Therapeutic potential of pteridine derivatives: A comprehensive review

Synthesis and pharmacodynamic evaluation of Dihydropteridone derivatives against PDCoV in vivo and in vitro

Porcine Delta Coronavirus (PDCoV) infection can induce serious dehydration, diarrhea and even death of piglets, which has caused huge losses to the breeding industry. PDCoV has been reported to have the potential for cross species transmission, and even reports of infecting humans have emerged. At present, there are still no effective prevention and control measures for PDCoV. In this study, we have designed and synthesized a series of unreported Dihydropteridone derivatives. All of these compounds were evaluated for the against PDCoV in vivo and in vitro for the first time. In this study, antiviral activity (17.34 ± 7.20 μM) and low cytotoxicity (>800 μM) was found in compound W8. Compound W8 exerts antiviral effect on PDCoV by inhibiting cell apoptosis and inflammatory factors caused by virus infection in vitro. In addition, lung and small intestinal lesions caused by PDCoV infection in mice could be significantly reduced by compound W8. These findings highlight the potential of compound W8 as a valuable therapeutic option against PDCoV infection, and lay a foundation for further research and development in this field.

The Leptospermum scoparium (Mānuka)-Specific Nectar and Honey Compound 3,6,7-Trimethyllumazine (LepteridineTM) That Inhibits Matrix Metalloproteinase 9 (MMP-9) Activity

3,6,7-trimethyllumazine (Lepteridine™) is a newly discovered natural pteridine derivative unique to Mānuka (Leptospermum scoparium) nectar and honey, with no previously reported biological activity. Pteridine derivative-based medicines, such as methotrexate, are used to treat auto-immune and inflammatory diseases, and Mānuka honey reportedly possesses anti-inflammatory properties and is used topically as a wound dressing. MMP-9 is a potential candidate protein target as it is upregulated in recalcitrant wounds and intestinal inflammation. Using gelatin zymography, 40 μg/mL LepteridineTM inhibited the gelatinase activities of both pro- (22%, p < 0.0001) and activated (59%, p < 0.01) MMP-9 forms. By comparison, LepteridineTM exerted modest (~10%) inhibition against a chromogenic peptide substrate and no effect against a fluorogenic peptide substrate. These findings suggest that LepteridineTM may not interact within the catalytic domain of MMP-9 and exerts a negligible effect on the active site hydrolysis of small soluble peptide substrates. Instead, the findings implicate fibronectin II domain interactions by LepteridineTM which impair gelatinase activity, possibly through perturbed tethering of MMP-9 to the gelatin matrix. Molecular modelling analyses were equivocal over interactions at the S1' pocket versus the fibronectin II domain, while molecular dynamic calculations indicated rapid exchange kinetics. No significant degradation of synthetic or natural LepteridineTM in Mānuka honey occurred during simulated gastrointestinal digestion. MMP-9 regulates skin and gastrointestinal inflammatory responses and extracellular matrix remodelling. These results potentially implicate LepteridineTM bioactivity in Mānuka honey's reported beneficial effects on wound healing via topical application and anti-inflammatory actions in gastrointestinal disorder models via oral consumption.

Highly regioselective 6-exo-dig iodo/bromo cyclizations of functionalized 5-amino propargyl pyrimidinones: an efficient synthesis of functionalized pteridines

The manuscript describes the highly regioselective 6-exo-dig iodo/bromo cyclization of functionalized N-propagyl-amino-pyrimidinones under ambient conditions. The cyclization afforded functionalized pteridines in excellent yields. The optimized procedures are mild, operationally simple and working successfully with different substrates. The synthesis of functionalized pteridines is of great significance because of their potential pharmacological profile.

