Antiproliferative activity of some 1,4-dimethylcarbazoles on cells that express estrogen receptors: part I

Novel carbazolyl-thiazolyl-chromone and carbazolyl-thiazolyl-pyrazole hybrids: synthesis, cytotoxicity evaluation and molecular docking studies

A simple synthetic method was performed to design a novel series of polycyclic systems consisting of carbazole-thiazolidinone-chromone hybrids 4a-e and carbazole-thiazolidinone-pyrazole hybrids 5a-e in excellent yields. The methodology depended on the one-pot four-component reaction of 3-amino-9-ethylcarbazole, substituted isothiocyanates, ethyl bromoacetate and 6-methyl-3-formylchromone in ethanol under ultrasound waves at 50 °C to give the carbazole-thiazolidinone-chromone hybrids 4a-e. The latter isolated products were treated with hydrazine hydrate in ethanol under ultrasound waves at 50 °C affording the corresponding carbazole-thiazolidinone-pyrazole hybrids 5a-e. Spectral and analytical data confirmed the structures of all the synthesized compounds. The target compounds were screened for their in vitro anticancer activities against HCT116, PC3 and HepG2 cancer cell lines using the standard SRB method. Fortunately, both compounds 5dand5e were the most active against all cancer cell lines compared with doxorubicin and can be promising anticancer agents. Both bioactive products 5band5e were studied by the molecular docking to see how they bind with VEGFR-2 receptor. The results indicated that those compounds exhibited high affinities towards VEGFR-2 and established remarkably similar interactions to those of the powerful VEGFR-2-KDR.

5,8-Dimethyl-9H-carbazole Derivatives Blocking hTopo I Activity and Actin Dynamics

Over the years, carbazoles have been largely studied for their numerous biological properties, including antibacterial, antimalarial, antioxidant, antidiabetic, neuroprotective, anticancer, and many more. Some of them have gained great interest for their anticancer activity in breast cancer due to their capability in inhibiting essential DNA-dependent enzymes, namely topoisomerases I and II. With this in mind, we studied the anticancer activity of a series of carbazole derivatives against two breast cancer cell lines, namely the triple negative MDA-MB-231 and MCF-7 cells. Compounds 3 and 4 were found to be the most active towards the MDA-MB-231 cell line without interfering with the normal counterpart. Using docking simulations, we assessed the ability of these carbazole derivatives to bind human topoisomerases I and II and actin. In vitro specific assays confirmed that the lead compounds selectively inhibited the human topoisomerase I and interfered with the normal organization of the actin system, triggering apoptosis as a final effect. Thus, compounds 3 and 4 are strong candidates for further drug development in multi-targeted therapy for the treatment of triple negative breast cancer, for which safe therapeutic regimens are not yet available.

Unique Carbazole-Oxadiazole Derivatives as New Potential Antibiotics for Combating Gram-Positive and -Negative Bacteria

Novel carbazole-oxadiazoles were developed as new potential antibacterial agents to combat dreadful resistance. Some target compounds displayed predominant inhibitory effects on the tested Gram-positive and -negative bacteria, and carbazole-oxadiazoles 5g, 5i-k, 16a-c, and tetrazole analogues 23b-c were found to be efficient in impeding the growth of MRSA and Pseudomonas aeruginosa ATCC 27853 (MICs = 0.25-4 μg/mL). Furthermore, compounds 5g and 23b-c not only possessed rapid bactericidal ability and low tendency to develop resistance but also exhibited low cytotoxic effects toward Hek 293T, HeLa, and red blood cells (RBCs), especially molecule 5g also showed low toxicity in vivo, which showed the therapeutic potential of these compounds. Further exploration indicated that compounds 5g, 5i, and 23b-c could disintegrate the integrity of bacterial cell membranes to leak the cytoplasmic contents, thus exerting excellent antibacterial effects. These facts mean that carbazole-based antibacterial agents might have bright prospects in confronting bacterial infections.

