Flame retardance-donated lignocellulose nanofibers (LCNFs) by the Mannich reaction with (amino-1,3,5-triazinyl)phosphoramidates and their properties.

Nitrogen/phosphorus-containing melamines (NPCM), a durable flame-retardant, were prepared by the successive treatment of ArOH (Ar = Br n C6H5-n , n = 0, 1, 2, and 3) with POCl3 and melamine monomer. The prepared flame-retardants were grafted through the CH2 unit to lignocellulose nanofibers (LCNFs) by the Mannich reaction. The resulting three-component products were characterized using FT-IR (ATR) and EA. The thermal behavior of the NPCM-treated LCNF fabric samples was determined using TGA and DSC analyses, and their flammability resistances were evaluated by measuring their Limited Oxygen Index (LOI) and the UL-94V test. A multitude of flame retardant elements in the fabric samples increased the LOI values as much as 45 from 20 of the untreated LCNFs. Moreover, the morphology of both the NPCM-treated LCNFs and their burnt fabrics was studied with a scanning electron microscope (SEM). The heat release lowering effect of the LCNF fabric against the water-based paint was observed with a cone calorimeter. Furthermore, the mechanical properties represented as the tensile strength of the NPCM-treated LCNF fabrics revealed that the increase of the NPCM content in the PP-composites led to an increased bending strength with enhancing the flame-retardance.

Structural Modifications of Nature-Inspired Indoloquinolines: A Mini Review of Their Potential Antiproliferative Activity.

Cryptolepine, neocryptolepine and isocryptolepine are naturally occurring indoloquinoline alkaloids with various spectrum of biological properties. Structural modification is an extremely effective means to improve their bioactivities. This review enumerates several neocryptolepine and isocryptolepine analogues with potent antiproliferative activity against MV4-11 (leukemia), A549 (lung cancer), HCT116 (colon cancer) cell lines in vitro. Its activity towards normal mouse fibroblasts BALB/3T3 was also evaluated. Furthermore, structure activity relationships (SAR) are briefly discussed. The anticancer screening of neocryptolepine derivatives was performed in order to determine their cytotoxic and growth inhibitory activities across the JFCR39 cancer cell line panel.

Synthesis and In Vitro Antiproliferative Activity of 11-Substituted Neocryptolepines with a Branched ω-Aminoalkylamino Chain.

Neocryptolepine, which is a kind of tetracyclic indoloquinoline alkaloid, exhibits the inhibition of topoisomerase II and shows antiproliferative activity. The present study describes the synthesis and antiproliferative evaluation of several neocryptolepine analogues carrying a branched, functionalized dibasic side chain at C11. These 2-substituted 5-methyl-indolo[2,3-b]quinoline derivatives were prepared by nucleophilic aromatic substitution (SNAr) of 11-chloroneocryptolepines with appropriate 1,2- and 1,3-diamines. Some of the 11-(ω-aminoalkylamino) derivatives were further transformed into 11-ureido and thioureido analogues. Many of the prepared neocryptolepine derivatives showed submicromolar antiproliferative activity against the human leukemia MV4-11 cell line. Among them, 11-(3-amino-2-hydroxy)propylamino derivatives 2h and 2k were the most cytotoxic with a mean IC50 value of 0.042 µM and 0.057 µM against the MV4-11 cell line, 0.197 µM and 0.1988 µM against the A549 cell line, and 0.138 µM and 0.117 µM against the BALB/3T3 cell line, respectively.

5-Methyl-N-(8-(5,6,7,8-tetrahydroacridin-9-ylamino)octyl)-5H-indolo[2,3-b]quinolin-11-amine: a highly potent human cholinesterase inhibitor.