Gene expression dynamics in input-responsive engineered living materials programmed for bioproduction

Engineered living materials (ELMs) fabricated by encapsulating microbes in hydrogels have great potential as bioreactors for sustained bioproduction. While long-term metabolic activity has been demonstrated in these systems, the capacity and dynamics of gene expression over time is not well understood. Thus, we investigate the long-term gene expression dynamics in microbial ELMs constructed using different microbes and hydrogel matrices. Through direct gene expression measurements of engineered E. coli in F127-bisurethane methacrylate (F127-BUM) hydrogels, we show that inducible, input-responsive genetic programs in ELMs can be activated multiple times and maintained for multiple weeks. Interestingly, the encapsulated bacteria sustain inducible gene expression almost 10 times longer than free-floating, planktonic cells. These ELMs exhibit dynamic responsiveness to repeated induction cycles, with up to 97% of the initial gene expression capacity retained following a subsequent induction event. We demonstrate multi-week bioproduction cycling by implementing inducible CRISPR transcriptional activation (CRISPRa) programs that regulate the expression of enzymes in a pteridine biosynthesis pathway. ELMs fabricated from engineered S. cerevisiae in bovine serum albumin (BSA) - polyethylene glycol diacrylate (PEGDA) hydrogels were programmed to express two different proteins, each under the control of a different chemical inducer. We observed scheduled bioproduction switching between betaxanthin pigment molecules and proteinase A in S. cerevisiae ELMs over the course of 27 days under continuous cultivation. Overall, these results suggest that the capacity for long-term genetic expression may be a general property of microbial ELMs. This work establishes approaches for implementing dynamic, input-responsive genetic programs to tailor ELM functions for a wide range of advanced applications.

Electrochemical detection of the oxidative damage of a potential pyrimido[5,4-g]pteridine-derived antitumor agent toward DNA

In this work, we design and synthesize 2,2'-(7,9-dimethyl-2,4,6,8-tetraoxo-6,7,8,9-tetrahydropyrimido[5,4-g]pteridine-1,3(2H,4H)-diyl)bis(N,N-bis(2-chloroethyl)acetamide) (PT-MCA) as a novel DNA intercalator and potential antitumor agent. Electrochemical analysis reveals the redox process of PT-MCA on the electrode surface. The bioelectrochemical sensors are obtained by modifying the surface of GCE with calf thymus DNA (ctDNA), poly (dG), poly (dA), and G-quadruplex, respectively. The DNA oxidative damage induced by PT-MCA is investigated by comparing the peak intensity change of dGuo and dAdo and monitoring the peaks of the oxidation products of guanine and/or adenine (8-oxoGua and/or 2,8-oxoAde). UV-vis absorption and fluorescence spectra and gel electrophoresis are further employed to understand the intercalation of PT-MCA into DNA base pairs. Moreover, PT-MCA is proved to exhibit stronger anti-proliferation activity than mitoxantrone against both 4T1 and B16-F10 cancer cells. At last, the oxidative damage of PT-MCA toward ctDNA is not interfered by the coexistence of ions and also can be detected in real serums.

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

Many heterocyclic compounds can be synthetized using diaza-1,3-butadienes (DADs) as key structural precursors. Isolated and in situ diaza-1,3-butadienes, produced from their respective precursors (typically imines and hydrazones) under a variety of conditions, can both react with a wide range of substrates in many kinds of reactions. Most of these reactions discussed here include nucleophilic additions, Michael-type reactions, cycloadditions, Diels–Alder, inverse electron demand Diels–Alder, and aza-Diels–Alder reactions. This review focuses on the reports during the last 10 years employing 1,2-diaza-, 1,3-diaza-, 2,3-diaza-, and 1,4-diaza-1,3-butadienes as intermediates to synthesize heterocycles such as indole, pyrazole, 1,2,3-triazole, imidazoline, pyrimidinone, pyrazoline, -lactam, and imidazolidine, among others. Fused heterocycles, such as quinazoline, isoquinoline, and dihydroquinoxaline derivatives, are also included in the review.

