Structure-activity relationships and mechanism of action of antitumor bis 8-hydroxyquinoline substituted benzylamines

Lipid peroxidation and changes in major antioxidant markers in copper quinolate fungicide-exposed rats

The present study investigated the toxic effects of sub-chronic exposure to copper quinolate (CuQ) fungicide on liver and kidney function. Twenty-four adult male Wistar rats were equally divided into a control group, and three treated groups received, respectively, by oral gavage, three increasing doses of CuQ: 47; 67.1; and 94 mg/kg b.w corresponding, respectively, LD50/100, LD50/70, and LD50/50 daily for 8 weeks. CuQ resulted in a significant increase in the serum enzymatic activity of aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and the serum levels of urea, creatinine, uric acid, and malondialdehyde, along with a marked decrease in alanine aminotransferase (ALT) activity, and the contents of total protein and albumin compared to those of the control group. Furthermore, glutathione content and the enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx) decreased significantly in a dose-dependent manner with respect to CuQ. The adverse effects of CuO were supported by the histopathological evaluations of liver and kidney tissues. Conclusively, sub-chronic CuQ exposure was shown to induce kidney and liver oxidative damage and dysfunction.

Bioactive Heterocyclic Compounds as Potential Therapeutics in the Treatment of Gliomas: A Review

Cancer is one of the most alarming diseases, with an estimation of 9.6 million deaths in 2018. Glioma occurs in glial cells surrounding nerve cells. The majority of the patients with gliomas have a terminal prognosis, and the ailment has significant sway on patients and their families, be it physical, psychological, or economic wellbeing. As Glioma exhibits, both intra and inter tumour heterogeneity with multidrug resistance and current therapies are ineffective. So the development of safer anti gliomas agents is the need of hour. Bioactive heterocyclic compounds, eithernatural or synthetic,are of potential interest since they have been active against different targets with a wide range of biological activities, including anticancer activities. In addition, they can cross the biological barriers and thus interfere with various signalling pathways to induce cancer cell death. All these advantages make bioactive natural compounds prospective candidates in the management of glioma. In this review, we assessed various bioactive heterocyclic compounds, such as jaceosidin, hispudlin, luteolin, silibinin, cannabidiol, tetrahydrocannabinol, didemnin B, thymoquinone, paclitaxel, doxorubicin, and cucurbitacins for their potential anti-glioma activity. Also, different kinds of chemical reactions to obtain various heterocyclic derivatives, e.g. indole, indazole, benzimidazole, benzoquinone, quinoline, quinazoline, pyrimidine, and triazine, are listed.

Ruthenacarborane and Quinoline: A Promising Combination for the Treatment of Brain Tumors

Gliomas and glioblastomas are very aggressive forms of brain tumors, prone to the development of a multitude of resistance mechanisms to therapeutic treatments, including cytoprotective autophagy. In this work, we investigated the role and mechanism of action of the combination of a ruthenacarborane derivative with 8-hydroxyquinoline (8-HQ), linked via an ester bond (complex 2), in rat astrocytoma C6 and human glioma U251 cells, in comparison with the two compounds alone, i.e., the free carboxylic acid (complex 1) and 8-HQ, and their non-covalent combination ([1 + 8-HQ], in 1:1 molar ratio). We found that only complex 2 was able to significantly affect cellular viability in glioma U251 cells (IC₅₀ 11.4 μM) via inhibition of the autophagic machinery, most likely acting at the early stages of the autophagic cascade. Contrary to 8-HQ alone, complex 2 was also able to impair cellular viability under conditions of glucose deprivation. We thus suggest different mechanisms of action of ruthenacarborane complex 2 than purely organic quinoline-based drugs, making complex 2 a very attractive candidate for evading the known resistances of brain tumors to chloroquine-based therapies.

