The synthesis of 4-arylamido-2-arylaminoprimidines as potent EGFR T790M/L858R inhibitors for NSCLC

A series of 4-arylamido-2-arylaminoprimidines bearing acrylamide pharmacophore were synthesized as potent EGFR^T790M/L858R inhibitors among which 9c (IC₅₀?=?0.5872?nM), 9d (IC₅₀?=?2.213?nM), or 9h (IC₅₀?=?12.57?nM) showed more potent anti-EGFR^T790M/L858R activity compared with AZD–9291 (IC₅₀?=?20.80?nM) and possessed high SI displaying 307.6, 56.5, or 12.5 for EGFR^T790M/L858R over the wild-type respectively. 9h also showed pretty good activity against H 1975 cells with an IC₅₀ of 1.664?μM and exhibited low toxicity against the normal HBE cells (IC₅₀?>?20?μΜ). 9h had moderate selectivity for H 1975 over A 431 (SI?=?7.0) and the other selected cell lines. Morphological staining results further indicated that 9h could promote apoptosis. Hence, 9h was a promising compound for further investigation as a potential EGFR^T790M/L858R inhibitor for the treatment of NSCLC.     

Substituted phenyl[(5-benzyl-1,3,4-oxadiazol-2-yl)sulfanyl]acetates/acetamides as alkaline phosphatase inhibitors: Synthesis,computational studies,enzyme inhibitory kinetics and DNA binding studies

Substituted phenyl[(5-benzyl-1,3,4-oxadiazol-2-yl)sulfanyl]acetates/acetamides 9a-j were synthesized as alkaline phosphatase inhibitors. Phenyl acetic acid 1 through a series of reactions was converted into 5-benzyl-1,3,4-oxadiazole-2-thione 4. The intermediate oxadiazole 4 was then reacted with chloroacetyl derivatives of phenols 6a-f and anilines derivatives 8a-d to afford the title oxadiazole derivatives 9a-j. All of the title compounds 9a-j were evaluated for their inhibitory activity against human alkaline phosphatise (ALP). It was found that compounds 9a-j exhibited good to excellent alkaline phosphatase inhibitory activity especially 9h displayed potent activity with IC₅₀ value 0.420 ± 0.012 µM while IC₅₀ value of standard (KH₂PO₄) was 2.80 µM. The enzyme inhibitory kinetics of most potent inhibitor 9h was determined by Line-weaever Burk plots showing non-competitive mode of binding with enzyme. Molecular docking studies were performed against alkaline phosphatase enzyme (1EW2) to check the binding affinity of the synthesized compounds 9a-j against target protein. The compound 9h exhibited excellent binding affinity having binding energy value (−7.90 kcal/mol) compared to other derivatives. The brine shrimp viability assay results proved that derivative 9h was non-toxic at concentration used for enzyme assay. The lead compound 9h showed LD₅₀ 106.71 µM while the standard potassium dichromate showed LD₅₀ 0.891 µM. The DNA binding interactions of the synthesized compound 9h was also determined experimentally by spectrophotometric and electrochemical methods. The compound 9h was found to bind with grooves of DNA as depicted by both UV–Vis spectroscopy and cyclic voltammetry with binding constant values 7.83 × 10³ and 7.95 × 10³ M⁻¹ respectively revealing significant strength of 9h-DNA complex. As dry lab and wet lab results concise each other it was concluded that synthesized compounds, especially compound 9h may serve as lead compound to design most potent inhibitors of human ALP.     

