Thiopurine derivatives containing triazole and steroid: synthesis, antimalarial and antileishmanial activities

Exploring Triazole-Connected Steroid-Pyrimidine Hybrids: Synthesis, Spectroscopic Characterization, and Biological Assessment

Molecules originating from natural sources are physicochemically and biologically diverse. The conjugation of two active biomolecules has become the foundation for medical and pharmaceutical sciences. An effective synthesis of 11 new steroid-pyrimidine conjugates containing 1,2,3-triazole rings was carried out. The group of 3α-OH bile acids (lithocholic, deoxycholic, cholic) and 3β-OH sterols (cholesterol, cholestanol) were respectively modified to azidoacetates. 2-thiouracil was converted into N(1)S and N(3)S dipropargyl derivatives. Azide-alkyne cycloaddition in the presence of copper(I) of the obtained compounds led to the preparation of 1,2,3-triazole derivatives. Based on a series of spectroscopic (1H NMR, 13C NMR, Fourier-transform infrared (FT-IR)), spectrometric analyses (Electrospray ionization-mass spectrometry (ESI-MS), electron impact-mass spectrometry (EI-MS)), and semiempirical calculations, the structures of all compounds were confirmed. In silico biological tests and molecular docking (for domain 1KZN, 2H94, 5V5Z, 1EZF, 2Q85) were performed for selected compounds. The tests performed indicate the theoretical antimicrobial potential of the obtained ligands.

Visible Light-Mediated Late-Stage Thioetherification of Mercaptopurine Derivatives

We disclose herein a novel and general radical approach to alkylthiopurines, encompassing 4 types of thiopurines, as well as their corresponding ribosides. This strategy is achieved through visible light-mediated late-stage functionalization of the sulfur atoms of mercaptopurines. The in situ-generated disulfide was proposed as the pivotal neutral intermediate for this transformation. We present herein a novel photo-mediated homolytic C-S bond formation for the preparation of alkylthiopurines and alkylthiopurine nucleosides. Despite the presence of reactive sites for the Minisci reaction, chemoselective S-alkylation remained the predominant pathway. This method allows for the late-stage introduction of a broad spectrum of alkyl groups onto the sulfur atom of unprotective mercaptopurine derivatives, encompassing 2-, 6-, and 8-mercaptopurine rings. Organoborons serve as efficient and eco-friendly alkylating reagents, providing advantages in terms of readily availability, stability, and reduced toxicity. Further derivatization of the thioetherified nucleosides, together with anti-tumor assays, led to the discovery of potent anti-tumor agents with an IC50 value reaching 6.1 μM (Comp. 31 for Jurkat).

Copper Catalyzed Three-Component Ullmann C-S Coupling in PEG for the Synthesis of 6-Aryl/alkylthio-purines

To tackle the environmental unfriendly issue in existing synthesis strategies for 6-substitued thiopurine derivatives, such as poor step economy, frequent use of malodorous organic sulfur starting materials, toxic organic solvents, and equivalent dosage of base, we have developed a CuI-catalyzed base-free three-component Ullmann C-S coupling synthetic strategy, featured using inorganic salt Na2S as the sulfur source and nontoxic PEG-600 as the solvent. The newly developed strategy is particularly effective for the synthesis of 6-arylthiopurines. The high catalytic efficiency in PEG-600 can be rationalized by the high soluble ability of CuI catalyst, likely due to the presence of multiple oxygen coordination sites in PEG.

