Sulfur and selenium derivatives of quinazoline and pyrido[2,3-d]pyrimidine: synthesis and study of their potential cytotoxic activity in vitro

Design and Synthesis of Polyheterocyclic Compounds Containing Pyrazolopyridopyrimidine Nucleus with Antimicrobial Activities

This study reports the design, synthesis, and antibacterial evaluation of a library of novel polyheterocyclic derivatives featuring a unique fused pyrimidopyridopyrazole moiety. A cyclocondensation reaction between an amino-pyrazolopyridopyrimidine precursor and malonates afforded a series of pyrimidopyridopyrazolopyrimidine derivatives. Further diversification was achieved through nucleophilic cyclocondensation, yielding a collection of complex polyheterocyclic systems encompassing various ring structures. All synthesized compounds were rigorously characterized using spectroscopic techniques and elemental analysis. The antibacterial activity of the newly synthesized compounds was assessed against a panel of Gram-positive and Gram-negative bacteria. Notably, several compounds exhibited promising antibacterial activity, highlighting their potential as leads for the development of novel antibiotics.

Induction of breast cancer cell apoptosis by novel thiouracil-fused heterocyclic compounds through boosting of Bax/Bcl-2 ratio and DFT study

Breast cancer is a common public health disease causing mortality worldwide. Thus, providing novel chemotherapies that tackle breast cancer is of great interest. In this investigation, novel pyrido[2,3-d]pyrimidine derivatives 3,4,(6a-c),(8a,b),9-20 were synthesized and characterized using a variety of spectrum analyses. The geometric and thermal parameters of the novel thiouracil derivatives 3,4,6a,(8a,b),11,12,17,18, 19 were measured using density functional theory (DFT) via DFT/B3LYP/6-31 + G(d,p) basis set. All synthesized compounds were evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) method using MCF-7 and MDA-MB-231 breast cancerous cells, compound 17 had the maximum anticancer activity against both breast cancerous cells, recording the lowest half-maximal inhibitory concentration (IC50) values (56.712 μg/mL for MCF-7 cells and 48.743 μg/mL for MDA-MB-231 cells). The results were confirmed in terms of the intrinsic mechanism of apoptosis, where compound 17 had the highest percentage in the case of both cancer cells and recorded Bax (Bcl-2 associated X)/Bcl-2 (B-cell lymphoma 2) ratio 17.5 and 96.667 for MCF-7 and MDA-MB-231 cells, while compound 19 came after 17 in the ability for induction of apoptosis, where the Bax/Bcl-2 ratio was 15.789 and 44.273 for both cancerous cells, respectively. Also, compound 11 recorded a high Bax/Bcl-2 ratio for both cells. The safety of the synthesized compounds was applied on normal WI-38 cells, showing minimum cytotoxic effect with undetectable IC50. Compounds 17, 11, and 19 recorded a significant increase of p53 upregulated modulator of apoptosis (PUMA) expression levels in the cancerous cells. The DFT method was also used to establish a connection between the experimentally determined values of the present investigated compounds and their predicted quantum chemical parameters. It was concluded that Compounds 17, 11, and 19 had anti-breast cancer potential through the induction of apoptotic Bax/Bcl-2 and PUMA expression levels.

Antiviral Effect of 5'-Arylchalcogeno-3-aminothymidine Derivatives in SARS-CoV-2 Infection

The understanding that zidovudine (ZDV or azidothymidine, AZT) inhibits the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 and that chalcogen atoms can increase the bioactivity and reduce the toxicity of AZT has directed our search for the discovery of novel potential anti-coronavirus compounds. Here, the antiviral activity of selenium and tellurium containing AZT derivatives in human type II pneumocytes cell model (Calu-3) and monkey kidney cells (Vero E6) infected with SARS-CoV-2, and their toxic effects on these cells, was evaluated. Cell viability analysis revealed that organoselenium (R3a-R3e) showed lower cytotoxicity than organotellurium (R3f, R3n-R3q), with CC50 ≥ 100 µM. The R3b and R3e were particularly noteworthy for inhibiting viral replication in both cell models and showed better selectivity index. In Vero E6, the EC50 values for R3b and R3e were 2.97 ± 0.62 µM and 1.99 ± 0.42 µM, respectively, while in Calu-3, concentrations of 3.82 ± 1.42 µM and 1.92 ± 0.43 µM (24 h treatment) and 1.33 ± 0.35 µM and 2.31 ± 0.54 µM (48 h) were observed, respectively. The molecular docking calculations were carried out to main protease (Mpro), papain-like protease (PLpro), and RdRp following non-competitive, competitive, and allosteric inhibitory approaches. The in silico results suggested that the organoselenium is a potential non-competitive inhibitor of RdRp, interacting in the allosteric cavity located in the palm region. Overall, the cell-based results indicated that the chalcogen-zidovudine derivatives were more potent than AZT in inhibiting SARS-CoV-2 replication and that the compounds R3b and R3e play an important inhibitory role, expanding the knowledge about the promising therapeutic capacity of organoselenium against COVID-19.

