Stereoselective synthesis of 11-phenylundeca-5Z,9Z-dienoic acid and investigation of its human topoisomerase I and IIα inhibitory activity

Interaction study with DNA/HSA, anti-topoisomerase IIα, cytotoxicity and in vitro antiproliferative evaluations and molecular docking of indole-thiosemicarbazone compounds

In this work we will discuss the antiproliferative evaluation and the possible mechanisms of action of indole-thiosemicarbazone compounds LTs with anti-inflammatory activity, previously described in the literature. In this perspective, some analyzes were carried out, such as the study of binding to human serum albumin (HSA) and to biological targets: DNA and human topoisomerase IIα (topo). Antiproliferative study was performed with DU-145, Jukart, MCF-7 and T-47D tumor lines and J774A.1, besides HepG2 macrophages and hemolytic activity. In the HSA interaction tests, the highest binding constant was 3.70 × 10⁶ M^-1, referring to LT89 and in the fluorescence, most compounds, except for LT76 and LT87, promoted fluorescent suppression with the largest Stern-Volmer constant for the LT88 3.55 × 10⁴. In the antiproliferative assay with DU-145 and Jurkat strains, compounds LT76 (0.98 ± 0.10/1.23 ± 0.32 μM), LT77 (0.94 ± 0.05/1.18 ± 0.08 μM) and LT87 (0.94 ± 0.12/0.84 ± 0.09 μM) stood out, due to their IC₅₀ values mentioned above. With the MCF-7 and T-47D cell lines, the lowest IC₅₀ was presented by LT81 with values of 0.74 ± 0.12 μM and 0.68 ± 0.10 μM, respectively, followed by the compounds LT76 and LT87. As well as the positive control amsacrine, the compounds LT76, LT81 and LT87 were able to inhibit the enzymatic action of human Topoisomerase IIα.

Direct Synthesis of Polyaromatic Cyclophanes Containing Bis-Methylene-Interrupted Z-Double Bonds and Study of Their Antitumor Activity In Vitro

An original synthetic route was developed for the preparation of previously unknown unsaturated polyaromatic macrolactones containing a 1Z,5Z-diene moiety in 48–71% yields and with >98% stereoselectivity. The method is based on intermolecular cyclocondensation of aromatic dicarboxylic acids with α,ω-alka-nZ,(n+4)Z-dienediols (1,12-dodeca-4Z,8Z-dienediol, 1,14-tetradeca-5Z,9Z-dienediol, 1,18-octadeca-7Z,11Z-dienediol) mediated by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)/4-dimethylaminopyridine (DMAP). The unsaturated diols were prepared by successive homo-cyclomagnesiation of tetrahydropyran ethers of O-containing 1,2-dienes with EtMgBr in the presence of Mg metal and the Cp₂TiCl₂ catalyst (10 mol.%) and subsequent treatment with 0.1 equiv. of para-toluenesulfonic acid of pyran ethers formed after the acid hydrolysis of magnesacyclopentanes. The resulting cyclophanes exhibited high cytotoxic activity in vitro against Jurkat, K562, U937, and HL60 cancer lines. Additionally, the synthesized products were studied for their effect on mitochondria, ability to induce apoptosis, and influence on the cell cycle using modern flow cytometry methods.

Synthesis and Anticancer Activity of Hybrid Molecules Based on Lithocholic and (5Z,9Z)-Tetradeca-5,9-dienedioic Acids Linked via Mono(di,tri,tetra)ethylene Glycol and α,ω-Diaminoalkane Units

For the first time, hybrid molecules were synthesized on the basis of lithocholic and (5Z,9Z)-1,14-tetradeca-5,9-dienedicarboxylic acids, obtained in two stages using the homo-cyclomagnesiation reaction of 2-(hepta-5,6-diene-1-yloxy)tetrahydro-2H-pyran at the key stage. The resulting hybrid molecules containing 5Z,9Z-dienoic acids are of interest as novel synthetic biologically active precursors to create modern drugs for the treatment of human oncological diseases. The synthesized hybrid molecules were found to exhibit extremely high in vitro inhibitory activity against human topoisomerase I, which is 2-4 times higher than that of camptothecin, a known topoisomerase I inhibitor. Using flow cytometry and fluorescence microscopy, it was first shown that these new molecules are efficient apoptosis inducers in HeLa, U937, Jurkat, K562, and Hek293 cell cultures. In addition, the results of investigations into the effect of the synthesized acids on mitochondria and studies of possible DNA damage in Jurkat tumor cells are also presented.