Novel carbazole-oxadiazoles as potential Staphylococcus aureus germicides

Staphylococcus aureus resistance poses nonnegligible threats to the livestock industry. In light of this, carbazole-oxadiazoles were designed and synthesized for treating S. aureus infection. Bioassay discovered that 3,6-dibromocarbazole derivative 13a had effective inhibitory activities to several Gram-positive bacteria, in particular to S. aureus, S. aureus ATCC 29213, MRSA and S. aureus ATCC 25923 (MICs = 0.6-4.6 nmol/mL), which was more active than norfloxacin (MICs = 6-40 nmol/mL). Subsequent studies showed that 3,6-dibromocarbazole derivative 13a acted rapidly on S. aureus ATCC 29213 and possessed no obvious tendency to induce bacterial resistance. Further evaluations indicated that 3,6-dibromocarbazole derivative 13a showed strong abilities to disrupt bacterial biofilm and interfere with DNA, which might be the power sources of antibacterial performances. Moreover, 3,6-dibromocarbazole derivative 13a also exhibited slight cell lethality toward Hek 293 T and LO2 cells and low hemolytic toxicity to red blood cells. The above results implied that the active molecule 13a could be studied in the future development of agricultural available antibiotics.

Carbazole Derivatives as Kinase-Targeting Inhibitors for Cancer Treatment

Protein Kinases (PKs) are a heterogeneous family of enzymes that modulate several biological pathways, including cell division, cytoskeletal rearrangement, differentiation and apoptosis. In particular, due to their crucial role during human tumorigenesis and cancer progression, PKs are ideal targets for the design and development of effective and low toxic chemotherapeutics and represent the second group of drug targets after G-protein-coupled receptors. Nowadays, several compounds have been claimed to be PKs inhibitors, and some of them, such as imatinib, erlotinib and gefitinib, have already been approved for clinical use, whereas more than 30 others are in various phases of clinical trials. Among them, some natural or synthetic carbazole-based molecules represent promising PKs inhibitors due to their capability to interfere with PK activity by different mechanisms of action including the ability to act as DNA intercalating agents, interfere with the activity of enzymes involved in DNA duplication, such as topoisomerases and telomerases, and inhibit other proteins such as cyclindependent kinases or antagonize estrogen receptors. Thus, carbazoles can be considered a promising this class of compounds to be adopted in targeted therapy of different types of cancer.

Metabolomic Comparison and Assessment of Co-cultivation and a Heat-Killed Inducer Strategy in Activation of Cryptic Biosynthetic Pathways

Co-cultivation has been used as a promising tool to turn on or up-regulate cryptic biosynthetic pathways for microbial natural product discovery. Recently, a modified culturing strategy similar to co-cultivation was investigated, where heat-killed inducer cultures were supplemented to the culture medium of producer fermentations to induce cryptic pathways. In the present study, the repeatability and effectiveness of both methods in turning on cryptic biosynthetic pathways were unbiasedly assessed using UHPLC-HRESIMS-based metabolomics analysis. Both induction methods had good repeatability, and they resulted in very different induced metabolites from the tested producers. Co-cultivation generated more induced mass features than the heat-killed inducer cultures, while both methods resulted in the induction of mass features not observed using the other induction method. As examples, pathways leading to two new natural products, N-carbamoyl-2-hydroxy-3-methoxybenzamide (1) and carbazoquinocin G (5), were induced and up-regulated through co-culturing a producer Streptomyces sp. RKND-216 with inducers Alteromonas sp. RKMC-009 and M. smegmatis ATCC 120515, respectively.

Carbazole Derivatives as Antiviral Agents: An Overview

Keywords: carbazole; tetrahydrocarbazole; antiviral agents.

N-thioalkylcarbazoles derivatives as new anti-proliferative agents: synthesis, characterisation and molecular mechanism evaluation

Synthetic or natural carbazole derivatives constitute an interesting class of heterocycles, which showed several pharmaceutical properties and occupied a promising place as antitumour tools in preclinical studies. They target several cellular key-points, e.g. DNA and Topoisomerases I and II. The most studied representative, i.e. Ellipticine, was introduced in the treatment of metastatic breast cancer. However, because of the onset of dramatic side effects, its use was almost dismissed. Many efforts were made in order to design and synthesise new carbazole derivatives with good activity and reduced side effects. The major goal of the present study was to synthesise a series of new N-thioalkylcarbazole derivatives with anti-proliferative effects. Two compounds, 5a and 5c, possess an interesting anti-proliferative activity against breast and uterine cancer cell lines without affecting non-tumoural cell lines viability. The most active compound (5c) induces cancer cells death triggering the intrinsic apoptotic pathway by inhibition of Topoisomerase II.

