Thiophene-expanded guanosine analogues of Gemcitabine

Efficient production of guanosine in Escherichia coli by combinatorial metabolic engineering

BACKGROUND

Guanosine is a purine nucleoside that is widely used as a raw material for food additives and pharmaceutical products. Microbial fermentation is the main production method of guanosine. However, the guanosine-producing strains possess multiple metabolic pathway interactions and complex regulatory mechanisms. The lack of strains with efficiently producing-guanosine greatly limited industrial application.

RESULTS

We attempted to efficiently produce guanosine in Escherichia coli using systematic metabolic engineering. First, we overexpressed the purine synthesis pathway from Bacillus subtilis and the prs gene, and deleted three genes involved in guanosine catabolism to increase guanosine accumulation. Subsequently, we attenuated purA expression and eliminated feedback and transcription dual inhibition. Then, we modified the metabolic flux of the glycolysis and Entner-Doudoroff (ED) pathways and performed redox cofactors rebalancing. Finally, transporter engineering and enhancing the guanosine synthesis pathway further increased the guanosine titre to 134.9 mg/L. After 72 h of the fed-batch fermentation in shake-flask, the guanosine titre achieved 289.8 mg/L.

CONCLUSIONS

Our results reveal that the guanosine synthesis pathway was successfully optimized by combinatorial metabolic engineering, which could be applicable to the efficient synthesis of other nucleoside products.

Iodine-catalyzed three-component annulation: access to highly fluorescent trisubstituted thiophenes

An efficient synthesis of highly fluorescent trisubstituted thiophenes was achieved via iodine-catalyzed, base-promoted annulation employing elemental sulfur as a sulfur source. The compounds exhibit excellent photophysical properties like solid-state fluorescence, high quantum yield and solvatochromism. As these thiophene derivatives have potential application in the development of optoelectronic devices, gram-scale synthesis of the desired heterocycles was demonstrated.

Synthesis and discovery of potential tyrosinase inhibitor of new coumarin-based thiophenyl-pyrazolylthiazole nuclei: In vitro evaluation, cytotoxicity, kinetic, and computational studies

A well-known key enzyme in melanogenesis and hyperpigmentation is tyrosinase. The present study introduces a novel series of thiophenyl-pyrazolylthiazole-coumarin hybrids (6a-6h) as tyrosinase inhibitors. The in-vitro tyrosinase inhibition results indicated that all compounds have strong tyrosinase inhibitory activity, particularly compound 6g (IC₅₀  = 0.043 ± 0.006 μM), was identified as the most active compound compared to the positive control (kojic acid, IC₅₀  = 18.521 ± 1.162 μM). Lineweaver-Burk plots were employed to analyze the kinetic mechanism, and compound 6g formed an enzyme-inhibitor complex by inhibiting tyrosinase non-competitively. Furthermore, all compounds demonstrated excellent antioxidant activity against DPPH. MTT assay was used to screen the cytotoxicity of all compounds on B16F10 melanoma cells, and they had no toxic effect on the cells. The binding affinity of compounds with tyrosinase was also investigated using molecular docking, and the ligands displayed good binding energy values. These molecules could be a promising lead for skin pigmentation and associated diseases as nontoxic pharmacological scaffolds.

Heteroaromatic Diazirines Are Essential Building Blocks for Material and Medicinal Chemistry

In materials (polymer) science and medicinal chemistry, heteroaromatic derivatives play the role of the central skeleton in development of novel devices and discovery of new drugs. On the other hand, (3-trifluoromethyl)phenyldiazirine (TPD) is a crucial chemical method for understanding biological processes such as ligand-receptor, nucleic acid-protein, lipid-protein, and protein-protein interactions. In particular, use of TPD has increased in recent materials science to create novel electric and polymer devices with comparative ease and reduced costs. Therefore, a combination of heteroaromatics and (3-trifluoromethyl)diazirine is a promising option for creating better materials and elucidating the unknown mechanisms of action of bioactive heteroaromatic compounds. In this review, a comprehensive synthesis of (3-trifluoromethyl)diazirine-substituted heteroaromatics is described.