New synthetic analogues of natural 5Z,9Z-dienoic acids: Stereoselective synthesis and study of the anticancer activity

A stereoselective method was developed for the synthesis of synthetic analogues of natural 5Z,9Z-dienoic acids by esterification of aliphatic and aromatic alcohols and carboxylic acids with (5Z,9Z)-1,14-tetradeca-5,9-dienedioic acid and (5Z,9Z)-1,14-tetradeca-5,9-dienediol, synthesized by Ti-catalyzed homo-cyclomagnesiation of the tetrahydropyran ether of hepta-5,6-dien-1-ol with Grignard reagents. In order to establish the effect of molecular structure on the antitumor activity, the obtained 5Z,9Z-dienoic acids were tested for the inhibitory activity against human topoisomerase I, the cytotoxic activity in vitro against several cancer and normal cell lines (Jurkat, HL-60, K562, U937, fibroblasts), the effect on the cell cycle, and apoptosis-inducing ability using flow cytofluorometry. In addition, the effect of the synthesized acids on the cancer cell production of some phosphorylated and unphosphorylated proteins responsible for proliferation and apoptosis was studied by a new multiplex assay technology, MAGPIX.

New 1Z,5Z-diene macrodiolides: Catalytic synthesis, anticancer activity, induction of mitochondrial apoptosis, and effect on the cell cycle

An original scheme was developed for the synthesis of previously undescribed unsaturated macrodiolides containing a 1Z,5Z-diene moiety in 44-80% yields and with high stereoselectivity (>95%) based on the intermolecular esterification of α,ω-diols with α,ω-alka-nZ,(n + 4)Z-dienedicarboxylic acids (1,12-dodeca-4Z,8Z-dienedicarboxylic acid, 1,14-tetradeca-5Z,9Z-dienedicarboxylic acid, 1,18-octadeca-7Z,11Z-dienedicarboxylic acid) catalyzed by hafnium triflate [Hf(OTf)₄]. The unsaturated dicarboxylic acids were prepared via homo-cyclomagnesiation of tetrahydropyran ethers of O-containing 1,2-dienes with EtMgBr in the presence of Mg metal and the Cp₂TiCl₂ catalyst (10 mol.%) and the subsequent Jones oxidation of pyran ethers formed after the acid hydrolysis of magnesacyclopentanes. The thus prepared macrodiolides exhibit high cytotoxic activity in vitro against Jurkat, K562, U937, Hek293 and HeLa cancer cell lines. It was found that induction of the programmed cell death in Jurkat cells by macrodiolides corresponds to the mitochondrial apoptosis pathway. Also, it was shown that the prepared macrodiolides efficiently suppress phosphorylation of Akt and p38 kinases and CREB transcription factor in cancer cells.

Synthesis of New Cu Complex Based on Natural 5Z,9Z-Eicosadienoic Acid: Effective Topoisomerase I Inhibitor and Cytotoxin against the Cisplatin-Resistant Cell Line

The complex (bipy)2Cu(5,9-eicd) was prepared by the reaction of Cu(OAc)2 with 5Z,9Z-eicosadienoic acid and 2,2'-bipyridine in methanol. The new copper complex showed high antitumor activity in vitro toward A2780cis, A2780, Hek293, K562, HL60, Jurkat, and U937 cell lines and efficiently inhibited human topoisomerase I. Using flow cytofluorometry, (bipy)2Cu(5,9-eicd) was studied for the effect on the cell cycle and apoptosis-inducing activity in tumor cells.

A comprehensive review of topoisomerase inhibitors as anticancer agents in the past decade

The topoisomerase enzymes play an important role in DNA metabolism, and searching for enzyme inhibitors is an important target in the search for new anticancer drugs. Discovery of new anticancer chemotherapeutical capable of inhibiting topoisomerase enzymes is highlighted in anticancer research. Therefore, biologists, organic chemists and medicinal chemists all around the world have been identifying, designing, synthesizing and evaluating a variety of novel bioactive molecules targeting topoisomerase. This review summarizes types of topoisomerase inhibitors in the past decade, and divides them into nine classes by structural characteristics, including N-heterocycles compounds, quinone derivatives, flavonoids derivatives, coumarin derivatives, lignan derivatives, polyphenol derivatives, diterpenes derivatives, fatty acids derivatives, and metal complexes. Then we discussed the application prospect and development of these anticancer compounds, as well as concluded parts of their structural-activity relationships. We believe this review would be invaluable in helping to further search potential topoisomerase inhibition as antitumor agent in clinical usage.

Alkenyl Magnesium Compounds: Generation and Synthetic Application

Alkenyl magnesium compounds have received much attention in synthetic organic chemistry because of their high reactivity. This review summarizes three types of alkenyl magnesium compounds which contain at least one [Mg-C=C] fragment, for example, (1) alkenyl Grignard reagents prepared by halogen-magnesium exchange reaction; (2) alkenyl magnesium carbenoids prepared by halogen-magnesium exchange reaction or sulfoxide-magnesium exchange reaction; (3) magnesacarbocycles containing at least one alkenyl magnesium bond prepared from Zr- or Ti-catalyzed cyclomagnesation or transmetalation, as well as their further reactions and applications.

