Multimodal action of antitumor agents on DNA: the ellipticine series

Bioactivities and Action Mechanisms of Ellipticine Derivatives Reported Prior to 2023

Currently, natural products are one of the priceless options for finding novel chemical pharmaceutical entities. Ellipticine is a naturally occurring alkaloid isolated from the leaves of Ochrosia elliptica Labill. Ellipticine and its derivatives are characterized by multiple biological activities. The purpose of this review was to provide a critical and systematic assessment of ellipticine and its derivatives as bioactive molecules over the last 60 years. Publications focused mainly on the total synthesis of alkaloids of this type without any evaluation of bioactivity have been excluded. We have reviewed papers dealing with the synthesis, bioactivity evaluation and mechanism of action of ellipticine and its derivatives. It was found that ellipticine and its derivatives showed cytotoxicity, antimicrobial ability, and anti-inflammatory activity, among which cytotoxicity toward cancer cell lines was the most investigated aspect. The inhibition of DNA topoisomerase II was the most relevant mechanism for cytotoxicity. The PI3K/AKT pathway, p53 pathway, and MAPK pathway were also closely related to the antiproliferative ability of these compounds. In addition, the structure-activity relationship was deduced, and future prospects were outlined. We are confident that these findings will lay a scientific foundation for ellipticine-based drug development, especially for anticancer agents.

Biological properties of pyrroloquinoline and pyrroloisoquinoline derivatives

In this review, we summarize pyrroloquinoline and pyrroloisoquinoline derivatives (PQs and PIQs) that act on a broad spectrum of biological targets and are used as bacteriostatic, antiviral, plasmodial, anticancer, antidiabetic and anticoagulant agents. Many of these compounds play important roles in the study of DNA and its interactions, the regulation of the cell cycle and programmed cell death. This review involves twenty-five types of skeletally analogical compounds bearing pyrrole and (iso)quinoline scaffolds with different mutual annelations.

The potential mechanism of Chebulae Fructus in the treatment of hepatocellular carcinoma on the basis of network pharmacology

INTRODUCTION AND OBJECTIVES

Hepatocellular carcinoma (HCC) ranks third on the list of the leading cause for cancer death globally. The treatment of HCC patients is unsatisfactory. However, the traditional Chinese medicine Chebulae Fructus has potential efficacy in the treatment of HCC.

MATERIALS AND METHODS

We mined the active ingredients of Chebulae Fructus and its main targets from the Traditional Chinese Medicine Systems Pharmacology database. HCC-related datasets were downloaded from The Cancer Genome Atlas database and differentially expressed genes (DEGs) in HCC were obtained by differential expression analysis. Top10 small molecule compounds capable of reversing HCC pathology were screened by the Connectivity Map database based on DEGs. Ellipticine, an extract of Chebulae Fructus, had the potential to reverse HCC pathology. Protein-Protein Interaction (PPI) networks of DEGs in HCC were constructed using STRING. Eighteen potential targets of Chebulae Fructus for the treatment of HCC were obtained by taking intersection of DEGs in HCC with targets corresponding to the active constituents of Chebulae Fructus. In addition, MTT assay was also employed to examine the effect of ellipticine on HCC cell viability.

RESULTS

It has been shown that ellipticine and ellagic acid have antitumor activity. Random Walk with Restart analysis of PPI networks was performed using potential targets as seeds, and the genes with the top 50 affinity coefficients were selected to construct a drug-active constituent-gene interaction network. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of key genes involved in the treatment of HCC with Chebulae Fructus demonstrated that these genes were mainly enriched in signaling pathways related to tumor metabolism such as cAMP signaling pathway and Ras signaling pathway. Finally, it was verified by MTT assay that proliferation of HCC cells could be remarkably hindered.

CONCLUSIONS

We excavated ellipticine, a key active constituent of Chebulae Fructus, by network pharmacology, and elucidated the signaling pathways involved in Chebulae Fructus, providing a theoretical basis for the use of Chebulae Fructus for HCC clinical application.

Lysosomal Exocytosis of Olivacine on the Way to Explain Drug Resistance in Cancer Cells

Ellipticine is an indole alkaloid with proven antitumor activity against various tumors in vitro and a diverse mechanism of action, which includes topoisomerase II inhibition, intercalation, and cell cycle impact. Olivacine—ellipticine’s isomer—shows similar properties. The objectives of this work were as follows: (a) to find a new path of olivacine synthesis, (b) to study the cytotoxic properties of olivacine and ellipticine in comparison to doxorubicin as well as their impact on the cell cycle, and (c) to investigate the cellular pharmacokinetics of the tested compounds to understand drug resistance in cancer cells better. SRB and MTT assays were used to study the anticancer activity of olivacine and ellipticine in vitro. Both compounds showed a cytotoxic effect on various cell lines, most notably on the doxorubicin-resistant LoVo/DX model, with olivacine’s cytotoxicity approximately three times higher than doxorubicin. Olivacine proved to be less effective against cancer cells and less cytotoxic to normal cells than ellipticine. Olivacine proved to have fluorescent properties. Microscopic observation of cells treated with olivacine showed the difference in sensitivity depending on the cell line, with A549 cells visibly affected by a much lower concentration of olivacine than normal NHDF cells. An increased percentage of cells in G0/G1 was observed after treatment with olivacine and ellipticine, suggesting an impact on cell cycle progression, potentially via higher p53 protein expression, which blocks the transition from G0/G1 to the S phase. Ellipticine induced apoptosis at a concentration as low as 1 μM. It has been proved that the tested compounds (ellipticine and olivacine) undergo lysosomal exocytosis. Reducing exocytosis is possible through the use of compounds that inhibit the activity of the proton pump. Olivacine and ellipticine exhibited diverse cytotoxicity against a panel of cancer cells. Analysis of the lysosomal exocytosis of olivacine and ellipticine shows the need to look for derivatives with comparable anticancer activity but reduced weak base character.