The synthesis, cholinesterase inhibition, molecular modelling and ADME properties of novel tacrine-neocryptolepine heterodimers are described. Compound 3 [5-methyl-N-(8-(5,6,7,8-tetrahydroacridin-9-ylamino)octyl)-5H-indolo[2,3-b]quinolin-11-amine], showing a moderate inhibition of the Aß1-42 self-aggregation (26.5% at a 1 : 5 ratio with Aß1-42), and a calculated log BB value (0.27) indicating excellent potential BBB penetration, is a highly potent human cholinesterase inhibitor [IC50 (hAChE) = 0.95 ± 0.04 nM; IC50 (hBuChE) = 2.29 ± 0.14 nM] which can be listed among the most potent hAChE inhibitors so far identified, and is not hepatotoxic in vitro at the concentrations at which the ChEs are inhibited. A molecular modeling study was also undertaken in order to elucidate the AChE and the BuChE bind modes of all the new compounds. The docking results show that all of them bind to AChE in extended conformations and to BuChE in folded conformations. Moreover, these studies revealed that the length of the linker is crucial to binding both the catalytic anionic site and the peripheral anionic site.

Donepezil-like multifunctional agents: Design, synthesis, molecular modeling and biological evaluation.

Currently available drugs against Alzheimer's disease (AD) are only able to ameliorate the disease symptoms resulting in a moderate improvement in memory and cognitive function without any efficacy in preventing and inhibiting the progression of the pathology. In an effort to obtain disease-modifying anti-Alzheimer's drugs (DMAADs) following the multifactorial nature of AD, we have recently developed multifunctional compounds. We herein describe the design, synthesis, molecular modeling and biological evaluation of a new series of donepezil-related compounds possessing metal chelating properties, and being capable of targeting different enzymatic systems related to AD (cholinesterases, ChEs, and monoamine oxidase A, MAO-A). Among this set of analogues compound 5f showed excellent ChEs inhibition potency and a selective MAO-A inhibition (vs MAO-B) coupled to strong complexing properties for zinc and copper ions, both known to be involved in the progression of AD. Moreover, 5f exhibited moderate antioxidant properties as found by in vitro assessment. This compound represents a novel donepezil-hydroxyquinoline hybrid with DMAAD profile paving the way to the development of a novel class of drugs potentially able to treat AD.

Design, synthesis, and biological evaluation of artemisinin-indoloquinoline hybrids as potent antiproliferative agents.

A series of artemisinin-indoloquinoline hybrids were designed and synthesized in an attempt to develop potent and selective anti-tumor agents. Compounds 7a-7f, 8 and 9 were prepared and characterized. Their antiproliferative activities against MV4-11, HCT-116, A549, and BALB/3T3 cell lines in vitro were tested. Nearly all of the tested compounds (7-9, except for compounds 7d and 7e against HCT-116) showed an increased antitumor activity against HCT-116 and A549 cell lines when compared to the dihydroartemisinin control. Especially for the artemisinin-indoloquinoline hybrid 8, with an 11-aminopropylamino-10H-indolo[3,2-b]quinoline substituent, the antiproliferative activity against the A549 cell line had improved more than ten times. The IC50 value of hybrid 8 against A549 cell lines was decreased to 1.328 ± 0.586 µM, while dihydroartemisin showed IC50 value of >20 µM in the same cell line. Thus, these results have proven that the strategy of introducing a planar basic fused aromatic moiety, such as the indoloquinoline skeleton, could improve the antiproliferative activity and selectivity towards cancer cell lines.

Donepezil + propargylamine + 8-hydroxyquinoline hybrids as new multifunctional metal-chelators, ChE and MAO inhibitors for the potential treatment of Alzheimer's disease.