Тhio-containing pteridines: Synthesis, modification, and biological activity

The present article is devoted to searching for biologically active agents among novel thio-containing pteridines. Synthetic protocols based on the condensation of 5,6-diamino-2-thioxo-2,3-dihydropyrimidin-4(1H)-ones with dicarbonyl compounds were elaborated and used for the synthesis of target products. The directions for further modification of the obtained thio-containing pteridines were substantiated and realized. The spectral properties of the obtained compounds were studied and described. The results of the in silico study revealed that the predicted affinity of the obtained compounds to the dihydrofolate reductase (DHFR) active site is comparable with the affinity of methotrexate, despite the differences in the nature of the ligand-enzyme interactions. The in vitro study of DHFR-inhibiting activity revealed that the most active compounds 3.9 and 4.2 have lg IC₅₀ values of -5.889 and -5.233, respectively, significantly inferior to methotrexate (lg IC₅₀  = -7.605). Additionally, the synthesized compounds were studied for their antiradical activity as a possible mechanism of pharmacological effects. Among the obtained pteridines, compounds 5.1 (lg EC₅₀  = -4.82) and 5.3 (lg EC₅₀ = -4.92) have antiradical activity higher than the reference compound ascorbic acid (lg EC₅₀ = -4.81). The conducted structure-activity relationship analysis provided valuable data for the further search for biologically active agents among thio-containing pteridines and related compounds.

Thiolumazines as Heavy-Atom-Free Photosensitizers for Applications in Daylight Photodynamic Therapy: Insights from Ultrafast Excited-State Dynamics

Finding appropriate photosensitizers (PSs) for daylight photodynamic therapy (dPDT) applications is extremely challenging, even though heavy-atom-free photosensitizers (HAFPSs) such as thiocarbonyl-modified nucleobases have shown a ray of hope. Few attempts have been made to find alternative natural products for dPDT applications. Pteridine heterocycles consisting of a pyrazine ring and a pyrimidine ring, such as lumazine, which exhibit many structural similarities to the alloxazine ring of the flavin molecule, could be an option for HAFPSs. The photophysical and quantum mechanical studies of the thio-modified lumazines revealed that sequential thiomodifications in lumazine result in a bathochromic shift. Additionally, higher tissue penetration depths were observed for thiolumazines. The fluorescence quenching in the case of thiomodified lumazines was explained using triplet state formation, whereas the contribution from the photoinduced electron transfer process cannot be ignored. It was also noticed that a strong one-photon absorption influenced the two-photon absorption (TPA) process, leading to a self-focusing effect in the visible spectral region. The higher tissue penetration and larger TPA cross section are the hallmark characteristics of the thiolumazines to be considered as potential HAFPSs for dPDT applications.

Dihydrofolate reductase, thymidylate synthase, and serine hydroxy methyltransferase: successful targets against some infectious diseases

Parasitic diseases have a serious impact on the world in terms of health and economics and are responsible for worldwide mortality and morbidity. The present review features the hybrid targeting involving three main enzymes for the treatment of different parasitic diseases. The enzymes Dihydrofolate reductase, thymidylate synthase, and Serine hydroxy methyltransferase play an essential role in the folate pathway. The present review focuses on these enzymes, which can be targeted against several diseases. It shed light on the past, present, and future of these targets, and it can be assessed that these targets can play a significant role against several infectious diseases. For combating viral and protozoal infectious diseases, these targets in combination should be addressed.

Efficient Synthesis and Biological Evaluation of 6-Trifluoroethoxy Functionalized Pteridine Derivatives as EGFR Inhibitors

BACKGROUND

Pteridine-based scaffolds have been widely prevalent in pharmaceuticals, such as kinase inhibitors targeting EGFR, FLT3 and PI3K/mTOR, which are attractive targets for anticancer therapy.

OBJECTIVE

This work aimed to design and synthesize 6-2,2,2-trifluoroethoxy functionalized pteridine-based derivatives for investigation of their anti-cancer activities as EGFR inhibitor.

METHOD

Pteridine-based derivatives were synthesized in 6 steps involving amination, bromination, cyclization, alkoxylation, chlorination and coupling reactions. Cellular anti-proliferative activities and inhibition activities on EGFR signaling of these pteridine derivatives in vitro were determined by the MTT assay and western blot analysis, respectively. Molecular docking simulation studies were carried out by the crystallographic structure of the erlotinib/EGFR kinase domain [Protein Data Bank (PDB) code: 1M17].

RESULTS

The compound 7m, with IC50 values of 27.40 μM on A549 cell line, exhibited comparable anti-proliferative activity relative to the positive control. Besides western blots showed its obvious down-regulation of p-EGFR and p-ERK expression at 0.8 μM. Molecular docking model displayed a hydrogen bond between Met-769 amide nitrogen and N-1 in pteridine motif of 7m which lay at the ATP binding site of EGFR kinase domain.