Characterization of Aminobenzylphenols as Protein Disulfide Isomerase Inhibitors in Glioblastoma Cell Lines

Disulfide bond formation is a critical post-translational modification of newly synthesized polypeptides in the oxidizing environment of the endoplasmic reticulum and is mediated by protein disulfide isomerase (PDIA1). In this study, we report a series of α-aminobenzylphenol analogues as potent PDI inhibitors. The lead compound, AS15, is a covalent nanomolar inhibitor of PDI, and the combination of AS15 analogues with glutathione synthesis inhibitor buthionine sulfoximine (BSO) leads to synergistic cell growth inhibition. Using nascent RNA sequencing, we show that an AS15 analogue triggers the unfolded protein response in glioblastoma cells. A BODIPY-labeled analogue binds proteins including PDIA1, suggesting that the compounds are cell-permeable and reach the intended target. Taken together, these findings demonstrate an extensive biochemical characterization of a novel series of highly potent reactive small molecules that covalently bind to PDI.

Targeting of endoplasmic reticulum (ER) stress in gliomas

Gliomas remain a group of malignant brain tumors with dismal prognosis and limited treatment options with molecular mechanisms being constantly investigated. The past decade, extracellular stress and intracellular DNA damage have been shown to disturb proteostasis leading to Endoplasmic Reticulum (ER) stress that is implicated in the regulation of gene expression and the pathogenesis of several tumor types, including gliomas. Upon ER stress induction, neoplastic cells activate the adaptive mechanism of unfolded protein response (UPR), an integrated signaling system that either restores ER homeostasis or induces cell apoptosis. Recently, the manipulation of the UPR has emerged as a new therapeutic target in glioma treatment. General UPR activators or selective GRP78, ATF6 and PERK inducers have been detected to modulate cell proliferation and induce apoptosis of glioma cells. At the same time, target-specific UPR inhibitors and small molecule proteostasis disruptors, work in reverse to increase misfolded proteins and cause a dysregulation in protein maturation and sorting, thus preventing the growth of neoplastic cells. Herein, we discuss the pathogenic implication of ER stress in gliomas onset and progression, providing an update on the current UPR modifying agents that can be potentially used in glioma treatment.

Synthesis and anti-phytopathogenic activity of 8-hydroxyquinoline derivatives

Phytopathogenic fungi have become a serious threat to the quality of agricultural products, food security and human health globally, necessitating the need to discover new antifungal agents with de novo chemical scaffolds and high efficiency. A series of 8-hydroxyquinoline derivatives were designed and synthesized, and their antifungal activity was evaluated against five phytopathogenic fungi. In vitro assays revealed that most of the tested compounds remarkably impacted the five target fungi and their inhibitory activities were better than that of the positive control azoxystrobin. Compound 2, in particular, exhibited the highest potency among all the tested compounds, with an EC₅₀ of 0.0021, 0.0016, 0.0124, 0.0059 and 0.0120 mM respectively against B. cinerea, S. sclerotiorum, F. graminearum, F. oxysporum and M. oryzae, followed by compound 5c. The morphological observations of optical microscopy and scanning electron microscopy revealed that compounds 2 and 5c caused mycelial abnormalities of S. sclerotiorum. Futhermore, the results of in vivo antifungal activity of compounds 2 and 5c against S. sclerotiorum showed that 5c possessed stronger protective and curative activity than that of 2, and the curative effects of 5c at 40 and 80 μg mL⁻¹ (84.18% and 95.44%) were better than those of azoxystrobin (77.32% and 83.59%). Therefore, compounds 2 and 5c are expected to be novel lead structures for the development of new fungicides.

Phytopathogenic fungi have become a serious threat to the quality of agricultural products, food security and human health globally, necessitating the need to discover new antifungal agents with de novo chemical scaffolds and high efficiency.

Recent advances in the discovery of small molecules targeting glioblastoma

Glioblastoma (GBM) is one of the most common central nervous system cancers. It is characterized as a fast-growing tumor that arises from multiple cell types with neural stem-cell-like properties. Additionally, GBM tumors are highly invasive, which is attributed to the presence of glioblastoma stem cells that makes surgery ineffective in most cases. Currently, temozolomide is the unique chemotherapy option approved by the U.S. Food and Drug Administration for GBM treatment. This review analyzes the emergence and development of new synthetic small molecules discovered as promising anti-glioblastoma agents. A number of compounds were described herein and grouped according to the main chemical class used in the drug discovery process. Importantly, we focused only on synthetic compounds published in the last 10 years, thus excluding natural products. Furthermore, we included in this review only those most biologically active compounds with proven in vitro and/or in vivo efficacy.

