Enhanced Sequence-Specific DNA Recognition Using Oligodeoxynucleotide-Benzimidazole Conjugates

Synthetic modification of oligodeoxynucleotides (ODNs) via conjugation to nucleic acid binding small molecules can improve hybridization and pharmacokinetic properties. In the present study, five Hoechst 33258 derived benzimidazoles were conjugated to T rich ODNs and their hybridization effectiveness was tested. Thermal denaturation studies revealed significant stabilization of complementary duplexes by ODN-benzimidazole conjugates, with the extent of stabilization being highly dependent on the length of the linker between DNA and benzimidazole. The increases in thermal stability were determined to be due to the binding of the benzimidazole moiety to the duplex. Circular dichroism and molecular modeling studies provided insights toward the influence of conjugation on duplex structure and how linker length impacts placement of the benzimidazole moiety in the minor groove. Furthermore, thermal denaturation studies with the complementary strand containing a single base mismatch or being RNA revealed that covalent conjugation of benzimidazoles to an ODN also enhances the sequence specificity. The fundamental studies reported herein provide a strategy to improve the stability and specificity properties of the ODN probes, which can be of use for targeting and diagnostics applications.

Sulfur (SⅥ)-containing heterocyclic hybrids as antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA) and its SAR

The discovery of new small molecule-based inhibitors is an attractive field in medicinal chemistry. Structurally diversified heterocyclic derivatives have been investigated to combat multi-drug resistant bacterial infections and they offers several mechanism of action. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming more and more deadly to humans because of its simple method of transmission, quick development of antibiotic resistance, and ability to cause hard-to-treat skin and filmy diseases. The sulfur (SVI) particularly sulfonyl and sulfonamide based heterocyclic moieties, have found to be good anti-MRSA agents. The development of new nontoxic, economical and highly active sulfur (SVI) containing derivatives has become hot research topics in drug discovery research. Presently, more than 150 FDA approved Sulfur (SVI)-based drugs are available in the market, and they are widely used to treat various types of diseases with different therapeutic potential. The present collective data provides the latest advancements in Sulfur (SVI)-hybrid compounds as antibacterial agents against MRSA. It also examines the outcomes of in-vitro and in-vivo investigations, exploring potential mechanisms of action and offering alternative perspectives on the structure-activity relationship (SAR). Sulfur (SVI)-hybrids exhibits synergistic effects with existing drugs to provide antibacterial action against MRSA.

Fluorinated azoles as effective weapons in fight against methicillin-resistance staphylococcus aureus (MRSA) and its SAR studies

The rapid spread of Methicillin-resistant Staphylococcus aureus (MRSA) and its difficult-to-treat skin and filmsy diseases are making MRSA a threat to human life. The most dangerous feature is the fast emergence of MRSA resistance to all recognized antibiotics, including vancomycin. The creation of novel, effective, and non-toxic drug candidates to combat MRSA isolates is urgently required. Fluorine containing small molecules have taken a centre stage in the field of drug development. Over the last 50 years, there have been a growing number of fluorinated compounds that have been approved since the clinical usage of fluorinated corticosteroids in the 1950 s and fluoroquinolones in the 1980 s. Due to its advantages in terms of potency and ADME (absorption, distribution, metabolism, and excretion), fluoro-pharmaceuticals have been regarded as a potent and useful tool in the rational drug design method. The flexible bioactive fluorinated azoles are ideal candidates for the development of new antibiotics. This review summarizes the decade developments of fluorinated azole derivatives with a wide antibacterial activity against diverged MRSA strains. In specific, we correlated the efficacy of structurally varied fluorinated azole analogues including thiazole, benzimidazole, oxadiazole and pyrazole against MRSA and discussed different angles of structure-activity relationship (SAR).

