Mono-quinoxaline-induced DNA structural alteration leads to ZBP1/RIP3/MLKL-driven necroptosis in cancer cells.

Evading the cellular apoptosis mechanism by modulating multiple pathways poses a sturdy barrier to effective chemotherapy. Cancer cell adeptly resists the apoptosis signaling pathway by regulating anti and pro-apoptotic proteins to escape cell death. Nevertheless, bypassing the apoptotic pathway through necroptosis, an alternative programmed cell death process, maybe a potential therapeutic modality for apoptosis-resistant cells. However, synthetic mono-quinoxaline-based intercalator-induced cellular necroptosis as an anti-cancer perspective remains under-explored. To address this concern, we undertook the design and synthesis of quinoxaline-based small molecules (3a-3l). Our approach involved enhancing the π-surface of the mandatory benzyl moiety to augment its ability to induce DNA structural alteration via intercalation, thereby promoting cytotoxicity across various cancer cell lines (HCT116, HT-29, and HeLa). Notably, the potent compound 3a demonstrated the capacity to induce DNA damage in cancer cells, leading to the induction of ZBP1-mediated necroptosis in the RIP3-expressed cell line (HT-29), where Z-VAD effectively blocked apoptosis-mediated cell death. Interestingly, we observed that 3a induced RIP3-driven necroptosis in combination with DNA hypomethylating agents, even in the RIP3-silenced cell lines (HeLa and HCT116). Overall, our synthesized compound 3a emerged as a promising candidate against various cancers, particularly in apoptosis-compromised cells, through the induction of necroptosis.

Examining the reactivity of tris(ortho-carboranyl)borane with Lewis bases and application in frustrated Lewis pair Si-H bond cleavage.

Reactions of tris(ortho-carboranyl)borane with Lewis bases reveals only small bases bind. The tremendous bulk and Lewis acidity is leveraged in frustrated Lewis pair Si-H cleavage with a wider range of Lewis bases and greater efficacy than B(C6F5)3.

Sequence-Specific Dual DNA Binding Modes and Cytotoxicities of N-6-Functionalized Norcryptotackieine Alkaloids.

Norcryptotackieine (1a) belongs to the indoloquinoline class of alkaloids isolated from Cryptolepis sanguinolenta, a plant species that has been traditionally used as an antimalarial agent. Additional structural modifications of 1a can potentially enhance its therapeutic potency. Indoloquinolines such as cryptolepine, neocryptolepine, isocryptolepine, and neoisocryptolepine show restricted clinical applications owing to their cytotoxicity deriving from interactions with DNA. Here, we examined the effect of substitutions at the N-6 position of norcryptotackieine on the cytotoxicity, as well as structure-activity relationship studies pertaining to sequence specific DNA-binding affinities. The representative compound 6d binds DNA in a nonintercalative/pseudointercalative fashion, in addition to nonspecific stacking on DNA, in a sequence selective manner. The DNA-binding studies clearly establish the mechanism of DNA binding by N-6-substituted norcryptotackieines and neocryptolepine. The synthesized norcryptotackieines 6c,d and known indoloquinolines were screened on different cell lines (HEK293, OVCAR3, SKOV3, B16F10, and HeLa) to assess their cytotoxicity. Norcryptotackieine 6d (IC50 value of 3.1 µM) showed 2-fold less potency when compared to the natural indoloquinoline cryptolepine 1c (IC50 value of 1.64 µM) in OVCAR3 (ovarian adenocarcinoma) cell lines.

A multispectroscopic approach for ultra-trace sensing of prostate specific antigen (PSA) by iron nanocomposite fabricated on graphene nanoplatelet.

Herein we report an easy, rapid and cost-effective method for spectroscopic sensing of a prostate cancer biomarker prostate specific antigen (PSA) using a novel nanocomposite. The material is a synthetic quinoxaline derivative-based iron nanocomposite fabricated on graphene nanoplatelet surface (1d-Fe-Gr). Presence of graphene enhanced the efficacy of synthesized 1d-Fe-Gr to sense PSA in serum medium with an impressive limit of detection (LOD) value of 0.878 pg/mL compared to 1d-Fe alone (LOD 17.619 pg/mL) using UV-visible absorption spectroscopy. LOD of PSA by 1d-Fe-Gr using Raman spectroscopy is even more impressive (0.410 pg/mL). Moreover, presence of interfering biomolecules like glucose, cholesterol, bilirubin and insulin in serum improves the detection threshold significantly in presence of 1d-Fe-Gr which otherwise cause LOD values of PSA to elevate in control sets. In presence of these biomolecules, the LOD values improve significantly as compared to healthy conditions in the range 0.623-3.499 pg/mL. Thus, this proposed detection method could also be applied efficiently to the patients suffering from different pathophysiological disorders. These biomolecules may also be added externally during analyses to improve the sensing ability. Fluorescence, Raman and circular dichroism spectroscopy were used to study the underlying mechanism of PSA sensing by 1d-Fe-Gr. Molecular docking studies confirm the selective interaction of 1d-Fe-Gr with PSA over other cancer biomarkers.