Novel hydrazide-hydrazone and amide substituted coumarin derivatives: Synthesis, cytotoxicity screening, microarray, radiolabeling and in vivo pharmacokinetic studies

The current work presents the synthesis and biological evaluation of new series of coumarin hydrazide-hydrazone derivatives that showed in vitro broad spectrum antitumor activities against resistant pancreatic carcinoma (Panc-1), hepatocellular carcinoma (HepG2) and leukemia (CCRF) cell lines using doxorubicin as reference standard. Bromocoumarin hydrazide-hydrazone derivative (BCHHD) 11b showed excellent anticancer activity against all tested cancer cell lines. Enzyme assays showed that BCHHD 11b induced apoptosis due to activation of caspases 3/7. Moreover, 11b inhibited GST and CYP3A4 in a dose dependent manner and the induced cell death could be attributed to metabolic inhibition. Moreover, 11b microarray analysis showed significant up- and down-regulation of many genes in the treated cells related to apoptosis, cell cycle, tumor growth and suppressor genes. All of the above presents BCHHD 11b as a potent anticancer agent able to overcome drug resistance. In addition, compound 11b was able to serve as a chemical carrier for ^99mTc and the in vivo biodistribution study of ^99mTc-11b complex revealed a remarkable targeting ability of ^99mTc into solid tumor showing that ^99mTc-11b might be used as a promising radiopharmaceutical imaging agent for cancer.

Do Cancer Drugs Counteract Neurodegeneration? Repurposing for Alzheimer's Disease

In spite of in depth investigations in the field of the amyloid cascade hypothesis, so far, no disease modifying therapy has been developed for Alzheimer's disease (AD). The pathophysiology provides some evidence of the inverse correlation between cancer and AD. Both AD and cancer are characterized by abnormal cellular behaviors; trigger factors along with a meta synchronously action is expected to drive cancer or neurodegeneration, supporting, respectively, progressive neuronal loss or uncontrolled cell proliferation in cancer cells. So far, cancer and AD are seemingly two opposite ends of the same biological spectrum. Basic science increasingly indicates shared molecular mechanisms between cancer and AD and gives weight to key relevant biological theories; according to them, the inverse tuning of clustered gene expression, the sharing of mutual independent pathway or the deregulated unfolded proteins system (UPR) may count for this inverse association. Additionally, the common biological background gave credibility to the recent discovery of a repurposing role for cancer drugs in AD. It refers to the development of new uses for existing pharmaceuticals having the same role as the original mechanism or to the discovery of a new drug action with disease modifying effects. The present review summarizes the most important biological theories that link neurodegeneration and cancer and provides an up-to-date revision of the repurposing cancer agents for AD. The review also addresses the gap of knowledge, since drug cancer repositioning holds an important promise but further investigations are warranted to ascertain the clinical relevance of such attractive clinical candidate compounds for AD.

ER stress in temozolomide-treated glioblastomas interferes with DNA repair and induces apoptosis

Glioblastoma multiforme (GBM) is a deadly grade IV brain tumor. Radiation in combination with temozolomide (TMZ), the current chemotherapeutic for GBMs, only provides 12–14 months survival post diagnosis. Because GBMs are dependent on both activation of the DNA damage pathway and the endoplasmic reticulum (ER) stress response, we asked if a novel ER stress inducing agent, JLK1486, increases the efficacy of TMZ.

We found that the combination of TMZ+JLK1486 resulted in decreased proliferation in a panel of adherent GBM cells lines and reduced secondary sphere formation in non-adherent and primary lines. Decreased proliferation correlated with increased cell death due to apoptosis. We found prolonged ER stress in TMZ+JLK1486 treated cells that resulted in sustained activation of the unfolded protein response (UPR) through increased levels of BiP, ATF4, and CHOP. In addition, TMZ+JLK1486 treatment caused decreased RAD51 levels, impairing DNA damage repair. Furthermore, we found delayed time to tumor doubling in TMZ+JLK1486 treated mice.

