Aziridinyl quinone antitumor agents based on indoles and cyclopent[b]indoles: structure-activity relationships for cytotoxicity and antitumor activity

Synthesis, molecular docking and mosquitocidal efficacy of lawsone and its derivatives against the dengue vector Aedes aegypti L. (Diptera: Culicidae)

BACKGROUND

Aedes aegypti is the primary dengue vector, a significant public health problem in many countries. Controlling the growth of Ae. aegypti is the biggest challenge in the mosquito control program, and there is a need for finding bioactive molecules to control Ae. aegypti in order to prevent dengue virus transmission.

OBJECTIVE

To assess the mosquitocidal property of lawsone and its 3-methyl-4H-chromen-3-yl-1-phenylbenzo[6,7]chromeno[2,3,c]pyrazole-dione derivatives (6a-6h) against various life stages of Ae. aegypti. Besides, to study the mode of action of the active compound by molecular docking and histopathological analysis.

METHODS

All derivatives were synthesized from the reaction between 2-hydroxy-1,4-naphthoquinone, chromene-3-carbaldehyde, and 1-phenyl-3-methyl-pyrazol-5-one by using one pot sequential multicomponent reaction. The mosquito life stages were subjected to diverse concentrations ranging from 1.25, 2.5, 5.0, and 10 ppm for lawsone and its derivatives. The structure of all synthesized compounds was characterized by spectroscopic analysis. Docking analysis was performed using autodock tools. Midgut sections of Ae. aegypti larvae were analyzed for histopathological effects.

RESULTS

Among the nine compounds screened, derivative 6e showed the highest mortality on Ae. aegypti life stages. The analyzed LC50 and LC90 results of derivative 6e were 3.01, 5.87 ppm, and 3.41, 6.28 ppm on larvae and pupae of Ae. aegypti, respectively. In the ovicidal assay, the derivative 6e recorded 47.2% egg mortality after 96-hour post-exposure to 10 ppm concentration. In molecular docking analysis, the derivative 6e confirmed strong binding interaction (-9.09 kcal/mol and -10.17 kcal/mol) with VAL 60 and HIS 62 of acetylcholinesterase 1 (AChE1) model and LYS 255, LYS 263 of kynurenine aminotransferase of Ae. aegypti, respectively. The histopathological results showed that the derivative 6e affected the columnar epithelial cells (CC) and peritrophic membrane (pM).

CONCLUSION

The derivative 6e is highly effective in the life stages of Ae. aegypti mosquito and it could be used in the integrated mosquito management programme.

Copper-catalyzed [4+1]-annulation of 2-alkenylindoles with diazoacetates: a facile access to dihydrocyclopenta[b]indoles

A copper-catalyzed [4+1]-annulation of 2-vinylindoles with diazoacetates: a facile access to the dihydrocyclopenta[b]indoles bearing two contiguous all-carbon quaternary centers.

The Antifungal Activity of Naphthoquinones: An Integrative Review

Naphthoquinones are the most commonly occurring type of quinones in nature. They are a diverse family of secondary metabolites that occur naturally in plants, lichens and various microorganisms. This subgroup is constantly being expanded through the discovery of new natural products and by the synthesis of new compounds via innovative techniques. Interest in quinones and the search for new biological activities within the members of this class have intensified in recent years, as evidenced by the evaluation of the potential antimicrobial activities of quinones. Among fungi of medical interest, yeasts of the genus Candida are of extreme importance due to their high frequency of colonization and infection in humans. The objective of this review is to describe the development of naphthoquinones as antifungals for the treatment of Candida species and to note the most promising compounds. By using certain criteria for selection of publications, 68 reports involving both synthetic and natural naphthoquinones are discussed. The activities of a large number of substances were evaluated against Candida albicans as well as against 7 other species of the genus Candida. The results discussed in this review allowed the identification of 30 naphthoquinones with higher antifungal activities than those of the currently used drugs.

Naïve Bayesian Models for Vero Cell Cytotoxicity

PURPOSE

To advance translational research of potential therapeutic small molecules against infectious microbes, the compounds must display a relative lack of mammalian cell cytotoxicity. Vero cell cytotoxicity (CC₅₀) is a common initial assay for this metric. We explored the development of naïve Bayesian models that can enhance the probability of identifying non-cytotoxic compounds.