Evaluation of Interactions of Selected Olivacine Derivatives with DNA and Topoisomerase II

Olivacine and ellipticine are model anticancer drugs acting as topoisomerase II inhibitors. Here, we present investigations performed on four olivacine derivatives in light of their antitumor activity. The aim of this study was to identify the best antitumor compound among the four tested olivacine derivatives. The study was performed using CCRF/CEM and MCF-7 cell lines. Comet assay, polarography, inhibition of topoisomerase II activity, histone acetylation, and molecular docking studies were performed. Each tested compound displayed interaction with DNA and topoisomerase II, but did not cause histone acetylation. Compound 2 (9-methoxy-5,6-dimethyl-1-({[1-hydroxy-2-(hydroxymethyl)butan-2-yl]amino}methyl)-6H-pyrido[4,3-b]carbazole) was found to be the best candidate as an anticancer drug because it had the highest affinity for topoisomerase II and caused the least genotoxic damage in cells.

Effective Antibacterial and Antihemolysin Activities of Ellipticine Hydrochloride against Streptococcus suis in a Mouse Model

Streptococcal toxic shock-like syndrome (STSLS) caused by the epidemic strain of Streptococcus suis leads to severe inflammation and high mortality. The life and health of humans and animals are also threatened by the increasingly severe antimicrobial resistance in Streptococcus suis There is an urgent need to discover novel strategies for the treatment of S. suis infection. Suilysin (SLY) is considered to be an important virulence factor in the pathogenesis of S. suis In this study, ellipticine hydrochloride (EH) was reported as a compound that antagonizes the hemolytic activity of SLY. In vitro, EH was found to effectively inhibit SLY-mediated hemolytic activity. Furthermore, EH had a strong affinity for SLY, thereby directly binding to SLY to interfere with the hemolytic activity. Meanwhile, it was worth noting that EH was also found to have a significant antibacterial activity. In vivo, compared with traditional ampicillin, EH not only significantly improved the survival rate of mice infected with S. suis 2 strain Sc19 but also relieved lung pathological damage. Furthermore, EH effectively decreased the levels of inflammatory cytokines (interleukin-6 [IL-6], tumor necrosis factor alpha [TNF-α]) and blood biochemistry enzymes (alanine transaminase [ALT], aspartate transaminase [AST], creatine kinase [CK]) in Sc19-infected mice. Additionally, EH markedly reduced the bacterial load of tissues in Sc19-infected mice. In conclusion, our findings suggest that EH can be a potential compound for treating S. suis infection in view of its antibacterial and antihemolysin activity.IMPORTANCE In recent years, the inappropriate use of antibiotics has unnecessarily caused the continuous emergence of resistant bacteria. The antimicrobial resistance of Streptococcus suis has also become an increasingly serious problem. Targeting virulence can reduce the selective pressure of bacteria on antibiotics, thereby alleviating the development of bacterial resistance to a certain extent. Meanwhile, the excessive inflammatory response caused by S. suis infection is considered the primary cause of acute death. Here, we found that ellipticine hydrochloride (EH) exhibited effective antibacterial and antihemolysin activities against S. suisin vitroIn vivo, compared with ampicillin, EH had a significant protective effect on S. suis serotype 2 strain Sc19-infected mice. Our results indicated that EH, with dual antibacterial and antivirulence effects, will contribute to treating S. suis infections and alleviating the antimicrobial resistance of S. suis to a certain extent. More importantly, EH may develop into a promising drug for the prevention of acute death caused by excessive inflammation.

Synthesis of Carbazoles by a Diverted Bischler-Napieralski Cascade Reaction

An unforeseen twist in a seemingly trivial Bischler–Napieralski reaction led to the selective formation of an unexpected carbazole product. The reaction proved to be general, providing access to a range of diversely substituted carbazoles from readily available substrates. Judicious variation of substituents revealed a complex cascade mechanism comprising no less than 10 elementary steps, that could be diverted in multiple ways toward various other carbazole derivatives.