Inhibition of Human Topoisomerase II by N,N,N-Trimethylethanammonium Iodide Alkylcarbazole Derivatives

Chemotherapy is used for the treatment of all stages of breast cancer, including the metastatic stage of the disease. Treatment regimens are generally tailored for each patient's particular situation. However, chemotherapeutic agents are the leading cause of serious drug-related adverse effects; moreover, drug resistance often occurs. In this study, we designed and synthesized a new series of N-alkylcarbazoles derived from ellipticine, an alkaloid with a carbazole skeleton initially used in the treatment of metastatic breast cancer and later dismissed because of poor aqueous solubility and severe side effects. After evaluating the binding modes of our class of newly synthesized compounds with human topoisomerase II (hTopo II), we performed hTopo II decatenation assays, identifying compound 4 f (2-(4-((3-chloro-9H-carbazol-9-yl)pentyl)piperazin-1-yl)-N,N,N-trimethylethanammonium iodide) as a good inhibitor. Moreover, 4 f and 4 g (2-(4-((3-chloro-9H-carbazol-9-yl)hexyl)piperazin-1-yl)-N,N,N-trimethylethanammonium iodide) showed a good anti-proliferative activity toward breast cancer cells, causing apoptosis by activation of the caspase pathway. Interestingly, the activity of these two compounds on triple-negative MDA-MB-231 cells, which tend to be highly metastatic and aggressive, is strictly connected to the observed inhibition of hTopo II.

Design, synthesis and biological evaluation of new carbazole derivatives as anti-cancer and anti-migratory agents

Based on the efficacy of EHop-016 as an inhibitor of migration and Rac1 activation, a new series of carbazole derivatives has been synthesized. Cytotoxic and anti-migratory effects of these compounds were evaluated in MCF-7 and MDA-MB-231 breast cancer cell lines. Preliminary investigations of their anticancer activity demonstrated that several compounds have moderate antiproliferative effects on cancer cell lines with GI50 values in the range of 13-50 µM. Furthermore, compounds 3b and 11b inhibit migration activity of metastatic cell line MDA-MB-231 by 32% and 34%, respectively. Compound 11b was shown to inhibit activation of the Rho GTPase Rac1 by 55% at 250 nM in both MDA-MB-231 and MDA-MB-435 cell lines. Compared with the IC50 of Rac1 inhibition by lead compound EHop-016 of 1.1 µM, compound 11b demonstrates 4X improved in vitro efficacy.

Novel Gold and Silver Carbene Complexes Exert Antitumor Effects Triggering the Reactive Oxygen Species Dependent Intrinsic Apoptotic Pathway

Cisplatin and other platinum-based drugs are well-known valid anticancer drugs. However, during chemotherapy, the presence of numerous side effects and the onset of frequent phenomena of resistance has pushed many research groups to devise new metal-based compounds holding improved anticancer properties and fewer undesired effects. Amongst the variety of synthesized compounds, significant antiproliferative effects have been obtained by employing organometallic compounds, particularly those based on silver and gold. With this in mind, we synthesized four compounds, two silver complexes and two gold complexes, with good inhibitory effects on the in vitro proliferation of breast and ovarian cancer-cell models. The antitumor activity of the most active compound, that is, AuL4, was found to be ninefold higher than that of cisplatin, and this compound induced dramatic morphological changes in HeLa cells. AuL4 induced PARP-1 cleavage, caspases 3/7 and 9 activation, mitochondria disruption, cytochrome c release in cancer-cell cytoplasm, and the intracellular production of reactive oxygen species. Thus, AuL4 treatment caused cancer-cell death by the intrinsic apoptotic pathway, whereas no cytotoxic effects were recorded upon treating non-tumor cell lines. The reported outcomes may be an important contribution to the expanding knowledge of medicinal bio-organometallic chemistry and enlarge the available anticancer toolbox, offering improved features, such as higher activity and/or selectivity, and opening the way to new discoveries and applications.

