Design, synthesis, molecular modelling and antitumor evaluation of S-glucosylated rhodanines through topo II inhibition and DNA intercalation

In the present study, 5-arylidene rhodanine derivatives 3a-f, N-glucosylation rhodanine 6, S-glucosylation rhodanine 7, N-glucoside rhodanine 8 and S-glucosylation 5-arylidene rhodanines 13a-c were synthesised and screened for cytotoxicity against a panel of cancer cells with investigating the effective molecular target and mechanistic cell death. The anomers were separated by flash column chromatography and their configurations were assigned by NMR spectroscopy. The stable structures of the compounds under study were modelled on a molecular level, and DFT calculations were carried out at the B3LYP/6-31 + G (d,p) level to examine their electronic and geometric features. A good correlation between the quantum chemical descriptors and experimental observations was found. Interestingly, compound 6 induced potent cytotoxicity against MCF-7, HepG2 and A549 cells, with IC₅₀ values of 11.7, 0.21, and 1.7 µM, compared to Dox 7.67, 8.28, and 6.62 µM, respectively. For the molecular target, compound 6 exhibited topoisomerase II inhibition and DNA intercalation with IC₅₀ values of 6.9 and 19.6 µM, respectively compared to Dox (IC₅₀ = 9.65 and 31.27 µM). Additionally, compound 6 treatmnet significantly activated apoptotic cell death in HepG2 cells by 80.7-fold, it induced total apoptosis by 34.73% (23.07% for early apoptosis, 11.66% for late apoptosis) compared to the untreated control group (0.43%) arresting the cell population at the S-phase by 49.6% compared to control 39.15%. Finally, compound 6 upregulated the apoptosis-related genes, while it inhibted the Bcl-2 expression. Hence, glucosylated rhodanines may serve as a promising drug candidates against cancer with promising topoisomerase II and DNA intercalation.

Nucleoside analogues: N-glycosylation methodologies, synthesis of antiviral and antitumor drugs and potential against drug-resistant bacteria and Alzheimer's disease

Nucleosides have gained significant attention since the discovery of the structure of DNA. Nucleoside analogues may be synthesized through multiple synthetic pathways, however the N-glycosylation of a nucleobase is the most common method. Amongst the different classical N-glycosylation methodologies, the Vorbrüggen glycosylation is the most popular method. This review focuses on the synthesis and therapeutic applications of several FDA approved nucleoside analogues as antiviral and anticancer agents. Moreover, this review also focuses on the potential of these compounds as new antibacterial and anti-Alzheimer's disease agents, offering an overview of the most recent research in these fields.

Design, Synthesis, Computational Investigations, and Antitumor Evaluation of N-Rhodanine Glycosides Derivatives as Potent DNA Intercalation and Topo II Inhibition against Cancer Cells

Nitrogen and sulfur glycosylation was carried out via the reaction of rhodanine (1) with α-acetobromoglucose 3 under basic conditions. Deacetylation of the protected nitrogen nucleoside 4 was performed with CH₃ONa in CH₃OH without cleavage of the rhodanine ring to afford the deprotected nitrogen nucleoside 6. Further, deacetylation of the protected sulfur nucleoside 5 was performed with CH₃ONa in CH₃OH with the cleavage of the rhodanine ring to give the hydrolysis product 7. The protected nitrogen nucleosides 11a-f were produced by condensing the protected nitrogen nucleoside 4 with the aromatic aldehydes 10a-f in C₂H₅OH while using morpholine as a secondary amine catalyst. Deacetylation of the protected nitrogen nucleosides 11a-f was performed with NaOCH₃/CH₃OH without cleavage of the rhodanine ring to afford the deprotected nitrogen nucleosides 12a-f. NMR spectroscopy was used to designate the anomers' configurations. To examine the electrical and geometric properties derived from the stable structure of the examined compounds, molecular modeling and DFT calculations using the B3LYP/6-31+G (d,p) level were carried out. The quantum chemical descriptors and experimental findings showed a strong connection. The IC₅₀ values for most compounds were very encouraging when evaluated against MCF-7, HepG2, and A549 cancer cells. Interestingly, IC₅₀ values for 11a, 12b, and 12f were much lower than those for Doxorubicin (7.67, 8.28, 6.62 μM): (3.7, 8.2, 9.8 μM), (3.1, 13.7, 21.8 μM), and (7.17, 2.2, 4.5 μM), respectively. Against Topo II inhibition and DNA intercalation, when compared to Dox (IC₅₀ = 9.65 and 31.27 μM), compound 12f showed IC₅₀ values of 7.3 and 18.2 μM, respectively. In addition, compound 12f induced a 65.6-fold increase in the rate of apoptotic cell death in HepG2 cells, with the cell cycle being arrested in the G2/M phase as a result. Additionally, it upregulated the apoptosis-mediated genes of P53, Bax, and caspase-3,8,9 by 9.53, 8.9, 4.16, 1.13, and 8.4-fold change, while it downregulated the Bcl-2 expression by 0.13-fold. Therefore, glucosylated Rhodanines may be useful as potential therapeutic candidates against cancer because of their topoisomerase II and DNA intercalation activity.