METHODS

Vero cell cytotoxicity assays were identified in PubChem, reformatted, and curated to create a training set with 8741 unique small molecules. These data were used to develop Bayesian classifiers, which were assessed with internal cross-validation, external tests with a set of 193 compounds from our laboratory, and independent validation with an additional diverse set of 1609 unique compounds from PubChem.

RESULTS

Evaluation with independent, external test and validation sets indicated that cytotoxicity Bayesian models constructed with the ECFP_6 descriptor were more accurate than those that used FCFP_6 fingerprints. The best cytotoxicity Bayesian model displayed predictive power in external evaluations, according to conventional and chance-corrected statistics, as well as enrichment factors.

CONCLUSIONS

The results from external tests demonstrate that our novel cytotoxicity Bayesian model displays sufficient predictive power to help guide translational research. To assist the chemical tool and drug discovery communities, our curated training set is being distributed as part of the Supplementary Material. Graphical Abstract Naive Bayesian models have been trained with publically available data and offer a useful tool for chemical biology and drug discovery to select for small molecules with a high probability of exhibiting acceptably low Vero cell cytotoxicity.

Investigation of cobalt(iii)–TPA complexes as potential bioreductively activated carriers for naphthoquinone-based drugs

Differently from CH₃, halogens as substituents foster incorporation of methoxide into NQs upon complexation.

Ultrasound assisted one-pot synthesis of benzo-fused indole-4, 9-dinones from 1,4-naphthoquinone and α-aminoacetals

A one-pot synthesis of benzo[f]indole-4,9-diones from 1,4-naphthoquinone with α-aminoacetals has been developed. This method provides a straightforward synthesis of benzo[f]indole-4,9-diones via intramolecular nucleophilic attack of aminoquinones to aldehydes under mild reaction conditions. The detailed mechanism was also investigated.

Synthesis and antitumor activity evaluation of novel substituted 5H-benzo[i][1,3,4]thiadiazolo[3,2-a]quinazoline-6,7-diones

A series of novel substituted 5H-benzo[i][1,3,4]thiadiazolo[3,2-a]quinazoline-6,7-diones were synthesized and all compounds exhibited excellent antitumor activities.

Synthetic methodologies leading to porphyrin-quinone conjugates

This review focuses on synthetic strategies that have been established for the preparation of porphyrin-quinone conjugates of potential biological significance and as donor–acceptor compounds for electron transfer processes.

Synthesis and biological evaluation of indolyl-pyridinyl-propenones having either methuosis or microtubule disruption activity

Methuosis is a form of nonapoptotic cell death characterized by an accumulation of macropinosome-derived vacuoles with eventual loss of membrane integrity. Small molecules inducing methuosis could offer significant advantages compared to more traditional anticancer drug therapies that typically rely on apoptosis. Herein we further define the effects of chemical substitutions at the 2- and 5-indolyl positions on our lead compound 3-(5-methoxy-2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propene-1-one (MOMIPP). We have identified a number of compounds that induce methuosis at similar potencies, including an interesting analogue having a hydroxypropyl substituent at the 2-position. In addition, we have discovered that certain substitutions on the 2-indolyl position redirect the mode of cytotoxicity from methuosis to microtubule disruption. This switch in activity is associated with an increase in potency as large as 2 orders of magnitude. These compounds appear to represent a new class of potent microtubule-active anticancer agents.

Lawsone in organic synthesis

Lawsone has been used as the starting material for the synthesis of a variety of biologically active compounds and materials.

BPR0C305, an orally active microtubule-disrupting anticancer agent

BPR0C305 is a novel N-substituted indolyl glyoxylamide previously reported with in-vitro cytotoxic activity against a panel of human cancer cells including P-gp-expressing multiple drug-resistant cell sublines. The present study further examined the underlying molecular mechanism of anticancer action and evaluated the in-vivo antitumor activities of BPR0C305. BPR0C305 is a novel synthetic small indole derivative that demonstrates in-vitro activities against human cancer cell growth by inhibiting tubulin polymerization, disrupting cellular microtubule assembly, and causing cell cycle arrest at the G2/M phase. It is also orally active against leukemia and solid tumor growths in mouse models. Findings of these pharmacological and pharmacokinetic studies suggest that BPR0C305 is a promising lead compound for further preclinical developments.