Assessment of antioxidant, antitumor and pro-apoptotic effects of Salvia fruticosa Mill. subsp. thomasii (Lacaita) Brullo, Guglielmo, Pavone & Terrasi (Lamiaceae)

The aim of the present study was to investigate the in vitro antioxidant and antitumor effects of Salvia fruticosa Mill subsp. thomasii (Lacaita) Brullo, Guglielmo, Pavone & Terrasi (Lamiaceae). The aerial parts were extracted by maceration with methanol. This extract was partitioned with methanol and n-hexane. Luteolin, luteolin 7-O-glucoside, rutin and salvigenin were isolated from the methanol-soluble fraction. n-Hexane fraction showed viridiflorol, β-pinene, 1,8-cineole, as main components. The methanol-soluble fraction exerted antitumor activity against human breast cancer (MCF-7 and MDA-MB-231) and human colorectal carcinoma (RKO and Caco-2) cells. TUNEL test revealed that S. fruticosa subsp. thomasii leads to cells death by apoptosis, with low cytotoxic effects on non-tumoral 3T3-L1 cells. Moreover, it exerted the highest protection of lipid peroxidation and reduced the oxidative stress induced by menadione treatment in 3T3-L1 murine fibroblasts. S. fruticosa subsp. thomasii bioactivity could promote its use not only as food but also in nutraceutical/pharmaceutical industries.

Tumour biomarkers: homeostasis as a novel prognostic indicator

The term 'personalized medicine' refers to a medical procedure that consists in the grouping of patients based on their predicted individual response to therapy or risk of disease. In oncologic patients, a 'tailored' therapeutic approach may potentially improve their survival and well-being by not only reducing the tumour, but also enhancing therapeutic response and minimizing the adverse effects. Diagnostic tests are often used to select appropriate and optimal therapies that rely both on patient genome and other molecular/cellular analysis. Several studies have shown that lifestyle and environmental factors can influence the epigenome and that epigenetic events may be involved in carcinogenesis. Thus, in addition to traditional biomarkers, epigenetic factors are raising considerable interest, because they could potentially be used as an excellent tool for cancer diagnosis and prognosis. In this review, we summarize the role of conventional cancer genetic biomarkers and their association with epigenomics. Furthermore, we will focus on the so-called 'homeostatic biomarkers' that result from the physiological response to cancer, emphasizing the concept that an altered 'new' homeostasis influence not only tumour environment, but also the whole organism.

N-heterocyclic carbene complexes of silver and gold as novel tools against breast cancer progression

AIM

Metal carbenic complexes have received considerable attention in both the catalysis and biological fields for their potential applications in cancer and antimicrobial therapies.

RESULTS

A small series of new silver and gold N-heterocyclic carbene complexes has been designed and synthesized. Among the tested complexes, one compound was particularly active in inhibiting anchorage-dependent and -independent breast cancer proliferation, and inducing cell apoptosis via a mitochondria-related process. The antitumor activity was associated to the transcriptional activation of the tumor suppressor gene p53 in an Sp1-dependent manner, as evidenced by biological and docking studies.

CONCLUSION

Our results highlight the importance and the versatility of N-heterocyclic carbene complexes of gold and silver as useful tools against breast cancer progression.

Multifaceted properties of 1,4-dimethylcarbazoles: Focus on trimethoxybenzamide and trimethoxyphenylurea derivatives as novel human topoisomerase II inhibitors

Natural or synthetic carbazole derivatives have recently attracted the attention of the scientific world because of their multiple biological activity, leading to an increase of designed, synthesized and studied analogues. In this paper, four 1,4-dimethylcarbazole derivatives, analogues of Ellipticine, have been investigated for their ability to block cancer cells growth, with low effects on the proliferation of normal cells. DNA topoisomerases inhibition assays, docking simulations, stability studies and effects on a membrane model are reported. Particularly, compounds 2 and 3 have been found thermally stable and able to inhibit, strongly and selectively, the human DNA topoisomerase II. These properties confer a good and broad antitumoral activity in vitro, with very low cytotoxic effect on the proliferation of normal cell lines and without damaging, in contrast with Ellipticine, the cell membrane model. The presented outcomes set the most active compounds as good candidates for pre-clinical studies useful in cancer treatment.