DNA Morphology: Global Alteration of DNA Topological States Induced by Chemotherapeutic Agents and Its Implication in Cancer.

The dynamic topological states of chromosomal DNA regulate many cellular fundamental processes universally in all three domains of life, that is, bacteria, archaea, and eukaryotes. DNA-binding proteins maintain the regional and global supercoiling of the chromosome and thereby regulate the chromatin architecture that ultimately influences the gene expression network and other DNA-centric molecular events in various microenvironments and growth phases. DNA-binding small molecules are pivotal weapons for treating a wide range of cancers. Recent advances in single-molecule biophysical tools have uncovered the fact that many DNA-binding ligands not only alter the regional DNA supercoiling but also modulate the overall morphology of DNA. Here we provide insight into recent advances in atomic force microscopy (AFM) acquired DNA structural change induced by therapeutically important mono- and bis-intercalating anticancer agents as well as DNA-adduct-forming anticancer drugs. We also emphasize the growing evidence of the mechanistic relevance of changes in DNA topology in the anticancer cellular responses of DNA-targeting chemotherapeutic agents.

Targeting aloe active compounds to c-KIT promoter G-quadruplex and comparative study of their anti proliferative property.

Small molecules targeting G-quadruplex of oncogene promoter is considered as a promising anticancer therapeutics approach. Natural aloe compounds aloe emodin, and its glycoside derivative aloe emodin-8-glucoside and aloin have anticancer activity and also have potential DNA binding ability. These three compounds have promising binding ability towards quadruplex structures particularly c-KIT G-quadruplex. Here, this study demonstrates complete biophysical study of these compounds to c-KIT quadruplex structure. Aloe emodin showed highest binding stabilization with c-KIT which has been proved by absorbance, fluorescence, dye displacement, ITC and SPR studies. Moreover, comparative study of these compounds with HCT 116 cells line also agreed to their anti proliferative property which may be helpful to establish these aloe compounds as potential anticancer drugs. This study comprises a complete biophysical study along with their anti proliferative property and demonstrates aloe emodin as a potent c-KIT binding molecule.

One-Pot Cascade Annulation-Triggered Synthesis of N-6-Substituted Norcryptotackieine Alkaloids and Evaluation of Their Antileishmanial Activities.

Norcryptotackieine or 6H-indolo[2,3-b]quinoline is an indoloquinoline class of alkaloid isolated from Cryptolepis sanguinolenta that is traditionally used for antimalarial therapy. Additional structural tuning can extend the therapeutic potency of these indoloquinolines as antileishmanial drug leads. Synthesis of N-6-functionalized norcryptotackieines suffers from the necessity of complex pre-synthesized starting materials, restricted scope of functionalization, or tedious processes. Consequently, a straightforward synthetic procedure for accessing non-natural N-6-functionalized 6H-indolo[2,3-b]quinolines with potent antileishmanial activities is highly sought-after. Herein, we report a two-step one-pot synthesis of N-6-functionalized norcryptotackieine through a Pd-catalyzed double annulation reaction of commercially available amphipathic amines, 2-iodobenzyl cyanide, and differently functionalized 2-bromobenzaldehydes. The reported procedure allows a broad flexibility of substitution at the N-6 position and access to diversified scaffolds, including two natural products norcryptotackieine and neocryptolepine. Interestingly, 6d showed potent antileishmanial activities by causing disruption in the cytoskeletal structure and apoptotic-mediated death of parasites. Together, our work manifests the shortest route to N-6-substituted norcryptotackieine-derived antileishmanial agents.

Does pedicle flap design influence the postoperative sequel of lower third molar surgery and quality of life?