Mitochondriotropic agents conjugated with NSAIDs through metal ions against breast cancer cells

Two copper(I) polymorphs of formula [Cu(SALH)(TPP)3] (1a and 1b) were prepared by the conjugation of the Non-Steroidal Anti-Inflammatory Drug (NSAID) salicylic acid (SALH2) with the mitochondriotropic agent triphenylphosphine (TPP) via metal ion. For comparison, the isomorph [Ag(SALH)(TPP)3] (2) was prepared. The conjugates 1a, 1b and 2 were characterized by melting point (m.p.), Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, Ultraviolet-Visible (UV-Vis) spectroscopy and nuclear magnetic resonance (1H NMR). The crystal structures of 1a, 1b and 2 were confirmed by X-ray diffraction crystallography (XRD). The ex vivo binding affinity of 1-2 towards CT (calf thymus)-DNA was studied by UV, fluorescence, viscosity and DNA Thermal Denaturation studies. Their inhibitory activity against lipoxygenase (LOX) (an enzyme which is mainly located in the mitochondrion) was determined. The in vitro activity of 1-2 was evaluated against human breast cancer cell lines MCF-7 (hormone depended (HD)) and MDA-MB 281 (hormone independent (HI)) cells. Compounds 1-2 inhibit stronger than cisplatin the cancerous cells. The molecular mechanism of action of 1-2 was suspected by the MCF-7 cells morphology and confirmed by DNA fragmentation, Acridine Orange/Ethidium Bromide (AO/EB) Staining and mitochondrial membrane permeabilization tests.

Electrochemical Synthesis of Benzo[d]imidazole via Intramolecular C(sp3)-H Amination

An electrochemical dehydrogenative amination for the synthesis of benzimidazoles was developed. This electrosynthesis method could address the limitations of the C(sp3)-H intramolecular amination synthesis reaction and provide novel access to obtain 1,2-disubstituted benzimidazoles without transition metals and oxidants. Under undivided electrolytic conditions, various benzimidazole derivatives could be synthesized, exhibiting functional group tolerance.

Ru(II) Complexes with Enaminone Structures for Rapid Sterilization of Staphylococcus aureus and MRSA with Little Accumulation of Drug Resistance

Drug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), pose a serious threat to human life. Therefore, there is urgent need to develop antibiotics with new chemical structures and antibacterial mechanisms, especially those that elicit little drug resistance after long-term use. Herein we synthesized three novel ruthenium complexes (Ru1-Ru3) containing the enaminone structures for the first time. At a concentration of 5 μM, Ru1-Ru3 can lead to a CFU reduction of about 5 log units towards S. aureus and MRSA. Interestingly, Ru3 displayed rapid bactericidal effects and could decrease the CFU numbers of both pathogens by 5 log units within 40 min. The control compounds (Ru4 and Ru5) without the enaminone structures displayed very poor antibacterial activity under the same conditions. Moreover, S. aureus did not show apparent drug resistance towards Ru3 after 20 passages incubation with a sublethal concentration. These results highlight the critical role of enaminone structures for antibacterial applications.

Benzimidazole and its derivatives as cancer therapeutics: The potential role from traditional to precision medicine

Cancer is the second leading cause of mortality globally which remains a continuing threat to human health today. Drug insensitivity and resistance are critical hurdles in cancer treatment; therefore, the development of new entities targeting malignant cells is considered a high priority. Targeted therapy is the cornerstone of precision medicine. The synthesis of benzimidazole has garnered the attention of medicinal chemists and biologists due to its remarkable medicinal and pharmacological properties. Benzimidazole has a heterocyclic pharmacophore, which is an essential scaffold in drug and pharmaceutical development. Multiple studies have demonstrated the bioactivities of benzimidazole and its derivatives as potential anticancer therapeutics, either through targeting specific molecules or non-gene-specific strategies. This review provides an update on the mechanism of actions of various benzimidazole derivatives and the structure‒activity relationship from conventional anticancer to precision healthcare and from bench to clinics.

Novel 1,2,5-Trisubstituted Benzimidazoles Potentiate Apoptosis by Mitochondrial Dysfunction in Panel of Cancer Cells