Bimetallic complexes of porphyrinphenanthroline: Preparation and catalytic activities

Condensation of tetraphenylporphyrin-2,3-dione with 1,10-phenanthroline-5,6-diamine provided porphyrinphenanthroline (2) as the desired ligand. Metallation of the porphyrinic site of 2 with CoCl₂, NiCl₂, ZnCl₂ and CuCl₂ afforded the corresponding metal complexes [Co(2)] (8a), [Ni(2)] (8b), [Zn(2)] (8c) and [Cu(2)] (8d), respectively. Subsequent reactions of these metalloporphyrins with [(COD)PdCl₂] yielded the corresponding bimetallic complexes [Co/Pd (9a), Ni/Pd (9b), Zn/Pd (9c) and Cu/Pd (9d)] in high yields. The bimetallic complex 9e (Mg/Pd) was prepared directly by complexation of 2 with MgBr₂ and [(COD)PdCl₂]. All complexes were characterized by both spectroscopic and elemental analyses. In addition, crystal structure of 9c was determined to confirm its formulation. The use of these bimetallic complexes as pre-catalysts for Mizoroki-Heck coupling reaction has been examined.     

New quinoline/chalcone hybrids as anti-cancer agents: Design,synthesis, and evaluations of cytotoxicity and PI3K inhibitory activity

A series of quinoline-chalcone hybrids was designed as potential anti-cancer agents, synthesized and evaluated. Different cytotoxic assays revealed that compounds experienced promising activity. Compounds 9i and 9j were the most potent against all the cell lines tested with IC₅₀ = 1.91–5.29 µM against A549 and K-562 cells. Mechanistically, 9i and 9j induced G₂/M cell cycle arrest and apoptosis in both A549 and K562 cells. Moreover, all PI3K isoforms were inhibited non selectively with IC₅₀s of 52–473 nM when tested against the two mentioned compounds with 9i being most potent against PI3K-γ (IC₅₀ = 52 nM). Docking of 9i and 9j showed a possible formation of H-bonding with essential valine residues in the active site of PI3K-γ isoform. Meanwhile, Western blotting analysis revealed that 9i and 9j inhibited the phosphorylation of PI3K, Akt, mTOR, as well as GSK-3β in both A549 and K562 cells, suggesting the correlation of blocking PI3K/Akt/mTOR pathway with the above antitumor activities. Together, our findings support the antitumor potential of quinoline-chalcone derivatives for NSCLC and CML by inhibiting the PI3K/Akt/mTOR pathway.     

Production of Reactive Oxygen Intermediates (O2˙−, H2O2, and ˙OH) by Maize Roots and Their Role in Wall Loosening and Elongation Growth

Cell extension in the growing zone of plant roots typically takes place with a maximum local growth rate of 50% length increase per hour. The biochemical mechanism of this dramatic growth process is still poorly understood. Here we test the hypothesis that the wall-loosening reaction controlling root elongation is effected by the production of reactive oxygen intermediates, initiated by a NAD(P)H oxidase-catalyzed formation of superoxide radicals (O₂^˙−) at the plasma membrane and culminating in the generation of polysaccharide-cleaving hydroxyl radicals (^˙OH) by cell wall peroxidase. The following results were obtained using primary roots of maize (Zea mays) seedlings as experimental material. (1) Production of O₂^˙−, H₂O₂, and ^˙OH can be demonstrated in the growing zone using specific histochemical assays and electron paramagnetic resonance spectroscopy. (2) Auxin-induced inhibition of growth is accompanied by a reduction of O₂^˙− production. (3) Experimental generation of ^˙OH in the cell walls with the Fenton reaction causes wall loosening (cell wall creep), specifically in the growing zone. Alternatively, wall loosening can be induced by ^˙OH produced by endogenous cell wall peroxidase in the presence of NADH and H₂O₂. (4) Inhibition of endogenous ^˙OH formation by O₂^˙− or ^˙OH scavengers, or inhibitors of NAD(P)H oxidase or peroxidase activity, suppress elongation growth. These results show that juvenile root cells transiently express the ability to generate ^˙OH, and to respond to ^˙OH by wall loosening, in passing through the growing zone. Moreover, inhibitor studies indicate that ^˙OH formation is essential for normal root growth.     