Preparation of Selenium-Based Drug-Modified Polymeric Ligand-Functionalised Fe3O4 Nanoparticles as Multimodal Drug Carrier and Magnetic Hyperthermia Inductor

In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe₃O₄ nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe₃O₄ nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe₃O₄ nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents.

Facile Access to 2-Selenoxo-1,2,3,4-tetrahydro-4-quinazolinone Scaffolds and Corresponding Diselenides via Cyclization between Methyl Anthranilate and Isoselenocyanates: Synthesis and Structural Features

A practical method for the synthesis of 2-selenoxo-1,2,3,4-tetrahydro-4-quinazolinone was reported. The latter compounds were found to undergo facile oxidation with H2O2 into corresponding diselenides. Novel organoselenium derivatives were characterized by the 1H, 77Se, and 13C NMR spectroscopies, high-resolution electrospray ionization mass spectrometry, IR, elemental analyses (C, H, N), and X-ray diffraction analysis for several of them. Novel heterocycles exhibited multiple remarkable chalcogen bonding (ChB) interactions in the solid state, which were studied theoretically.

New Organoselenium (NSAIDs-Selenourea and Isoselenocyanate) Derivatives as Potential Antiproliferative Agents: Synthesis, Biological Evaluation and in Silico Calculations

In this study, we report on the synthesis of new organoselenium derivatives, including nonsteroidal anti-inflammatory drugs (NSAIDs) scaffolds and Se functionalities (isoselenocyanate and selenourea), which were evaluated against four types of cancer cell line: SW480 (human colon adenocarcinoma cells), HeLa (human cervical cancer cells), A549 (human lung carcinoma cells), MCF-7 (human breast adenocarcinoma cells). Among these compounds, most of the investigated compounds reduced the viability of different cancer cell lines. The most promising compound 6b showed IC₅₀ values under 10 μM against the four cancer cell lines, particularly to HeLa and MCF-7, with IC₅₀ values of 2.3 and 2.5 μM, respectively. Furthermore, two compounds, 6b and 6f, were selected to investigate their ability to induce apoptosis in MCF-7 cells via modulation of the expression of anti-apoptotic Bcl-2 protein, pro-inflammatory cytokines (IL-2) and proapoptotic caspase-3 protein. The redox properties of the NSAIDs-Se derivatives were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), bleomycin-dependent DNA damage and glutathione peroxidase (GPx)-like assays. Finally, a molecular docking study revealed that an interaction with the active site of thioredoxin reductase 1 (TrxR1) predicted the antiproliferative activity of the synthesized candidates. Overall, these results could serve as a promising launch point for further designs of NSAIDs-Se derivatives as potential antiproliferative agents.

Synthesis and In Silico Docking of New Pyrazolo[4,3-e]pyrido[1,2-a]pyrimidine-based Cytotoxic Agents

To explore a new set of anticancer agents, a novel series of pyrazolo[4,3-e]pyrido[1,2-a]pyrimidine derivativeshave been designed and synthesized viacyclocondensation reactions of pyrazolo-enaminone with a series of arylidenemalononitriles; compound 5 was obtained from 5-amino-4-cyanopyrazole. The structures of the target compounds were investigated by spectral techniques and elemental analysis (IR, UV-Vis, ¹H NMR, ¹³C NMR and ESI-MS). All compounds were evaluated for their in vitro cytotoxicity employing a panel of different human tumor cell lines, A375, HT29, MCF7, A2780, FaDu as well as non-malignant NIH 3T3 and HEK293 cells. It has been found that the pyrazolo-pyrido-pyrimidine analog bearing a 4-Br-phenyl moiety was the most active toward many cell lines with EC₅₀ values ranging between 9.1 and 13.5 µM. Moreover, in silico docking studies of the latter with six anticancer drug targets, i.e., DHFR, VEGFR2, HER-2/neu, hCA-IX, CDK6 and LOX5, were also performed, in order to gain some insights into their putative mode of binding interaction and to estimate the free binding energy of this bioactive molecule.

