Synthesis and biological evaluation of thiazolidine-2,4-dione-pyrazole conjugates as antidiabetic,anti-inflammatory and antioxidant agents

A series of fourteen novel thiazolidine-2,4-dione derivatives clubbed with pyrazole moiety were synthesized via four step reaction procedure. Reactions were monitored by thin layer chromatography and were characterized by physicochemical and spectrophotometric (IR, Mass, ¹HNMR and ¹³CNMR) analysis. The spectral data were in good agreement with their structures. The title compounds were docked against peroxisome proliferated activated receptors (PPAR-γ) and alpha-amylase and further evaluated for in vivo and in vitro antidiabetic, in vitro anti-inflammatory and antioxidant activities. Compound GB14 exhibited significant blood glucose lowering activity and was also found to be active inhibitor of alpha-amylase. Compound GB7 was found to be potent anti-inflammatory agent in terms of reducing inflammatory markers (TNF-α, IL-β, MDA) and also showed antioxidant activity to good extent. Therefore, these compounds may be considered as promising candidates for the development of new antidiabetic agents.     

<Emphasis Type="Italic">Trans</Emphasis>-chalcone: a novel small molecule inhibitor of mammalian alpha-amylase

Trans-chalcone (1,3-diphenyl-2-propen-1-one), a biphenolic core structure of flavonoids precursor was tested for inhibitory activity toward alpha-amylase. Porcine pancreatic alpha-amylase was observed to be effectively inhibited by this compound, which showed competitive behavior with a K _i of 48 μM. Soluble starch (the natural substrate of the enzyme) was used in this study in order to obtain more realistic results. The possible binding mode of the compound was assessed in silico, and the two residues Trp59, and Tyr62 were proposed as main interacting residues with trans-chalcone. In conclusion, this compound could be used to design effective inhibitors of alpha-amylase.     

Synthesis,neuroprotective and antioxidant capacity of PBN-related indanonitrones

In this work six PBN-related indanonitrones 1–6 have been designed, synthesized, and their neuroprotection capacity tested in vitro, under OGD conditions, in SH-SY5Y human neuroblastoma cell cultures. As a result, we have identified indanonitrones 1, 3 and 4 (EC₅₀ = 6.64 ± 0.28 μM) as the most neuroprotective agents, and in particular, among them, indanonitrone 4 was also the most potent and balanced nitrone, showing antioxidant activity in three experiments [LOX (100 μM), APPH (51%), DPPH (36.5%)], being clearly more potent antioxidant agent than nitrone PBN. Consequently, we have identified (Z)-5-hydroxy-N-methyl-2,3-dihydro-1H-inden-1-imine oxide (4) as a hit-molecule for further investigation.     

Synthesis and structure–activity relationship studies of phenolic hydroxyl derivatives based on quinoxalinone as aldose reductase inhibitors with antioxidant activity

To enhance aldose reductase (ALR2) inhibition and add antioxidant ability, phenolic hydroxyl was introduced both to the quinoxalinone core and C3 side chain, resulting in a series of derivatives as ALR2 inhibitors. Biological activity tests suggested that most of the derivatives were potent and selective inhibitors with IC₅₀ values ranging from 0.059 to 6.825 μM, and 2-(3-(4-hydroxystyryl)-7-methoxy-2-oxoquinoxalin-1(2H)-yl)acetic acid (6b) was the most active. Particularly, it was encouraging to find that some derivatives endowed with obvious antioxidant activity, and among them the phenolic 3,4-dihydroxyl compound 6f with 7-hydroxyl in the quinoxalinone core showed the most potent activity, even comparable with the well-known antioxidant Trolox. Structure-activity relationship and docking studies highlighted the importance of phenolic hydroxyl both in C3 side chain and the core structure for constructing potent ALR2 inhibitors with antioxidant activity.     

