A 4-aminoquinoline derivative that markedly sensitizes tumor cell killing by Akt inhibitors with a minimum cytotoxicity to non-cancer cells

Therapeutic vulnerabilities of cancer stem cells and effects of natural products

Covering: 1995 to 2022Tumors possess both genetic and phenotypic heterogeneity leading to the survival of subpopulations post-treatment. The term cancer stem cells (CSCs) describes a subpopulation that is resistant to many types of chemotherapy and which also possess enhanced migratory and anchorage-independent growth capabilities. These cells are enriched in residual tumor material post-treatment and can serve as the seed for future tumor re-growth, at both primary and metastatic sites. Elimination of CSCs is a key goal in enhancing cancer treatment and may be aided by application of natural products in conjunction with conventional treatments. In this review, we highlight molecular features of CSCs and discuss synthesis, structure-activity relationships, derivatization, and effects of six natural products with anti-CSC activity.

Anticancer properties of bisaminoquinolines with modified linkers

We have previously reported the unique features of dimeric bisaminoquinolines as anticancer agents and have identified their cellular target as PPT1, a protein palmitoyl-thioesterase. We now report a systematic study on the role of the linker in these constructs, both with respect to the distance between the heterocycles, the linker hydrophobicity and the methylation status (primary vs. secondary vs. tertiary) of the central nitrogen atom on the observed biological activity.

Microwave-assisted Synthesis of Novel Mannich Base and Conazole Derivatives Containing Biologically Active Pharmacological Groups

Background:

The aim of this study was to synthesize new mannich bases and conazol derivatives with biological activity by the microwave-assisted method.

Introduction:

1,2,4-Triazole-3-one (3) acquired from tryptamine was transformed to the corresponding carbox(thio)amides (6a-c) via several steps. Compounds 6a-c were refluxed with sodium hydroxide to yield 1,2,4-triazole derivatives (7a-c). Compounds 3 and 7a-c on treatment with different heterocyclic secondary amines in an ambiance with formaldehyde afforded the mannich bases 8-15 having diverse pharmacophore units with biologically active sites. The reaction of compound 3 and 2-bromo-1-(4-chlorophenyl) ethanone in the presence of sodium ethoxide gave the corresponding product 2-substituted-1,2,4-triazole-3-one, 16, which was reduced to 1,2,4-triazoles (17). Synthesis of compounds 18, 19, and 20 was carried out starting from compounds 17 with 4-chlorobenzyl chloride (for 18), 2,4-dichlorobenzyl chloride (for 19), and 2,6-dichlorobenzyl chloride (for 20).

Methods:

he conventional technique was utilized for the synthesis of compounds, 3-7, and microwave- assisted technique for the compounds, 8-20. That is, green chemistry techniques were applied during these reactions. The structures of molecules were elucidated on the foundation of 1H NMR, 13C NMR, FT-IR, EI-MS methods, and elemental analysis. Novel synthesized molecules were investigated for their antimicrobial activity using MIC (minimum inhibitory concentration) method.

Results:

Aminoalkylation of triazole derivatives 3 and 7a-c with fluoroquinolones such as ciprofloxacin and norfloxacin provided an enhancement to the bioactivity of mannich bases 8-11 against the tested microorganisms. The MIC values ranged between <0.24 and 3.9 μg/mL. Moreover, molecules 10 and 11 exhibited more effects on M. smegmatis than the other compounds by the MIC values of <1 μg/mL. They have shown very good antituberculosis activity.

Conclusion:

Most of the synthesized structures were observed to have excellent antimicrobial activity against most microorganisms taken into account. These molecules have better activity than the standard drug ampicillin and streptomycin.

6-Polyamino-substituted quinolines: synthesis and multiple metal (CuII, HgII and ZnII) monitoring in aqueous media

Chemoselective palladium-catalyzed arylation of polyamines with 6-bromoquinoline has been explored to prepare chelators for the detection of metal cations in aqueous media. The introduction of a single aromatic moiety into non-protected polyamine molecules was achieved using the commercially available Pd(dba)2/BINAP precatalyst to afford nitrogen chelators, in which the aromatic signalling unit is directly attached to the polyamine residue. Water-soluble receptors were then synthesized using N-alkylation of these polyamines by hydrophilic coordinating residues. By combining rich photophysical properties of the 6-aminoquinoline unit with a high coordination affinity of chelating polyamines and a hydrophilic character of carboxamido-substituted phosphonic acid diesters in a single molecular device, we synthesized chemosensor 5 for selective double-channel (UV-vis and fluorescence spectroscopies) detection of CuII ions in aqueous media at physiological levels. This receptor is suitable for the analysis of drinking water and fabrication of paper test strips for the naked-eye detection of CuII ions under UV-light. By increasing the number of donor sites we also obtained chemosensor 6 which is efficient for the detection of HgII ions. Moreover, chemosensor 6 is also suitable for multiple detection of metal ions because it chelates not only HgII but also CuII and ZnII ions displaying different responses of emission in the presence of these three cations.