Synthetic small molecules have been very effective in decimating cancer cells by targeting various aberrantly overexpressed oncogenic proteins. These small molecules target proteins involved in cell cycle regulation, cell division, migration, invasion, angiogenesis, and other regulatory proteins to induce apoptosis in cancer cells. In this study, we have synthesized a novel 1,2,5-trisubstituted benzimidazole chemical library of small molecules and unveiled their anticancer potential against a panel of cancer cell lines such as Jurkat, K-562, MOLT-4, HeLa, HCT116, and MIA PaCa-2 cancer cells. The MTT assay and Trypan blue dye exclusion assay clearly unveiled the cytotoxic effect of methyl 1-benzyl-2-(4-fluoro-3-nitrophenyl)-1H-benzo[d]imidazole-5-carboxylate (TJ08) and its potential to induce apoptosis with effective IC₅₀ of 1.88 ± 0.51, 1.89 ± 0.55, 2.05 ± 0.72, 2.11 ± 0.62, 3.04 ± 0.8, and 3.82 ± 0.25 μM against Jurkat, K562, MOLT-4, HeLa, HCT116, and MIA PaCa-2 cancer cell lines, respectively. Altered mitochondrial membrane potential was observed in HeLa, HCT116, and Jurkat cells due to TJ08 treatment, which was unveiled by JC10 staining. Induction of early and late apoptosis by TJ08 treatment was also unveiled by apoptotic analysis and immunofluorescence imaging. Cell cycle analysis distribution confirms the accumulation of cells in the S-phase in a dose-dependent manner.

Synthesis of Morpholine-, Piperidine-, and N-Substituted Piperazine-Coupled 2-(Benzimidazol-2-yl)-3-arylquinoxalines as Novel Potent Antitumor Agents

A novel series of 2-(benzimidazol-2-yl)quinoxalines with three types of pharmacophore groups, namely, piperazine, piperidine, and morpholine moieties, which are part of known antitumor drugs, was designed and synthesized. The compounds have been characterized by NMR and IR spectroscopy, high- and low-resolution mass spectrometry, and X-ray crystallography. 2-(Benzimidazol-2-yl)quinoxalines with N-methylpiperazine substituents showed promising activity against a wide range of cancer lines, without causing hemolysis and showing little cytotoxicity against normal human Wi-38 cells (human fetal lung). A mixture of regioisomers 2-(benzimidazol-2-yl)-3-(4-fluorophenyl)-6(and 7)-(4-methylpiperazin-1-yl)quinoxalines (mri BIQ 13da/14da) showed a highly selective cytotoxic effect against human lung adenocarcinoma (cell line A549) with a half-maximal inhibitory concentration at the level of doxorubicin with a selectivity index of 12. The data obtained by flow cytometry, fluorescence microscopy, and multiparametric fluorescence analysis suggested that the mechanism of the cytotoxic effect of the mri BIQ 13da/14da on A549 cells may be associated with the stopping of the cell cycle in phase S and inhibition of DNA synthesis as well as with the induction of mithochondrial apoptosis. Thus, mri BIQ 13da/14da can be considered as a leading compound deserving further study, optimization, and development as a new anticancer agent.

Metal-Free Synthesis of N-Heterocycles via Intramolecular Electrochemical C-H Aminations

N-heterocycles are key structural units in many drugs, biologically interesting molecules and functional materials. To avoid the residues of metal catalysts, the construction of N-heterocycles under metal-free conditions has attracted much research attention in academia and industry. Among them, the intramolecular electrochemical C-H aminations arguably constitute environmentally friendly methodologies for the metal-free construction of N-heterocycles, mainly due to the direct use of clean electricity as the redox agents. With the recent renaissance of organic electrosynthesis, the intramolecular electrochemical C-H aminations have undergone much progress in recent years. In this article, we would like to summarize the advances in this research field since 2019. The emphasis is placed on the reaction design and mechanistic insight. The challenges and future developments in the intramolecular electrochemical C-H aminations are also discussed.

Transcriptome profiling reveals that VNPP433-3β, the lead next-generation galeterone analog inhibits prostate cancer stem cells by downregulating epithelial-mesenchymal transition and stem cell markers

Cancer stem cells (CSCs) virtually present in all tumors albeit in small numbers are primarily responsible for driving cancer progression, metastasis, drug resistance, and recurrence. Prostate cancer (PCa) is the second most frequent cancer in men worldwide, and castration resistant prostate cancer (CRPC) remains a major challenge despite the tremendous advancements in medicine. Currently, none of the available treatment options are effective in treating CRPC. We earlier reported that VNPP433-3β, the lead next-generation galeterone analog is effective in treating preclinical in vivo models of CRPC. In this study using RNA-seq, cytological, and biochemical methods, we report that VNPP433-3β inhibits prostate CSCs by targeting key pathways critical to stemness and epithelial-mesenchymal transition. VNPP433-3β inhibits CSCs in PCa, presumably by degrading the androgen receptor (AR) thereby decreasing the AR-mediated transcription of several stem cell markers including BMI1 and KLF4. Transcriptome analyses by RNA-seq, Ingenuity Pathway Analysis, and Gene Set Enrichment Analysis demonstrate that VNPP433-3β inhibits transcription of several genes and functional pathways critical to the prostate CSCs thereby inhibiting CSCs in PCa besides targeting the bulk of the tumor.