Synthesis, Cytotoxicity, ADMET and Molecular Docking Studies of Some Quinoline-Pyrimidine Hybrid Compounds: 3-(2-Amino-6-arylpyrimidin-4- yl)-4-hydroxy-1-methylquinolin-2(1H)-ones

AIMS

Synthesis of 3-(2-amino-6-arylpyrimidin-4-yl)-4-hydroxy-1-methylquinolin-2(1H)-ones and estimation their anticancer activities on HepG2 and KB cancer lines.

BACKGROUND

Many derivatives of quinoline-2-on have been consider to synthesize and evaluate their biological properties by organic chemists due to their various biological effects, including antibacterial, antioxidant, anti-inflammatory, anticancer activities. Quinolinepyrimidine hybrid compounds exhibited various biological activities, such as antituberculosis, antibacterial, anticancer, antifungal, etc. The connection of 4-hydroxyquinoline-2-one with 2-amino-pyrimidine could initiate the new activities.

OBJECTIVE

α,β-Unsaturated ketones of 3-acetyl-4-hydroxy-N-methylquinolin-2-one were prepared. Novel 2-amino-6-aryl-4-(4'-hydroxy-Nmethylquinolin- 2'-on-3'-yl)pyrimidines have been synthesized by reaction of these corresponding α,β-unsaturated ketones with guanidine hydrochloride. Human hepatocellular carcinoma HepG2 and squamous cell carcinoma KB cancer lines were used for screening their cytotoxicity.

METHOD

3-Acetyl-4-hydroxy-N-methylquinolin-2-one was prepared from N-methylaniline and diethyl malonate. Reaction of (un)substituted benzaldehydes with this 4-hydroxyquinoline-2-one produced corresponding substituted α ,β-unsaturated ketones in the presence of piperidine as catalyst. 2-Amino-6-aryl-4-(4'-hydroxy-N-methylquinolin-2'-on-3'-yl)pyrimidines have been synthesized from these α,β-unsaturated ketones of 3-acetyl-4-hydroxy-N-methylquinolin-2-one by reaction of corresponding α ,β-unsaturated ketones with guanidine hydrochloride. All obtained pyrimidines were screened for anticancer activity using MTT bio-assay method.

RESULT

Seven substituted (E)-4-hydroxy-3-(3-(aryl)acryloyl)-1-methylquinolin-2(1H)-ones were prepared and converted to corresponding substituted 2-amino-6-aryl-4-(4'-hydroxy-N-methylquinolin-2'-on-3'-yl)pyrimidines with yields of 58-74%. All the synthesized pyrimidines were screened for their in vitro anticancer activity against human hepatocellular carcinoma HepG2 and squamous cell carcinoma KB cancer lines. Compounds 6b and 6e had the best activity in the series, with IC50 values equal to 1.32 and 1.33 μM, respectively. ADMET properties showed that compounds 6b, 6e, and 6f possessed the drug-likeness behavior. Cross-docking results indicated that residues GLN778(A), DT8(C), DT9(D), DA12(F), and DG13(F) in the binding pocket as potential ligand binding hot-spot residues for compounds 6b, 6e, and 6f.

CONCLUSION

New substituted 2-amino-6-aryl-4-(4'-hydroxy-N-methylquinolin-2'-on-3'-yl)pyrimidines were obtained and displayed significant inhibition against human hepatocellular carcinoma HepG2 and squamous cell carcinoma KB cancer lines.

Anticancer and Immunomodulatory Activities of a Novel Water-Soluble Derivative of Ellipticine

Cancer still remains a major public health concern around the world and the search for new potential antitumor molecules is essential for fighting the disease. This study evaluated the anticancer and immunomodulatory potential of the newly synthetized ellipticine derivate: sodium bromo-5,11-dimethyl-6H-pyrido[4,3-b]carbazole-7-sulfonate (Br-Ell-SO₃Na). It was prepared by the chlorosulfonation of 9-bromoellipticine. The ellipticine-7-sulfonic acid itself is not soluble, but its saponification with sodium hydroxide afforded a water-soluble sodium salt. The cytotoxicity of Br-Ell-SO₃Na was tested against cancerous (K562 cell line) and non-cancerous cells (Vero cell line and human peripheral blood mononuclear cells (PBMC)) using a Methylthiazoletetrazolium (MTT) assay. Cell cycle arrest was assessed by flow cytometry and the immunomodulatory activity was analyzed through an enzyme-linked immunosorbent assay (ELISA)_. The results showed that the Br-Ell-SO₃Na molecule has specific anticancer activity (IC₅₀ = 35 µM) against the K562 cell line, once no cytotoxicity effect was verified against non-cancerous cells. Cell cycle analysis demonstrated that K562 cells treated with Br-Ell-SO₃Na were arrested in the phase S. Moreover, the production of IL-6 increased and the expression of IL-8 was inhibited in the human PBMC treated with Br-Ell-SO₃Na. The results demonstrated that Br-Ell-SO₃Na is a promising anticancer molecule attested by its noteworthy activity against the K562 tumor cell line and immunomodulatory activity in human PBMC cells.