Gas-phase reactivity of 2-hydroxy-1,4-naphthoquinones: a computational and mass spectrometry study of lapachol congeners

In order to understand the influence of alkyl side chains on the gas-phase reactivity of 1,4-naphthoquinone derivatives, some 2-hydroxy-1,4-naphthoquinone derivatives have been prepared and studied by electrospray ionization tandem mass spectrometry in combination with computational quantum chemistry calculations. Protonation and deprotonation sites were suggested on the basis of gas-phase basicity, proton affinity, gas-phase acidity (ΔG(acid) ), atomic charges and frontier orbital analyses. The nature of the intramolecular interaction as well as of the hydrogen bond in the systems was investigated by the atoms-in-molecules theory and the natural bond orbital analysis. The results were compared with data published for lapachol (2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone). For the protonated molecules, water elimination was verified to occur at lower proportion when compared with side chain elimination, as evidenced in earlier studies on lapachol. The side chain at position C(3) was found to play important roles in the fragmentation mechanisms of these compounds.

Characterization of novel synthesized small molecular compounds against non-small cell lung cancer

BACKGROUND

With the exception of surgery, the standard platinum-based chemotherapeutic agents are the preferred treatment for non-small cell lung cancer (NSCLC); however little improvement (5-year survival) has been made. Therefore it is highly desirable to develop innovative therapeutic agents for NSCLC treatment.

METHODS

Highly enantioselective synthetic methods were developed and a broad compound library was established. Cell toxicity, cell sensitivity, cell proliferation, cell invasion, and three-dimensional colony formation assays were used to assess the anticancer potential of these compounds in non-small-cell lung cancer (NSCLC) cell lines.

RESULTS

We found that the S-form of compound PL54 (PL54S, 5-20 μM) exhibited strong anticancer activity in 5 tested NSCLC cell lines. We further synthesized a highly pure R-form enantiomer of PL54 (PL54R) and its racemate (PL54Rac) and characterized their anticancer activities. The results showed that PL54S is more potent than PL54R and PL54Rac against the tested cell lines. Furthermore, less cellular toxicity was observed in the normal human lung fibroblasts. Similarly, PL54S displayed greater anti-colony formation activity compared with PL54R and PL54Rac. The cellular sensitivity assay revealed that PL54S and PL54Rac significantly suppressed cologenic formation compared with PL54R and dimethyl sulfoxide controls (p<0.01). All PL54 compounds (5 to 20 μM) significantly inhibited cell proliferation and invasion of the A549 cell line (p<0.01). A soft agar colony formation assay revealed that PL54S and PL54Rac (10 mM), but not PL54R, significantly inhibited colony formation of tested NSCLC cells (p<0.01).

CONCLUSIONS

The stereospecific compounds may prove to be a novel technique for the treatment of NSCLC.

First synthesis of an aziridinyl fused pyrrolo[1,2-a]benzimidazole and toxicity evaluation towards normal and breast cancer cell lines

Anionic aromatic ipso-substitution has allowed an aziridine ring to be fused onto pyrrolo[1,2-a]benzimidazole. This diazole analogue of aziridinomitosene, and N-[(aziridinyl)methyl]-1H-benzimidazole are shown to be significantly more cytotoxic towards the human breast cancer cell lines MCF-7 and HCC1937 than towards a human normal fibroblast cell line (GM00637). The aziridinyl fused pyrrolo[1,2-a]benzimidazole is less cytotoxic than the non-ring fused aziridinyl analogue towards all three cell lines. The BRCA1-deficient HCC1937 cells are more sensitive to mitomycin C (MMC) compared to GM00637 and MCF-7 cells. The evidence provided indicates that different pathways may mediate cellular response to benzimidazole-containing aziridine compounds compared to MMC.

Novel, one-pot, three-component route to indol-3-yl substituted spirooxindole derivatives

A simple and efficient approach to the synthesis of a novel series of polysubstituted 6'-(1H-indol-3-yl)-1',7'-dihydrospiro[indoline-3,4'-pyrazolo[3,4-b]pyridine]-2-one derivatives in high yields was developed from a one-pot, three-component reaction of 3-cyanoacetyl indoles, isatins, and 1H-pyrazol-5-amines in H(2)O/HOAc.