Pyrimidine: a review on anticancer activity with key emphasis on SAR

Background

Cancer is a global health challenge, it impacts the quality of life and its treatment is associated with several side effects. Resistance of the cancer cells to the existing drugs has led to search for novel anticancer agents. Pyrimidine, a privileged scaffold, is part of living organisms and plays vital role in various biological procedures as well as in cancer pathogenesis. Due to resemblance in structure with the nucleotide base pair of DNA and RNA, it is recognized as valuable compound in the treatment of cancer.

Main text

Many novel pyrimidine derivatives have been designed and developed for their anticancer activity in the last few years. The present review aims to focus on the structure activity relationship (SAR) of pyrimidine derivatives as anticancer agent from the last decade.

Conclusion

This review intends to assist in the development of more potent and efficacious anticancer drugs with pyrimidine scaffold.

Graphical abstract

Small molecule selenium-containing compounds: Recent development and therapeutic applications

Selenium (Se) is an essential micronutrient of organism and has important function. It participates in the functions of selenoprotein in several manners. In recent years, Se has attracted much attention because of its therapeutic potential against several diseases. Many natural and synthetic organic Se-containing compounds were studied and explored for the treatment of cancer and other diseases. Studies have showed that incorporation of Se atom into small molecules significantly enhanced their bioactivities. In this paper, according to different applications and structural characteristics, the research progress and therapeutic application of Se-containing compounds are reviewed, and more than 110 Se-containing compounds were selected as representatives which showed potent activities such as anticancer, antioxidant, antifibrolytic, antiparasitic, antibacterial, antiviral, antifungal and central nervous system related effects. This review is expected to provide a basis for further study of new promising Se-containing compounds.

Synthesis and biological evaluation of organoselenium (NSAIDs-SeCN and SeCF3) derivatives as potential anticancer agents

A series of organoselenium compounds based on the hybridization of nonsteroidal antiinflammatory drugs (NSAIDs) scaffolds and Se functionalities (-SeCN and -SeCF₃) were synthesized and characterized, and evaluated against four types of cancer cell lines, SW480 (human colon adenocarcinoma cells), HeLa (human cervical cancer cells), A549 (human lung carcinoma cells), MCF-7 (human breast adenocarcinoma cells). Interestingly, most of the investigated compounds showed active in reducing the viability of different cancer cell lines. The most active compound 3h showed IC₅₀ values lower than 20 μM against the four cancer cell lines, particularly to SW480 and MCF-7 with IC 50 values of 4.9 and 3.4 μM, respectively. Furthermore, NSAIDs-SeCN derivatives (2h and 2i) and NSAIDs-SeCF₃ derivatives (3h and 3i) were selected to investigate their ability to induce apoptosis in MCF-7 cells via modulation the expression of anti-apoptotic Bcl-2 protein, pro-inflammatory cytokines (IL-2) and proapoptotic caspase-3 protein. Moreover, the redox properties of the synthesized organoselenium candidates were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), bleomycin dependent DNA damage and glutathione peroxidase (GPx)-like assays. Taken together, these NSAIDs-Se candidates could provide promising new lead derivatives for further potential anticancer drug development.

Design, synthesis and molecular modeling studies of 2-styrylquinazoline derivatives as EGFR inhibitors and apoptosis inducers

Herein, we report the synthesis of novel 2-substituted styrylquinazolines conjugated with aniline or sulfonamide moieties, anticipated to act as potent anticancer therapeutic agents through preferential EGFR inhibition. In doing so, all the synthesized compounds were screened for their in vitro anticancer activities (nine subpanels) at the National Cancer Institute (NCI), USA. The resulting two most active anticancer compounds (7b and 8c) were then chemically manipulated to investigate feasible derivatives (12a-e and 15a-d). MTT cytotoxicity, in vitro cell free EGFR and anti-proliferative activity against EGFR/ A549 cell line evaluation for the most active broadly spectrum candidates (7a/b, 8c/e, 12b and 15d) was conducted. Promising results were obtained for the styrylquinazoline-benzenesulfonamide derivative 8c (IC50 = 8.62 µM, 0.190 µM and = 79.25%), if compared to lapatanib (IC50 = 11.98 µM, 0.190 µM, and 79.25%), respectively. Moreover, its apoptotic induction potential was studied through cell cycle analysis, Annexin-V and caspase-3 activation assays. Results showed a clear cell arrest at G2/M phase, a late apoptotic increase (76 folds) and a fruitful caspase-3 expression change (8 folds), compared to the control. Finally, molecular docking studies of compounds 7a/b, 8c/e, 12b and 15d revealed proper fitting into the active site of EGFR with a low binding energy score for compound 8c (-13.19 Kcal/mole), compared to lapatanib (-14.54 Kcal/mole).