Our data shows that the addition of JLK1486 to TMZ increases the efficaciousness of the treatment by decreasing proliferation and inducing cell death. We propose increased cell death is due to two factors. One, prolonged ER stress driving the expression of the pro-apoptotic transcription factor CHOP, and, second, unresolved DNA double strand breaks, due to decreased RAD51 levels. The combination of TMZ+JLK1486 is a potential novel therapeutic combination and suggests an inverse relationship between unresolved ER stress and the DNA damage response pathway.

Inhibition of Zinc-Dependent Histone Deacetylases with a Chemically Triggered Electrophile

Unbiased binding assays involving small-molecule microarrays were used to identify compounds that display unique patterns of selectivity among members of the zinc-dependent histone deacetylase family of enzymes. A novel, hydroxyquinoline-containing compound, BRD4354, was shown to preferentially inhibit activity of HDAC5 and HDAC9 in vitro. Inhibition of deacetylase activity appears to be time-dependent and reversible. Mechanistic studies suggest that the compound undergoes zinc-catalyzed decomposition to an ortho-quinone methide, which covalently modifies nucleophilic cysteines within the proteins. The covalent nature of the compound-enzyme interaction has been demonstrated in experiments with biotinylated probe compound and with electrospray ionization-mass spectrometry.

8-Hydroxyquinoline: a privileged structure with a broad-ranging pharmacological potential

An overview of the broad-ranging pharmacological applications of 8-HQ derivatives.

JLK1486, a N,N-[(8-hydroxyquinoline)methyl]-substituted benzylamine analogue, inhibits melanoma proliferation and induces autophagy

OBJECTIVES

To investigate anti-proliferatory activity of a selected N,N-[(8-hydroxyquinoline)methyl]-substituted benzylamine (JLK1486) on melanoma cells and to characterize its mechanism of cell population growth inhibition.

MATERIALS AND METHODS

In vitro cultures of B16F10 (mouse melanoma) cells were used as a model to characterize anti-proliferatory activity of JLK1486 using MTT growth assay, trypan blue viability assessment, cell cycle analysis, melanin production, β-galactosidase and acridine orange staining.

RESULTS

Proliferating B16F10 and also MeWo (human melanoma) cells were strongly growth inhibited by JLK1486, displaying IC50 values of 196 nm and 110 nm respectively. Anti-proliferatory effects were independent of cell death and were characterized by a distinct accumulation of cells in G0 /G1 phase. Tyrosinase activity and relative melanin content remained unchanged indicating that the anti-proliferatory activity was not due to phenotype differentiation. Although treated B16F10 cells stained strongly positive for senescence marker β-galactosidase, cells regained near normal proliferatory activity after removal of JLK1486. Increased acridine orange staining and presence of perinuclear vacuoles suggested induction of autophagy in B16F10 cells. Furthermore, JLK1486 pre-treatment completely abolished melphalan and antimycin A-induced apoptosis.

CONCLUSION

JLK1486 provides a promising chemical scaffold to develop new anti-melanoma drugs or combination therapies, due to its potent inhibition of cell proliferation and induction of autophagy, at pharmacologically relevant concentrations.

JLK1486, a Bis 8-Hydroxyquinoline-Substituted Benzylamine, Displays Cytostatic Effects in Experimental Gliomas through MyT1 and STAT1 Activation and, to a Lesser Extent, PPARγ Activation

Gliomas account for 5% to 7% of all solid cancers in adults and up to 30% of solid cancers in children; glioblastomas are the most malignant type of glioma and often have dismal prognoses. The alkylating agent temozolomide provides the greatest chemotherapeutic benefits currently available; however, glioblastoma patients cannot be cured. Novel drugs that efficiently combat glioblastomas are therefore of great interest. We report here that JLK1486, an 8-hydroxyquinoline-substituted benzylamine, could represent a novel chemical scaffold to reach this goal. Indeed, JLK1486 mediated anticancer activity in vivo (through intravenous as well as oral routes of administrations) in an orthotopic xenograft model and displayed efficiency similar to that of temozolomide. The therapeutic benefits of JLK1486 seem to relate to its ability to activate various transcription factors (including Myt1, STAT1, and peroxisome proliferator-activated receptor γ) in glioma cells. These transcription factors are implicated in the control of glioma cell proliferation, and the resultant global effect of their activation by JLK1486 was cytostatic, not cytotoxic. Thus, the current study opens the door for the development of novel compounds to combat glioblastoma using 8-hydroxyquinoline benzylamine analogs.