Half-sandwich Ru[9]aneS3 complexes structurally similar to antitumor-active organometallic piano-stool compounds: Preparation, structural characterization and in vitro cytotoxic activity

The preparation, structural characterization, and chemical behavior in aqueous solution of a series of new Ru[9]aneS₃ half-sandwich complexes of the type [Ru([9]aneS₃)Cl(NN)][CF₃SO₃] and [Ru([9]aneS₃)(dmso-S)(NN)][CF₃SO₃]₂ (5–15, NN = substituted bpy or 2 × 1-methylimidazole) are described. The X-ray structures of [Ru([9]aneS₃)Cl(3,3′-H₂dcbpy)][CF₃SO₃] (9) (3,3′-H₂dcbpy = 3,3′-dicarboxy-2,2′-bipyridine), [Ru([9]aneS₃)Cl(4,4′-dmobpy)][CF₃SO₃] (13) (4,4′-dmobpy = 4,4′-dimethoxy-2,2′-bipyridine), and [Ru([9]aneS₃)Cl(1-MeIm)₂][CF₃SO₃] (15) (1-MeIm = 1-methylimidazole) were also determined. The new compounds are structurally similar to anticancer-active organometallic half-sandwich complexes of formula [Ru(η⁶-arene)Cl(NN)][PF₆]. Three chloro compounds (5, 9, 15) were tested in vitro for cytotoxic activity against two human cancer cell lines in comparison with the previously described [Ru([9]aneS₃)Cl(en)][CF₃SO₃] (1, en = ethylenediamine), [Ru([9]aneS₃)Cl(bpy)][CF₃SO₃] (2), and with their common dmso precursor [Ru([9]aneS₃)Cl(dmso-S)₂][CF₃SO₃] (3). Only the ethylenediamine complex 1 showed some antiproliferative activity, ca. one order of magnitude lower than the reference organometallic half-sandwich compound RM175 that contains biphenyl instead of [9]aneS₃. This compound was further tested against a panel of human cancer cell lines (including one resistant to cisplatin).     

Synthesis,anticancer effect and molecular modeling of new thiazolylpyrazolyl coumarin derivatives targeting VEGFR-2 kinase and inducing cell cycle arrest and apoptosis

New thiazolylpyrazolyl coumarin derivatives were synthesized and tested for their anticancer potential in vitro against five different human cell lines, including breast MCF-7, lung A549, prostate PC3, liver HepG2 and normal melanocyte HFB4. Breast carcinoma revealed higher sensitivity towards compounds 7a, 8c, 9b, 9c and 9d with IC₅₀ values ranging from 5.41 to 10.75 μM in comparison to the reference drug doxorubicin (IC₅₀ = 6.73 μM). In addition, no noticeable toxicity was exhibited towards normal cells HFB4. Moreover, in vitro studies of the VEGFR-2 inhibition in human breast cancer MCF-7 cell line for the promising cytotoxic compounds showed that compounds 7a, 8c, 9b, 9c and 9d were potent inhibitors at low micromolar concentrations (IC₅₀ = 0.034–0.582 μM) compared to the reference drug, sorafenib (IC₅₀ = 0.019 μM). Several theoretical and experimental studies were done to reveal the molecular mechanisms that control breast carcinoma metastasis. The mechanistic effectiveness in cell cycle progression, apoptotic induction and gene regulation were assessed for the promising compound 9d due to its remarkable cytotoxic activity against MCF-7 and significant VEGFR-2 inhibition. Flow cytometeric analysis showed that compound 9d induced cell growth cessation at G2/M phase and increased the percentage of cells at pre-G1 phase that stimulates the apoptotic death of MCF-7 cells. Furthermore, real time PCR assay illustrated that compound 9d up regulated p53 gene expression and elevated Bax/Bcl-2 ratio which confirmed the mechanistic pathway of compound 9d. Moreover, the apoptotic induction of breast cancer cells MCF-7 was enhanced effectively through activation of caspases-7 and 9 by compound 9d. On the other hand, a set of in silico methods such as molecular docking, molecular dynamics simulation, QSAR analysis as well as ADMET analysis was performed in order to study the protein-ligand interactions and the relationship between the physicochemical properties and the inhibitory activity of the promising compounds 7a, 8c and 9d. Based on the aforementioned findings, compound 9d could be considered as effective apoptosis modulator and promising lead for future development of new anti-breast cancer agents.     