An overview on synthetic and pharmaceutical prospective of pyrido[2,3-d]pyrimidines scaffold

Pyrido[2,3-d]pyrimidine, a fused hetero-bicyclic nucleus containing pyridine and pyrimidine rings has attained the momentary attention in the sphere of multicomponent synthetic protocol and medicinal chemist. Pyrido[2,3-d]pyrimidine derived drugs have manifested diverse pharmacological activities, particularly, anti-inflammatory, cytotoxic, antimicrobial, phosphodiesterase inhibitors and cytokine inhibitors etc. The present review illustrates various modern synthetic strategies adopted, the structure-activity relationship (SAR) aspects and discloses the extensive crucial biological properties (anticancer, anti-infectious, anti-diabetics and CNS agents) of pyrido[2,3-d]pyrimidines.

Novel N,N'-Disubstituted Acylselenoureas as Potential Antioxidant and Cytotoxic Agents

Selenium compounds are pivotal in medicinal chemistry for their antitumoral and antioxidant properties. Forty seven acylselenoureas have been designed and synthesized following a fragment-based approach. Different scaffolds, including carbo- and hetero-cycles, along with mono- and bi-cyclic moieties, have been linked to the selenium containing skeleton. The dose- and time-dependent radical scavenging activity for all of the compounds were assessed using the in vitro 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assays. Some of them showed a greater radical scavenging capacity at low doses and shorter times than ascorbic acid. Therefore, four compounds were evaluated to test their protective effects against H₂O₂-induced oxidative stress. One derivative protected cells against H₂O₂-induced damage, increasing cell survival by up to 3.6-fold. Additionally, in vitro cytotoxic activity of all compounds was screened against several cancer cells. Eight compounds were selected to determine their half maximal inhibitory concentration (IC₅₀) values towards breast and lung cancer cells, along with their selectivity indexes. The breast cancer cells turned out to be much more sensitive than the lung. Two compounds (5d and 10a) stood out with IC₅₀ values between 4.2 μM and 8.0 μM towards MCF-7 and T47D cells, with selectivity indexes greater than 22.9. In addition, compound 10b exhibited dual antioxidant and cytotoxic activities. Although further evidence is needed, the acylselenourea scaffold could be a feasible frame to develop new dual agents.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

This review summarizes recent advances in C–S and C–Se formationsviatransition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

Synthesis and Leishmanicidal Activity of Novel Urea, Thiourea, and Selenourea Derivatives of Diselenides

A novel series of thirty-one N-substituted urea, thiourea, and selenourea derivatives containing diphenyldiselenide entities were synthesized, fully characterized by spectroscopic and analytical methods, and screened for their in vitro leishmanicidal activities. The cytotoxic activity of these derivatives was tested against Leishmania infantum axenic amastigotes, and selectivity was assessed in human THP-1 cells. Thirteen of the synthesized compounds showed a significant antileishmanial activity, with 50% effective concentration (EC₅₀) values lower than that for the reference drug miltefosine (EC₅₀, 2.84 μM). In addition, the derivatives 9, 11, 42, and 47, with EC₅₀ between 1.1 and 1.95 μM, also displayed excellent selectivity (selectivity index ranged from 12.4 to 22.7) and were tested against infected macrophages. Compound 11, a derivative with a cyclohexyl chain, exhibited the highest activity against intracellular amastigotes, with EC₅₀ values similar to those observed for the standard drug edelfosine. Structure-activity relationship analyses revealed that N-aliphatic substitution in urea and selenourea is recommended for the leishmanicidal activity of these analogs. Preliminary studies of the mechanism of action for the hit compounds was carried out by measuring their ability to inhibit trypanothione reductase. Even though the obtained results suggest that this enzyme is not the target for most of these derivatives, their activity comparable to that of the standards and lack of toxicity in THP-1 cells highlight the potential of these compounds to be optimized for leishmaniasis treatment.