New structure–activity relationship studies in a series of N,N-bis(cyclohexanol)amine aryl esters as potent reversers of P-glycoprotein-mediated multidrug resistance (MDR)

As a continuation of previous research on a new series of potent and efficacious P-gp-dependent multidrug resistant (MDR) reversers with a N,N-bis(cyclohexanol)amine scaffold, we have designed and synthesized several analogs by modulation of the two aromatic moieties linked through ester functions to the N,N-bis(cyclohexanol)amine, aiming to optimize activity and to extend structure–activity relationships (SAR) within the series. This scaffold, when esterified with two different aromatic carboxylic acids, gives origin to four geometric isomers (cis/trans, trans/trans, cis/cis and trans/cis).The new compounds were tested on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Most of them resulted in being potent modulators of the extrusion pump P-gp, showing potency values ([I]_0.5) in the submicromolar and nanomolar range. Of these, compounds 2b, 2c, 3d, 5a–d and 6d, showed excellent efficacy with a α_max close to 1. Selected compounds (2d, 3a, 3b, 5a–d) were further studied to evaluate their doxorubicin cytotoxicity potentiation (RF) on doxorubicin-resistant erythroleukemia K562 cells and were found able to enhance significantly doxorubicin cytotoxicity on K562/DOX cells.The results of both pirarubicin uptake and the cytotoxicity assay, indicate that the new compounds of the series are potent P-gp-mediated MDR reversers. They present a structure with a mix of flexible and rigid moieties, a property that seems critical to allow the molecules to choose the most productive of the several binding modes possible in the transporter recognition site.In particular, compounds 5c and 5d, similar to the already reported analogous isomers 1c and 1d,²⁹ are potent and efficacious modulators of P-gp-dependent MDR and may be promising leads for the development of MDR-reversal drugs.     

Natural products-based insecticidal agents 6. Design,semisynthesis, and insecticidal activity of novel monomethyl phthalate derivatives of podophyllotoxin against Mythimna separata Walker in vivo

To discover the more potent analogs, 12 novel monomethyl phthalate derivatives of podophyllotoxin were synthesized and preliminarily tested against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1 mg/mL. Compounds 8e–i showed the higher insecticidal activity than podophyllotoxin. Especially 8g exhibited the most potent insecticidal activity compared with toosendanin, a commercially available insecticide derived from Melia azedarach. The structure–activity relationships demonstrated that trans-lactone, 4β-substitution, 2β-chlorine substitution, and 4′-methoxy group were the important structural properties of podophyllotoxins for good insecticidal activity.     

Synthesis and molecular docking of N′-arylidene-5-(4-chlorophenyl)-1-(3,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carbohydrazides as novel hypoglycemic and antioxidant dual agents

Herein, the design and synthesis of 10 novel N′-arylidene pyrazole-3-carbohydrazides are described. Compounds were pretended to act as dual agents against diabetes and oxidative stress, two correlated pathologies involved in metabolic syndrome development and progression. The antioxidant capacity was evaluated by means of DPPH and FRAP in vitro assays. It was found that compounds bearing a hydroxyl group at 4-position of the hydrazone moiety are potent antioxidant entities, being compound 3g (a syringaldehyde derivative) the most active compound. In addition, the in vivo hypoglycemic effect of the analogues was determined. With regard to the above, the cinnamaldehyde derivatives showed a scarce biological activity, while the 4-hydroxy analogues showed the higher glycemia reduction at 7 h after administration. Interestingly, the most potent antioxidants 3b and 3g also were of the most active compounds in reducing the plasma glucose, reaching 80% of reduction in the case of 3g. Molecular docking binding poses conducted to a plausible interpretation of the biological outcomes and a possible interaction between a hydroxy group and Asn287 of CB1R was proposed as an important feature for enhancing the observed activity.     

Structure-based design of some isonicotinic acid hydrazide analogues as potential antitubercular agents

New pyridine derivatives were designed and synthesized as Isonicotinic acid hydrazide (INH) analogues. The synthesized compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis strain H₃₇R_v. Ten compounds (3c, 3e-g, 5a-c, 6h, 10 and 11b) showed promising antitubercular activity with MIC range 7.30 µM–19.39 µM. Compounds 3e, 3g, 5b and 11b were the most potent analogues, with MIC 7.30–8.74 µM. They were equipotent to the standard drug Ethambutol (MIC 7.64 µM) and more active than the standard drug Pyrazinamide (MIC 50.77 µM). They were further examined for cytotoxicity in human embryonic kidney (HEK) cell line at the concentration of 50 µg/mL using MTT assay. Results declared that most compounds showed acceptable safety margin. Molecular Docking studies into 2-trans-enoyl-acyl carrier protein reductase, called InhA have been conducted for compounds 3e, 3g, 5b and 11b using Molecular Operating Enviroment software (MOE 2016.0802), where reasonable binding interactions have been identified and effective overall docking scores have been recorded. Their drug-likeness has been assessed using Molinspiration and Osiris software.     