Design and synthesis of 4-piperazinyl quinoline derived urea/thioureas for anti-breast cancer activity by a hybrid pharmacophore approach

In an attempt to improve anti-breast cancer activity, a new series of 4-piperazinylquinoline derivatives based on the urea/thiourea scaffold were designed and synthesised by a pharmacophore hybrid approach. We then examined for their antiproliferative effects on three human breast tumor cell lines, MDA-MB231, MDA-MB468 and MCF7, and two non-cancer breast epithelial cell lines, 184B5 and MCF10A. Among those 26 novel compounds examined, 5, 9, 17, 18, 21, 23 and 29 showed significantly improved antiproliferative activity on breast cancer cells. Compound 23 (4-(7-chloro-quinolin-4-yl)-piperazine-1-carbothioic acid (2-morpholin-4-yl-ethyl)-amide) (RL-15) is especially desirable, since its antigrowth/cell-killing activity is 7-11 fold higher on cancer than non-cancer cells. Data from cell biological studies demonstrated that cancer cells compromised plasma membrane integrity in the presence of compound 23. The cancer cell-specific property of compound 23 shown in cell culture stands in vivo test, this compound can be an excellent lead for effective and safe anticancer drug.

Synthesis of Chromen-4-One-Oxadiazole Substituted Analogs as Potent β-Glucuronidase Inhibitors

Chromen-4-one substituted oxadiazole analogs 1-19 have been synthesized, characterized and evaluated for β-glucuronidase inhibition. All analogs exhibited a variable degree of β-glucuronidase inhibitory activity with IC₅₀ values ranging in between 0.8 ± 0.1-42.3 ± 0.8 μM when compared with the standard d-saccharic acid 1,4 lactone (IC₅₀ = 48.1 ± 1.2 μM). Structure activity relationship has been established for all compounds. Molecular docking studies were performed to predict the binding interaction of the compounds with the active site of enzyme.

Chloroquine-based hybrid molecules as promising novel chemotherapeutic agents

Chloroquine (CQ) has a broad spectrum of pharmacological activities including anticancer and anti-inflammatory, in addition to its well-known antimalarial activity. This very useful property of CQ may be rendered through a variety of different molecular and cellular mechanisms, including the induction of apoptosis, necrosis and lysosomal dysfunction. CQ alone may not be as effective as many well-known anticancer drugs; however, it often shows synergisticts when combined with other anticancer agents, without causing substantial ill-effects. To increase its pharmacological activity, scientists synthesized many different chloroquine derivatives by a repositioning approach, some of which show higher activities than the parental CQ. To further improve anticancer activity, medicinal chemists have recently been focusing on generating CQ hybrid molecules by joining, directly or through a linker, 4-aminoquinoline and other pharmacologically active phamarcophore(s). Indeed, some CQ hybrid molecules substantially improved anticancer activity while maintaining desirable CQ property, providing an excellent opportunity of developing effective and safe novel anticancer agents. Since the approach of developing CQ hybrid molecules has advanced much more in the antimalarial drug research, it can provide an excellent template for anticancer drug development. This review provides an overview of CQ-based hybrid molecules by focusing on: (1) the potential advantage of the hybrid approach in developing effective and safe anticancer agents; (2) what we can learn from the CQ hybrid approach used in the development of effective antimalarial agents; and (3) CQ hybrid molecules as potential anticancer agents in different categories classified based on their chemical compositions.

