Anticancer activity of (1,2,3,5-tetrahydro-4,1-benzoxazepine-3-yl)-pyrimidines and -purines against the MCF-7 cell line: Preliminary cDNA microarray studies

Study of Direct N7 Regioselective tert-Alkylation of 6-Substituted Purines and Their Modification at Position C6 through O, S, N, and C Substituents

A new N7 direct regioselective method allowing the introduction of tert-alkyl groups into appropriate 6-substituted purine derivatives is developed. This method is based on a reaction of N-trimethylsilylated purines with a tert-alkyl halide using SnCl4 as a catalyst. In this work, we study the structure and optimal reaction conditions leading to the N7 isomer and in some cases also to the N9 isomer. The main goal is devoted to preparing 7-(tert-butyl)-6-chloropurine as a suitable compound for other purine transformations. The stability of the tert-butyl group at the N7 position is tested for classic model reactions, leading to the preparation of new 6,7-disubstituted purine derivatives, which is also interesting from the point of view of possible biological activity.

Enantioenriched 1,4-Benzoxazepines via Chiral Brønsted Acid-Catalyzed Enantioselective Desymmetrization of 3-Substituted Oxetanes

Herein, we present a highly enantioselective desymmetrization of 3-substituted oxetanes enabled by a confined chiral phosphoric acid. This metal-free process allows effective access to chiral seven-membered 1,4-benzoxazepines with a high degree of enantiocontrol, under mild reaction conditions. The developed synthetic strategy tolerates a broad substrate scope and demonstrates its synthetic utility in various enantioselective product transformations, thus proving its effectiveness in diverse scenarios.

A Synthetic Overview of Benzoxazines and Benzoxazepines as Anticancer Agents

Benzoxazines and benzoxazepines are nitrogen and oxygen-containing six and seven-membered benzo-fused heterocyclic scaffolds, respectively. Benzoxazepines and benzoxazines are well-known pharmacophores in pharmaceutical chemistry, which are of significant interest and have been extensively studied because of their promising activity against various diseases including their wide range of anticancer activity. Several reports are known for synthesizing benzoxazine and benzoxazepine-based compounds in the literature. Herein this review provides a critical analysis of synthetic strategies towards benzoxazines and benzoxazepines along with various ranges of anticancer activities based on these molecules that have been reported from 2010 onwards. This review also focuses on the structure-activity relationship of the benzoxazine and benzoxazepine scaffolds containing bioactive compounds and describes how the structural modification affects their anticancer activity.

Design, synthesis, HER2 inhibition and anticancer evaluation of new substituted 1,5-dihydro-4,1-benzoxazepines

A series of 11 new substituted 1,5-dihydro-4,1-benzoxazepine derivatives was synthesised to study the influence of the methyl group in the 1-(benzenesulphonyl) moiety, the replacement of the purine by the benzotriazole bioisosteric analogue, and the introduction of a bulky substituent at position 6 of the purine, on the biological effects. Their inhibition against isolated HER2 was studied and the structure–activity relationships have been confirmed by molecular modelling studies. The most potent compound against isolated HER2 is 9a with an IC₅₀ of 7.31 µM. We have investigated the effects of the target compounds on cell proliferation. The most active compound (7c) against all the tumour cell lines studied (IC₅₀ 0.42–0.86 µM) does not produce any modification in the expression of pro-caspase 3, but increases the caspase 1 expression, and promotes pyroptosis.

Access to Benzoxazepines and Fully Substituted Indoles via HDDA Coupling

The HDDA-derived benzyne intermediate was captured by oxazolines based on the addition reaction of benzyne to the C═N double bond. Benzoxazepine derivatives, fused benzoxazepine derivatives, and fully substituted indoles are synthesized in one step. The reaction does not require any catalyst or additives. Possible reaction mechanisms are presented.

Purine derivatives with heterocyclic moieties and related analogs as new antitumor agents

AIM

Identification of new antiproliferative compounds.

METHODOLOGY

Four series of compounds were synthesized by the Mitsunobu reaction. Their antiproliferative activity was studied against several cancer cells and a noncancerous fibroblast cell line. Their apoptotic activity was analyzed using a caspase 3/7 fluorescence assay.

RESULTS & CONCLUSION

9-alkylated-6-halogenated and 2,6-dihalogenated purines show remarkable inhibition of tumor cell proliferation, with the dichloro derivatives being the most potent of all the series. The most promising compound, tetrahydroquinoline 4c, exhibits significant antiproliferative activity against the cancer cells tested, while displaying a 19-fold lower potency against noncancerous fibroblasts, a key feature that indicates potential selectivity against cancer cells. This compound produces a high percentage of apoptosis (58%) after 24 h treatment in human breast cancer MCF-7 cells.