Benzimidazole analogues as efficient arsenals in war against methicillin-resistance staphylococcus aureus (MRSA) and its SAR studies

Small molecule based inhibitors development is a growing field in medicinal chemistry. In recent years, different heterocyclic derivatives have been designed to counter the infections caused by multi-drug resistant bacteria. Indeed, small molecule inhibitors can be employed as an efficient antibacterial agents with different mechanism of action. Methicillin-resistant Staphylococcus aureus (MRSA) is becoming lethal to mankind due to easy transmission mode, rapid resistance development to existing antibiotics and affect difficult-to-treat skin and filmsy diseases. Benzimidazoles are a class of heterocyclic compounds which have capability to fight against MRSA. High biocompatibility of benzimidazoles, synergistic behaviour with antibiotics and their tunable physico-chemical properties attracted the researchers to develop new benzimidazole based antibacterial agents. The present review focus on recent developments of benzimidazole-hybrid molecules as anti MRSA agents and the results of in-vitro and in-vivo studies with possible mechanism of action and discussing structure-activity relationship (SAR) in different directions. Benzimdazoles act as DNA binding agents, enzyme inhibitors, anti-biofilm agents and showed synergistic effect with available antibiotics to achieve antibacterial activity against MRSA. This cumulative figures would help to design new benzimidazole-based MRSA growth inhibitors.

Apoptotic Effect of Novel Benzimidazole Derivatives Bearing Pyridyl/Pyrimidinyl Piperazine Moiety

BACKGROUND

Benzimidazole derivatives bearing pyridyl/pyrimidinyl piperazine moiety has attracted attention in medicinal chemistry and modern drug discovery since it exhibited a variety of biological activities, including anticancer activity.

OBJECTIVE

In this study, we have designed and synthesized novel 1-[2-oxo-2-(4-substituted phenyl)ethyl]benzimidazol-2-yl)methyl 4-(2-pyridyl/pyrimidin-2-yl)piperazine-1-carbodithioate derivatives (2a-m). We also investigated their anticancer activities against A549 lung adenocarcinoma and C6 rat glioma cell lines and selectivity against NIH/3T3 mouse embryonic fibroblast cell lines. Cholinesterase inhibition effects of these compounds were also measured to investigate the relationship between anticancer activity and cholinesterases.

METHOD

The cytotoxic activities of these acquired thirteen final compounds were screened using MTT assay on A549, C6, and NIH/3T3 cell lines. Cell proliferation ELISA, BRDU (colorimetric) assay was used for measuring proliferation in replicative cells in which DNA synthesis occurs. Flow cytometric analysis was used for measuring apoptotic cell percentages, caspase 3 activity, and mitochondrial membrane depolarised cell percentages.

RESULTS

Compounds 2e, 2f, and 2k have been established as the most active antitumor agents with selective cytotoxicities (76.58±6.43, 55.13±5.75, and 32.94±3.02 µM respectively for A549; 86.48±3.60, 97.12±30.21, and 59.29±3.95 µM respectively for C6), high DNA synthesis inhibition rates and high apoptotic cell percentages on both cell lines.

CONCLUSION

The results have shown that compounds 2e, 2f, and 2k have potential anticancer agents against A549 and C6 cell lines.