The potential of quinoline derivatives for the treatment of Toxoplasma gondii infection

Here we reported our investigation, as part of our drug repositioning effort, on anti-Toxoplasma properties of newly synthesized quinoline compounds. A collection of 4-aminoquinoline and 4-piperazinylquinoline analogs have recently been synthesized for use in cancer chemotherapy. Some analogs were able to outperform chloroquine, a quinoline derivative drug which is commonly used in the treatment of malaria and other parasitic infections. Herein 58 compounds containing one or two quinoline rings were examined for their effectiveness as potential anti-Toxoplasma compounds. Of these 58 compounds, 32 were efficient at inhibiting Toxoplasma growth (IC50<100 μM). Five compounds with single and simple quinoline rings exhibited similar cLogP values of ∼2 and IC50 values between 5 and 6 μM, with one exception of 8-hydroxyquinoline whose IC50 value was 213 nM. The addition of one hydroxyl group at position 8 caused a 40-fold increase in the inhibitory effect of quinoline. A significant improvement in anti-Toxoplasma effect among quinoline derivatives was detected in B11, B12, B23, and B24, whose structures carry two quinoline rings, and their resultant cLogP values are ⩾7. Among these compounds, B23 was the most effective compound with IC50 value of 425±35 nM, and TI value of 4.9. It was also noted that compounds with at least one quinoline ring, displaying anti-Toxoplasma effects were capable of causing the disappearance of the apicoplast, a plastid-like organelle. When treated with quinoline, 8-hydroxyquinoline or B23, 40-45% of the parasites lost their apicoplasts. Our findings recapitulate the properties of quinoline derivatives in diminishing apicoplast. This could aid further investigations of anti-parasitic treatments specific to Apicomplexan. More importantly, B12 and B23 which harbor superior anti-cancer properties than chloroquine, have effective anti-Toxoplasma activity. These compounds therefore have significant potential for future development of chemotherapeutic agents for patients suffering from breast cancers and parasitic infection.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for anticancer hybrids

A Hybrid drug which comprises the incorporation of two drug pharmacophores in one single molecule are basically designed to interact with multiple targets or to amplify its effect through action on another bio target as one single molecule or to counterbalance the known side effects associated with the other hybrid part(.) The present review article offers a detailed account of the design strategies employed for the synthesis of anticancer agents via molecular hybridization techniques. Over the years, the researchers have employed this technique to discover some promising chemical architectures displaying significant anticancer profiles. Molecular hybridization as a tool has been particularly utilized for targeting tubulin protein as exemplified through the number of research papers. The microtubule inhibitors such as taxol, colchicine, chalcones, combretasatin, phenstatins and vinca alkaloids have been utilized as one of the functionality of the hybrids and promising results have been obtained in most of the cases with some of the tubulin based hybrids exhibiting anticancer activity at nanomolar level. Linkage with steroids as biological carrier vector for anticancer drugs and the inclusion of pyrrolo [2,1-c] [1,4]benzodiazepines (PBDs), a family of DNA interactive antitumor antibiotics derived from Streptomyces species in hybrid structure based drug design has also emerged as a potential strategy. Various heteroaryl based hybrids in particular isatin and coumarins have also been designed and reported to posses' remarkable inhibitory potential. Apart from presenting the design strategies, the article also highlights the structure activity relationship along with mechanistic insights revealed during the biological evaluation of the hybrids.

Chloroquine has tumor-inhibitory and tumor-promoting effects in triple-negative breast cancer

Toll-like receptor-9 (TLR9) is an intracellular DNA receptor that is widely expressed in breast and other cancers. We previously demonstrated that low tumor TLR9 expression upon diagnosis is associated with significantly shortened disease-specific survival times in patients with triple-negative breast cancer (TNBC). There are no targeted therapies for this subgroup of patients whose prognosis is among the worst in breast cancer. Due to the previously detected in vitro anti-invasive effects of chloroquine in these cell lines, the present study aimed to investigate the in vivo effects of chloroquine against two clinical subtypes of TNBC that differ in TLR9 expression. Chloroquine suppressed matrix metalloproteinase (MMP)-2 and MMP-9 mRNA expression and protein activity, whereas MMP-13 mRNA expression and proteolytic activity were increased. Despite enhancing TLR9 mRNA expression, chloroquine suppressed TLR9 protein expression in vitro. Daily treatment of mice with intraperitoneal (i.p.) chloroquine (80 mg/kg/day) for 22 days, did not inhibit the growth of control siRNA or TLR9 siRNA MDA-MB-231 breast cancer cells. In conclusion, despite the favorable in vitro effects on TNBC invasion and viability, particularly in hypoxic conditions, chloroquine does not prevent the growth of the triple-negative MDA-MB-231 cells with high or low TLR9 expression levels in vivo. This may be explained by the activating effects of chloroquine on MMP-13 expression or by the fact that chloroquine, by suppressing TLR9 expression, permits the activation of currently unknown molecular pathways, which allow the aggressive behavior of TNBC cells with low TLR9 expression in hypoxia.