Identification of some benzoxazepines as anticancer agents inducing cancer cell apoptosis

AIM

Using cytotoxic agents with apoptosis induction may represent one of new strategies for cancer treatment to overcome the increased resistance of the disease.

METHODOLOGY

Two series of benzo[f][1,4]oxazepine-3,5(2H,4H)-diones (compounds 5, 6a-f) and 3-phenylbenzo[f][1,4]oxazepin-5(4H)-ones (compounds 10, 11a-f) were synthesized and screened for their cytotoxicity against leukemia K-562 and breast T-47D cancer cell lines as well as normal fibroblasts WI-38.

RESULTS

The tested compounds revealed good cytotoxicity and selectivity toward cancer cell lines relative to the normal cells, especially compounds 6f, 10 and 11e, f. These compounds were screened for cell cycle disturbance and apoptosis induction. They were found to cause PreG1 apoptosis and complete cell growth arrest at G2/M. They induce apoptosis via caspase-3 and Bax activation and downregulation of Bcl2.

CONCLUSION

benzo[f][1,4]oxazepine represents a scaffold for further optimization to obtain promising anticancer agents.

Design, synthesis, and in vitro antiproliferative and kinase inhibitory effects of pyrimidinylpyrazole derivatives terminating with arylsulfonamido or cyclic sulfamide substituents

A novel series of substituted pyrimidine compounds bearing N-phenylpyrazole and terminating with aryl and cyclic sulfonamido moiety were designed, synthesized, and evaluated in vitro as antiproliferative agents against a panel of 53 cell lines of different tissues at the NCI. Among them, compound 1d with p-chlorobenzenesulfonamido terminal moiety, ethylene spacer, and 4-chloro-3-methoxyphenyl ring at position 3 of the pyrazole nucleus showed the highest mean percentage inhibition value over the whole cancer cell line panel at 10 μM concentration. It showed broad-spectrum antiproliferative activity over many cell lines of different cancer types. For instance, compound 1d inhibited the growth of HL-60 (TB), SR leukemia, and T-47D and MCF-7 breast cancer cell line by 135.92%, 119.44%, 95.32%, and 82.03% at 10 μM, respectively. And it inhibited the growth of COLO 205 colon, HT29 colon, BT-549 breast, and ACHN renal cancer cell lines by more than 80% at the same test concentration. However, testing compound 1d upon determining its IC₅₀ against the most sensitive cell lines showed to good extent selectivity against HT29 colon cancer cell line than HL-60 leukemia and MRC-5 lung fibroblasts (normal cells). Compound 1d was further tested against 12 kinases of different kinase families, and the highest inhibitory effect was exerted against RAF1, V600E-B-RAF, and V600K-B-RAF kinases.

Vibrational spectra (experimental and theoretical), molecular structure, natural bond orbital, HOMO-LUMO energy, Mulliken charge and thermodynamic analysis of N'-hydroxy-pyrimidine-2-carboximidamide by DFT approach

The FT-IR, FT-Raman, (1)H, (13)C NMR and UV-Visible spectral measurements of N'-hydroxy-pyrimidine-2-carboximidamide (HPCI) and complete analysis of the observed spectra have been proposed. DFT calculation has been performed and the structural parameters of the compound was determined from the optimized geometry with 6-311+G(d,p) basis set and giving energies, harmonic vibrational frequencies and force constants. The results of the optimized molecular structure are presented and compared with the experimental. The geometric parameters, harmonic vibrational frequencies and chemical shifts were compared with the experimental data of the molecule. The title compound, C5H6N4O, is approximately planar, with an angle of 11.04 (15)°. The crystal structure is also stabilized by intermolecular N-H⋯O, N-H⋯N, O-H⋯N, C-H⋯O hydrogen bond and offset π-π stacking interactions. The influences of hydroxy and carboximidamide groups on the skeletal modes and proton chemical shifts have been investigated. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and band gap. The kinetic, thermodynamic stability and chemical hardness of the molecule have been determined. Complete NBO analysis was also carried out to find out the intermolecular electronic interactions and their stabilization energy. The thermodynamic properties like entropies and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structure.