A key review on oxadiazole analogs as potential methicillin-resistant Staphylococcus aureus (MRSA) activity: Structure-activity relationship studies

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming dangerous to human beings due to easy transmission mode and leading to the difficult-to-treat situation. The rapid resistance development of MRSA to many approved antibiotics is of major concern. There is a lot of scope to develop novel, efficient, specific, and nontoxic drug candidates to fight against MRSA isolates. The interesting molecular structure and adaptable feature of oxadiazole moiety which are bioisosteres of esters and amides, and these functional groups show improved resistance to esterases mediated hydrolytic cleavage, attracting researchers to develop required novel antibiotics based on oxadiazole core. This review summarizes the developments of oxadiazole-containing derivatives as potent antibacterial agents against multidrug-resistant MRSA strains and discussing the structure-activity relationship (SAR) in various directions. The current survey is the highlight of the present scenario of oxadiazole hybrids on MRSA studies, covering articles published from 2011 to 2020. This collective information may become a good platform to plan and develop new oxadiazole-based small molecule growth inhibitors of MRSA with minimal side effects.

Pyrazole-based analogs as potential antibacterial agents against methicillin-resistance staphylococcus aureus (MRSA) and its SAR elucidation

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming lethal to humanity due to easy transmission and difficult-to-treat skin and flimsy diseases. The most threatening aspect is the rapid resistance development of MRSA to any approved antibiotics, including vancomycin. The development of new, efficient, and nontoxic drug candidate to fight against MRSA isolates is the need of the hour. The intriguing molecular structure and versatile bioactive pyrazole core attracting to development required novel antibiotics. This review presents the decade developments of pyrazole-containing derivatives with a broad antibacterial movement against diverged bacterial strains. In specific, we correlated the efficacy of structurally diversified pyrazole analogs against MRSA and discussed different angles of structure-activity relationship (SAR). The current survey highlights pyrazole hybrids' present scenario on MRSA studies, covering articles published from 2011 to 2020. This collective information may become an excellent platform to plan and develop new pyrazole-based small MRSA growth inhibitors with minimal side effects.

Astaxanthin protects oxidative stress mediated DNA damage and enhances longevity in Saccharomyces cerevisiae

Reactive oxygen species (ROS) have long been found to play an important role in oxidative mediated DNA damage. Fortunately, cells possess an antioxidant system that can neutralize ROS. However, oxidative stress occurs when antioxidants are overwhelmed by ROS or impaired antioxidant pathways. This study was carried out to find the protective effect of astaxanthin on the yeast DNA repair-deficient mutant cells under hydrogen peroxide stress. The results showed that astaxanthin enhances the percent cell growth of rad1∆, rad51∆, apn1∆, apn2∆ and ogg1∆ cells. Further, the spot test and colony-forming unit count results confirmed that astaxanthin protects DNA repair mutant cells from oxidative stress. The DNA binding property of astaxanthin studied by in silico and in vitro methods indicated that astaxanthin binds to the DNA in the major and minor groove, and that might protect DNA against oxidative stress induced by Fenton's reagent. The intracellular ROS, 8-OHdG level and the DNA fragmentation as measured by comet tail was reduced by astaxanthin under oxidative stress. Similarly, reduced nuclear fragmentation and chromatin condensation results suggest that astaxanthin might reduce apoptosis. Finally, we show that astaxanthin decreases the accumulation of mutation rate and enhances the longevity of DNA repair-deficient mutants' cells during a chronological lifespan.

Effective synthesis of benzimidazoles-imidazo[1,2-a]pyrazine conjugates: A comparative study of mono-and bis-benzimidazoles for antitumor activity

A novel series of 6-substituted-8-(1-cyclohexyl-1H-benzo[d]imidazole-6-yl)imidazo[1,2-a]pyrazine and 6-substituted-8-(1-benzyl-1H-benzo[d]imidazole-6-yl)imidazo[1,2-a]pyrazine is first time synthesized and screen in vitro biological activity for 60 human cancer cell lines representing nine different cancer types. Derivatives 10 and 36 show antitumor activity for all tested cell lines, display comparable full panel mean-graph midpoint growth inhibition (MG_MID GI₅₀) values of 2.10 and 2.23 μM, respectively. Furthermore, these derivatives show strong binding interactions with DNA and bovine serum albumin (BSA), studied through absorption, emission, and circular dichroism techniques. These spectroscopic studies reveal that imidazo[1,2-a]pyrazine-benzimidazoles 10 and 36, intercalate with ct-DNA as a leading interaction for fundamental biologically significant effects, with monobenzimidazole show better activity than bisbenzimidazole. These experiments have confirmed that the imidazo[1,2-a]pyrazine and benzimidazole moieties are efficient pharmacophores to trigger binding to DNA. These compounds have also interacted with bovine serum albumin protein that demonstrating high values of binding constant.