Anti-angiogenic and anticancer effects of baicalein derivatives based on transgenic zebrafish model

Angiogenesis leads to tumor neovascularization by promoting tumor growth and metastatic spread, therefore, angiogenesis is considered as an attractive target for potential small molecule anticancer drug discovery. Herein, we report the structural modification and biological evaluation of baicalein derivatives, among which compound 42 had potent in vivo anti-angiogenic activity and wide security treatment window in transgenic zebrafish model. Further, 42 exhibited the most potent inhibitory activity on HUVEC proliferation, migration and tube formation in vitro. Moreover, 42 significantly inhibited growth of human lung cancer A549 cells and weak influence on human normal fibroblast L929 cells. The present research demonstrated that the significant anti-angiogenic and anticancer effects, which provided the supportive evidence for 42 could be used as a potential compound of cancer therapy.     

New carboxamides bearing benzenesulphonamides: Synthesis,molecular docking and pharmacological properties

Ten new derivatives of benzenesulphonamide bearing carboxamide functionality were synthesized and investigated for their in vitro antimicrobial, antioxidant and in vivo anti-inflammatory activities. Compound 9d inhibited carrageenan induced rat-paw oedema at 93.81, 88.79 and 86.09% at 1 h, 2 h and 3 h administration respectively. In the antimicrobial activity, compound 9a (6.54, 6.69 and 6.64 mg/mL) was most potent against S. aureus, B. subtilis and C. albicans respectively, compound 9e (6.45 and 6.46 mg/mL) was most active against P. aeruginosa and A. niger respectively while compound 9i (6.24 mg/mL) was most active against E. coli. Only compound 9a (IC₅₀ 0.3052 mg/mL) had comparable activity with Vitamin C (IC₅₀ 0.2090 mg/mL) in the antioxidant assay.     

Synthesis and antioxidant activity of a procyanidin B3 analogue

Proanthocyanidin, an oligomer of catechin, is a natural antioxidant and a potent inhibitor of lectin-like oxidized LDL receptor-1, which is involved in the pathogenesis of arteriosclerosis. We synthesized proanthocyanidin analogue 1, in which the geometry of one catechin molecule in procyanidin B3, a dimer of (+)-catechin, is constrained to be planar. The antioxidant activities of the compounds were evaluated in terms of their capacities to scavenge galvinoxyl radicals, and results demonstrate that while procyanidin was 3.8 times more potent than (+)-catechin, the radical scavenging activity of proanthocyanidin analogue 1 was further increased to 1.9 times that of procyanidin B3. This newly designed proanthocyanidin analogue 1 may be a promising lead compound for the treatment of arteriosclerosis and related cerebrovascular diseases.     

Stereoselective synthesis of enantiopure N-substituted pyrrolidin-2,5-dione derivatives by 1,3-dipolar cycloaddition and assessment of their in vitro antioxidant and antibacterial activities

1,3-Dipolar cycloaddition between a chiral nitrone and N-substituted maleimides afforded unprecedented enantiopure spiro-fused heterocycles in good yields with a high enantio- and diastereoselectivity. The reaction was taking place on the less hindered face of the nitrone. The obtaining heterocycles were screened for their in vitro antioxidant properties and the results revealed that the potent antioxidant activity was generally recorded to compounds (3g) and (3e). The in vitro antibacterial activities of these two compounds were also investigated and the results demonstrated the strongest potential of compound (3g) against all the tested bacteria. Molecular properties were analyzed and showed good oral drug candidate like properties and that could be exploited as a potential antioxidant and antimicrobial agent. Finally, the preliminary results obtained from this investigation attempted to clarify if the structurally different side chains of active compounds interfere with their biological properties.     