Design, synthesis and biological evaluation of new 1,ω-Bis-(5-alkyl-3-tosyl-1,3,4,2-triazaphospholino)alkanes as in vitro α-amylase and lipase inhibitors

A series of new 1,ω-bis-(5-alkyl-3-tosyl-1,3,4,2-triazaphospholino)alkanes 2 and 3 were obtained in excellent yields by the condensation of 1,ω-bis-(1-tosylamidrazone)alkanes 1 with two equivalent molars of Lawesson's Reagent (LR) and trisdimethylaminophosphine, respectively. All synthesized compounds were characterized by various spectroscopic techniques including IR, 1H NMR, 13C NMR and 31P NMR and elemental analysis. The newly synthesized compounds were evaluated against key enzymes related to diabetes and obesity such as α-amylase and lipase. This study showed that the compounds 3a and 2b are an excellent inhibitor of α-amylase (with IC50 = 18.8 mM) and lipase (with IC50 = 19 mM) respectively, as compared with standard, orlistat (IC50 = 22 mM). Among this series, compounds 3a and 2b with the CH3 or C2H5 group at position 6 were identified as the most potent inhibitors against α-amylase, and lipase enzymes. The remaining compounds were found to be moderately active. Further, molecular docking simulation studies were done to identify the interactions and binding mode of synthesized analogs at binding site of α-amylase and lipase enzymes.

Molecular Hybridization of Alkaloids Using 1,2,3-Triazole-Based Click Chemistry

Alkaloids found in multiple species, known as 'driver species', are more likely to be included in early-stage drug development due to their high biodiversity compared to rare alkaloids. Many synthetic approaches have been employed to hybridize the natural alkaloids in drug development. Click chemistry is a highly efficient and versatile reaction targeting specific areas, making it a valuable tool for creating complex natural products and diverse molecular structures. It has been used to create hybrid alkaloids that address their limitations and serve as potential drugs that mimic natural products. In this review, we highlight the recent advancements made in modifying alkaloids using click chemistry and their potential medicinal applications. We discuss the significance, current trends, and prospects of click chemistry in natural product-based medicine. Furthermore, we have employed computational methods to evaluate the ADMET properties and drug-like qualities of hybrid molecules.

Alkylation of 6-thiopurine derivatives by the Mitsunobu reaction

Alkylation of thiopurine derivatives with alcohols by the Mitsunobu reaction are reported in moderated to good yields. The method was applied in synthesis of number of thiopurine and thiopurine ribosides derivatives.

1,2,3-Triazole derivatives: synthesis, docking, cytotoxicity analysis and in vivo antimalarial activity

Malaria remains one of the most important parasitic diseases in the world. The multidrug-resistant Plasmodium strains make the treatment currently available for malaria less effective. Therefore, the development of new drugs is necessary to overcome therapy resistance. Triazole derivatives exhibit several biological activities and provide a moiety that is promising from the biological perspective. Due to the structural similarity to NADH, it is believed that triazoles can bind to the active site of the Plasmodium lactate dehydrogenase (pLDH) enzyme. The present work evaluates the antimalarial activity of 1,2,3-triazole derivatives by in silico, in vitro, and in vivo studies. Preliminary in silico ADMET studies of the compounds demonstrated good pharmacokinetic properties. In silico docking analysis against LDH of Plasmodium berghei (PbLDH) showed that all compounds presented interactions with the catalytic residue in the active site and affinity similar to that presented by chloroquine; the most common antimalarial drug. Cytotoxicity and hemolysis by these derivatives were evaluated in vitro. The compounds 1, 2, 5, 8, and 9 proved to be non-cytotoxic in the performed tests. In vivo antimalarial activity was evaluated using mice infected with Plasmodium berghei NK65. The five compounds tested exhibited antimalarial activity until nine days post-infection. The compound 5 showed promising activities, with about 70% parasitemia suppression. Considering the in vitro and in vivo studies, we believe the compound 5 to be the most promising molecule for further studies in antimalarial chemotherapy.