Differentiation of adipose-derived stem cells into functional chondrocytes by a small molecule that induces Sox9

Osteoarthritis (OA) is a common joint disease that results from the disintegration of joint cartilage and the underlying bone. Because cartilage and chondrocytes lack the ability to self-regenerate, efforts have been made to utilize stem cells to treat OA. Although various methods have been used to differentiate stem cells into functional chondrocytes, the currently available methods cannot induce stem cells to undergo differentiation into chondrocyte-like cells without inducing characteristics of hypertrophic chondrocytes, which finally lead to cartilage disintegration and calcification. Therefore, an optimized method to differentiate stem cells into chondrocytes that do not display undesired phenotypes is needed. This study focused on differentiating adipose-derived stem cells (ASCs) into functional chondrocytes using a small molecule that regulated the expression of Sox9 as a key factor in cartilage development and then explored its ability to treat OA. We selected ellipticine (ELPC), which induces chondrocyte differentiation of ASCs, using a GFP-Sox9 promoter vector screening system. An in vivo study was performed to confirm the recovery rate of cartilage regeneration with ASC differentiation into chondrocytes by ELPC in a collagenase-induced animal model of OA. Taken together, these data indicate that ellipticine induces ASCs to differentiate into mature chondrocytes without hypertrophic chondrocytes in vitro and in vivo, thus overcoming a problem encountered in previous studies. These results indicate that ELPC is a novel chondrocyte differentiation-inducing drug that shows potential as a cell therapy for OA.

Synthesis, cytotoxic activity, ADMET and molecular docking study of quinoline-based hybrid compounds of 1,5-benzothiazepines

Some α,β-unsaturated ketones 4a–g of 3-acetyl-4-hydroxyquinolin-2(1H)-one were prepared and converted into a series of new hybrid compounds, quinoline-benzothiazepine 6a–g. Compounds 6d and 6g had the best activity against HepG2 and KB cell lines.

Synthetic Optimization of Ellipticine and Antitumor Activity of Novel Hexacyclic Derivatives of Ellipticine

Background:

For decades, a great deal of research work has been done to synthesize ellipticine and its derivatives because of their potential antitumor properties and anti-HIV activities. However, the resonance structures in different media, a low level of solubility at physiological pH and systemic toxicity have prevented the use of ellipticine as a therapeutic agent. Besides, the low yield and complex steps of ellipticine synthesis limit its application.

Methods:

A high-yield synthetic procedure of ellipticine has been optimized, and the total yield was up to 50% without silica gel column chromatography. Novel hexacyclic ellipticine derivatives were synthesized by coupling ellipticine with o-aminobenzoic acid. Their cytotoxicities against HCT116, MGC803, HT29 and MCF-7 tumor cells were evaluated.

Results:

The synthesis process of ellipticine was optimized, and the total yield of the synthetic route was increased to 50% through several operation steps optimization. Fourteen ellipticine hexacyclic derivatives were synthesized. The synthetic compounds were screened for anti-tumor activity in vivo and in vitro, and some of the derivatives had good anti-tumor activity.

Conclusion:

Compared with ellipticine, the compound 1l showed higher antitumor activity and better tolerance to tumor models. The compound 1l treatment increased the percentage of late apoptotic cells from 3.1% (DMSO) to 21.6% (20.0 μM) in NCI-H460 cells. It also was observed the effect of 1l on G2 phase arrest was similar as that of ellipticine. The mechanism of action indicated compound 1l could be a topoisomerase IIα poison. These studies provided the basis for the pharmacodynamics and toxicology of ellipticine, and further clarifies the structureactivity relationship of antitumor activity of ellipticine.

Ellipticine, its Derivatives: Re-evaluation of Clinical Suitability with the Aid of Drug Delivery Systems

Targeted drug delivery systems gave newer dimensions for safer and more effective use of therapeutic drugs, thus helping in circumventing the issues of toxicity and unintended drug accumulation. These ongoing developments in delivery systems can, in turn, bring back drugs that suffered various limitations, Ellipticine (EPT) being a candidate. EPT derivatives witnessed entry into clinical settings but failed to survive in clinics citing various toxic side effects. A large body of preclinical data deliberates the potency of drug delivery systems in increasing the efficiency of EPT/derivatives while decreasing their toxic side effects. Recent developments in drug delivery systems provide a platform to explore EPT and its derivatives as good clinical candidates in treating tumors. The present review deals with delivery mechanisms of EPT/EPT derivatives as antitumor drugs, in vitro and in vivo, and evaluates the suitability of EPT-carriers in clinical settings.

The Histone Deacetylase Inhibitor Valproic Acid Exerts a Synergistic Cytotoxicity with the DNA-Damaging Drug Ellipticine in Neuroblastoma Cells

Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with ellipticine and VPA increased the formation of ellipticine-derived DNA adducts, which indicates an easier accessibility of ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.