Derivatives (halogen,nitro and amino) of 8-hydroxyquinoline with highly potent antimicrobial and antioxidant activities

8-Hydroxyquinoline (8HQ) compounds have been reported to possess diverse bioactivities. In recent years, drug repositioning has gained considerable attention in drug discovery and development. Herein, 8HQ (1) and its derivatives (2–9) bearing various substituents (amino, nitro, cyano and halogen) were investigated for their antimicrobial against 27 microorganisms (agar dilution method) and antioxidant (DPPH method) activities. The parent 8HQ (1) exerted a highly potent antimicrobial activity against Gram-positive bacteria including diploid fungi and yeast with MIC values in the range of 3.44–13.78 μM. Moreover, the halogenated 8HQ, especially 7-bromo-8HQ (4) and clioquinol (6), displayed a high antigrowth activity against Gram-negative bacteria compared with the parent compound (1). Apparently, the derivatives with a relatively high safely index, e.g., nitroxoline (2), exhibited strong antibacterial activity against Aeromonas hydrophila (MIC=5.26 μM) and selectively inhibited the growth of P. aeruginosa with the MIC value of 84.14 μM; cloxyquin (3) showed a strong activity against Listseria monocytogenes and Plesiomonas shigelloides with MIC values of 5.57 and 11.14 μM, respectively. Most compounds displayed an antioxidant activity. Specifically, 5-amino-8HQ (8) was shown to be the most potent antioxidant (IC₅₀=8.70 μM) compared with the positive control (α-tocopherol) with IC₅₀ of 13.47 μM. The findings reveal that 8HQ derivatives are potential candidates to be further developed as antimicrobial and antioxidant agents.     

Rational design,synthesis and biological evaluation of novel multitargeting anti-AD iron chelators with potent MAO-B inhibitory and antioxidant activity

A series of (3-hydroxypyridin-4-one)-coumarin hybrids were developed and investigated as potential multitargeting candidates for the treatment of Alzheimer's disease (AD) through the incorporation of iron-chelating and monoamine oxidase B (MAO-B) inhibition. This combination endowed the hybrids with good capacity to inhibit MAO-B as well as excellent iron-chelating effects. The pFe³⁺ values of the compounds were ranging from 16.91 to 20.16, comparable to more potent than the reference drug deferiprone (DFP). Among them, compound 18d exhibited the most promising activity against MAO-B, with an IC₅₀ value of 87.9 nM. Moreover, compound 18d exerted favorable antioxidant activity, significantly reversed the amyloid-β_1-42 (Aβ_1-42) induced PC12 cell damage. More importantly, 18d remarkably ameliorated the cognitive dysfunction in a scopolamine-induced mice AD model. In brief, a series of hybrids with potential anti-AD effect were successfully obtained, indicating that the design of iron chelators with MAO-B inhibitory and antioxidant activities is an attractive strategy against AD progression.     

Design,synthesis and antimycobacterial activity evaluation of natural oridonin derivatives

In an effort to develop novel potent antitubercular drugs, thirty-one oridonin derivatives were designed and prepared. All the compounds obtained were screened for their in vitro activities against Mycobacterium phlei, Mycobacterium smegmatis and Mycobacterium marinum. Among them, thirteen compounds showed significant inhibitory activity against M. phlei with MICs less than 2 μg/mL. Compounds 2k, 8d, 10c, 10d containing trans-cinnamic acid moiety were the most potent (MIC = 0.5 μg/mL), comparable to the well-known antitubercular drug streptomycin. The preliminary structure–activity relationships (SARs) were also analyzed.     

Xanthones from the stems of Cratoxylum cochinchinense

Three xanthones, named cratoxylumxanthones B–D (1–3), along with five known xanthones (4–8), were isolated from the stems of Cratoxylum cochinchinense (Lour.) Blume. Their structures were elucidated by interpretation of spectroscopic data. Among these xanthones, cochinxanthone D (4) exhibited the most potent antioxidant activity in both the DPPH radical scavenging and the lipid peroxidation inhibition assays.     