Green Design, Synthesis, and Molecular Docking Study of Novel Quinoxaline Derivatives with Insecticidal Potential against Aphis craccivora

An efficient and environmentally friendly method was established for designing novel 3-amino-1,4-dihydroquinoxaline-2-carbonitrile (1) via the reaction of bromomalononitrile and benzene-1,2-diamine under microwave irradiation in an excellent yield (93%). This targeted amino derivative was utilized for the construction of a series of Schiff bases (8-13). A new series of thiazolidinone derivatives (15-20) were synthesized in high yields (89-96%) via treatment of thioglycolic acid with Schiff bases (8-13) under microwave irradiation in high yields (89-96%). Moreover, new pyrimidine derivatives (26-30 and 35-38) were prepared by treatment of compound 1 with arylidenes (21-25) and/or alkylidenemalononitriles (31-34) using piperidine as a basic catalyst under microwave conditions. Based on elemental analyses and spectral data, the structures of the new assembled compounds were determined. The newly synthesized quinoxaline derivatives were screened and studied as an insecticidal agent against Aphis craccivora. The obtained results indicate that compound 16 is the most toxicological agent against nymphs of cowpea aphids (Aphis craccivora) compared to the other synthesized pyrimidine and thiazolidinone derivatives. The molecular docking study of the new quinoxaline derivatives registered that compound 16 had the highest binding score (-10.54 kcal/mol) and the thiazolidinone moiety formed hydrogen bonds with Trp143.

Synthesis of C-Pseudonucleosides Bearing Thiazolidin-4-one as a Novel Potential Immunostimulating Agent

Several novel C-pseudonucleosides bearing thiazolidin-4-one were synthesized by one-pot three-component condensation using unprotected sugar aldehyde at room temperature, and their effects on T cells, B cells, the cytokine secretion of IL-2, IL-4, and IFN-γ, T cell-associated molecules (CD3, CD4, CD8), and B cell-associated molecules (CD19) were first evaluated. The experimental data demonstrated that such thiazolidin-4-one C-pseudonucleosides hold potential as immunostimulating agents.

A new approach for the N- and S-galactosylation of 5-arylidene-2-thioxo-4-thiazolidinones

N- and S-galactosylation was carried out via the reaction of 5-((Z)-arylidene)-2-thioxo-4-thiazolidinones with 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide under alkaline conditions or under silylation conditions. Deacetylation of the N-galactosylation products was performed with concentrated hydrochloric acid in methanol (3.5%) or sodium methoxide in methanol without cleavage of the 2-thioxo-4-thaizolidinone ring by means of acid hydrolysis. The anomers were separated by flash column chromatography, and their configurations were assigned by NMR spectroscopy. The deprotected nucleosides were screened against leukemia L-1210 and were found inactive.

Synthesis and biological activity of novel thiazolidin-4-ones with a carbohydrate moiety

Some novel 2-aryl-3-[5-deoxy-1,2-O-isopropylidene-alpha-D-xylofuranose-5-C-yl] thiazolidin-4-ones were synthesized by the three-component condensation of an amino sugar 1, an aromatic aldehyde 2, and mercaptoacetic acid 3 in the presence of DCC and DMAP at room temperature. Two diastereoisomers 4 and 5 were afforded as the main products in totally isolated yields of 25.4-70%. The reaction was carried out with almost no observed stereoselectivity except in the case of 2c, which showed a moderate stereoselectivity. The structures of the new compounds were determined by NMR spectroscopy and mass spectrometry (MS), and the configuration of the newly generated chiral carbon (C-2) in the thiazolidin-4-one ring was tentatively assigned based on the X-ray crystallographic structure of 5d and the comparison of their corresponding NMR signals. The antitumor (human cervical cancer cells) activity and the inhibition against the glycosidases (alpha-glucosidase, beta-glucosidase, alpha-amylase) have been evaluated for the new compounds, some of which exhibited antitumor activity.

Synthesis of heterocyclic analogues of epibatidine via 7-azabicyclo[2.2.1]hept-2-yl radical intermediates. 1. Intermolecular reactions

The synthesis and reactivity of the 7-azabicyclo[2.2.1]hept-2-yl radical has been extensively investigated in inter- and intramolecular reaction processes for the first time. In this work we will present the preparation of the radical and its successful intermolecular reaction with radical acceptors such as tert-butylisocyanide and acrylonitrile. Computational analyses have been carried out to show and explain the mechanisms and stereochemical outcome of these transformations. Overall and from the chemical point of view, a new and convenient synthetic approach has been developed for the synthesis of exo-2-(cyano)alkyl substituted 7-azabicyclo[2.2.1]heptane derivatives, a series of compounds of wide interest for the synthesis of heterocyclic analogues of epibatidine. As a result, we describe here the synthesis of the tetrazoloepibatidines (8 and 15) and the oxadiazoloepibatidine (10).