The selective cytotoxic activity in breast cancer cells by an anthranilic alcohol-derived acyclic 5-fluorouracil O,N-acetal is mediated by endoplasmic reticulum stress-induced apoptosis

Advance in the knowledge of molecular biology has thrown light on many aspects of apoptosis regulation mechanisms. This has allowed a change in anti-cancer therapy trends, from classic cytotoxic strategies to the development of new non-harmful therapies which target the apoptosis response selectively only in tumour cells. We have selected an anthranilic alcohol-derived acyclic 5-fluorouracil O,N-acetal (5) to carry out the anti-cancer studies. This compound shows activity as a potent growth inhibitor of the tumour cell line MCF-7 at a very low concentration. Moreover, when this compound was administered to the non-neoplastic cell line, MCF-10A displayed less toxicity resulting in lower rates of apoptosis. Further studies by microarray hybridization, real-time PCR and western blot showed that when administered to human breast cancer cells, MCF-7, 5 had no activity against classic pro-apoptotic genes such as p53, and even induced the down-regulation of anti-apoptotic genes such as Bcl-2. In contrast, several pro-apoptotic genes related with the endoplasmic reticulum (ER)-stress-induced apoptosis, such as BBC3 and Noxa, appeared up-regulated. These results seem to show that the mechanism of action and selectivity of 5 was via the activation of the ER stress-induced apoptosis. The selective activity of this compound against tumour cells via the ER stress-induced apoptosis supposes a great advantage for future therapeutic use.

Remodelling of the natural product fumagillol employing a reaction discovery approach

In the search for new biologically active molecules, diversity-oriented synthetic strategies break through the limitation of traditional library synthesis by sampling new chemical space. Many natural products can be regarded as intriguing starting points for diversity-oriented synthesis, wherein stereochemically rich core structures may be reorganized into chemotypes that are distinctly different from the parent structure. Ideally, to be suited to library applications, such transformations should be general and involve few steps. With this objective in mind, the highly oxygenated natural product fumagillol has been successfully remodelled in several ways using a reaction-discovery-based approach. In reactions with amines, excellent regiocontrol in a bis-epoxide opening/cyclization sequence can be obtained by size-dependent interaction of an appropriate catalyst with the parent molecule, forming either perhydroisoindole or perhydroisoquinoline products. Perhydroisoindoles can be further remodelled by cascade processes to afford either morpholinone or bridged 4,1-benzoxazepine-containing structures.

New (RS)-benzoxazepin-purines with antitumour activity: The chiral switch from (RS)-2,6-dichloro-9-[1-(p-nitrobenzenesulfonyl)-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]-9H-purine

Completing an SAR study, a series of (RS)-6-substituted-7- or 9-(1,2,3,5-tetrahydro-4,1-benzoxazepine-3-yl)-7H or 9H-purines has been prepared under microwave-assisted conditions. Their antiproliferative activities on MCF-7 and MDA-MB-231 cancerous cell lines are presented, being the majority of the IC(50) values below 1μM. The most active compound (RS)-2,6-dichloro-9-[1-(p-nitrobenzenesulfonyl)-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]-9H-purine (14) presents an IC(50) of 0.166μM against the human cancerous cell line MDA-MB-231. Compound 14 was the most selective against the human breast adenocarcinoma MCF-7 and MDA-MB-231 cancer cell lines (Therapeutic Indexes, TIs=5.1 and 11.0, respectively) in relation to the normal one MCF-10A. (RS)-14 was resolved into its enantiomers. Both enantiomers are equally potent, but more potent than the corresponding racemic mixture. (R)-14 induces apoptosis against MCF-7 up to 52.50% of cell population after 48h, being more potent than the clinical-used drug paclitaxel (43%). (RS)-14 induces no acute toxicity in mice after two weeks of treatment.

Synthesis and evaluation of antimicrobial activity of some pyrimidine glycosides

Reaction of ethyl 4-thioxo-3,4-dihydropyrimidine-5-carboxylate derivatives 1a,b and ethyl 4-oxo-3,4-dihydropyrimidine-5-carboxylate 1c with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide in KOH or TEA afforded ethyl 2-aryl-4-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosylthio or/ oxy)-6-methylpyrimidine-5-carboxylate 6a-c. The glucosides 6a and 6b were obtained by the reaction of 1a and 1b with peracetylated glucose3 under MW irradiation. Mercuration of 1a followed by reaction with acetobromoglucose gave the same product 6a. The reaction of 1a-c with peracetylated ribose 4 under MW irradiation gave ethyl 2-aryl-4-(2',3',5'-tri-O-acetyl-beta-D-ribofuranosylthio)-6-methylpyrimidine-5-carboxylate 8a-c. The deprotection of 6a-c and 8a-c in the presence of methanol and TEA/H(2)O afforded the deprotected products 7a-c and 9a-c. The structure were confirmed by using (1)H and (13)CNMR spectra. Selected members of these compounds were screened for antimicrobial activity.