3-(Dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (DPA-HBFQ-1) plays an inhibitory role on breast cancer cell growth and progression

A series of unknown 3-(alkyl(dialkyl)amino)benzofuro[2,3-f]quinazolin-1(2H)-ones 4-17 has been synthesized as new ellipticine analogs, in which the carbazole moiety and the pyridine ring were replaced by a dibenzofuran residue and a pyrimidine ring, respectively. The synthesis of these benzofuroquinazolinones 4-17 was performed in a simple one-pot reaction using 3-aminodibenzofuran or its 2-methoxy derivative, as starting materials. From 3-(dipropylamino)-5-methoxybenzofuro[2,3-f] quinazolin-1(2H)-one (13), we prepared 3-(dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (18), referred to as DPA-HBFQ-1. The cytotoxic activities of all the synthesized compounds, tested in different human breast cancer cell lines, revealed that DPA-HBFQ-1 was the most active compound. In particular, the latter was able to inhibit anchorage-dependent and -independent cell growth and to induce apoptosis in estrogen receptor alpha (ERα)-positive and -negative breast cancer cells. It did not affect proliferation and apoptotic responses in MCF-10A normal breast epithelial cells. The observed effects have been ascribed to an enhanced p21(Cip1/WAF1) expression in a p53-dependent manner of tumor suppressor and to a selective inhibition of human topoisomerase II. In addition, DPA-HBFQ-1 exerted growth inhibitory effects also in other cancer cell lines, even though with a lower cytotoxic activity. Our results indicate DPA-HBFQ-1 as a good candidate to be useful as cancer therapeutic agent, particularly for breast cancer.

Inhibition of human topoisomerase I and II and anti-proliferative effects on MCF-7 cells by new titanocene complexes

The antitumor activity shown by many platinum complexes has produced a strong interest in research of new organometallic compounds having anticancer action. Among the many metal compounds synthesized and tested, those based on titanium have received considerable attention because of their cytotoxic activity against solid tumors. Particularly, new titanocene compounds containing aromatic groups linked to the Cp (cyclopentadienyl ring, C5H5) have been synthetized, such as the titanocene Y (bis-[(p-methoxybenzyl)cyclopentadienyl]titanium dichloride) that displayed promising medium-high cytotoxic activity on breast cancer cell lines. Other titanocene complexes recently synthesized, obtained by replacing the substituent methoxy-aryl of cyclopentadienes of titanocene Y with ethenyl-methoxide or ethenyl-phenoxide, showed increased cytotoxic activity on breast cancer cell lines being more stable compounds. In this paper, we report that new titanocene complexes holding lipophilic groups, for instance a methyl group on benzyl carbon, exhibit improved antiproliferative effect on breast cancer cell line MCF-7. Similar results have been obtained introducing a 5-methoxy naphthyl group to further stabilize the titanocene complexes. These inhibitory effects on breast cancer cells have been ascribed to human topoisomerase I and II inhibition as demonstrated by specific enzymatic assays.

Synthesis and biological evaluation of novel pyrano[3,2-c]carbazole derivatives as anti-tumor agents inducing apoptosis via tubulin polymerization inhibition

A series of novel pyrano[3,2-c]carbazole derivatives have been synthesized and antiproliferative activity of the derivatives were investigated on various cancer cell lines.

Acetylated hyaluronic acid: enhanced bioavailability and biological studies

Hyaluronic acid (HA), a macropolysaccharidic component of the extracellular matrix, is common to most species and it is found in many sites of the human body, including skin and soft tissue. Not only does HA play a variety of roles in physiologic and in pathologic events, but it also has been extensively employed in cosmetic and skin-care products as drug delivery agent or for several biomedical applications. The most important limitations of HA are due to its short half-life and quick degradation in vivo and its consequently poor bioavailability. In the aim to overcome these difficulties, HA is generally subjected to several chemical changes. In this paper we obtained an acetylated form of HA with increased bioavailability with respect to the HA free form. Furthermore, an improved radical scavenging and anti-inflammatory activity has been evidenced, respectively, on ABTS radical cation and murine monocyte/macrophage cell lines (J774.A1).