Synthesis and biological evaluation of purine-pyrazole hybrids incorporating thiazole,thiazolidinone or rhodanine moiety as 15-LOX inhibitors endowed with anticancer and antioxidant potential

Novel purine-pyrazole hybrids combining thiazoles, thiazolidinones and rhodanines, were designed and tested as 15-LOX inhibitors, potential anticancer and antioxidant agents. All tested compounds were found to be potent 15-LOX inhibitors with IC₅₀ ranging from 1.76 to 6.12 µM. The prepared compounds were evaluated in vitro against five cancer cell lines: A549 (lung), Caco-2 (colon), PC3 (prostate), MCF-7 (breast) and HepG-2 (liver). Compounds 7b and 8b displayed broad spectrum anticancer activity against the five tested cell lines (IC₅₀ = 18.5–95.39 µM). While, compound 7h demonstrated moderate anticancer activity against lung A549 and colon Caco-2 cell lines. Antioxidant screening revealed that six compounds (5a, 5b, 6b, 7b, 7h and 8b) with IC₅₀ ranging from 0.93 to 14.43 µg/ml were found to be more potent scavengers of 2,2- diphenyl-1-picrylhydrazyl (DPPH) than the reference ascorbic acid with IC₅₀ value of 15.34 µg/ml. Compounds 7b, 7h and 8b, when evaluated for their antioxidant activity, where found to be potent DPPH scavengers. Moreover, compound 7b displayed twice the potency of ascorbic acid as NO scavenger. Docking study was performed to elucidate the possible binding mode of the most active compounds with the active site of 15-LOX enzyme. Collectively, the purine-pyrazole hybrids having thiazoline or thizolidinone moieties (7b, 7h and 8b) constitute a promising scaffold in designing more potent 15-LOX inhibitors with anticancer and antioxidant potential.     

Identification of 3′,4′,5′-trimethoxychalcone analogues as potent inhibitors of Helicobacter pylori-induced inflammation in human gastric epithelial cells

Efforts to identify potent small molecule inhibitors of Helicobacter pylori led to the evaluation of 23 3′,4′,5′-trimethoxychalcone analogues. Some of the compounds displayed potent antibacterial activity against H. pylori. Three most active and selective compounds 1, 7, and 13 also showed the bactericide activity against the reference as well as multidrug-resistant strains of H. pylori. Additionally, the aforementioned three compounds potentially inhibited the H. pylori adhesion and invasion to human gastric epithelial (AGS) cells. Furthermore, these selective compounds inhibited the H. pylori-induced gastric inflammation by reduced inflammatory mediator’s nuclear factor kappa B activation, and the secretion of interleukin-8.     

Chemical constituents from Tribulus terrestris and screening of their antioxidant activity

Two oligosaccharides (1, 2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (4–8). The structures of the compounds were established as O-β-d-fructofuranosyl-(2 → 6)-α-d-glucopyranosyl-(1 → 6)-β-d-fructofuranosyl-(2 → 6)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranosyl-(6 → 2)-β-d-fructofuranoside (1), O-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 2)-β-d-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR (¹H, ¹³C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4).The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.     

Design,synthesis and evaluation of γ-turn mimetics as LSD1-selective inhibitors

Lysine-specific demethylase 1 (LSD1) is an attractive molecular target for cancer therapy. We have previously reported potent LSD1-selective inhibitors (i.e., NCD18, NCD38, and their analogs) consisting of trans-2-phenylcyclopropylamine (PCPA) or trans-2-arylcyclopropylamine (ACPA) and a lysine moiety that could form a γ-turn structure in the active site of LSD1. Herein we report the design, synthesis and evaluation of γ-turn mimetic compounds for further improvement of LSD1 inhibitory activity and anticancer activity. Among a series of γ-turn mimetic compounds synthesized by a Mitsunobu-reaction-based amination strategy, we identified 1n as a potent and selective LSD1 inhibitor. Compound 1n induced cell cycle arrest and apoptosis through histone methylation in human lung cancer cells. The γ-turn mimetics approach should offer new insights into drug design for LSD1-selective inhibitors.