Objective: To determine the impact of the buccal envelope flap and pedicle design on the post-operative outcome and quality of life following lower third molar surgery (QoL). Materials and methods: A randomized case-control clinical study was carried out from September 2017 to September 2019. In this study, a total number of 50 patients with mandibular third molar impaction underwent surgical removal of the same using buccal envelope flap (group A) and pedicle flap (group B). The patients were assessed postoperatively for pain, swelling, trismus, wound dehiscence, dry socket, and quality of life for one month. Results: In terms of pain, swelling, and trismus, there was no statistical difference between the two groups (p > 0.05). However, there was a statistically significant difference found in group B (pedicle flap) in terms of wound dehiscence, dry socket, and quality of life (p < 0.05). Conclusion: The pedicle flap demonstrates fewer incidences of wound dehiscence, dry socket, and a better quality of life when compared to the envelope flap.

Cleavage of Abasic Sites in DNA by an Aminoquinoxaline Compound: Augmented Cytotoxicity and DNA Damage in Combination with an Anticancer Drug Chlorambucil in Human Colorectal Carcinoma Cells.

The elevated level of endogenous oxidative DNA damage and spontaneous deamination of DNA bases in cancer cells substantially increase the abasic sites in DNA via base excision repairs (BERs). Thus, the predominant BER pathway is a favorable target for cancer therapy. Interestingly, elevated levels of glutathione (GSH) in certain cancer cells, such as colon cancer, are associated with acquired resistance to several chemotherapeutic agents, which increase the difficulty for the treatment of cancer. Here, we have reported an ideal nitro group-containing monoquinoxaline DNA intercalator (1d), which is reduced into a fluorescent quinoxaline amine (1e) in the presence of GSH; concurrently, 1e (∼100 nM concentration) selectively causes the in vitro cleavage of abasic sites in DNA. 1e also binds to the tetrahydrofuran analogue of the abasic site in the nanomolar to low micromolar range depending on the nucleotide sequence opposite to the abasic site and also induces a structural change in abasic DNA. Furthermore, the amine compound (1e) augments the response of the specific bifunctional alkylating drug chlorambucil at a much lower concentration in the human colorectal carcinoma cell (HCT-116), and their combination shows a potential strategy for targeted therapy. Alone or in combination, 1d and 1e lead to a cascade of cellular events such as induction of DNA double-stranded breaks and cell arrest at G0/G1 and G2/M phases, eventually leading to apoptotic cell death in HCT-116 cells. Hence, the outcome of this study provides a definitive approach that will help optimize the therapeutic applications for targeting the abasic site in cancer cells.

A randomized, double-blind, split-mouth controlled clinical trial of systemically administered Lycopene on periodontal health.

BACKGROUND/PURPOSE: This research aimed to compare the effects of systemically prescribed Lycopene as a monotherapy and as an alternative to scaling and root planing in patients with chronic gingivitis. MATERIALS AND METHODS: The participants were randomly assigned to one of two treatment groups: the experimental group (n = 50), which received 10 mg of Lycopene a day for two weeks, or the control group (n = 50) received a placebo for two weeks. For each category, quadrant distribution was randomized, with two quadrants receiving oral prophylaxis (OP) and two quadrants receiving no care (non-OP). At baseline, 1st, and 2nd weeks, the sulcus bleeding index, plaque index, gingival index, and salivary uric acid level were measured. RESULTS: All clinical criteria, including SBI, PI, GI, and salivary uric acid levels, showed a statistically significant decline in all patient types. Both clinical parameters were significantly reduced (p < 0.001) in the OP-lycopene group relative to the non-OP-placebo group and non-OP lycopene group (p < 0.05). The PI value in the OP-lycopene group was statistically significantly lower (p < 0.001) than in the non-OP-placebo group; there was no statistically significant difference in the other groups. Salivary uric acid levels in the OP- and non-OP- lycopene groups were significantly lower (p < 0.001) than in the non-OP-placebo population. CONCLUSION: Based on the findings of this study, Lycopene seems to have a bright future as a treatment option for plaque-induced generalized chronic marginal gingivitis. More research with a broad sample size and multicentre trials is required. CLINICAL RELEVANCE: The article reveals the positive relationship between Lycopene and gingivitis. The analysis shows that a combination of systemically administered Lycopene with oral prophylaxis can be a valuable tool in treating chronic gingivitis and controlling respiratory oxidative stress.

Substituent effect of benzyl moiety in nitroquinoxaline small molecules upon DNA binding: Cumulative destacking of DNA nucleobases leading to histone eviction.