Simultaneous ultrasound- and microwave-assisted one-pot 'click' synthesis of 3-formyl-indole clubbed 1,2,3-triazole derivatives and their biological evaluation

An environment friendly, high yielding, promising one-pot protocol for the click reaction of N-propargyl-3-formylindole 2(a-b), chloroacetic acid/ester 3(a-b) and sodium azide, leading to the formation of 3-formyl-indole clubbed 1,4-disubstituted-1,2,3-triazole derivatives 4(a-b), 5(a-b) and 6(a-f) aided by CuI catalyst accomplished under acceleration of simultaneous ultrasound and microwave irradiation in a very short reaction time has been described. Further, acid derivative 4(a-b) is subjected to acid-amine coupling reaction with secondary amine (p-t) in the presence of HATU to afford 6(p-t) and 7(p-t). The perspective of this protocol is to get rid of the hectic preparation and handling of organic azide which are generated in situ. Consequently, this protocol blossoms the click process by making it environment benign, user-friendly, safe and clean technique. All the synthesized compounds have been preliminarily screen for their in vitro antimicrobial activity against a panel of pathogenic strains. The majority of compounds possess noticeably inhibitory action against E. Coli, S. Typhi, P. Aeruginosa, C. tetani, S. aureus and B. subtillis. Among all compounds, 6p and 7q exhibit excellent inhibitory action against E.Coli and P. Aeruginosa strain, respectively, as compared to standard drug. One compound 5b shows remarkable potency against fungal strain. Molecular docking study was carried out to understand binding of compound with protein. In silico ADME prediction was carried out to check physicochemical properties of synthesized compound.

Updates in bile acid-bioactive molecule conjugates and their applications

Bile acid conjugates are emerging as important chemical resources due to their low cost and wide availability of bile acids, making them privileged molecules in drug carrier systems and building blocks for derivatization and chiral template introduction into bioactive molecules. In recent years, bile acids as scaffolds in supramolecular, medicinal, and material chemistry attracted prime focus of researchers as an area of research to be followed with passion. Due to peculiar physicochemical and biological properties, bile acid exhibited various applications in biomedical and pharmaceutical fields. In this review, the bile acid conjugations with different bioactive compounds have been discussed to understand their influence on the bioavailability of bioactive compounds.

Design, synthesis, brine shrimp lethality and cytotoxicity of some novel 17a-aza-D-homo-androster-17-one derivatives

In this work, twenty-eight novel 17a-aza-D-homo-androster-17-one derivatives, which divided into two categories, were synthesized with commercial available starting material (dehydroepiandrosterone) via oximation reaction, Beckmann rearrangement, hydroxyl protection, N-alkylation and deprotection. All compounds were characterized by ¹H NMR, ¹³C NMR and HRMS. The structure of 14 g was also identified by X-ray single crystal diffraction. The bioactivities, brine shrimp toxicity and cytotoxicity, of all derivatives were tested. The results indicated that compounds 11 h, 11i, 11 m, 11 s, 14 b and 14 g exhibited excellent toxicity against brine shrimp with LC₅₀ values ranging from 5.34 to 16.89 μg/mL, and compounds 11 s and 14 g displayed significant cytotoxicity against HT29 cells and A549 cells with IC₅₀ values of 9.70 μM and 8.85 μM, respectively. Structure-activity relationships are discussed based on the results obtained from our research, and some important determinants for further modification of steroids towards the development of novel drug candidates are identified.

Exploring the Chemistry and Therapeutic Potential of Triazoles: A Comprehensive Literature Review

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Triazole is a valuable platform in medicinal chemistry, possessing assorted pharmacological properties, which could play a major role in the common mechanisms associated with various disorders like cancer, infections, inflammation, convulsions, oxidative stress and neurodegeneration. Structural modification of this scaffold could be helpful in the generation of new therapeutically useful agents. Although research endeavors are moving towards the growth of synthetic analogs of triazole, there is still a lot of scope to achieve drug discovery break-through in this area. Upcoming therapeutic prospective of this moiety has captured the attention of medicinal chemists to synthesize novel triazole derivatives. The authors amalgamated the chemistry, synthetic strategies and detailed pharmacological activities of the triazole nucleus in the present review. Information regarding the marketed triazole derivatives has also been incorporated. The objective of the review is to provide insights to designing and synthesizing novel triazole derivatives with advanced and unexplored pharmacological implications.