CONCLUSION

The inhibition of 7m on cellular growth was comparable to that of the positive control. The inhibitory activities of 7m on EGFR phosphorylation and ERK phosphorylation in A549 cell line were relatively superior to that of the positive control. Both results suggested that the anti-proliferative activity of 7m against A549 cell line was caused by inhibition of EGFR signaling pathway, providing a new perspective for modification on pteridine-based derivatives as EGFR inhibitor.

A Review of Small-Molecule Inhibitors of One-Carbon Enzymes: SHMT2 and MTHFD2 in the Spotlight

Metabolic reprogramming is a key hallmark of cancer and shifts cellular metabolism to meet the demands of biomass production necessary for abnormal cell reproduction. One-carbon metabolism (1CM) contributes to many biosynthetic pathways that fuel growth and is comprised of a complex network of enzymes. Methotrexate and 5-fluorouracil were pioneering drugs in this field and are still widely used today as anticancer agents as well as for other diseases such as arthritis. Besides dihydrofolate reductase and thymidylate synthase, two other enzymes of the folate cycle arm of 1CM have not been targeted clinically: serine hydroxymethyltransferase (SHMT) and methylenetetrahydrofolate dehydrogenase (MTHFD). An increasing body of literature suggests that the mitochondrial isoforms of these enzymes (SHMT2 and MTHFD2) are clinically relevant in the context of cancer. In this review, we focused on the 1CM pathway as a target for cancer therapy and, in particular, SHMT2 and MTHFD2. The function, regulation, and clinical relevance of SHMT2 and MTHFD2 are all discussed. We expand on previous clinical studies and evaluate the prognostic significance of these critical enzymes by performing a pan-cancer analysis of patient data from the The Cancer Genome Atlas and a transcriptional coexpression network enrichment analysis. We also provide an overview of preclinical and clinical inhibitors targeting the folate pathway, the methionine cycle, and folate-dependent purine biosynthesis enzymes.

A New Family of Fused Azolo[1,5-a]pteridines and Azolo[5,1-b]purines

The nitration of azolo[1,5-a]pyrimidin-7-amines with several nitration agents (such as acetic nitric anhydride, nitronium tetrafluoroborate, and a mixture of concentrated nitric acid and sulfuric acid) has been investigated. It has been shown that, depending on the conditions, the nitration of pyrazolopyrimidin-7-amines bearing electron-withdrawing groups in the pyrazole ring leads to nitration products in the pyrimidine and/or pyrazole ring. The nitration of triazolo[1,5-a]pyrimidin-7-amines with "nitrating mixture" has been optimized, thus allowing us to obtain a series of 6-nitro[1,2,4]triazolo[1,5-a]pyrimidin-7-amines, followed by their reduction into the corresponding [1,2,4]triazolo[1,5-a]pyrimidin-6,7-diamines (yields 86-89%). The latter have been subjected to heterocyclization by a variety of electrophilic compounds (such as CS₂, glyoxal, triethyl orthoformate) with the formation of five- or six-membered annulated cycles.

Microwave Assisted Reactions of Azaheterocycles Formedicinal Chemistry Applications

Microwave (MW) assisted reactions have became a powerful tool in azaheterocycles chemistry during the last decades. Five and six membered ring azaheterocycles are privileged scaffolds in modern medicinal chemistry possessing a large variety of biological activity. This review is focused on the recent relevant advances in the MW assisted reactions applied to azaheterocyclic derivatives and their medicinal chemistry applications from the last five years. The review is divided according to the main series of azaheterocycles, more precisely 5- and 6-membered ring azaheterocycles (with one, two, and more heteroatoms) and their fused analogues. In each case, the reaction pathways, the advantages of using MW, and considerations concerning biological activity of the obtained products were briefly presented.