Cooperative disruption of Watson-Crick hydrogen bonds, as well as base-destacking, is shown to be triggered by a quinoxaline-based small molecule consisting of an N,N-dimethylaminopropyl tether, and a para-substituted benzyl moiety. This events lead to superstructure formation and DNA condensation as evident from biophysical experiments and classical molecular dynamics simulations. The DNA superstructure formation by mono-quinoxaline derivatives is highly entropically favored and predominantly driven by hydrophobic interactions. Furthermore, oversupercoiling of DNA and base-destacking cumulatively induces histone eviction from in-vitro assembled nucleosomes at lower micromolar concentrations implicating biological relevance. The DNA structural modulation and histone eviction capacity of the benzyl para-substituents are in the order: -I > -CF3> -Br > -Me > -OMe > -OH, which is largely guided by the polarity of benzyl para-substituent and the resulting molecular topology. The most hydrophobic derivative 3c with para-iodo benzyl moiety causes maximal disruption of base pairing and generation of superstructures. Both these events gradually diminish as the polarity of the benzyl para-substituent increases. On the other hand, quinoxaline derivatives having heterocyclic ring instead of benzyl ring, or in the absence of N,N-dimethylamino head-group, is incapable of inducing any DNA structural change and histone eviction. Further, the quinoxaline compounds displayed potent anticancer activities against different cancer cell lines which directly correlates with the hydrophobic effects of the benzyl para-substituents. Overall, the present study provides new insights into the mechanistic approach of DNA structural modulation driven histone eviction guided by the hydrophobicity of synthesized compounds leading to cellular cytotoxicity towards cancer cells.

The identification of circulating tumour DNA using MassARRAY technology in non-small-cell lung cancer (NSCLC).

OBJECTIVES: Attaining tumour material from lung cancer patients can be challenging with limited sample availability. Therefore, non-invasive means of assessing tumour material is becoming increasingly more important. Circulating tumour DNA (ctDNA), extracted from a blood sample is appealing for the patient, and can be performed serially over the course of treatment. MATERIALS AND METHODS: Here, we describe an approach for profiling the blood samples of 103 NSCLC patients for 73 variants in ctDNA across a panel of actionable lung cancer mutations using the UltraSEEK lung Panel (Agena Biosciences). RESULTS: Our cross-sectional study showed tumour and blood concordance in the detection of KRAS mutations (G12C, G12D, G12A/V, G12R, G12RC, Q61H) in 17/27 (63%), EGFR mutations (e746_a750del, e747_A750, T790M, L861Q) in 16/20 (80%) with additional PIK3CA_p545K mutations across both cohorts. In patients without reported tumour mutations, 11/56 (19.6%) presented with plasma mutations across EGFR, KRAS and PIK3CA. Where ctDNA mutations were measured longitudinally (n = 4 patients), the individual mutations mirrored the response to therapy/progression of disease. CONCLUSION: Whilst preliminary, this study demonstrates the utility of detecting clinically actionable mutations in the blood samples of NSCLC patients at the time of presentation, and over the course of therapy.

Binding Studies of Aloe-Active Compounds with G-Quadruplex Sequences.

G-quadruplex, a unique DNA quartet motif with a pivotal role in regulation of the gene expression, has been established as a potent therapeutic target for the treatment of cancer. Small-molecule-mediated stabilization of the G-quadruplex and thus inhibition of the expression from the oncogene promoter and telomere region may be a promising anticancer strategy. Aloe vera-derived natural compounds like aloe emodin, aloe emodin-8-glucoside, and aloin have significant anticancer activity. Comparative binding studies of these three molecules with varieties of G-quadruplex sequences were carried out using different biophysical techniques like absorption spectral titration, fluorescence spectral titration, dye displacement, ferrocyanide quenching assay, and CD and DSC thermogram studies. Overall, this study revealed aloe emodin and aloe emodin-8-glucoside as potent quadruplex-binding molecules mostly in the case of c-KIT and c-MYC sequences with a binding affinity value of 105 order that is higher than their duplex DNA binding ability. This observation may be correlated to the anticancer activity of these aloe-active compounds and also be helpful in the potential therapeutic application of natural compound-based molecules.

Interaction of a Triantennary Quinoline Glycoconjugate with the Asialoglycoprotein Receptor.

