Vorinostat (IC₅₀ = 1.48 ± 0.20 μM). So these five compounds could be used as novel lead compounds for further design of HDACs inhibitors. The anti-proliferative activities of a few compounds and the structure–activity relationships are also briefly discussed.