Preparation and characterization of (9-methyladenine)triammineplatinum(II) and trans-dihydroxo(9-methyladenine)triammineplatinum(IV) complexes

The preparation is reported of [(NH₃)₃Pt(9- MeA)] X₂ (9-MeA = 9-methyladenine) with XCl (1a) and XClO₄ (1b) and of trans-[(OH)₂Pt(NH₃)₃- (9-MeA)]X₂ with XCl (2a) and XClO₄ (2b), and the crystal structure of 1b. [(NH₃)₃Pt(C₆H₇N₅)](ClO₄)₂ crystallizes in space group P2₁/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, R_w = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from ³J coupling between H8 of the adenine ring and ¹⁹⁵Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different ³J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me₂SO-d₆, hydrogen bonding occurs between Cl^? and C(8)H of 9-MeA as weil as between Cl^? and the NH₃ groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using ¹H NMR spectroscopy and pK_a values for the N1 protonated 9-MeA ligands were determined in D₂O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.     

High analgesic and anti-inflammatory in vivo activities of six new hybrids NSAIAs tetrahydropyran derivatives

We present in this article syntheses of six new hybrids compounds (4–9) that were efficiently prepared in one or two steps (70–84.6%) from our previous prototype (±)-cis-4-chloro-6-(naphthalen-1-yl)-tetrahydro-2H-pyran-2-yl)methanol (3) and the NSAIAs: acetyl salicylic acid, indomethacin, ibuprofen, ketoprofen, naproxen and diclofenac. The acetic acid-induced writhing method is able to determine that all investigated new hybrids showed stronger antinociceptive properties (2- to 10-fold less ED₅₀ values) than their precursors. The highest antinociceptive effect was observed for compound 9 showing more than 10-fold less ED₅₀ values than diclofenac and ninefold less ED₅₀ value than compound 2. All compounds presented greater activity than the control group in the tail-flick test confirming the central antinociceptive effect. New hybrids did not alter the motor performance of mice by rota-rod performance and open-field tests. Investigated compounds 4–9 were not toxic after oral administration (LD₅₀ >2000 mg/kg).     

Design,synthesis, docking study, α-glucosidase inhibition,and cytotoxic activities of acridine linked to thioacetamides as novel agents in treatment of type 2 diabetes

A novel series of acridine linked to thioacetamides 9a–o were synthesized and evaluated for their α-glucosidase inhibitory and cytotoxic activities. All the synthesized compounds exhibited excellent α-glucosidase inhibitory activity in the range of IC₅₀ = 80.0 ± 2.0–383.1 ± 2.0 µM against yeast α-glucosidase, when compared to the standard drug acarbose (IC₅₀ = 750.0 ± 1.5 µM). Among the synthesized compounds, 2-((6-chloro-2-methoxyacridin-9-yl)thio)-N-(p-tolyl) acetamide 9b displayed the highest α-glucosidase inhibitory activity (IC₅₀ = 80.0 ± 2.0 μM). The in vitro cytotoxic assay of compounds 9a–o against MCF-7 cell line revealed that only the compounds 9d, 9c, and 9n exhibited cytotoxic activity. Cytotoxic compounds 9d, 9c, and 9n did not show cytotoxic activity against the normal human cell lines HDF. Kinetic study revealed that the most potent compound 9b is a competitive inhibitor with a K_i of 85 μM. Furthermore, the interaction modes of the most potent compounds 9b and 9f with α-glucosidase were evaluated through the molecular docking studies.     

1,3-Di(quinolin-2-yl)guanidine binds to GGCCCC hexanucleotide repeat DNA in C9ORF72

Aberrant expansion of GGGGCC (G4C2) hexanucleotide repeat (HNR) in the first intron of C9ORF72 has been found in frontotemporal dementia and amyotrophic lateral sclerosis (FTD/ALD). The non-canonical DNA structures of the expanded repeats are causative to repeat instability leading to contraction and expansion. We demonstrate that 1,3-di(quinolin-2-yl)guanidine (DQG) binds to GGCCCC/GGCCCC (G2C4/G2C4) motif in double stranded DNA and also antisense G2C4 HNR DNA in C9ORF72. Large increase in the melting temperature of dsDNA containing the G2C4/G2C4 motif was confirmed by the binding of DQG. The marked CD spectral changes indicated structural transition of d(G2C4)₉ from i-motifs and/or hairpins to DQG-stabilized d(G2C4)₉ structures.     