Organoselenium Compounds as Novel Adjuvants of Chemotherapy Drugs-A Promising Approach to Fight Cancer Drug Resistance

Malignant diseases present a serious public health burden and their treatment with traditional chemotherapy cannot be considered an all-round solution, due to toxic side effects. Selenium compounds (Se-compounds) have received substantial attention in medicinal chemistry, especially in experimental chemotherapy, both as cytotoxic agents and adjuvants in chemotherapy. A checkerboard microplate method was applied to study the drug interactions of Se-compounds and clinically relevant chemotherapeutic drugs against the multidrug-resistant (MDR) subtype of mouse t-lymphoma cells overexpressing the ABCB1 transporter. Se-compounds showed synergistic interactions with chemotherapeutic agents targeting the topoisomerase enzymes or the microtubule apparatus. The ketone-containing selenoesters showed synergism at lower concentrations (1.25 µM). Most of the tested compounds interacted antagonistically with alkylating agents and verapamil. A thiophene-containing Se-compound showed synergism with all tested drugs, except cisplatin. While the exact mechanism of drug interactions is yet unknown, the potency of the selenocompounds as efflux pump inhibitors or the potentiation of their efficacy as reactive oxygen species modulators may play a role in their complementary activity against the tested MDR lymphoma cell line.

Organic selenium compounds as potential chemotherapeutic agents for improved cancer treatment

Selenium(Se)-containing compounds have attracted a growing interest as anticancer agents over recent decades, with mounting reports demonstrating their high efficacy and selectivity against cancer cells. Typically, Se compounds exert their cytotoxic effects by acting as pro-oxidants that alter cellular redox homeostasis. However, the precise intracellular targets, signalling pathways affected and mechanisms of cell death engaged following treatment vary with the chemical properties of the selenocompound and its metabolites, as well as the cancer model that is used. Naturally occurring organic Se compounds, besides encompassing a significant antitumor activity with an apparent ability to prevent metastasis, also seem to have fewer side effects and less systemic effects as reported for many inorganic Se compounds. On this basis, many novel organoselenium compounds have also been synthesized and examined as potential chemotherapeutic agents. This review aims to summarize the most well studied natural and synthetic organoselenium compounds and provide the most recent developments in our understanding of the molecular mechanisms that underlie their potential anticancer effects.

Novel Methylselenoesters Induce Programed Cell Death via Entosis in Pancreatic Cancer Cells

Redox active selenium (Se) compounds have gained substantial attention in the last decade as potential cancer therapeutic agents. Several Se compounds have shown high selectivity and sensitivity against malignant cells. The cytotoxic effects are exerted by their biologically active metabolites, with methylselenol (CH₃SeH) being one of the key executors. In search of novel CH₃SeH precursors, we previously synthesized a series of methylselenoesters that were active (GI₅₀ < 10 µM at 72 h) against a panel of cancer cell lines. Herein, we refined the mechanism of action of the two lead compounds with the additional synthesis of new analogs (ethyl, pentyl, and benzyl derivatives). A novel mechanism for the programmed cell death mechanism for Se-compounds was identified. Both methylseleninic acid and the novel CH₃SeH precursors induced entosis by cell detachment through downregulation of cell division control protein 42 homolog (CDC42) and its downstream effector β1-integrin (CD29). To our knowledge, this is the first time that Se compounds have been reported to induce this type of cell death and is of importance in the characterization of the anticancerogenic properties of these compounds.

Phosphatase CDC25B Inhibitors Produced by Basic Alumina-Supported One-Pot Gram-Scale Synthesis of Fluorinated 2-Alkylthio-4-aminoquinazolines Using Microwave Irradiation

An efficient, environmentally benign, and inexpensive procedure has been developed for the synthesis of fluorinated 2-alkylthio-4-aminoquinazolines by microwave irradiation using basic alumina as a solid-support agent as well as a solid base. Notably, this protocol features improved energy efficiency, broad isothiourea substrate scope, easily available starting materials, and high atom efficiency and applicability toward gram-scale synthesis. Additionally, the target compounds were evaluated for the cytotoxic effect against human colon adenocarcinoma (HCT116 and HT29), human gastric cancer (SGC-7901), human lung adenocarcinoma (A549), and human hepatocyte carcinoma (HepG2) cells, and it was found that these compounds have excellent antitumor activities. Among them, compound 3e was found to be one of the most potent derivatives with IC₅₀ values lower than 9.44 μM against five human tumor cell lines, making it more active than cisplatin (DDP). Furthermore, for the first time, the fluorinated 2-alkylthio-substituted 4-aminoquinazolines were identified as phosphatase CDC25B inhibitors.