Ferrocene-containing hybrids as potential anticancer agents: Current developments, mechanisms of action and structure-activity relationships

Cancer is one of the most fatal threatens to human health throughout the world. The major challenges in the control and eradication of cancers are the continuous emergency of drug-resistant cancer and the low specificity of anticancer agents, creating an urgent need to develop novel anticancer agents. Organometallic compounds especially ferrocene derivatives possess remarkable structural and mechanistic diversity, inherent stability towards air, heat and light, low toxicity, low cost, reversible redox, ligand exchange, and catalytic properties, making them promising drug candidates for cancer therapy. Ferrocifen, a ferrocene-phenol hybrid, has demonstrated promising anticancer properties on drug-resistant cancers. Currently, Ferrocifen is in pre-clinical trial against cancers. Obviously, ferrocene moiety is a useful template for the development of novel anticancer agents. This review will provide an overview of ferrocene-containing hybrids with potential application in the treatment of cancers covering articles published between 2010 and 2020. The mechanisms of action, the critical aspects of design and structure-activity relationships are also discussed.

Dual and selective inhibitors of pteridine reductase 1 (PTR1) and dihydrofolate reductase-thymidylate synthase (DHFR-TS) from Leishmania chagasi

Leishmaniasis is a tropical disease found in more than 90 countries. The drugs available to treat this disease have nonspecific action and high toxicity. In order to develop novel therapeutic alternatives to fight this ailment, pteridine reductase 1 (PTR1) and dihydrofolate reductase-thymidylate synthase (DHF-TS) have been targeted, once Leishmania is auxotrophic for folates. Although PTR1 and DHFR-TS from other protozoan parasites have been studied, their homologs in Leishmania chagasi have been poorly characterized. Hence, this work describes the optimal conditions to express the recombinant LcPTR1 and LcDHFR-TS enzymes, as well as balanced assay conditions for screening. Last but not the least, we show that 2,4 diaminopyrimidine derivatives are low-micromolar competitive inhibitors of both enzymes (LcPTR1 Ki = 1.50-2.30 µM and LcDHFR Ki = 0.28-3.00 µM) with poor selectivity index. On the other hand, compound 5 (2,4-diaminoquinazoline derivative) is a selective LcPTR1 inhibitor (Ki = 0.47 µM, selectivity index = 20).

Naturally Occurring Lumazines

Natural products containing a lumazine motif were first isolated from natural sources in 1940. These natural products are relatively rare, with fewer than 100 lumazines known to occur in Nature. This review discusses the isolation of lumazines, their biological activity, and their biosynthesis, where known.

Anti-leukemia activity of 4-amino-2-aryl-6,9-dichlorobenzo[g]pteridines

Pteridines are bicyclic heterocyclic compounds with a pyrazino[2,3-d]pyrimidine nucleus that have shown a wide range of therapeutic utilities. Concretely, 4-aminopteridine derivatives have demonstrated both anti-inflammatory and anti-cancer properties, and some of them, such as methotrexate, are profusely used in medical practice. We have recently synthesized and tested the biological activity of a novel series of 4-amino-2-aryl-6,9-dichlorobenzo[g]pteridines, finding that they present anti-inflammatory properties, as they were able to inhibit in vitro the production of pro-inflammatory cytokines TNF-α and IL-6. Now, we have evaluated the anti-tumor potential of these compounds on HL-60 and K562 leukemia cell lines. Cells growing at exponential rate were exposed to decreasing doses of each compound, from 50 to 0.39 μM, for 24, 48, and 72 h. Cell viability was tested by MTT assay and cell death fashion determined by annexin V/propidium iodide assay. The cytotoxicity of the compounds was determined in differentiated macrophage-like HL-60 cells and in human peripheral blood mononuclear cells to evaluate the potential side effects on quiescent tumor cells and normal cells, respectively. Among the series, compounds 1a, 1b, 1g, 1j, and 1k showed anti-proliferative activity. Compounds 1j and 1k were active against both HL-60 and K562 cells, with a lower IC₅₀ against HL-60 cells. Compounds 1a, 1b, and 1g had a great cytotoxic activity against HL-60, but they were far less potent against K562 cells. None had side effects in differentiated tumor cells or in human peripheral blood mononuclear cells. In conclusion, our results demonstrate that some compounds of this series of 4-amino-2-aryl-6,9-dichlorobenzo[g]pteridines have anti-cancer properties in vitro.