Synthesis and evaluation of novel D-ring substituted steroidal pyrazolines as potential anti-inflammatory agents

To identify new potential anti-inflammatory agents, a number of novel steroidal derivatives with nitrogen heterocyclic side chains 4a-4l were synthesized and evaluated for their anti-inflammatory effects in activated RAW 264.7 macrophage cells. The synthesis scheme involves two steps, Claisen-Schmidt condensation with the corresponding pregnenolone and aromatic aldehydes as the first step followed by nucleophilic addition of thiosemicarbazide across an α, β-unsaturated carbonyl as a later step. Compound structures were confirmed by ¹H NMR, ¹³C NMR, HRMS, and IR. The compounds were assayed to test their anti-inflammatory effects in activated RAW 264.7 cells. Compound 4g, 3β-hydroxy-pregn-5-en-17β-yl-5'-(m-fluorophenyl)-4', 5'-dihydro-1'-carbothioic acid amido pyrazole, was identified as the most potent anti-inflammatory agent of the analysed compounds, with an IC₅₀ value of 0.86 µM on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells for 24 h compared to dexamethasone (IC₅₀ = 0.62 µM) and low cytotoxicity against RAW 264.7 cells. Compound 4g significantly inhibited NO produced by LPS-induced RAW 264.7 cells. Further studies showed that compound 4g markedly inhibited the expression of pro-inflammatory factors, including inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) in LPS-induced RAW 264.7 cells. These results indicate that derivatives bearing pyrazoline structure might be considered for further research and scaffold optimization in designing anti-inflammatory drugs and compound 4g might be a promising therapeutic anti-inflammatory drug candidate.

Triazole derivatives and their antiplasmodial and antimalarial activities

Malaria, caused by protozoan parasites of the genus Plasmodium especially by the most prevalent parasite Plasmodium falciparum, represents one of the most devastating and common infectious disease globally. Nearly half of the world population is under the risk of being infected, and more than 200 million new clinical cases with around half a million deaths occur annually. Drug therapy is the mainstay of antimalarial therapy, yet current drugs are threatened by the development of resistance, so it's imperative to develop new antimalarials with great potency against both drug-susceptible and drug-resistant malaria. Triazoles, bearing a five-membered heterocyclic ring with three nitrogen atoms, exhibit promising in vitro antiplasmodial and in vivo antimalarial activities. Moreover, several triazole-based drugs have already used in clinics for the treatment of various diseases, demonstrating the excellent pharmaceutical profiles. Therefore, triazole derivatives have the potential for clinical deployment in the control and eradication of malaria. This review covers the recent advances of triazole derivatives especially triazole hybrids as potential antimalarials. The structure-activity relationship is also discussed to provide an insight for rational designs of more efficient antimalarial candidates.

New cholic acid analogs: synthesis and 17β-hydroxydehydrogenase (17β-HSD) inhibition activity

The 17β-hydroxysteroid dehydrogenase (17β-HSD) enzyme family is involved in the biosynthesis of active steroids and its inhibition constitutes an interesting approach for treating estrogen-, androgen-dependent cancers and osteoporosis. In this study, a new series of cholic acid analogs was designed with the goal of improving the biological activity as 17β-HSD1 and 17β-HSD2 inhibitors. To this end, 23-cholyl amides 4–7, 3-O-p-toluenesulfonyl-23-cholyl amides 10–12, 23-cholyl-carbohydrazide 14, carbothioamide analog 15, and 23-cholyl-acylhydrazone derivatives 18–22 were synthesized from cholic acid (3) via coupling, sulfonation and substitution reactions. Basic treatment of keto group of 5 with p-bromoaniline afforded 8, meanwhile acidic treatment of 3 with thiosemicarbazide furnished the 23-cholyl-thiadiazole derivative 16. The synthesized compounds were evaluated for their inhibition activity against 17β-HSD1 and 17β-HSD2, and were found inactive at 1.0 μm concentration (inhibition <10%). However, the steroids 12, 21 and 22 showed inhibition of 21.1, 23.9 and 21.3%, respectively, against 17β-HSD2 at the same concentration. Therefore, these steroidal analogs can be further structurally modified to optimize their inhibition activity against 17β-HSD2 for the development of potential therapeutics.