Autophagy inhibitor Lys05 has single-agent antitumor activity and reproduces the phenotype of a genetic autophagy deficiency

Autophagy is a lysosome-dependent degradative process that protects cancer cells from multiple stresses. In preclinical models, autophagy inhibition with chloroquine (CQ) derivatives augments the efficacy of many anticancer therapies, but CQ has limited activity as a single agent. Clinical trials are underway combining anticancer agents with hydroxychloroquine (HCQ), but concentrations of HCQ required to inhibit autophagy are not consistently achievable in the clinic. We report the synthesis and characterization of bisaminoquinoline autophagy inhibitors that potently inhibit autophagy and impair tumor growth in vivo. The structural motifs that are necessary for improved autophagy inhibition compared with CQ include the presence of two aminoquinoline rings and a triamine linker and C-7 chlorine. The lead compound, Lys01, is a 10-fold more potent autophagy inhibitor than HCQ. Compared with HCQ, Lys05, a water-soluble salt of Lys01, more potently accumulates within and deacidifies the lysosome, resulting in impaired autophagy and tumor growth. At the highest dose administered, some mice develop Paneth cell dysfunction that resembles the intestinal phenotype of mice and humans with genetic defects in the autophagy gene ATG16L1, providing in vivo evidence that Lys05 targets autophagy. Unlike HCQ, significant single-agent antitumor activity is observed without toxicity in mice treated with lower doses of Lys05, establishing the therapeutic potential of this compound in cancer.

Akt and p53 are potential mediators of reduced mammary tumor growth by cloroquine and the mTOR inhibitor RAD001

PI3K/Akt/mTOR and p53 signaling pathways are frequently deregulated in tumors. The anticancer drug RAD001 (everolimus) is a known mTOR-inhibitor, but mTOR-inhibition leads to phosphorylation of Akt inducing resistance against RAD001 treatment. There is growing evidence that conflicting signals transduced by the oncogene Akt and the tumorsuppressor p53 are integrated via negative feedback between the two pathways. We previously showed that the anti-malarial Chloroquine, a 4-alkylamino substituted quinoline, is a p53 activator and reduced the incidence of breast tumors in animal models. Additionally, Chloroquine is an effective chemosensitizer when used in combination with PI3K/Akt inhibitors but the mechanism is unknown. Therefore, our aim was to test, if Chloroquine could inhibit tumor growth and prevent RAD001-induced Akt activation. Chloroquine and RAD001 caused G1 cell cycle arrest in luminal MCF7 but not in mesenchymal MDA-MB-231 breast cancer cells, they significantly reduced MCF7 cell proliferation on a collagen matrix and mammospheroid formation. In a murine MCF7 xenograft model, combined treatment of Chloroquine and RAD001 significantly reduced mammary tumor growth by 4.6-fold (p = 0.0002) compared to controls. Chloroquine and RAD001 inhibited phosphorylation of mTOR and its downstream target, S6K1. Furthermore, Chloroquine was able to block the RAD001-induced phosphorylation of Akt serine 473. The Chloroquine effect of overcoming the RAD001-induced activation of the oncogene Akt, as well as the promising antitumor activity in our mammary tumor animal model present Chloroquine as an interesting combination partner for the mTOR-inhibitor RAD001.

Cyclization of some carbothioamide derivatives containing antipyrine and triazole moieties and investigation of their antimicrobial activities

Acetohydrazide derivative containing both antipyrine and triazole nuclei (5) was obtained starting from ethyl hydrazinecarboxylate derivative (2) and 4-aminoantipyrine (1) by three steps. The treatment of compound 5 with CS(2) afforded the conversion of hydrazide function into 5-mercapto-1,3,4-oxadiazole ring leading to the formation of 7. Then, 7 gave the product containing triazolotriazine moiety (9) by the reaction with hydrazine hydrate. The synthesis of the compounds incorporating the 1,3,4-thiadiazole (10a-c), 1,2,4-triazole (11a-c) or 1,3-thiazole (12, 13) nucleus as third heterocycle was performed by the acidic or basic treatment of compounds 6a-c which were obtained from the reaction of 5 with several isothiocyanates, or by the condensation of 6a with two different phenacyl bromides, respectively. The antimicrobial activity study revealed that all the compounds showed good activities except 3-5.