Metallocene-uracil conjugates: Synthesis and biological evaluation of novel mono-, di- and tri-nuclear systems

Ferrocenyl Azoles: Versatile N-Containing Heterocycles and their Anticancer Activities

The medicinal chemistry of ferrocene has gained its momentum after the discovery of biological activities of ferrocifen and ferroquine. These ferrocenyl drugs have been designed by replacing the aromatic moiety of the organic drugs, tamoxifen and chloroquine respectively, with a ferrocenyl unit. The promising biological activities of these ferrocenyl drugs have paved a path to explore the medicinal applications of several ferrocenyl conjugates. In these conjugates, the ferrocenyl moiety has played a vital role in enhancing or imparting the anticancer activity to the molecule. The ferrocenyl conjugates induce the cytotoxicity by generating reactive oxygen species and thereby damaging the DNA. In medicinal chemistry, the five membered nitrogen heterocycles (azoles) play a significant role due to their rigid ring structure and hydrogen bonding ability with the biomolecules. Several potent drug candidates with azole groups have been in use as chemotherapeutics. Considering the importance of ferrocenyl moiety and azole groups, several ferrocenyl azole conjugates have been synthesized and screened for their biological activities. Hence, in the view of a wide scope in the development of potent drugs based on ferrocenyl azole conjugates, herein we present the details of synthesis and the anticancer activities of ferrocenyl compounds bearing azole groups such as imidazole, triazoles, thiazole and isoxazoles.

New Nucleic Base-Tethered Trithiolato-Bridged Dinuclear Ruthenium(II)-Arene Compounds: Synthesis and Antiparasitic Activity

Aiming toward compounds with improved anti-Toxoplasma activity by exploiting the parasite auxotrophies, a library of nucleobase-tethered trithiolato-bridged dinuclear ruthenium(II)-arene conjugates was synthesized and evaluated. Structural features such as the type of nucleobase and linking unit were progressively modified. For comparison, diruthenium hybrids with other type of molecules were also synthesized and assessed. A total of 37 compounds (diruthenium conjugates and intermediates) were evaluated in a primary screening for in vitro activity against transgenic Toxoplasma gondii tachyzoites constitutively expressing β-galactosidase (T. gondii β-gal) at 0.1 and 1 µM. In parallel, the cytotoxicity in non-infected host cells (human foreskin fibroblasts, HFF) was determined by alamarBlue assay. Twenty compounds strongly impairing parasite proliferation with little effect on HFF viability were subjected to T. gondii β-gal half maximal inhibitory concentration determination (IC₅₀) and their toxicity for HFF was assessed at 2.5 µM. Two promising compounds were identified: 14, ester conjugate with 9-(2-oxyethyl)adenine, and 36, a click conjugate bearing a 2-(4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl)methyl substituent, with IC₅₀ values of 0.059 and 0.111 µM respectively, significantly lower compared to pyrimethamine standard (IC₅₀ = 0.326 µM). Both 14 and 36 exhibited low toxicity against HFF when applied at 2.5 µM and are candidates for potential treatment options in a suitable in vivo model.

Extension of furopyrimidine nucleosides with 5-alkynyl substituent: Synthesis, high fluorescence, and antiviral effect in the absence of free ribose hydroxyl groups

A novel methodology to access alkynyl nucleoside analogues is elaborated. Highly fluorescent 5-alkynylfuropyrimidines were synthesized (97-46%) and their antiviral properties investigated in vitro. Regiochemistry of the functionalization was achieved with the aid of 5-endo-dig electrophilic halocyclization of acetyl 5-p-tolyl- or 5-p-pentylphenyl-2'-deoxyuridine. Structure of one of the resulting nucleosides, 6-p-tolyl-5-iodo-2'-deoxyribofuranosyl-furo[2,3-d]pyrimidin-2-one, was confirmed by X-ray crystallography, and its conformation was compared to related nucleosides. Diverse alkynyl substituents were introduced at the heterobicyclic base C-5 position via Sonogashira coupling of 5-iodo-2'-deoxyribofuranosyl-furo[2,3-d]pyrimidin-2-ones. The resulting compounds had fluorescence emissions of 452-481 nm. High quantum yields of 0.53-0.60 were observed for 9-ethynyl-9-fluorenol and propargyl alcohol/methyl ether-modified furopyrimidines. These modified nucleosides, designed in the form of ribose acetyl esters, are potential tools for fluorescent tagging, studying nucleoside metabolism, 2'-deoxyribonucleoside kinase activity, and antiviral activity. Antiviral assays against a broad spectrum of DNA and RNA viruses showed that in human embryonic lung (HEL) cell cultures some of the compounds posess antiviral activity (EC50 1.3-13.2 μM) against varicella-zoster virus (VZV). The alkynyl furopyrimidine with two p-pentylphenyl substituents emerged as the best compound with reasonable and selective anti-VZV activity, confirming p-pentylphenyl potency as a pharmacophore.

Synthesis and In Vitro Anticancer Activity of 6-Ferrocenylpyrimidin-4(3H)-one Derivatives

AIM AND OBJECTIVE

Some ferrocenyl derivatives are active in vitro and in vivo against cancer. Generally, ferrocenyl derivatives for cancer research have three key components: a ferrocene moiety, a conjugated linker that lowers the oxidation potential and some derivative (peptide, nucleobase and others) that can interact with biomolecules. Since the pyrimidine fragment can easily pass through the membrane into the cells and become involved in metabolism; it appears to be promising. Furthermore, this fragment is an electron-acceptor group, so a spacer can be excluded. Therefore, the synthesis of 6-ferrocenylpyrimidin-4(3H)-one derivatives and the study of their anticancer activity have scientific and practical interest.