Anticancer Activity of Thiophene Carboxamide Derivatives as CA-4 Biomimetics: Synthesis, Biological Potency, 3D Spheroid Model, and Molecular Dynamics Simulation

The present study aimed to synthesize thiophene carboxamide derivatives, which are considered biomimetics of the anticancer medication Combretastatin A-4 (CA-4), and compare the similarity in the polar surface area (PSA) between the novel series and CA-4. Our results showed that the PSA of the most synthesized structures was biomimetic to CA-4, and similar chemical and biological properties were observed against Hep3B cancer cell line. Among the synthesized series 2b and 2e compounds were the most active molecules on Hep3B (IC50 = 5.46 and 12.58 µM, respectively). The 3D results revealed that both 2b and 2e structures confuse the surface of Hep3B cancer cell lines' spheroid formation and force these cells to aggregate into a globular-shaped spheroid. The 2b and 2e showed a comparable interaction pattern to that observed for CA-4 and colchicine within the tubulin-colchicine-binding pocket. The thiophene ring, due to holding a high aromaticity character, participated critically in that observed interaction profile and showed additional advanced interactions over CA-4. The 2b and 2e tubulin complexes showed optimal dynamics trajectories within a time scale of 100 ns at 300 K temperature, which asserts their high stability and compactness. Together, these findings revealed the biomimetic role of 2b and 2e compounds in CA-4 in preventing cancer progression.

Design, synthesis and biological evaluation of 7-(5-((substituted - amino)-methyl)-thiophen-2-yl)-spiro-[chroman-2,4'-piperidin]-4-one hydrochloride analogues as anticancer agents

A series of thirty-one novel 7-(5-((amino)-methyl)-thiophen-2-yl)-spiro-[chroman-2,4'-piperidin]-4-one hydrochloride analogues (Cst 1 - 31) have been designed, synthesized and characterized by ¹H NMR, ¹³C NMR and MS spectral analysis. Here, we evaluated the anticancer potential and biological results of low-molecular-weight bridgehead oxygen and nitrogen-containing spirochromanones on proliferation and apoptosis of the human breast cancer cell line (MCF-7) and Murine melanoma (B16F10). The anticancer activity ranged from 2.9 to 35.0 µM. The most potent compounds Cst-22, Cst-24 and Cst-31 were found to be less toxic against human embryonic kidney (HEK-293) cell lines. Cst-24 and Cst-31 were found to be causing significant cytotoxicity through apoptotic cell death and also G2 phase arrest of cell cycle in B16F10 cells. In-silico ADME prediction stidies of the titled compounds were found within the rules outlined, and these compounds may not face any pharmacokinetic associated issues in the mere future upon developmental stage. These conjugates may serve as a lead for the discovery of potential anticancer drug candidate with better therapeutic profile.

Synthesis of Novel Aryl (4-Aryl-1H-Pyrrol-3-yl) (Thiophen-2-yl) Methanone Derivatives: Molecular Modelling, In Silico ADMET, Anti-Inflammatory and Anti-Ulcer Activities

BACKGROUND

Due to the presence of both five-membered heterocyclics like pyrrole and thiophene in one molecule considerable attention was made for their enormous pharmacological activities out of which include anti-inflammatory and anti-ulcer activities.

OBJECTIVE

Chalcones with toluenesulfonylmethyl isocyanide (TosMIC) undergo synthesis to form some new aryl (4-aryl-1H-pyrrol-3-yl) (thiophen-2-yl) methanone derivatives. Molecular docking of synthesized compounds with protein receptors of anti-inflammatory COX-1(3N8Y), COX-2 (1PXX) along with anti-ulcer H+/K+ATPase enzyme (2XZB) followed with drug-likeness, and in silico ADMET properties.