Cytochrome b5 plays a dual role in the reaction cycle of cytochrome P450 3A4 during oxidation of the anticancer drug ellipticine

Abstract

Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b₅ reductase and/or cytochrome b₅ in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b₅ reductase, to mediate ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyellipticine and the ellipticine N²-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine. Using the ³²P-postlabeling method two ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyellipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b₅ stimulated the CYP3A4-mediated oxidation of ellipticine, but the stimulation effect differed for individual ellipticine metabolites. This heme protein also stimulated the formation of both ellipticine-DNA adducts. The results demonstrate that cytochrome b₅ plays a dual role in the CYP3A4-catalyzed oxidation of ellipticine: (1) cytochrome b₅ mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b₅ reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b₅ can act as an allosteric modifier of the CYP3A4 oxygenase.

Graphical abstract

ATM participates in the regulation of viability and cell cycle via ellipticine in bladder cancer

Ellipticine, an alkaloid isolated from Apocyanaceae plants, has been demonstrated to exhibit antitumor activity in several cancers. However, the effect and the mechanisms underlying its action have not been investigated in human bladder cancer cells. The aim of the present study was to investigate the effect and mechanism of ellipticine on the behavior of T-24 bladder cancer cells. T-24 cells were treated with varying concentrations and durations of ellipticine. Cell viability was evaluated by Cell Counting Kit-8 assay. Cell motility was analyzed by Transwell migration assay. Flow cytometry, reverse transcription-quantitative polymerase chain reaction and western blot analyses were performed to detect the cell cycle and signaling pathways involved. The results demonstrated that ellipticine suppressed proliferation and inhibited the migration ability of T-24 bladder cancer cells in a dose- and time-dependent manner, and resulted in G2/M cell cycle arrest. The mechanism of this action was demonstrated to be due to ellipticine-triggered activation of the ATM serine/threonine kinase pathway. These data therefore suggest that ellipticine may be effective towards treating human bladder cancer.

Anticancer Alkaloids from Trees: Development into Drugs

Trees have made an enormous phytochemical contribution in anticancer drugs' development more than any other life form. The contributions include alkaloids that are biosynthesized in various ways and yield. Lead alkaloids isolated from the trees are taxol and camptothecins that currently have annual sales in billion dollars. Other important alkaloids isolated from these life forms include rohitukine, harringtonine, acronycine, thalicarpine, usambarensine, ellipticine, and matrines. Studies on their mechanism of action and target on the DNA and protein of cancerous cells aided the development of potent hemisynthesized congeners. The molecules and their congeners passed/are passing a long period of historical development before approved as antineoplastic drugs for cancer chemotherapy. Some of them did not find the application as anticancer drugs due to ineffectiveness in clinical trials; others are generating research interest in the antineoplastic activity at the present and have reached clinical trial stages. Potentials in antineoplastic molecules from trees are high and are hoped to be commensurate with cancer types afflicting human society in the future.

Synthesis and antibacterial activity of N1-(carbazol-3-yl)amidrazones incorporating piperazines and related congeners

A selected set of N1-(4-chloro-9-ethylcarbazol-3-yl)amidrazones (7a–n) has been synthesized by reacting the respective hydrazonoyl chloride 5 derived from 3-amino-9-ethylcarbazole (3), with an appropriate sec-cyclic amine (6a–n) in ethanol in the presence of triethylamine. Unexpectedly, aromatic ring chlorination occurred at C-4 of 3 during its conversion to 6 as evidenced by analytical and spectral data and further confirmed by single crystal X-ray structure determination of the amidrazone 7n. Compounds 7a–n were tested for their in vitro antibacterial activity. Among the tested bacterial strains, methicillin-resistant Staphylococcus aureus was the most susceptible to 7f and Bacillus cereus to 7b both with a minimum inhibitory concentration value of 1.56 µg mL−1. Compounds 7c, 7f, and 7h could be useful as lead structures for further development of new antibacterial agents against Gram-positive and Gram-negative pathogens.

New Caledonia: A Hot Spot for Valuable Chemodiversity Part 3: Santalales, Caryophyllales, and Asterids

The flora of New Caledonia encompasses more than 3000 plant species and an endemism of almost 80%. New Caledonia is even considered as one of the 34 'hot spots' for biodiversity. Considering the current global loss of biodiversity and the fact that several drugs and pesticides become obsolete, there is an urgent need to increase sampling and research on new natural products. In this context, here, we reviewed the chemical knowledge available on New Caledonian native flora from economical perspectives. We expect that a better knowledge of the economic potential of plant chemistry will encourage the plantation of native plants for the development of a sustainable economy which will participate in the conservation of biodiversity. This review is divided into three parts, and the third part which is presented here summarizes the scientific literature related to the chemistry of endemic santalales, caryophyllales, and asterids. We show that the high rate of endemism is correlated with the originality of phytochemicals encountered in New Caledonian plants. A total of 176 original natural compounds have been identified from these plants, whereas many species have not been investigated so far. We also discuss the economic potential of plants and molecules with consideration of their medicinal and industrial perspectives. This review finally highlights several groups, such as Sapotaceae, that are unexplored in New Caledonia despite the high chemical interest in them. These plants are considered to have priority in future chemical investigations.