Selective cyclooxygenase inhibition and ulcerogenic liability of some newly prepared anti-inflammatory agents having thiazolo[4,5-d]pyrimidine scaffold

Novel candidates of thiazolo[4,5-d]pyrimidines (9a-l) were synthesized and their structures were elucidated by spectral and elemental analyses. All the novel derivatives were screened for their cyclooxygenase inhibitory effect, anti-inflammatory activity and ulcerogenic liability. All the new compounds exhibited anti-inflammatory activity, especially 1-(4-[7-(4-nitrophenyl)-5-thioxo-5,6-dihydro-3H-thiazolo[4,5-d]pyrimidin-2-ylideneamino]phenyl)ethanone (9g) was the most active derivative with 57%, 88% and 88% inhibition of inflammation after 1, 3 and 5h, respectively. Furthermore, this derivative 9g recorded higher anti-inflammatory activity than celecoxib which showed 43%, 43% and 54% inhibition after 1, 3 and 5h, sequentially. Moreover, the target derivatives 9a-l demonstrated moderate to high potent inhibitory action towards COX-2 (IC₅₀ = 0.87–3.78 µM), in particular, the derivatives 9e (IC₅₀ = 0.92 µM), 9g (IC₅₀ = 0.87 µM) and 9k (IC₅₀ = 1.02 µM) recorded higher COX-2 inhibitory effect than the selective COX-2 inhibitor drug celecoxib (IC₅₀ = 1.11 µM). The in vivo potent compounds (9e, 9g and 9k) caused variable ulceration effect (ulcer index = 5–12.25) in comparison to that of celecoxib (ulcer index = 3). Molecular docking was performed to the most potent COX-2 inhibitors (9e, 9g and 9k) to explore the binding mode of these derivatives with Cyclooxygenase-2 enzyme.     

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,biological evaluation and docking study of 1,3,4-thiadiazole-thiazolidinone hybrids as anti-inflammatory agents with dual inhibition of COX-2 and 15-LOX

Selective inhibition of both cyclooxygenase-2 (COX-2) and 15-lipooxygenase (15-LOX) may provide good strategy for alleviation of inflammatory disorders while minimizing side effects associated with current anti-inflammatory drugs. The present study describes the synthesis, full characterization and biological evaluation of a series of thiadiazole-thiazolidinone hybrids bearing 5-alk/arylidene as dual inhibitors of these enzymes. Our design was based on merging pharmacophores that exhibit portent anti-inflammatory activities in one molecular frame. 5-(4-hydroxyphenyl)-1,3,4-thiadiazol-2-amine (3) was efficiently synthesized, chloroacetylated and cyclized to give the key 4-thiazolidinone (5). Knovenagel condensation of 5 with different aldehydes afforded the final compounds 6a-m, 7, 8 and 9. These compounds were subjected to in vitro COX-1/COX-2, 15-LOX inhibition assays. Compounds (6a, 6f, 6i, 6l, 6m and 9) with promising potency (IC₅₀ = 70–100 nM) and selectivity index (SI = 220-55) were further tested for in vivo anti-inflammatory activity and effect on gastric mucosa. The most promising compound (6l) inhibits COX-2 enzyme at a nanomolar concentration (IC₅₀ = 70 nM, SI = 220) with simultaneous inhibition of 15-LOX (IC₅₀ = 11 µM). These results are comparable to the potency and selectivity of the standard drugs of both enzymes; celecoxib (COX-2 IC₅₀ = 49 nM, SI = 308) and zileuton (15-LOX IC₅₀ = 15 µM) in one construct. Interestingly three compounds (6a, 6l and 9) exhibited equivalent to or even higher than that of celecoxib in vivo anti-inflammatory activity at 3 h interval with good GIT safety profile. Molecular docking study conferred binding sites of these compounds on COX-2 and 15-LOX. Such type of compounds would represent valuable leads for further investigation and derivatization.     