N-alkyl carbazole derivatives as new tools for Alzheimer's disease: preliminary studies

Alzheimer's disease (AD) is a progressive and age-related neurodegenerative disorder affecting brain cells and is the most common form of "dementia", because of the cognitive detriment which takes place. Neuronal disruption represents its major feature, due to the cytosolic accumulation of amyloid β-peptide (Aβ) which leads to senile plaques formation and intracellular neurofibrillary tangles. Many studies have focused on the design and therapeutic use of new molecules able to inhibit Aβ aggregation. In this context, we evaluated the ability of two recently synthesized series of N-alkyl carbazole derivatives to increase the Aβ soluble forms, through molecular docking simulations and in vitro experiments. Our data evidenced that two carbazole derivatives, the most active, adopt distinct binding modes involving key residues for Aβ fibrillization. They exhibit a good interfering activity on Aβ aggregation in mouse (N2a) cells, stably expressing wild-type human amyloid precursor protein (APP) 695. These preliminary results are promising and we are confident that the N-alkyl carbazole derivatives may encourage next future studies needed for enlarging the knowledge about the AD disease approach.

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.

Synthesis and evaluation of cytotoxic activities of new guanidines derived from carbazoles

Several new alkylguanidines derived from carbazole have been synthesized in a simple one-pot reaction starting from 3-aminocarbazole derivatives. The aminocarbazoles were reacted with ethoxycarbonylisothiocyanate, to give thiourea intermediates, followed by the addition of an alkylamine and HgCl2 to give ethoxycarbonylguanidine intermediates. The reaction mixture was then heated at 160 °C to give the N-(1,4-dimethyl-9H-carbazol-3-yl)-N'-alkylguanidines. The cytotoxic activity of all the synthesized guanidines was evaluated against different cell lines.

Biological activity of 3-chloro-azetidin-2-one derivatives having interesting antiproliferative activity on human breast cancer cell lines

Resveratrol (3,4',5 tri-hydroxystilbene), a natural plant polyphenol, has gained interest as a non-toxic agent capable of inducing tumor cell death in a variety of cancer types. However, therapeutic application of these beneficial effects remains very limited due to its short biological half-life, labile properties, rapid metabolism and elimination. Different studies were undertaken to obtain synthetic analogs of resveratrol with major bioavailability and anticancer activity. We have synthesized a series 3-chloro-azetidin-2-one derivatives, in which an azetidinone nucleus connects two aromatic rings. Aim of the present study was to investigate the effects of these new 3-chloro-azetidin-2-one resveratrol derivatives on human breast cancer cell lines proliferation. Our results indicate that some azetidin-based resveratrol derivatives may become new potent alternative tools for the treatment of human breast cancer.

Synthesis and cytotoxic activity evaluation of 2,3-thiazolidin-4-one derivatives on human breast cancer cell lines

It is well known that resveratrol (RSV) displayed cancer-preventing and anticancer properties but its clinical application is limited because of a low bioavailability and a rapid clearance from the circulation. Aim of this work was to synthesize pharmacologically active resveratrol analogs with an enhanced structural rigidity and bioavailability. In particular, we have synthesized a library of 2,3-thiazolidin-4-one derivatives in which a thiazolidinone nucleus connects two aromatic rings. Some of these compounds showed strong inhibitory effects on breast cancer cell growth. Our results indicate that some of thiazolidin-based resveratrol derivatives may become a new potent alternative tool for the treatment of human breast cancer.

Synthesis, characterization and cytotoxic activity on breast cancer cells of new half-titanocene derivatives

A series of novel titanocene-complexes has been prepared and evaluated for their growth regulatory effects in MCF7 and SkBr3 breast cancer cells. The capability of some of these compound to elicit relevant repressive effects on cancer cell growth could be taken into account towards novel pharmacological approaches in cancer therapy.