Inhibition of human DNA topoisomerase IIα by two novel ellipticine derivatives

Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an antineoplastic agent that intercalates into DNA and alters topoisomerase II activity. Unfortunately, this compound displays a number of adverse properties. Therefore, to investigate new ellipticine-based compounds for their potential as topoisomerase II-targeted drugs, we synthesized two novel derivatives, N-methyl-5-demethyl ellipticine (ET-1) and 2-methyl-N-methyl-5-demethyl ellipticinium iodide (ET-2). As determined by DNA decatenation and cleavage assays, ET-1 and ET-2 act as catalytic inhibitors of human topoisomerase IIα and are both more potent than the parent compound. Neither compound impairs the ability of the type II enzyme to bind its DNA substrate. Finally, the potency of ET-1 and ET-2 as catalytic inhibitors of topoisomerase IIα appears to be related to their ability to intercalate into the double helix.

New Caledonia: A ' Hot Spot' for Valuable Chemodiversity: Part 2: Basal Angiosperms and Eudicot Rosids

The flora of New Caledonia encompasses more than 3000 plant species and almost 80% are endemic. New Caledonia is considered as a 'hot spot' for biodiversity. With the current global loss of biodiversity and the fact that several drugs and pesticides become obsolete, there is an urgent need to increase sampling and research on new natural products. In this context, we review the chemical knowledge available on New Caledonian native flora from economical perspectives. We expect that a better knowledge of the economic potential of plant chemistry will encourage the plantation of native plants for the development of a sustainable economy which will participate in the conservation of biodiversity. In the second part of this review, we focus on the results exposed in 60 scientific articles and describe the identification of 225 original compounds from basal angiosperms and eudicot rosids. We discuss the economic potential of plants and molecules from medicinal and industrial perspectives. This review also highlights several plants and groups, such as Amborella sp., Piperaceae, or Phyllanthaceae, that are unexplored in New Caledonia despite their high chemical interest. Those plants are considered to have priority in future chemical investigations.

Synthesis and biological evaluation of novel carbazolyl glyoxamides as anticancer and antibacterial agents

A new library of 24 carbazolyl glyoxamides14a–xwere designed and synthesized from glyoxalic acids and arylamines in the presence of HATU as a coupling reagent under MW irradiation.

Screening of Pharmacologically Active Small Molecule Compounds Identifies Antifungal Agents Against Candida Biofilms

Candida species have emerged as important and common opportunistic human pathogens, particularly in immunocompromised individuals. The current antifungal therapies either have toxic side effects or are insufficiently effect. The aim of this study is develop new small-molecule antifungal compounds by library screening methods using Candida albicans, and to evaluate their antifungal effects on Candida biofilms and cytotoxic effects on human cells. Wild-type C. albicans strain SC5314 was used in library screening. To identify antifungal compounds, we screened a small-molecule library of 1,280 pharmacologically active compounds (LOPAC(1280TM)) using an antifungal susceptibility test (AST). To investigate the antifungal effects of the hit compounds, ASTs were conducted using Candida strains in various growth modes, including biofilms. We tested the cytotoxicity of the hit compounds using human gingival fibroblast (hGF) cells to evaluate their clinical safety. Only 35 compounds were identified by screening, which inhibited the metabolic activity of C. albicans by >50%. Of these, 26 compounds had fungistatic effects and nine compounds had fungicidal effects on C. albicans. Five compounds, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate, ellipticine and CV-3988, had strong fungicidal effects and could inhibit the metabolic activity of Candida biofilms. However, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine were cytotoxic to hGF cells at low concentrations. CV-3988 showed no cytotoxicity at a fungicidal concentration. Four of the compounds identified, BAY11-7082, BAY11-7085, sanguinarine chloride hydrate and ellipticine, had toxic effects on Candida strains and hGF cells. In contrast, CV-3988 had fungicidal effects on Candida strains, but low cytotoxic effects on hGF cells. Therefore, this screening reveals agent, CV-3988 that was previously unknown to be antifungal agent, which could be a novel therapies for superficial mucosal candidiasis.

Partitioning of prototropic species of an anticancer drug ellipticine in bile salt aggregates of different head groups and hydrophobic skeletons: a photophysical study to probe bile salts as multisite drug carriers

The entrapment of neutral and cationic species of an anticancer drug, namely ellipticine and their dynamic features in different bile salt aggregates have been investigated for the first time using steady state and time-resolved fluorescence spectroscopy. Because ellipticine exists in various prototropic forms under physiological conditions, we performed comparative photophysical and dynamical studies on these prototropic species in different bile salts varying in their head groups and hydrophobic skeletons. We found that the initial interaction between ellipticine and bile salts is governed by the electrostatic forces where cationic ellipticine is anchored to the head groups of bile salts. Bile salts having conjugated head groups are better candidates to bind with the cationic species than those having the non-conjugated ones. The fact implies that binding of cationic species to different bile salts depends on the pK(a) of the corresponding bile acids. The hydrophobic interaction dominates at higher concentrations of bile salts due to formation of aggregates and results in entrapment of neutral ellipticine molecules according to their hydrophobicity indices. Thus bile salts act as multisite drug carriers. The rotational relaxation parameters of cationic ellipticine were found to be dependent on head groups and the number of hydroxyl groups on the hydrophilic surface of bile salts. Cationic ellipticine exhibits a faster rotational relaxation in the tri-hydroxy bile salt aggregates than in di-hydroxy bile salts. We interpreted this observation from the fact that tri-hydroxy bile salts hold a higher number of water molecules in their hydrophilic surface offering a less viscous environment for ellipticine compared to di-hydroxy bile salts. Surprisingly, the neutral ellipticine molecules display almost the same rotational relaxation in all the bile salts. The observation indicates that after intercalation inside the hydrophobic pocket, neutral ellipticine molecules experience similar confinement in all the bile salts.