The synthesis, biochemical evaluation, ADMET, toxicity and molecular modeling of novel multi-target-directed Donepezil + Propargylamine + 8-Hydroxyquinoline (DPH) hybrids 1-7 for the potential prevention and treatment of Alzheimer's disease is described. The most interesting derivative was racemic α-aminotrile4-(1-benzylpiperidin-4-yl)-2-(((8-hydroxyquinolin-5-yl)methyl)(prop-2-yn-1-yl)amino) butanenitrile (DPH6) [MAO A (IC50 = 6.2 ± 0.7 µM; MAO B (IC50 = 10.2 ± 0.9 µM); AChE (IC50 = 1.8 ± 0.1 µM); BuChE (IC50 = 1.6 ± 0.25 µM)], an irreversible MAO A/B inhibitor and mixed-type AChE inhibitor with metal-chelating properties. According to docking studies, both DPH6 enantiomers interact simultaneously with the catalytic and peripheral site of EeAChE through a linker of appropriate length, supporting the observed mixed-type AChE inhibition. Both enantiomers exhibited a relatively similar position of both hydroxyquinoline and benzyl moieties with the rest of the molecule easily accommodated in the relatively large cavity of MAO A. For MAO B, the quinoline system was hosted at the cavity entrance whereas for MAO A this system occupied the substrate cavity. In this disposition the quinoline moiety interacted directly with the FAD aromatic ring. Very similar binding affinity values were also observed for both enantiomers with ChE and MAO enzymes. DPH derivatives exhibited moderate to good ADMET properties and brain penetration capacity for CNS activity. DPH6 was less toxic than donepezil at high concentrations; while at low concentrations both displayed a similar cell viability profile. Finally, in a passive avoidance task, the antiamnesic effect of DPH6 was tested on mice with experimentally induced amnesia. DPH6 was capable to significantly decrease scopolamine-induced learning deficits in healthy adult mice.

Synthesis, ß-haematin inhibition, and in vitro antimalarial testing of isocryptolepine analogues: SAR study of indolo[3,2-c]quinolines with various substituents at C2, C6, and N11.

A series of indolo[3,2-c]quinolines were synthesized by modifying the side chains of the ω-aminoalkylamines at the C6 position and introducing substituents at the C2 position, such as F, Cl, Br, Me, MeO and NO2, and a methyl group at the N11 position for an SAR study. The in vitro antiplasmodial activities of the derivative agents against two different strains (CQS: NF54 and CQR: K1) and the cytotoxic activity against normal L6 cells were evaluated. The test results showed that compounds 6k and 6l containing the branched methyl groups of 3-aminopropylamino at C6 with a Cl atom at C2 exhibited a very low cytotoxicity with IC50 values above 4000 nM, high antimalarial activities with IC50 values of about 11 nM for CQS (NF54), IC50 values of about 17 nM for CQR (K1), and RI resistance indices of 1.6. Furthermore, the compounds were tested for ß-haematic inhibition, and QSAR revealed an interesting linear correlation between the biological activity of CQS (NF54) and three contributing factors, namely solubility, hydrophilic surface area, and ß-haematin inhibition for this series. In vivo testing of 6l showed a reduction in parasitaemia on day 4 with an activity of 38%.

Synthesis and in vitro cytotoxic effect of 6-amino-substituted 11H- and 11Me-indolo[3,2-c]quinolines.

A series of 6-amino-11H- indolo[3,2-c]quinoline derivatives with various substituents on the quinoline ring were synthesized. A methyl group introduced to N-11 of the intermediate 4 to elaborate novel analog 7. The cytotoxic effect of these 6-amino-substituted 11H- and 11-methyl-indolo[3,2-c]quinoline derivatives in vitro were tested against MV4-11 (human leukemia), A549 (non-small cell lung cancer) and HCT116 (colon cancer) and BALB/3T3 (normal murine fibroblasts). All the N-11 methylated compounds significantly increased the cytotoxicity. Compound 7p was most active with the IC50 value of 0.052 µM against the MV4-11 cell line, and also exhibited a selective activity against A549, HCT116 and BALB/3T3 cell line, with the respective IC50 values of 0.112, 0.007 and 0.083 µM, which were higher or comparable to those of the anticancer drug doxorubicin HCl. The binding constants of 5g and 7h to salmon fish sperm DNA were also evaluated using UV-vis absorption spectroscopy, indicating intercalation binding with constants of 1.05 × 10(6) L/mol and 4.84 × 10(6) L/mol.

Design, synthesis, and in vitro cancer cell growth inhibition evaluation and antimalarial testing of trioxanes installed in cyclic 2-enoate substructures.