Design, synthesis, and DNA interaction studies of furo-imidazo[3.3.3]propellane derivatives: Potential anticancer agents

A large number of natural products containing the propellane scaffold have been reported to exhibit cytotoxicity against several cancers; however, their mechanism of action is still unknown. Anticancer drugs targeting DNA are mainly composed of small planar molecule/s that can interact with the DNA helix, causing DNA malfunction and cell death. The aim of this study was to design and synthesize propellane derivatives that can act as DNA intercalators and/or groove binders. The unique structure of the propellane derivatives and their ability to display planar ligands with numerous possible geometries, renders them potential starting points to design new drugs targeting DNA in cancer cells. New substituted furo-imidazo[3.3.3]propellanes were synthesized via the reaction of substituted alkenylidene-hydrazinecarbothioamides with 2-(1,3-dioxo-2,3-dihydro-1H-2-ylidene)propanedinitrile in tetrahydrofuran at room temperature. The structures of the products were confirmed by a combination of elemental analysis, NMR, ESI-MS, IR and single crystal X-ray analysis. Interestingly, 5c, 5d and 5f showed an ability to interact with Calf Thymus DNA (CT-DNA). Their DNA-binding mode was investigated using a combination of absorption spectroscopy, DNA melting, viscosity, CD spectroscopy measurements, as well as competitive binding studies with several dyes. Their cytotoxicity was evaluated against the NCI-60 panel of cancer cell lines. 5c, 5d and 5f exhibited similar anti-proliferative activity against the A549 non-small cell lung cancer (NSCLC) cell line. Further mechanistic studies revealed their ability to induce DNA damage in the A549 cell line, as well as apoptosis, evidenced by elevated Annexin V expression, enhanced caspase 3/7 activation and PARP cleavage. In this study, we present the potential for designing novel propellanes to provoke cytotoxic activity, likely through DNA binding-induced DNA damage and apoptosis.

Sulfated Ceria Catalyzed Synthesis of Imidazopyridines and Their Implementation as DNA Minor Groove Binders

The small molecules that bind to DNA minor groove are considered as potential therapeutic agents to fight against many human diseases. They induce cell death by interfering with transcription, replication and progression of cell cycle. Herein, we report the synthesis of imidazopyridine-3-amines using sulfated ceria catalyst by employing Groebkee-Blackburne-Bienayme reaction. We evaluated the possible antiproliferative and antimycobacterial activity against A549 cells and Mycobacterium tuberculosis, respectively. Among the tested compounds, N-tert-butyl-2-(2-butyl-4-chloro-1H-imidazol-5-yl)-5,7-dimethylimidazo[1,2-a]pyridin-3-amine (4g) was identified as cytotoxic heterocycle and antimycobacterial agent. Molecular docking studies of the imidazopyridine derivatives revealed the consistent positioning in the minor groove with a tight shape fit between receptor and ligands. Therefore, we speculate that new imidazopyridines induce their pharmacological effect by targeting the minor groove of DNA.

Synthesis, anti-bacterial and anti-protozoal activities of amidinobenzimidazole derivatives and their interactions with DNA and RNA

Amidinobenzimidazole derivatives connected to 1-aryl-substituted 1,2,3-triazole through phenoxymethylene linkers 7a-7e, 8a-8e, and 9a-9e were designed and synthesised with the aim of evaluating their anti-bacterial and anti-trypanosomal activities and DNA/RNA binding affinity. Results from anti-bacterial evaluations of antibiotic-resistant pathogenic bacteria revealed that both o-chlorophenyl-1,2,3-triazole and N-isopropylamidine moieties in 8c led to strong inhibitory activity against resistant Gram-positive bacteria, particularly the MRSA strain. Furthermore, the non-substituted amidine and phenyl ring in 7a induced a marked anti-bacterial effect, with potency against ESBL-producing Gram-negative E. coli better than those of the antibiotics ceftazidime and ciprofloxacin. UV-Vis and CD spectroscopy, as well as thermal denaturation assays, indicated that compounds 7a and 8c showed also binding affinities towards ctDNA. Anti-trypanosomal evaluations showed that the p-methoxyphenyl-1,2,3-triazole moiety in 7b and 9b enhanced inhibitory activity against T. brucei, with 8b being more potent than nifurtimox, and having minimal toxicity towards mammalian cells.