Synthesis and anticancer activity of multisubstituted purines and xanthines with one or two propynylthio and aminobutynylthio groups

A synthesis of new 2,6-disubstituted and 2,6,8-trisubstituted 7-methylpurines as well as 8-substituted 3,7-dimethylxanthines containing a triple bond chain have been worked out. Purinethiones and xanthinethiones were converted into propynylthio derivatives, which were then further transformed via a Mannich reaction into aminobutynylthio derivatives (amine = pyrrolidine, piperidine, morpholine, and diethylamine). The products thus obtained represent various types of the purine and xanthine structure: 8-mono-, 2,6- and 6,8-dipropynylthio, 6- and 8-monoaminobutynylthio, 2,6- and 6,8-diaminobutynylthio derivatives. All of these compounds were tested for their anticancer activity against human glioblastoma SNB-19, human adenocarcinoma MDA-MB-231, and melanoma C-32 cell lines. The anticancer activity depends on the nature of the substituent and its localization in the purine and xanthine framework. Generally, compounds possessing two alkynylthio groups (propynylthio or aminobutynylthio) were more active than those possessing only one group. Some compounds exhibited stronger or similar anticancer activity to cisplatin. All compounds were also tested for their cytotoxic activity against normal human fibroblasts (HFF-1). The most promising anticancer compounds were found to be 2,6-dipropynylthio-7-methylpurine 4, 2-chloro-6,8-dipropynylthio-7-methylpurine 14, and 2-chloro-6,8-di(N-morpholinylbutynylthio)-7-methylpurine 15c acting selectively on glioblastoma SNB-19, melanoma C-32, and adenocarcinoma MDA-MB-231 with the IC₅₀ = 0.07-4.08 μg/mL.

Medicinal attributes of 1,2,3-triazoles: Current developments

1,2,3-Triazoles are important five-membered heterocyclic scaffold due to their extensive biological activities. This framework can be readily obtained in good to excellent yields on the multigram scale through click chemistry via reaction of aryl/alkyl halides, alkynes and NaN₃ under ambient conditions. It has been an emerging area of interest for many researchers throughout the globe owing to its immense pharmacological scope. The present work aims to summarize the current approaches adopted for the synthesis of the 1,2,3-triazole and medicinal significance of these architectures as a lead structure for the discovery of drug molecules such as COX-1/COX-2 inhibitors (celecoxib, pyrazofurin), HIV protease inhibitors, CB1 cannabinoid receptor antagonist and much more which are in the pipeline of clinical trials. The emphasis has been given on the major advancements in the medicinal prospectus of this pharmacophore for the period during 2008-2016.

Synthesis of novel 13α-18-norandrostane-ferrocene conjugates via homogeneous catalytic methods and their investigation on TRPV1 receptor activation

13α-Steroid-ferrocene derivatives were synthesized via two reaction pathways starting from an unnatural 16-keto-18-nor-13α-steroid. The unnatural steroid was converted to ferrocene derivatives via copper-catalyzed azide-alkyne cycloaddition or palladium-catalyzed aminocarbonylation. 16-Azido- and 16-N-(prop-2-ynyl)-carboxamido-steroids were synthesized as starting materials for azide-alkyne cycloaddition with the appropriate ferrocene derivatives. Based on our earlier work, aminocarbonylation of 16-iodo-16-ene and 16-iodo-15-ene derivatives was studied with ferrocenylmethylamine. The new products were obtained in moderate to good yields and were characterized by (1)H and (13)C NMR, IR and MS. The solid state structure of the starting material 13α-18-norandrostan-16-one and two carboxamide products were determined by X-ray crystallography. Evidences were provided that the N-propargyl-carboxamide compound as well as its ferrocenylmethyltriazole derivative are able to decrease the activation of TRPV1 receptor on TRG neurons.