{2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic acid methyl ester (MIAM): its anti-cancer efficacy and intercalation mechanism identified via multi-model systems

{2-[1-(3-Methoxycarbonylmethyl-1H-indol-2-yl)-1-methyl-ethyl]-1H-indol-3-yl}-acetic acid methyl ester (MIAM) was provided as a DNA-intercalator. For the comprehensive evaluation of this new intercalator, an assay system consisting of cell, S180 mouse, healthy mouse, spectrum, non-spectrum, and gel electrophoresis models was constructed. On the cell (S180, K562, MCF-7, HeLa and HepG2) models, MIAM selectively inhibited the viability of HeLa. On the S180 mouse model, 0.89, 8.9, 89 and 890 μmol kg(-1) of MIAM dose-dependently inhibited the tumor growth. Even at a dose of 890 μmol kg(-1), MIAM did not damage the treated S180 mice. The safety of MIAM was supported by a high spleen index and an obvious increase of body weight of the treated S180 mice. On the healthy mouse model the LD(50) value of MIAM is higher than 890 μmol kg(-1). The ultraviolet (UV), fluorescence, circular dichroism (CD), relative viscosity, melting curve, and gel electrophoresis assays of DNA with or without MIAM consistently supported an intercalation mechanism for MIAM.

Discovery of quinolinediones exhibiting a heat shock response and angiogenesis inhibition

A series of substituted quinoline-5,8-diones were synthesized and evaluated as inhibitors of the chaperone protein Hsp90 using two assays: competition for binding to C-terminal ATP-binding site and competition for binding to N-terminal ATP-binding site. In addition, the ability of the compounds to induce the heat shock response was determined using a reporter fibroblast cell line. Of all the compounds assayed, only 6-aziridinyl-2-biphenylquinoline-5,8-dione induced a heat shock response and did so without interacting at the ATP binding sites of Hsp90. COMPARE analysis was carried out on quinoline-5,8-diones active in the National Cancer Institute's 60-cell line screen with the goal of discovering quinoline-5,8-dione structures that interact with other cellular targets (molecular targets) important for cancer chemotherapy. COMPARE analysis led to the discovery of a combretastatin-like quinoline-5,8-dione structure that, in fact, inhibited angiogenesis.

Synthesis and potent antitumor activity of new arylamino derivatives of nor-β-lapachone and nor-α-lapachone

Several arylamino derivatives of nor-beta-lapachone were synthesized in moderate to high yields and found to show very potent cytotoxicity against six neoplastic cancer cells: SF-295 (central nervous system), HCT-8 (colon), MDAMB-435 (breast), HL-60 (leukaemia), PC-3 (prostate), and B-16 (murine melanoma), with IC(50) below 1 microg/mL. Their cytotoxicities were compared to doxorubicin and with their synthetic precursors, beta-lapachone and nor-beta-lapachone. The activity against a normal murine fibroblast L-929 showed that some of the compounds were selective against cancer cells. The absence of hemolytic activity (EC(50)>200 microg/mL), performed with erythrocyte suspensions, suggests that the cytotoxicity of the compounds was not related to membrane damage of mouse erythrocytes. For comparison purposes, one isomeric compound based on nor-alpha-lapachone was also synthesized and showed lower activity than the related ortho-derivative. The modified arylamino quinones appear as interesting new lead compounds in anti-cancer drug development.

Synthesis of marine alkaloid: 8,9-dihydrocoscinamide B and its analogues as Novel class of antileishmanial agents

A series of marine alkaloid 8,9-dihydrocoscinamide B, its analogues and indolylglyoxylamide derivatives have been synthesized and screened for their in vitro antileishmanial activity profile in promastigote and amastigote models. Compounds 7 and 10 have shown 99-100% inhibition against promastigotes and 97-98% inhibition against amastigotes at a concentration of 10 microg/ml.

Indolequinone antitumour agents: correlation between quinone structure and rate of metabolism by recombinant human NAD(P)H:quinone oxidoreductase

A series of indolequinones bearing a range of substituents at the (indol-2-yl)methyl position has been synthesized. The ability of these indolequinones to act as substrates for recombinant human NAD(P)H:quinone oxidoreductase (NQO1), a two-electron reductase upregulated in tumour cells, was determined, along with their toxicity to an isogenic tumour cell line pair that is differentiated as either NQO1-expressing cells (BE-NQ) or NQO1-null cells (BE-WT). Overall, the 2-substituted indolequinones were relatively poor substrates for NQO1. Hydroxymethyl groups at C-2 led to higher rates of reduction, a finding that was observed previously with 3-hydroxymethylated indolequinones. Predictably, the best substrate had an electron-withdrawing ester group at the indole-2-position. The indolequinones were generally non-toxic to both cell lines with the exception of those quinones that had methylaziridine groups at the indole-5-position. These compounds could form DNA cross-links when activated by reduction and were up to 3-fold more toxic to the BE-NQ cells than the BE-WT cells.