New Caledonia: A 'Hot Spot' for Valuable Chemodiversity. Part 1: Gymnosperms

The flora of New Caledonia encompasses more than 3,000 species and almost 80% of them are endemic. New Caledonia is considered as a 'hot spot' for biodiversity. With the current global loss of biodiversity, and the fact that several drugs and pesticides are becoming obsolete, there is an urgent need to increase sampling and research on new natural products. In this context, we review the chemical information available on New Caledonian native flora from economical perspectives. We expect that a better knowledge of the economic potential will encourage the plantation of native plants for the development of a sustainable economy which will participate in the conservation of biodiversity. In the first part of this review, we discuss the results reported in 18 scientific articles on the chemicals isolated from 23 endemic conifers of New Caledonia. Several bioactive and original products, such as neocallitropsene or libocedrins, have been isolated from these conifers. This review also highlights several groups, such as Podocarpus spp., that are unexplored in New Caledonia despite the fact that they have been described in other countries to contain a wide range of original bioactive compounds. Those plants are considered as priority for future chemical investigations.

Long lasting control of viral rebound with a new drug ABX464 targeting Rev - mediated viral RNA biogenesis

BACKGROUND

Current therapies have succeeded in controlling AIDS pandemic. However, there is a continuing need for new drugs, in particular those acting through new and as yet unexplored mechanisms of action to achieve HIV infection cure. We took advantage of the unique feature of proviral genome to require both activation and inhibition of splicing of viral transcripts to develop molecules capable of achieving long lasting effect on viral replication in humanized mouse models through inhibition of Rev-mediated viral RNA biogenesis.

RESULTS

Current HIV therapies reduce viral load during treatment but titers rebound after treatment is discontinued. We devised a new drug that has a long lasting effect after viral load reduction. We demonstrate here that ABX464 compromises HIV replication of clinical isolates of different subtypes without selecting for drug resistance in PBMCs or macrophages. ABX464 alone, also efficiently compromised viral proliferation in two humanized mouse models infected with HIV that require a combination of 3TC, Raltegravir and Tenofovir (HAART) to achieve viral inhibition in current protocols. Crucially, while viral load increased dramatically just one week after stopping HAART treatment, only slight rebound was observed following treatment cessation with ABX464 and the magnitude of the rebound was maintained below to that of HAART for two months after stopping the treatment. Using a system to visualize single HIV RNA molecules in living cells, we show that ABX464 inhibits viral replication by preventing Rev-mediated export of unspliced HIV-1 transcripts to the cytoplasm and by interacting with the Cap Binding Complex (CBC). Deep sequencing of viral RNA from treated cells established that retained viral RNA is massively spliced but importantly, normal cellular splicing is unaffected by the drug. Consistently ABX464 is non-toxic in humans and therefore represents a promising complement to current HIV therapies.

CONCLUSIONS

ABX464 represents a novel class of anti-HIV molecules with unique properties. ABX464 has a long lasting effect in humanized mice and neutralizes the expression of HIV-1 proviral genome of infected immune cells including reservoirs and it is therefore a promising drug toward a functional cure of HIV.

A Pd-catalyzed direct entry to 11-substituted 6H-isoindolo[2,1-a]indol-6-one derivatives as potential anticancer agents

11-Substituted 6H-isoindolo[2,1-a]indol-6-ones are preparedviaa sequential intramolecular Heck reaction of dihaloN-allyl substitutedN-arylbenzamide derivatives.

Co-delivery of drug nanoparticles and siRNA mediated by a modified cell penetrating peptide for inhibiting cancer cell proliferation

Modified cell penetrating peptide can stabilize drug nanoparticles with improved efficacy and co-deliver siRNA inducing synergy on the inhibition of cancer cell growth.