A novel series of 1,2,4-trioxanes were synthesized from 2H-pyrans via photooxidation, and their antiproliferative and growth factor inhibitory activity has been investigated across a variety of human cancer cell lines. Compounds 5k, 5l, 5s, 7a and 7c exhibited the highest activity and selectivity against a human leukemia (MV4-11) cell line (IC50 = 0.5 µM). Compound 5o showed the highest growth factor inhibitory activity against a melanoma (LOX-IMVI) cancer cell line (GI50 = 1.0 µM). A SAR study has confirmed the importance of the 1,2,4-trioxane unit as a pharmacophore for anticancer activity. The computer-assisted database analysis, COMPARE, has suggested that the compounds have unique mechanisms of actions that were different from those of known anticancer drugs. Some of the selected trioxanes were tested against the NF54 strain, albeit showing weak antiplasmodial activity. The molecular docking of trioxanes and hemin reveals that a short distance (1.30 Å) leads to their physical contact. The UV-vis spectroscopic analysis ensured the definite complexation between 1,2,4-trioxanes and hemin. The role of hemin-trioxane interaction in the hemin-induced oxidative damage has been studied using methylene blue as a substrate by UV-vis spectroscopy.

Cyclopentanoids from cyclopentadiene: synthesis of (-)-methyl jasmonate and (+)-12-oxophytodienoic acid.

Linoleic acid metabolites, (-)-methyl jasmonate and (+)-12-oxophytodienoic acid ((+)-12-oxo-PDA), were prepared from the same precursor (1,2-trans, 1,3-cis, 2'Z)-2-(pent-2'-enyl)-cyclopent-4-en-1,3-diol, which was obtained by regioselective pent-2-enylation of cyclopentadiene and following photooxidation to cis-1,3-diol. A methoxycarbonylmethyl substituent was introduced to the cyclopentane ring via alkylation of the pi-allyl palladium intermediate derived from (1R,2S,3S,2'Z)-3-acetoxy-2-(pent-2'-enyl)cyclopent-4-ene-1-ol with dimethyl malonate for (-)-methyl jasmonate. The alpha-chain was introduced to the cyclopentane ring via the S(N)2 type nucleophilic substitution of (1S,2R,3R,2'Z)-3-acetoxy-2-(pent-2'-enyl)cyclopent-4-ene-1-ol with a dialkylcuprate for (+)-12-oxo-PDA.

Synthesis and antimalarial testing of neocryptolepine analogues: addition of ester function in SAR study of 2,11-disubstituted indolo[2,3-b]quinolines.

This report describes the synthesis, and in vitro and in vivo antimalarial evaluations of certain ester-modified neocryptolepine (5-methyl-5H-indolo[2,3-b]quinoline) derivatives. The modifications were carried out by introducing ester groups at the C2 and/or C9 position on the neocryptolepine core and the terminal amino group of the 3-aminopropylamine substituents at the C11 position with a urea/thiourea unit. The antiplasmodial activities of our derivative agents against two different strains (CQS: NF54, and CQR: K1) and the cytotoxic activity against normal L6 cells were evaluated. The test results showed that the ester modified neocryptolepine derivatives have higher antiplasmodial activities against both strains and a low cytotoxic activity against normal cells. The best results were achieved by compounds 9c and 12b against the NF54 strain with the IC50/SI value as 2.27 nM/361 and 1.81 nM/321, respectively. While against K1 strain, all the tested compounds showed higher activity than the well-known antimalarial drug chloroquine. Furthermore, the compounds were tested for ß-haematin inhibition and 12 were found to be more active than chloroquine (IC50 = 18 µM). Structure activity relationship studies exposed an interesting linear correlation between polar surface area of the molecule and ß-haematin inhibition for this series. In vivo testing of compounds 7 and 8a against NF54 strain on Plasmodium berghei female mice showed that the introduction of the ester group increased the antiplasmodial activity of the neocryptolepine core substantially.

Synthesis and in vitro antimalarial testing of neocryptolepines: SAR study for improved activity by introduction and modifications of side chains at C2 and C11 on indolo[2,3-b]quinolines.