In vitro anticancer activity, toxicity and structure-activity relationships of phyllostictine A, a natural oxazatricycloalkenone produced by the fungus Phyllosticta cirsii

The in vitro anticancer activity and toxicity of phyllostictine A, a novel oxazatricycloalkenone recently isolated from a plant-pathogenic fungus (Phyllosticta cirsii) was characterized in six normal and five cancer cell lines. Phyllostictine A displays in vitro growth-inhibitory activity both in normal and cancer cells without actual bioselectivity, while proliferating cells appear significantly more sensitive to phyllostictine A than non-proliferating ones. The main mechanism of action by which phyllostictine displays cytotoxic effects in cancer cells does not seem to relate to a direct activation of apoptosis. In the same manner, phyllostictine A seems not to bind or bond with DNA as part of its mechanism of action. In contrast, phyllostictine A strongly reacts with GSH, which is a bionucleophile. The experimental data from the present study are in favor of a bonding process between GSH and phyllostictine A to form a complex though Michael attack at C=C bond at the acrylamide-like system. Considering the data obtained, two new hemisynthesized phyllostictine A derivatives together with three other natural phyllostictines (B, C and D) were also tested in vitro in five cancer cell lines. Compared to phyllostictine A, the two derivatives displayed a higher, phyllostictines B and D a lower, and phyllostictine C an almost equal, growth-inhibitory activity, respectively. These results led us to propose preliminary conclusions in terms of the structure-activity relationship (SAR) analyses for the anticancer activity of phyllostictine A and its related compounds, at least in vitro.

N,N-Bis-(8-hydroxyquinoline-5-yl methyl)-benzyl substituted amines (HQNBA): peroxisome proliferator-activated receptor (PPAR-γ) agonists with neuroprotective properties

We report on the neuroprotective effects of N,N-bis-(8-hydroxyquinoline-5-yl methyl)-benzyl substituted amines (HQNBA) in a model of oxidative stress-induced nerve cell death using mouse hippocampal-derived HT22 cells. The four derivatives (JLK1472, JLK1486, JLK1522 and JLK1535) protected the HT22 cells from death at concentrations ranging from 0.1 to 1 μM. Their action is partially dependent on their ability to act as PPARγ agonists. These analogues also maintain GSH levels suggesting that they have indirect anti-oxidant effects.

QSAR analysis of antitumor active amides and quinolones from thiophene series

QSAR models for predicting antitumor activity of heterocyclic amides and quinolones from benzo[b]thiophene-, thieno[3,2-b]thiophene- and thieno[2,3-b], thiophene series against MiaPaCa-2 and MCF-7 cells were built. Complete dataset consisted of 59 compounds and several QSAR models with different predictive ability were derived. Beside standard approaches for building QSAR models, the approach based on a small dataset of 10 compounds selected regarding the results of principal component analysis was tested. The latter approach was shown as successful and can be useful for planning future experiments in order to speed up and simplify the search for new drug candidates. Based on the derived QSAR models, the most important properties for compound's antitumor activity against MiaPaCa-2 and MCF-7 cells were identified. Volume, sum of the hydrophobic surfaces and presence of the group that can be easily ionized in the pH range from 4 to 9, were found to be highly important for successful antitumor activity of the examined heterocyclic amides and quinolones. New compounds, with potentially higher biological activity against MiaPaCa-2 and MCF-7 cells, were proposed. Their activities were predicted using the derived QSAR models and the proposed compounds were shown as promising antitumor candidates.