The anticancer drug ellipticine activated with cytochrome P450 mediates DNA damage determining its pharmacological efficiencies: studies with rats, Hepatic Cytochrome P450 Reductase Null (HRN™) mice and pure enzymes

Ellipticine is a DNA-damaging agent acting as a prodrug whose pharmacological efficiencies and genotoxic side effects are dictated by activation with cytochrome P450 (CYP). Over the last decade we have gained extensive experience in using pure enzymes and various animal models that helped to identify CYPs metabolizing ellipticine. In this review we focus on comparison between the in vitro and in vivo studies and show a necessity of both approaches to obtain valid information on CYP enzymes contributing to ellipticine metabolism. Discrepancies were found between the CYP enzymes activating ellipticine to 13-hydroxy- and 12-hydroxyellipticine generating covalent DNA adducts and those detoxifying this drug to 9-hydroxy- and 7-hydroellipticine in vitro and in vivo. In vivo, formation of ellipticine-DNA adducts is dependent not only on expression levels of CYP3A, catalyzing ellipticine activation in vitro, but also on those of CYP1A that oxidize ellipticine in vitro mainly to the detoxification products. The finding showing that cytochrome b5 alters the ratio of ellipticine metabolites generated by CYP1A1/2 and 3A4 explained this paradox. Whereas the detoxification of ellipticine by CYP1A and 3A is either decreased or not changed by cytochrome b5, activation leading to ellipticine-DNA adducts increased considerably. We show that (I) the pharmacological effects of ellipticine mediated by covalent ellipticine-derived DNA adducts are dictated by expression levels of CYP1A, 3A and cytochrome b5, and its own potency to induce these enzymes in tumor tissues, (II) animal models, where levels of CYPs are either knocked out or induced are appropriate to identify CYPs metabolizing ellipticine in vivo, and (III) extrapolation from in vitro data to the situation in vivo is not always possible, confirming the need for these animal models.

Formation of DNA adducts by ellipticine and its micellar form in rats - a comparative study

The requirements for early diagnostics as well as effective treatment of cancer diseases have increased the pressure on development of efficient methods for targeted drug delivery as well as imaging of the treatment success. One of the most recent approaches covering the drug delivery aspects is benefitting from the unique properties of nanomaterials. Ellipticine and its derivatives are efficient anticancer compounds that function through multiple mechanisms. Formation of covalent DNA adducts after ellipticine enzymatic activation is one of the most important mechanisms of its pharmacological action. In this study, we investigated whether ellipticine might be released from its micellar (encapsulated) form to generate covalent adducts analogous to those formed by free ellipticine. The ³²P-postlabeling technique was used as a useful imaging method to detect and quantify covalent ellipticine-derived DNA adducts. We compared the efficiencies of free ellipticine and its micellar form (the poly(ethylene oxide)-block-poly(allyl glycidyl ether) (PAGE-PEO) block copolymer, P 119 nanoparticles) to form ellipticine-DNA adducts in rats in vivo. Here, we demonstrate for the first time that treatment of rats with ellipticine in micelles resulted in formation of ellipticine-derived DNA adducts in vivo and suggest that a gradual release of ellipticine from its micellar form might produce the enhanced permeation and retention effect of this ellipticine-micellar delivery system.

Synthesis and in vitro antitumor activity of novel 2-alkyl-5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazol-2-ium and 2-alkylellipticin-2-ium chloride derivatives

Twenty-one types of novel ellipticine derivatives and pyridocarbazoles (5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazoles) with a nitrosourea moiety, linked by an oxydiethylene unit at the 2 position, were synthesized, and their cytotoxicity against HeLa S-3 cells was evaluated. Some of these new compounds exhibited potent antitumor activity by comparison with that of ellipticine.

Magnetic molecularly imprinted polymers (MMIPs) for carbazole derivative release in targeted cancer therapy

Magnetic Molecularly Imprinted Polymers (MMIPs) are synthesized with the aim to prepare novel devices for 9H-carbazole derivative sustained delivery in targeted cancer therapy.

Effects of ellipticine on ALDH1A1-expressing breast cancer stem cells--an in vitro and in silico study

Targeting breast cancer stem cells (BCSCs) offers a promising strategy for breast cancer treatment. We examined the plant alkaloid ellipticine for its efficacy to inhibit the expression of aldehyde dehydrogenase 1 class A1 (ALDH1A1)-positive BCSCs by in vitro and in silico methods. At 3 mM concentration, ellipticine decreased the expression of ALDH1A1-positive BCSCs by 62% (p = 0.073) in the MCF7 cell line and by 53% (p = 0.024) in the SUM159 cell line compared to vehicle-treated cultures. Ellipticine significantly reduced the formation of mammospheres, whereas paclitaxel enhanced mammosphere formation in both the treated cell lines. Interestingly, when treated with a combination of ellipticine and paclitaxel, the percentage of ALDH1A1-positive BCSCs dropped by several fold in vitro. A homology model of Homo sapiens ALDH1A1 was built using the crystal structure of NAD-bound sheep liver class I aldehyde dehydrogenase [PDB ID: 1BXS] as a template. Molecular simulation and docking studies revealed that the amino acids Asn-117 and Asn-121, Glu-249, Cys-302, and Gln-350, present in the active site of human ALDH1A1, played a vital role in interacting with the drug. The present study suggests that ellipticine reduces the proliferation and self-renewal ability of ALDH1A1-positive BCSCs and can be used in combination with a cytotoxic drug like paclitaxel for potential targeting of BCSCs.