MATERIALS AND METHODS

The multicomponent reaction was carried out by the intermediate formation of α, β-unsaturated ketone from carbonyl compounds which on sequential addition undergoes [3+2] cycloaddition reaction in same medium affords aryl (4-aryl-1H-pyrrol-3-yl) (thiophen-2-yl) methanone derivatives by addition of TosMIC in basic medium had resulted in series of compounds PY1 to PY12. All the new synthesized compounds were screened for their in-vitro anti-inflammatory activity by bovine serum albumin method followe with COX assay, and in-vivo by using carrageenan-induced rat paw edema method of the selected compounds PY1, PY5 and PY12 which is also screened for anti-ulcer activity by pylorus ligation method, respectively. Molecular docking was performed using autodock tools, drug-likeness by OSIRIS property explorer and admetSAR properties.

RESULTS AND DISCUSSION

From the synthesized compounds of aryl (4-aryl-1H-pyrrol-3-yl) (thiophen- 2-yl) methanone derivatives PY5 showed decent in-vitro and in-vivo anti-inflammatory along selectivity index of 6.2 for COX-1 with IC50(μM) value of 9.54 over diclofenac with 8.74 and PY1 showed decent in-vivo anti-ulcer activities along with drug-likeness and in silico ADMET predictions revealed that all the synthesized compounds have minimal toxic effects with good absorption as well as solubility characteristics. The selected compounds may serve as potential lead compounds for developing new anti-inflammatory and anti-ulcer drugs.

CONCLUSION

From the newly synthesized molecules PY5 was found to be effective for anti-inflammatory and PY1 was found to be effective for anti-ulcer activities further derivitization and designed of modification to achieve more compounds with potent anti-inflammatory and anti-ulcer activities.

Three-Component Regio- and Stereoselective Polymerizations toward Functional Chalcogen-Rich Polymers with AIE-Activities

Polymers containing rich chalcogen elements are rarely reported due to the lack of facile synthesis methods. Herein, a novel multicomponent polymerization route toward chalcogen-rich polymers was introduced. A series of poly(vinyl sulfones) (PVSs) were synthesized at room temperature using readily prepared monomers. PVSs were generated with high regio- and stereo-selectivity in high yields (up to 92.3%). Rich chalcogen elements endowed PVSs with distingctive multifunctionalities. The PVSs possessed good solubility and film-forming ability. Their thin films exhibited outstanding refractive indices up to 1.8062 at 550.0 nm together with good optical transparency in the visible region. Thin films of some polymers can also be fabricated into well-resolved fluorescent photopatterns by photolithography. Thanks to the unique redox properties of selenium, postmodification by oxidation reaction of P1a/2/3a successfully eliminates the caused heavy atom effect and endow resulting polymers with novel functionality as fluorescent bioprobes for cellular imaging.

Probing the Effects of Pyrimidine Functional Group Switches on Acyclic Fleximer Analogues for Antiviral Activity

Due to their ability to inhibit viral DNA or RNA replication, nucleoside analogues have been used for decades as potent antiviral therapeutics. However, one of the major limitations of nucleoside analogues is the development of antiviral resistance. In that regard, flexible nucleoside analogues known as “fleximers” have garnered attention over the years due to their ability to survey different amino acids in enzyme binding sites, thus overcoming the potential development of antiviral resistance. Acyclic fleximers have previously demonstrated antiviral activity against numerous viruses including Middle East Respiratory Syndrome coronavirus (MERS-CoV), Ebola virus (EBOV), and, most recently, flaviviruses such as Dengue (DENV) and Yellow Fever Virus (YFV). Due to these interesting results, a Structure Activity Relationship (SAR) study was pursued in order to analyze the effect of the pyrimidine functional group and acyl protecting group on antiviral activity, cytotoxicity, and conformation. The results of those studies are presented herein.

Flexibility-Not just for yoga anymore!

Over the past few years, nucleosides have maintained a prominent role as one of the cornerstones of antiviral and anticancer therapeutics, and many approaches to nucleoside drug design have been pursued. One such approach involves flexibility in the sugar moiety of nucleosides, for example, in the highly successful anti-HIV and HBV drug tenofovir. In contrast, introduction of flexibility to the nucleobase scaffold has only more recently gained significance with the invention of our fleximers. The history, development, and some biological relevance for this innovative class of nucleosides are detailed herein.