Targeted intracellular delivery is an efficient strategy for developing therapeutics against cancer and other intracellular infections. Nonspecific drug delivery shows limited clinical applications owing to high dosage, cytotoxicity, nonspecific action, high cost, etc. Therefore, targeted delivery of less cytotoxic drug candidates to hepatocytes through ASGPR-mediated endocytosis could be an efficient strategy to surmount the prevailing shortcomings. In the present work, the gene encoding ASGPR-H1-CRD was amplified from Huh7 cells, cloned into pET 11a vector, and the ASGPR-H1-CRD protein was expressed and purified from E. coli. A novel triantennary galactose-conjugated quinoline derivative 4 was synthesized that demonstrates 17-fold higher binding affinity to isolated ASGPR-H1-CRD protein receptor (Kd ∼54 µM) in comparison to D-galactose (Kd ∼900 µM). Moreover, micro-calorimetric studies for the interaction of glycoconjugate 4 with ASGPR protein on live hepatocytes showed notable thermal response in case of ASGPR-containing Huh7 cells, in comparison to non-ASGPR Chang cells. These results might serve as an approach towards targeted delivery of small glycoconjugates to hepatocytes.

A Pyrimido-Quinoxaline Fused Heterocycle Lights Up Transfer RNA upon Binding at the Mg2+ Binding Site.

Transfer RNAs (tRNAs) are fundamental molecules in cellular translation. In this study we have highlighted a fluorescence-based perceptive approach for tRNAs by using a quinoxaline small molecule. We have synthesised a water-soluble fluorescent pyrimido-quinoxaline-fused heterocycle containing a mandatory piperazine tail (DS1) with a large Stokes shift (∼160 nm). The interaction between DS1 and tRNA results in significant fluorescence enhancement of the molecule with Kd ∼5 µM and multiple binding sites. Our work reveals that the DS1 binding site overlaps with the specific Mg2+ ion binding site in the D loop of tRNA. As a proof-of-concept, the molecule inhibited Pb2+ -induced cleavage of yeast tRNAPhe in the D loop. In competitive binding assays, the fluorescence of DS1-tRNA complex is quenched by a known tRNA-binder, tobramycin. This indicates the displacement of DS1 and, indeed, a substantiation of specific binding at the site of tertiary interaction in the central region of tRNA. The ability of compound DS1 to bind tRNA with a higher affinity compared to DNA and single-stranded RNA offers a promising approach to developing tRNA-based biomarker diagnostics in the future.

Quinoxaline derivatives disrupt the base stacking of hepatitis C virus-internal ribosome entry site RNA: reduce translation and replication.

RNA-biased small molecules with a monoquinoxaline core target the L-shaped structure of subdomain IIa of Hepatitis C virus internal ribosome entry site (IRES) RNA in proximity to the Mg2+ binding site. The binding event leads to the destacking of RNA bases, resulting in the inhibition of IRES-mediated translation and HCV RNA replication.

DNA Structural Alteration Leading to Antibacterial Properties of 6-Nitroquinoxaline Derivatives.

Structural integrity of the bacterial genome plays an important role in bacterial survival. Cellular consequences of an intolerable amount of change in the DNA structure are not well understood in bacteria. Here we have stated that binding of synthetic 6-nitroquinoxaline derivatives with DNA led to change in its global structure, subsequently culminating with over-supercoiled form through in-path intermediates. This structural change results in induction of programmed cell death like physiological hallmarks, which is dependent on substitution driven structural modulation properties of the scaffold. A sublethal dose of a representative derivative, 3a, significantly inhibits DNA synthesis, produces fragmented nucleoids, and alters membrane architecture. We have also shown that exposure to the compound changes the native morphology of Staphylococcus aureus cells and significantly disrupts preformed biofilms. Thus, our study gives new insight into bacterial responses to local or global DNA structural changes induced by 6-nitroquinoxaline small molecules.

Record-high thermal stability achieved in a novel single-component all-organic ferroelectric crystal exhibiting polymorphism.

Traditionally, lead and heavy metal containing inorganic oxides dominate the area of ferroelectricity. Although, recently, lightweight non-toxic organic ferroelectrics have emerged as excellent alternatives, achieving higher temperature up to which the ferroelectric phase can persist has remained a challenge. Moreover, only a few of those are single-component molecular ferroelectrics and were discovered upon revisiting their crystal structures. Here we report a novel phenanthroimidazole derivative, which not only displays notable spontaneous and highly stable remnant polarizations with a low coercive field but also retains its ferroelectric phase up to a record-high temperature of ∼521 K. Subsequently, the crystal undergoes phase transition to form non-polar and centrosymmetric polymorphs, the first study of its kind in a single-component ferroelectric crystal. Moreover, the compound exhibits a significantly high thermal stability. Given the excellent figures-of-merit for ferroelectricity, this material is likely to find potential applications in microelectronic devices pertaining to non-volatile memory.