Synthesis of 28a-homoselenolupanes and 28a-homoselenolupane saponins

A practical synthesis of 28a-homo-28a-selenolupane triterpenes and the corresponding selenosaponins containing d-mannose, l-arabinose, l-rhamnose, and d-idose moieties is described. Selenium containing triterpenes were obtained from the readily available 3-O-allyl-homobetulin mesylate by nucleophilic substitution with the selenocyanate ion which upon reduction of the -SeCN group afforded the free selenol. Glycosylation using classical Schmidt donors gave 1,2-trans selenosaponins as the main product as well as minute amounts of 1,2-cis isomers. This is one of the very few examples of the synthesis of selenoglycosides by direct glycosylation of free selenols. The studied selenol showed high resistance to air oxidation resulting in good stability during the synthesis of selenolupane derivatives. Cytotoxic activities of new homoselenolupane derivatives were also evaluated in vitro and revealed that some triterpenes exhibited an interesting profile against human cancer cell lines.

An insight into the therapeutic potential of quinazoline derivatives as anticancer agents

Cancer is one of the major causes of worldwide human mortality. A wide range of cytotoxic drugs are available on the market, and several compounds are in different phases of clinical trials. Many studies suggest that these cytotoxic molecules are also associated with different types of adverse side effects; therefore researchers around the globe are involved in the development of more efficient and safer anticancer drugs. In recent years, quinazoline and its derivatives have been considered as a novel class of cancer chemotherapeutic agents that show promising activity against different tumors. The aim of this article is to comprehensively review and highlight the recent developments concerning the anticancer activity of quinazoline derivatives as well as offer perspectives on the development of novel quinazoline derivatives as anticancer agents in the near future.

Improved Potency of Indole-Based NorA Efflux Pump Inhibitors: From Serendipity toward Rational Design and Development

The NorA efflux pump is a potential drug target for reversal of resistance to selected antibacterial agents, and recently we described indole-based inhibitor candidates. Herein we report a second class of inhibitors derived from them but with significant differences in shape and size. In particular, compounds 13 and 14 are very potent inhibitors in that they demonstrated the lowest IC₅₀ values (2 μM) ever observed among all indole-based compounds we have evaluated.

Chalcogen containing heterocyclic scaffolds: New hybrids with antitumoral activity

In this work, 27 novel hybrid derivatives containing diverse substituents with chalcogen atoms (selenium or sulfur) and several active heterocyclic scaffolds have been synthesized. Compounds were tested against two human cancer cells lines (MCF7 and PC-3) and a normal human mammary epithelial cell line (184B5) in order to determine their activity and selectivity against malignant cells. Ten compounds showed GI50 values below 10 μM in at least one of the cancer cell lines and six of them exhibited a selectivity index higher than 9. In general, selenium-containing compounds were more active than their corresponding sulfur analogs but we found some thiocyanate derivatives with comparable or higher activity and selectivity. Among the different substituents, the seleno- and thio-cyanate groups showed the most promising results. On the basis of their potent activity and high selectivity index, compounds 7e and 8f (containing a thiocyanate and a selenocyanate group, respectively) were selected for further biological evaluation. Both the compounds induced caspase-dependent cell death and cell cycle arrest in G2/M phase. In addition, these compounds do not violate any of the Lipinski's Rule of Five and thus possess good potential to become drugs, compound 7e being particularly promising.

Antitumor activity of a rhenium (I)-diselenoether complex in experimental models of human breast cancer

Rhenium (I)-diselenother (Re-diselenoether) is a water soluble metal-based compound, combining one atom of rhenium and two atoms of selenium. This compound has been reported to exhibit marked activities against several solid tumor cell lines. We now disclose an improved synthesis of this complex. The Re-diselenoether showed a potent inhibitory effect on MDA-MB231 cell division in vitro, which lasted when the complex was no longer present in the culture. Re-diselenoether induced a remarkable reduction of the volume of the primitive breast tumors and of the pulmonary metastases without clinical signs of toxicity, in mice-bearing a MDA-MB231 Luc+ tumor, orthotopically transplanted, after a daily oral administration at the dose of 10 mg/kg/d. Interestingly, an antagonism was observed when cisplatin was administered as a single i.p. injection 1 week after the end of the Re-diselenoether administration. In an effort to gain insight of the mechanisms of action of Re-diselenoether complex, interaction with 9-methylguanine as a nucleic acid base model was studied. We have shown that Re-diselenoether gave both mono- and bis-guanine Re adducts, the species assumed to be responsible for the DNA intrastrand lesions.