Synthesis of thiophene derivatives and their anti-microbial, antioxidant, anticorrosion and anticancer activity

Background

A new series of thiophene analogues was synthesized and checked for their in vitro antibacterial, antifungal, antioxidant, anticorrosion and anticancer activities.

Results

A series of ethyl-2-(substituted benzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate derivatives were synthesized by using Gewald synthesis and their structures were confirmed by FTIR, MS and ¹H-NMR. The synthesized compounds were further evaluated for their in vitro biological potentials i.e. antimicrobial activity against selected microbial species using tube dilution method, antiproliferative activity against human lung cancer cell line (A-549) by sulforhodamine B assay, antioxidant activity by using DPPH method and anticorrosion activity by gravimetric method.

Conclusion

Antimicrobial screening results showed that compound S ₁ was the most potent antibacterial agent against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhi having MIC value 0.81 µM/ml and compound S ₄ also displayed excellent antifungal activity against both Candida albicans and Aspergillus niger (MIC = 0.91 µM/ml) when compared with cefadroxil (antibacterial) and fluconazole (antifungal) as standard drug. The antioxidant screening results indicated that compound S ₄ and S ₆ exhibited excellent antioxidant activity with IC₅₀ values 48.45 and 45.33 respectively when compared with the ascorbic acid as standard drug. Anticorrosion screening results indicated that compound S ₇ showed more anticorrosion efficiency (97.90%) with low corrosion rate. Results of anticancer screening indicated that compound S ₈ showed effective cytotoxic activity against human lung cancer cell line (A-549) at dose of 10^-4 M when compared with adriamycin as standard.

The evolution of antiviral nucleoside analogues: A review for chemists and non-chemists. Part II: Complex modifications to the nucleoside scaffold

This is the second of two invited articles reviewing the development of nucleoside analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. As with the first paper, rather than providing a chronological account, we have chosen to examine particular examples of structural modifications made to nucleoside analogues that have proven fruitful as various antiviral, anticancer, and other therapeutics. The first review covered the more common, and in most cases, single modifications to the sugar and base moieties of the nucleoside scaffold. This paper focuses on more recent developments, especially nucleoside analogues that contain more than one modification to the nucleoside scaffold. We hope that these two articles will provide an informative historical perspective of some of the successfully designed analogues, as well as many candidate compounds that encountered obstacles.

Antiviral activity spectrum of phenoxazine nucleoside derivatives

The phenoxazine scaffold is widely used to stabilize nucleic acid duplexes, as a part of fluorescent probes for the study of nucleic acid structure, recognition, and metabolism, etc. Here we present the synthesis of phenoxazine-based nucleoside derivatives and their antiviral activity against a panel of structurally diverse viruses: enveloped DNA herpesviruses varicella zoster virus (VZV) and human cytomegalovirus, enveloped RNA tick-borne encephalitis virus (TBEV), and non-enveloped RNA enteroviruses. Studied compounds were effective against DNA and RNA viruses reproduction in cell culture. 3-(2'-Deoxy-β-D-ribofuranosyl)-1,3-diaza-2-oxophenoxazine proved to be a potent inhibitor of VZV replication with superior activity against wild type than thymidine kinase deficient strains (EC₅₀ 0.06 and 10 μM, respectively). This compound did not show cytotoxicity on all the studied cell lines. Several compounds showed promising activity against TBEV (EC₅₀ 0.35-0.91 μM), but the activity was accompanied by pronounced cytotoxicity. These compounds may be considered as a good starting point for further structure optimization as antiherpesviral or antiflaviviral compounds.