Design,synthesis, molecular docking and biological activity evaluation of some novel indole derivatives as potent anticancer active agents and apoptosis inducers

Reaction of 5-morphilinosulfonylisatin (1) with acetophenones (2a–e) afforded 3-hydroxy-3-substituted-2-oxoindoles 3a-e, when treated with acetic acid the expected 3-phenacylidene-2-oxoindoles 4a-d and 4-hydroxy-5′-(morpholinosulfonyl) spiro [chromene-2, 3′-indolin]-2′-one 6 were obtained. Isatin derivative (1) was stirred with cyano derivatives to produce the arylidines (7a-c), while under reflux condition, it gave pyrrolo[2,3–b]indoles (8, 9). Moreover, istain (1) reacted with pyrazolo-5-one or 3-substituted phenol in presence of malononitrile to afford spiroxindole derivatives (10a,b) and (11a,b). Also, compounds (10a,b) and (11a,b) were obtained through cyclization of (7a) with pyrazolo-5-one or 3-substituted phenol. The obtained compounds were identified by IR, ¹H NMR, ¹³C NMR and elemental analysis. Anticancer activity against three cancer cell lines (HepG-2, HCT-116 and MCF-7) were evaluated using sulforhodamine B assay method. Compounds 4b, 4c, 7a, 7c and 9 showed broad spectrum anticancer activity on the three tested cell lines with IC₅₀ values less than 10 µM. Cell cycle analysis was performed for the most promising derivatives, compounds 4b and 7c arrested HepG-2 cells at G2-M phase, while compounds 7a and 9 accumulated cells at G0-G1 phase, all of them induced apoptosis at priG1 phase in the range of (11.32–19.17%). Additionally compounds 4b, 7a and 9 showed more potent activity against EGFR than Lapatinib, their IC₅₀ values are from 0.019 to 0.026 µM while IC₅₀ of Lapatinib is 0.028 µM. Molecular docking studies were conducted to investigate the binding mode, amino acid interactions and free binding energy of these potent derivatives.     

Enzymatic nitration of the oleic acid derivatives: Synthesis,isolation and characterization

Unsaturated fatty acids are nitrated endogenously to produce nitrated lipids. Recent studies have shown that these nitrated lipids have high chemical reactivity and profound biological implications. We report an efficient, enzymatic synthesis of nitrated derivatives of the oleic acid. The methyl oleate could react with NO and horseradish peroxidase (HRP)/H₂O₂/NO based nitrating systems to give various nitration products which could be isolated by silica gel column and TLC fractionation, respectively. As reacting directly with NO, the obtained products contain (E)-methyl 9-nitrooctadec-9-enoate (1), (E)-methyl 10-nitrooctadec-9-enoate (2), (E)-methyl 9-nitrooctadec-10-enoate (3) and (E)-methyl 10-nitrooctadec-8-enoate (4), characterized by extensive IR, NMR and GC–MS analysis. Whereas the products of the reaction between the methyl oleate and NO with the presence of HRP/H₂O₂ were mainly composed of (E)-methyl 9-nitrooctadec-9-enoate and (E)-methyl 10-nitrooctadec-9-enoate. The improving selectivity of the products is attributed to the HRP catalysis system.     