Synthesis of conjugated bile acids/azastilbenes as potential antioxidant and photoprotective agents

A series of 14 bile acids/azastilbenes conjugates (1a-g and 2a-g) was prepared through the condensation of bile amides (1 and 2) and aromatic aldehydes. The newly synthesized conjugates were evaluated in vitro for their antioxidant and photoprotective activities. Six compounds (1, 1a, 1b, 2, 2a and 2b) showed promising antioxidant activity with IC50 values of 19.60-31.83 μg mL(-1). The synthesized compounds presented a varied photoprotection profile, with the SPF ranging from 2 to 9. Among the 16 compounds tested for the protection against UVB sunrays, 3 compounds (2c, 2e and 2g) presented more significant protection than resveratrol and the free azastilbene 3; while the UVAPF increased from 2 in resveratrol and 5 in 3 to 5-11 in the majority of the conjugates.

Synthesis and anticancer activity of thiosubstituted purines

New thiopurines with the propargylthio, pyrrolidinobutynylthio, sulfenamide, and sulfonamide groups in the pyrimidine ring were synthesized. The anticancer activity of these compounds and previously obtained 2- or 6-substituted azathioprine analogs and dialkylaminoalkylthiopurines were tested in vitro against three cell lines: glioblastoma SNB-19, melanoma C-32, and human ductal breast epithelial tumor T47D. 2-Chloro-7-methyl-6-pyrrolidinobutynylthiopurine (5b) was the most potent compound against SBN-19 and C-32 cell lines with the activity similar to cisplatin (EC₅₀ = 5.00 and 7.58 μg/ml, respectively). The dialkylaminoalkylthio derivatives (4b, 4c, 4e, and 4f) showed good activity against SBN-19 cell line (EC₅₀ < 10 μg/ml). The azathioprine analogs (2a, 2b, and 3a) were more active than azathioprine against SBN-19 and C-32 cell lines. The sulfenamide and sulfonamide derivatives of purine were very weak active against tested cell lines. All studied thiopurines were less toxic than cisplatin.

Antileishmanial drug discovery: comprehensive review of the last 10 years

This review covers the current aspects of leishmaniasis including marketed drugs, new antileishmanial agents, and possible drug targets of antileishmanial agents.

Malaria in South America: a drug discovery perspective

The challenge of controlling and eventually eradicating malaria means that new tools are urgently needed. South America's role in this fight spans both ends of the research and development spectrum: both as a continent capable of discovering and developing new medicines, and also as a continent with significant numbers of malaria patients. This article reviews the contribution of groups in the South American continent to the research and development of new medicines over the last decade. Therefore, the current situation of research targeting malaria control and eradication is discussed, including endemicity, geographical distribution, treatment, drug-resistance and diagnosis. This sets the scene for a review of efforts within South America to discover and optimize compounds with anti-malarial activity.

Synthesis of ferrocene-labeled steroids via copper-catalyzed azide-alkyne cycloaddition. Reactivity difference between 2β-, 6β- and 16β-azido-androstanes

Copper-catalyzed cycloaddition of steroidal azides and ferrocenyl-alkynes were found to be an efficient methodology for the synthesis of ferrocene-labeled steroids. At the same time, a great difference between the reactivity of 2β- or 16β-azido-androstanes and a sterically hindered 6β-azido steroid toward both ferrocenyl-alkynes and simple alkynes, such as phenylacetylene, 1-octyne, propargyl acetate and methyl propiolate, was observed.