Therapeutic importance of synthetic thiophene

Thiophene and its substituted derivatives are very important class of heterocyclic compounds which shows interesting applications in the field of medicinal chemistry. It has made an indispensable anchor for medicinal chemists to produce combinatorial library and carry out exhaustive efforts in the search of lead molecules. It has been reported to possess a wide range of therapeutic properties with diverse applications in medicinal chemistry and material science, attracting great interest in industry as well as academia. It has been proven to be effectual drugs in present respective disease scenario. They are remarkably effective compounds both with respect to their biological and physiological functions such as anti-inflammatory, anti-psychotic, anti-arrhythmic, anti-anxiety, anti-fungal, antioxidant, estrogen receptor modulating, anti-mitotic, anti-microbial, kinases inhibiting and anti-cancer. Thus the synthesis and characterization of novel thiophene moieties with wider therapeutic activity is a topic of interest for the medicinal chemist to synthesize and investigate new structural prototypes with more effective pharmacological activity. However, several commercially available drugs such as Tipepidine, Tiquizium Bromides, Timepidium Bromide, Dorzolamide, Tioconazole, Citizolam, Sertaconazole Nitrate and Benocyclidine also contain thiophene nucleus. Therefore, it seems to be a requirement to collect recent information in order to understand the current status of the thiophene nucleus in medicinal chemistry research.

The evolution of nucleoside analogue antivirals: A review for chemists and non-chemists. Part 1: Early structural modifications to the nucleoside scaffold

This is the first of two invited articles reviewing the development of nucleoside-analogue antiviral drugs, written for a target audience of virologists and other non-chemists, as well as chemists who may not be familiar with the field. Rather than providing a simple chronological account, we have examined and attempted to explain the thought processes, advances in synthetic chemistry and lessons learned from antiviral testing that led to a few molecules being moved forward to eventual approval for human therapies, while others were discarded. The present paper focuses on early, relatively simplistic changes made to the nucleoside scaffold, beginning with modifications of the nucleoside sugars of Ara-C and other arabinose-derived nucleoside analogues in the 1960's. A future paper will review more recent developments, focusing especially on more complex modifications, particularly those involving multiple changes to the nucleoside scaffold. We hope that these articles will help virologists and others outside the field of medicinal chemistry to understand why certain drugs were successfully developed, while the majority of candidate compounds encountered barriers due to low-yielding synthetic routes, toxicity or other problems that led to their abandonment.

Mesenchymal Stromal Cells for Antineoplastic Drug Loading and Delivery

Mesenchymal stromal cells are a population of undifferentiated multipotent adult cells possessing extensive self-renewal properties and the potential to differentiate into a variety of mesenchymal lineage cells. They express broad anti-inflammatory and immunomodulatory activity on the immune system and after transplantation can interact with the surrounding microenvironment, promoting tissue healing and regeneration. For this reason, mesenchymal stromal cells have been widely used in regenerative medicine, both in preclinical and clinical settings. Another clinical application of mesenchymal stromal cells is the targeted delivery of chemotherapeutic agents to neoplastic cells, maximizing the cytotoxic activity against cancer cells and minimizing collateral damage to non-neoplastic tissues. Mesenchymal stem cells are home to the stroma of several primary and metastatic neoplasms and hence can be used as vectors for targeted delivery of antineoplastic drugs to the tumour microenvironment, thereby reducing systemic toxicity and maximizing antitumour effects. Paclitaxel and gemcitabine are the chemotherapeutic drugs best loaded by mesenchymal stromal cells and delivered to neoplastic cells, whereas other agents, like pemetrexed, are not internalized by mesenchymal stromal cells and therefore are not suitable for advanced antineoplastic therapy. This review focuses on the state of the art of advanced antineoplastic cell therapy and its future perspectives, emphasizing in vitro and in vivo preclinical results and future clinical applications.

Scaffold-hopping from xanthines to tricyclic guanines: A case study of dipeptidyl peptidase 4 (DPP4) inhibitors

Molecular modeling of unbound tricyclic guanine scaffolds indicated that they can serve as effective bioisosteric replacements of xanthines. This notion was further confirmed by a combination of X-ray crystallography and SAR studies, indicating that tricyclic guanine DPP4 inhibitors mimic the binding mode of xanthine inhibitors, exemplified by linagliptin. Realization of the bioisosteric relationship between these scaffolds potentially will lead to a wider application of cyclic guanines as xanthine replacements in drug discovery programs for a variety of biological targets. Newly designed DPP4 inhibitors achieved sub-nanomolar potency range and demonstrated oral activity in vivo in mouse glucose tolerance test.