Synthesis and NMDA receptor affinity of fluorinated dioxadrol analogues

A series of dioxadrol analogues with fluorine substituents in position 4 of the piperidine ring has been synthesized and pharmacologically evaluated. The key step in the synthesis was the fluorination of diastereomeric piperidones 6a and 6c as well as diastereomeric alcohols 9a and 9c with DAST. The reaction of the alcohols 9a and 9c took place with inversion of configuration. After removal of the Cbz-protective group, the NMDA receptor affinities of the resulting secondary amines 8a, 8c, 12b, and 12d were investigated in receptor binding studies. It was shown that the like-configuration of the ring junction was crucial for high NMDA receptor affinity. An axially oriented fluorine atom in position 4 led to 2-(2,2-diphenyl-1,3-dioxolan-4-yl)-4-fluoropiperidine (12d, WMS-2517) with a K_i-value of 27 nM. The NMDA receptor affinity of 8c (WMS-2513) with an additional fluorine atom in equatorial 4-position was slightly reduced (K_i = 81 nM). Both fluorinated dioxadrol derivatives 8c and 12d showed high selectivity against σ₁ and σ₂ receptors as well as the polyamine binding site of NR2B receptors.     

Biological evaluation of 3'-O-alkylated analogs of salacinol, the role of hydrophobic alkyl group at 3' position in the side chain on the α-glucosidase inhibitory activity

Four analogs with 3′-O-alkyl groups (9a: CH₃, 9b: C₂H₅, 9c: C₁₃H₂₇ or 9d: CH₂Ph) instead of the 3′-O-sulfate anion in salacinol (1), a naturally occurring potent α-glucosidase inhibitor, were synthesized by the coupling reaction of 1,4-dideoxy-1,4-epithio-d-arabinitols (18a and 18b) with appropriate epoxides (10a-10d). These analogs showed equal or considerably higher inhibitory activity against rat small intestinal α-glucosidases than the original sulfate (1), and one of them (9d) was found more potent than currently used α-glucosidase inhibitors as antidiabetics. Thus, introduction of a hydrophobic moiety at the C3′ position of this new class of inhibitor was found beneficial for onset of stronger inhibition against these enzymes.     

Phytochemical and cytotoxic studies on the roots of Euphorbia fischeriana

With the aim of supporting the folk applications of Euphorbia fischeriana, a phytochemical study was performed, which led to the discovery of 9 compounds, including three new ones (1–3) and six known ones (4–9). Their structures were determined by 1D, 2D NMR, and HRESIMS analysis. In the cytotoxic assays on Hep-3B cell line, 2 showed stronger inhibitory effects (IC₅₀ 8.1 μmol/L) than that of positive control, and 1, 8 and 9 also gave inhibitory effects in a certain degree with IC₅₀ values of 12.5, 12.0 and 18.7 μmol/L, respectively. While on A549, the cytotoxic activities of 1 (IC₅₀ 11.9 μmol/L) and 8 (IC₅₀ 9.4 μmol/L) were superior to that of 5-Fu, and those of 4 and 9 were moderate with IC₅₀ values of 28.2 and 29.8 μmol/L, respectively. In addition, both petroleum ether and dichloromethane extracts showed cytotoxic activities with different degree, while n-butanol extracts had no effect. The results clarified that the low-polarity fractions of E. fischeriana, including triterpenoids, abietane and tigliane-type diterpenoids might be the potential bioactive ingredients which will exert strong antitumor effects.     

Identification of novel peptidomimetics targeting the polo-box domain of polo-like kinase 1

A series of new peptidomimetics targeting the polo-box domain (PBD) of polo-like kinase 1 (Plk1) was identified based on the potent and selective pentapeptide Plk1 PBD inhibitor PLHSpT. Unnatural amino acid residues were introduced to the newly designed compound and the N-terminal substituent of the peptidomimetic was investigated. The optimized compound 9 inhibited the Plk1 PBD with IC₅₀ of 0.267 μM and showed almost no inhibition to Plk2 PBD or Plk3 PBD at 100 μM. Biolayer interferometry studies demonstrated that compound 9 showed potent binding affinity to Plk1 with a K_d value of 0.164 μM, while no K_d were detected against Plk2 and Plk3. Compound 9 showed improved stability in rat plasma compared to PLHSpT. Binding mode analysis was performed and in agreement with the observed experimental results. There are only two natural amino acids remained in the chemical structure of 9. This study may provide new information for further research on Plk1 PBD inhibitors.