To obtain a high antimalarial activity with neocryptolepine derivatives, modifying and changing the side chains at the C11 position with varying the substituents of an electron-withdrawing or electron-donating nature at the C2 position for a SAR study were executed. Installation of alkylamino and ω-aminoalkylamino groups at the C11 position of the neocryptolepine core was successful. For further variation, the aminoalkylamino substituents were transformed into the corresponding acyclic or cyclic carbamides or thiocarbamides. These side chain modified neocryptolepine derivatives were tested for antimalarial activity against CQR (K1) and CQS (NF54) of Plasmodium falciparum in vitro and for cytotoxicity toward mammalian L6 cells. Among the tested compounds, the compound 17f showed an IC50 of 2.2 nM for CQS (NF54) and a selectivity index of 1400, and 17i showed an IC50 of 2.2 nM for CQR (K1), a selectivity index of 1243, and a resistance index of 0.5.

Synthesis and in vitro testing of antimalarial activity of non-natural-type neocryptolepines: structure­activity relationship study of 2,11- and 9,11-disubstituted 6-methylindolo[2,3-b]quinolines.

This report describes the synthesis and in vitro anti-malarial evaluations of certain C2 or C8 and C11-disubstituted 6-methyl-5H-indolo[2,3-b]quinoline (neocryptolepine congener) derivatives. To attain higher activities, the structure­activity relationship (SAR) studies were conducted by varying the kind of alkylamino or ω-aminoalkylamino stubstituents at C11 and with Cl at the C2 position, or CO2Me at the C9 position. The anti-malarial activities of the tested compounds were significantly increased compared to the 11-non(alkylamino) derivatives. The 3-aminopropylamino group at C11 was further modified to urea and thiourea, which improved the cytotoxicity against normal cells. The best results were achieved with compounds 8 and 9d against the NF54 strain with the IC(50)/SI values as of 86 nM/20 and 317 nM/370, respectively. Furthermore, the compounds were tested for ß-haematin inhibition. Twelve were found to have IC(50) values below 100 µM and a linear correlation between the ß-haematin inhibition and cell growth inhibition in the NF54 strain was found for those derivatives with basic amino side chains. A second correlation was identified between the NF54 activity and physico-chemical factors related to solvation and polarity.

Synthesis and in vitro antiproliferative activity of new 11-aminoalkylamino-substituted chromeno[2,3-b]indoles.

To search for new biological activities of the chromeno[2,3-b]indoles, the 5-oxa analog of the indolo[2,3-b]quinolines that are known to have a potent antitumor activity, a series of 11-amino derivatives with various substituents at the C-2 position were prepared. The synthesis of the chromeno[2,3-b]indole structure involves the cyclization of 2-phenoxy-3-indolecarboxylates 3, accessible from the indole-3-carboxylate 1 and phenols 2, producing the chromeno[2,3-b]indol-11(6H)-ones 4, which is followed by dehydroxychlorination with phosphorus oxychloride to afford the 11-chlorochromeno[2,3-b]indoles 5. The treatment of 5 with various amines produced the corresponding 11-aminated chromeno[2,3-b]indoles 6, while some of the 11-ω-aminoalkylamino derivatives 6 were transformed into the 11-ω-sulfonylaminoalkylamino derivatives 8. The antiproliferative activity of these 11-aminochromeno[2,3-b]indoles 6 and 8 in vitro were tested using MV4-11 (human leukemia), A549 (lung cancer), HCT116 (colon cancer), and the normal mice fibroblast (BALB/3T3) and their potencies were described.

Synthesis and in vitro antiproliferative activity of new 11-aminoalkylamino-substituted 5H- and 6H-indolo[2,3-b]quinolines; structure-activity relationships of neocryptolepines and 6-methyl congeners.