METHODS

The syntheses of 6-ferrocenylpyrimidin-4(3H)-one derivatives were performed by the condensation of ethyl 3-ferrocenyl-3-oxopropionate with thiourea or acetamidine or guanidine. The cytotoxicity of four 6- ferrocenylpyrimidin-4(3H)-one derivatives was evaluated by using the MTT assay in vitro against Human breast adenocarcinoma MCF-7 and normal human skin fibroblast HSF cells. The tested derivatives induced a concentration-dependent cytotoxic response in cell lines.

RESULTS

A study of the cytotoxic activity of 6-ferrocenylpyrimidin-4(3H)-one derivatives by the MTT test has found that all compounds have a dose-dependent toxic effect on the lines of breast cancer cells (MCF-7) and normal human fibroblast cells (HSF). The most pronounced cytotoxic effect is exhibited by 2-methyl-6-ferrocenylpyrimidin- 4(3H)-one (MCF-7, IC50 17 ± 1 µM).

CONCLUSION

The experimental results confirm the importance of investigation and design of ferrocenylpyrimidin- 4(3H)-one derivatives as anticancer agents. Compounds where the pyrimidine derivatives are directly linked to the ferrocene unit rather than via a spacer group also may be of interest for antiproliferative drug design.

Formylation of a metathesis-derived ansa[4]-ferrocene: a simple route to anticancer organometallics

Ansa-Ferrocenealdehyde, obtained by formylation of a metathesis-derived ansa-ferrocene, was transformed into a conjugate with triazole and uracil with anticancer activity.

Water soluble palladium(ii) and platinum(ii) acyclic diaminocarbene complexes: solution behavior, DNA binding, and antiproliferative activity

Water soluble Pd(ii) and Pt(ii)–ADC species synthesized via the metal-mediated coupling of isocyanides and 1,2-diaminobenzene have demonstrated antitumor potential.

Luminescent pyrenyl-GNA nucleosides: synthesis, photophysics and confocal microscopy studies in cancer HeLa cells

Glycol nucleic acids (GNA) are synthetic genetic-like polymers with an acyclic three-carbon propylene glycol phosphodiester backbone. Here, synthesis, luminescence properties, circular dichroism (CD) spectra, and confocal microscopy speciation studies of (R,S) and (S,R) pyrenyl-GNA (pyr-GNA) nucleosides are reported in HeLa cells. Enantiomerically pure nucleosides were obtained by a Sharpless asymmetric dihydroxylation reaction followed by semi-preparative high-performance liquid chromatography (HPLC) separation using Amylose-2 as the chiral stationary phase. The enantiomeric relationship between stereoisomers was confirmed by CD spectra, and the absolute configurations were assigned based on experimental and theoretical CD spectra comparisons. The pyr-GNA nucleosides were not cytotoxic against human cervical (HeLa) cancer cells and thus were utilized as luminescent probes in the imaging of these cells with confocal microscopy. Cellular staining patterns were identical for both enantiomers in HeLa cells. Compounds showed no photocytotoxic effect and were localized in the lipid membranes of the mitochondria, in cellular vesicles and in other lipid cellular compartments. The overall distribution of the pyrene and pyrenyl-GNA nucleosides inside the living HeLa cells differed, since the former compound gives a more granular staining pattern and the latter a more diffuse one.

Conjugates of Classical DNA/RNA Binder with Nucleobase: Chemical, Biochemical and Biomedical Applications

Among the most intensively studied classes of small molecules (molecular weight < 650) in biomedical research are small molecules that non-covalently bind to DNA/RNA, and another intensively studied class is nucleobase derivatives. Both classes have been intensively elaborated in many books and reviews. However, conjugates consisting of DNA/RNA binder covalently linked to nucleobase are much less studied and have not been reviewed in the last two decades. Therefore, this review summarized reports on the design of classical DNA/RNA binder - nucleobase conjugates, as well as data about their interactions with various DNA or RNA targets, and even in some cases protein targets are involved. According to these data, the most important structural aspects of selective or even specific recognition between small molecule and target are proposed, and where possible related biochemical and biomedical aspects were discussed. The general conclusion is that this, rather new class of molecules showed an amazing set of recognition tools for numerous DNA or RNA targets in the last two decades, as well as few intriguing in vitro and in vivo selectivities. Several lead research lines show promising advancements toward either novel, highly selective markers or bioactive, potentially druggable molecules.

Current research on anti-breast cancer synthetic compounds

Breast cancer (BC) is the most common cancer for females and its incidence tends to increase year by year.

Synthesis and cytotoxic evaluation of several oleanolic acid–uracil/thymine conjugates

Some IC₅₀ values of sixteen synthesized oleanolic acid–uracil/thymine hybrids were under 0.1 μM against tested cells (Hep-G2, A549, BGC-823, MCF-7 and PC-3).

The length of the bridging chain in ansa-metallocenes influences their antiproliferative activity against triple negative breast cancer cells (TNBC)

[n]Ferrocenophane and [n]ruthenocenophane derivatives have been synthesized and their antiproliferative activity evaluated against MDA-MB-231 cells.