An overview of recent advances in duplex DNA recognition by small molecules

As the carrier of genetic information, the DNA double helix interacts with many natural ligands during the cell cycle, and is amenable to such intervention in diseases such as cancer biogenesis. Proteins bind DNA in a site-specific manner, not only distinguishing between the geometry of the major and minor grooves, but also by making close contacts with individual bases within the local helix architecture. Over the last four decades, much research has been reported on the development of small non-natural ligands as therapeutics to either block, or in some cases, mimic a DNA–protein interaction of interest. This review presents the latest findings in the pursuit of novel synthetic DNA binders. This article provides recent coverage of major strategies (such as groove recognition, intercalation and cross-linking) adopted in the duplex DNA recognition by small molecules, with an emphasis on major works of the past few years.

Relationship between the photoinduced electron transfer and binding modes of a pyrene-porphyrin dyad to DNA

The binding modes of a pyrene-porphyrin dyad, (1-pyrenyl)-tris(N-methyl-p-pyridino)porphyrin (PyTMpyP), to DNA and its photophysical properties have been investigated using various spectroscopic techniques. The circular dichroism (CD) spectrum of PyTMpyP bound to DNA (PyTMpyP-DNA) showed one negative and two positive bands in the Soret region. The CD signal in the pyrene absorption region was positive. The shape of the CD spectrum does not support an intercalative binding mode of TMpyP, which would typically afford a negative CD band in the absence of the pyrene moiety. Linear dichroism (LD) experiments revealed a very small signal in the Soret region, which also challenges the intercalation of TMpyP into DNA. Upon excitation of the pyrene moiety, the emission intensity of porphyrin in aqueous solution was quenched due to a photoinduced electron transfer (PET) process between the pyrenyl and porphyrin moieties. On the other hand, the emission of porphyrin was markedly enhanced upon binding to DNA, as the PET process from the excited pyrene moiety to TMpyP was suppressed when bound to DNA. The PET process occurs in the timescale of 65 ps, and could be detected by femtosecond transient absorption spectroscopic methods. Two fluorescence decay times were observed for PyTMpyP in aqueous solution (0.78 and 4.8 ns). Both decay times increased upon binding to DNA owing to environment and/or conformational changes in PyTMpyP. The driving force (ΔG) of the PET process was evaluated under conditions of minor and major groove binding. The PET process and photophysical properties of the PyTMpyP dyad were concluded to be influenced by the binding mode.

A Benzothiazole Derivative (5g) Induces DNA Damage And Potent G2/M Arrest In Cancer Cells

Chemically synthesized small molecules play important role in anticancer therapy. Several chemical compounds have been reported to damage the DNA, either directly or indirectly slowing down the cancer cell progression by causing a cell cycle arrest. Direct or indirect reactive oxygen species formation causes DNA damage leading to cell cycle arrest and subsequent cell death. Therefore, identification of chemically synthesized compounds with anticancer potential is important. Here we investigate the effect of benzothiazole derivative (5g) for its ability to inhibit cell proliferation in different cancer models. Interestingly, 5g interfered with cell proliferation in both, cell lines and tumor cells leading to significant G2/M arrest. 5g treatment resulted in elevated levels of ROS and subsequently, DNA double-strand breaks (DSBs) explaining observed G2/M arrest. Consistently, we observed deregulation of many cell cycle associated proteins such as CDK1, BCL2 and their phosphorylated form, CyclinB1, CDC25c etc. Besides, 5g treatment led to decreased levels of mitochondrial membrane potential and activation of apoptosis. Interestingly, 5g administration inhibited tumor growth in mice without significant side effects. Thus, our study identifies 5g as a potent biochemical inhibitor to induce G2/M phase arrest of the cell cycle, and demonstrates its anticancer properties both ex vivo and in vivo.

Novel PARP inhibitors sensitize human leukemic cells in an endogenous PARP activity dependent manner

Poly(ADP-ribose) polymerase (PARP) is a critical nuclear enzyme which helps in DNA repair. In this study we report, synthesis and biological studies of novel pyridazine derivatives as PARP inhibitors.