The present report describes the synthesis and antiproliferative evaluation of certain 11-aminoalkylamino-substituted 5H- and 6H-indolo[2,3-b]quinolines and their methylated derivatives. These 5-Me- and 6-Me-indolo[2,3-b]quinoline derivatives 10-14, 20 were prepared by amination at the C-11 position of the 11-chloro-5-methyl-5H- and 11-chloro-6-methyl-6H-indolo[2,3-b]quinolines with different substituents on the quinoline ring. The 11-aminoalkylaminomethylated 23, the homologue of 11, was prepared from the same intermediate for a further SAR study. These intermediates are accessible from 4-substituted anilines or their N-methylated analogues and methyl indole-3-carboxylate as a counterpart. The in vitro antiproliferative assay indicated that the 5-methylated derivatives 10-14 are more cytotoxic than their respective 6-methylated 6H-indolo[2,3-b]quinoline derivatives 20. Among them, N-(3-aminopropyl)-2-bromo-5-methyl-5H-indolo[2,3-b]quinolin-11-amine 12f was the most cytotoxic with a mean IC(50) value of 0.12 µM against human leukemia MV4-11 cell line, and also exhibited selective cytotoxicities against A549 (lung cancer), HCT116 (colon cancer) cell lines and normal fibroblast BALB/3T3 with IC(50) values of 0.543, 0.274 and 0.869 µM, respectively. The binding constant of products 12f and 20f to salmon fish sperm DNA were also evaluated using UV-vis absorption spectroscopy, indicating intercalation binding with a constant of 2.93×10(5) and 3.28×10(5)Lmol(-1), respectively.

Solvent-free microwave-assisted multi-component reaction for preparation of 2-amino-1-aryl-2-(cyclohex-1-enyl)ethanones as precursors of pseudoephedrine analogues.

Microwave irradiation of chloroacetylarenes and enamines induced an aza-Darzens reaction followed by rearrangement of the aziridinium intermediate to give (2-amino-3-alkenoyl)arenes that were reduced selectively to syn-beta-aminoalcohols as pseudo-ephedrine analogues.

Synthetic access to poly-substituted 6-alkoxyindoles from 1,3-cyclohexanediones and nitroolefins through facile aromatization reaction.

6-Alkoxy-3-arylindoles were efficiently prepared from 1,3-cyclohexanedione enol ethers and beta-nitrostyrenes. Michael addition using the kinetically generated enolate, followed by Zn reduction of a nitro group of the resulting adducts produced the nitrones which were then treated with acetic anhydride to induce aromatization by dehydration and N-acetylation, which furnished the desired indoles by the DDQ oxidation. This methodology provides an easy entry toward various poly-substituted 6-alkoxyindoles.

Alkylation, aldol, and related reactions of O-alkanoyl- and 2-alkenoylTEMPOs (2,2,6,6-tetramethylpiperidine-N-oxyl): insight into the reactivity of their anionic species in comparison with esters and amides.

The lithium anionic species generated from O-alkanoylTEMPOs upon treatment with LDA were first employed as a nucleophile for alkylation, Michael addition, direct aldol reaction, and others. The alkylation occurred smoothly at the methylene carbon, and no alkylation was found in the isobutyryl analogue, while silylation was scarcely attainable. Substitutions of the heteroatom were achieved by reaction with PhSSPh and DEAD. The reactivity of these anionic species is successfully extended to aldol reactions in which moderate anti or syn selectivity was executed with propionyl derivatives. Tandem Michael addition of lithium amide followed by aldol reaction was performed on the O-crotonoylTEMPOs.

E- or Z-selective Knoevenagel condensation of acetoacetic derivatives: effect of acylated substituent, that is, TEMPO and amines, as an auxiliary, and new accesses to trisubstituted E- and Z-2-alkenals and furans.

Knoevenagel condensation of O-acetoacetylTEMPOs (2,2,6,6-tetramethylpiperidine-1-oxyl) with aldehydes substituted with an electron-withdrawing group such as aromatic and heteroaromatic ones leads preferentially to E-adducts, while acylacetoamides including Weinreb amides produce Z-adducts, exclusively. These E- and Z-adducts are selectively converted to the corresponding (2E)- and (2Z)-2-hyroxyalkyl-2-alkenals, respectively, by stepwise reductions of the acyl group with DIBALH and then the carboxylic functions after protection of the hydroxy group. Transformation of the Knoevenagel products by taking advantage of the E-geometry to trisubstituted furans is also developed.