Monocyclic β-lactam and unexpected oxazinone formation: synthesis, crystal structure, docking studies and antibacterial evaluation

Novel monocyclic β-lactam derivatives bearing aryl, phenyl and heterocyclic rings were synthesized as possible antibacterial agents. Cyclization of imines (3h, 3t) with phenylacetic acid in the presence of phosphoryl chloride and triethyl amine did not afford the expected β-lactams. Instead, highly substituted 1,3-oxazin-4-ones (4h, 4t) were isolated as the only product and confirmed by single crystal X-ray analysis of 4t. The results of antibacterial activity showed that compound 4l exhibited considerable antibacterial activity with MIC and MBC values of 62.5 µg/mL against Klebsiella pneumoniae. Cytotoxicity assay on Chinese Hamster Ovary (CHO) cell line revealed non-cytotoxic behavior of compounds 4d, 4h, 4k and 4l up to 200 μg/mL conc. Molecular docking was performed for compound 4l with penicillin binding protein-5 to identify the nature of interactions. The results of both in silico and in vitro evaluation provide the basis for compound 4l to be carried as a potential lead molecule in the drug discovery pipeline against bacterial infections.

Recent advances in the chemistry and biology of pyridopyrimidines

The interest in pyridopyrimidine cores for pharmaceutical products makes this scaffold a highly useful building block for organic chemistry. These derivatives have found applications in various areas of medicine such as anticancer, CNS, fungicidal, antiviral, anti-inflammatory, antimicrobial, and antibacterial therapies. This review mainly focuses on the progress achieved since 2004 in the chemistry and biological activity of pyridopyrimidines.

Selenium compounds as therapeutic agents in cancer

BACKGROUND

With cancer cells encompassing consistently higher production of reactive oxygen species (ROS) and with an induced antioxidant defense to counteract the increased basal ROS production, tumors have a limited reserve capacity resulting in an increased vulnerability of some cancer cells to ROS. Based on this, oxidative stress has been recognized as a tumor-specific target for the rational design of new anticancer agents. Among redox modulating compounds, selenium compounds have gained substantial attention due to their promising chemotherapeutic potential.

SCOPE OF REVIEW

This review aims in summarizing and providing the recent developments of our understanding of the molecular mechanisms that underlie the potential anticancer effects of selenium compounds.

MAJOR CONCLUSIONS

It is well established that selenium at higher doses readily can turn into a prooxidant and thereby exert its potential anticancer properties. However, the biological activity of selenium compounds and the mechanism behind these effects are highly dependent on its speciation and the specific metabolic pathways of cells and tissues. Conversely, the chemical properties and the main molecular mechanisms of the most relevant inorganic and organic selenium compounds as well as selenium-based nanoparticles must be taken into account and are discussed herein.

GENERAL SIGNIFICANCE

Elucidating and deepening our mechanistic knowledge of selenium compounds will help in designing and optimizing compounds with more specific antitumor properties for possible future application of selenium compounds in the treatment of cancer. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Synthesis and biological evaluation of novel 3,4-diaryl-1,2,5-selenadiazol analogues of combretastatin A-4

A set of novel selenium-containing heterocyclic analogues of combretastatin A-4 (CA-4) have been designed and synthesised using a rigid 1,2,5-selenadiazole as a linker to fix the cis-orientation of ring-A and ring-B. All of the target compounds were evaluated for their in vitro anti-proliferative activities. Among these compounds, compounds 3a, 3i, 3n and 3q exhibited superior potency against different tumour cell lines with IC50 values at the nanomolar level. Moreover, compound 3n significantly induced cell cycle arrest in the G2/M phase, inhibited tubulin polymerisation into microtubules and caused microtubule destabilisation. A molecular modelling study of compound 3n was performed to elucidate its binding mode at the colchicine site in the tubulin dimer and to provide a basis for the further structure-guided design of novel CA-4 analogues.