First Total Synthesis of ω-Phenyl Δ6 Fatty Acids and their Leishmanicidal and Anticancer Properties

INTRODUCTION

The first total synthesis of ω-phenyl Δ6 fatty acids (FA) and their cytotoxicity (A549) and leishmanicidal (L. infantum) activities are described. The novel 16-phenyl-6-hexadecynoic acid (1) and the known 16-phenylhexadecanoic acid (2) were synthesized in 7-8 steps with overall yields of 46 % and 41 %, respectively. The syntheses of the unprecedented 10-phenyl-6-decynoic acid (3), 10-cyclohexyl-6-decynoic acid (4) and 10-(4-methoxyphenyl)-6-decynoic acid (5) was also performed in 3 steps with 73-76 % overall yields. The use of lithium acetylide coupling enabled the 4-step synthesis of 10-phenyl-6Z-decenoic acid (6) with a 100 % cis-stereochemistry. The cytotoxicity of these novel FA was determined against A549 cells and L. infantum promastigotes and amastigotes. Among the ω-phenylated FA, the best cytotoxicity towards A549 was displayed by 1, with an IC50 of 18 ± 1 μM. On the other hand, among the C10 acids, the ω-cyclohexyl acid 4 presented the best cytotoxicity (IC50 = 40 ± 2 μM) towards A549.

RESULTS

Based on caspase-3/7 studies neither of the FA induced apoptosis in A549, thus implying other mechanisms of cell death.

CONCLUSION

The antileishmanial studies were performed with the top Leishmania donovani topoisomerase IB (LdTopIB) inhibitors, namely 1 and 2 (EC50 between 14 and 36 μM, respectively), acids that did not stabilize the cleavage complexes between LdTopIB and DNA. Acids 1 and 2 displayed cytotoxicity towards L. infantum amastigotes (IC50 = 3-6 μM) and L. infantum promastigotes (IC50 = 60- 70 μM), but low toxicity towards murine splenocytes. Our results identified 1 as the optimum ω- phenylated acid of the series.

The first total synthesis of the marine acetylenic alcohol, lembehyne B - a selective inducer of early apoptosis in leukemia cancer cells

The communication reports a new stereoselective method for the synthesis of a natural acetylenic alcohol, lembehyne B. The key stage of the process uses new cross-cyclomagnesiation reaction of aliphatic and oxygenated 1,2-dienes with Grignard reagents in the presence of a catalytic amount of Cp₂TiCl₂. A study of the cytotoxic properties of lembehyne B on tumor cell lines using flow cytometry demonstrated that this is a selective inducer of early apoptosis of the Jurkat, HL-60 and K562 cell cultures and hypodiploid (sub-G1) sub-population inducer in cell cycle studies for all cell lines used.

Novel bivalent securinine mimetics as topoisomerase I inhibitors

A series of novel bivalent securinine mimetics incorporating different linkers between C-15 and C-15' were synthesized and their topoisomerase I (Topo I) inhibitory activities evaluated. It was thus revealed that mimetic R2 incorporating a rigid m-substituted benzene linker exhibits Topo I inhibitory activity three times that of parent securinine. Comprehensive structure-activity relationship analyses in combination with docking studies were used to rationalize the potent activity of these bivalent mimetics. Mechanistic studies served to confirm the deductions arising from docking studies that the active bivalent mimetics not only inhibited complexation between Topo I and DNA but also stabilized the Topo I-DNA complex itself.

Short Route to the Total Synthesis of Natural Muricadienin and Investigation of Its Cytotoxic Properties

An original synthesis of the acetogenin muricadienin, the bioprecursor of solamin, has been developed. The key step in the five-step 41% overall yield synthesis is the catalytic cross-cyclomagnesiation reaction of functionally substituted 1,2-dienes with EtMgBr in the presence of Cp2TiCl2 and magnesium metal. It has been demonstrated for the first time that muricadienin exhibits a moderate in vitro inhibitory activity against topoisomerases I and IIα, key cell cycle enzymes. Using flow cytometry, muricadienin was shown to have high cytotoxicity toward the HEK293 kidney cancer cells (IC50 0.39 μM).

Novel Very Long-Chain α-Methoxylated Δ5,9 Fatty Acids from the Sponge Asteropus niger Are Effective Inhibitors of Topoisomerases IB

The novel fatty acids (2R,5Z,9Z)-2-methoxy-25-methyl-5,9-hexacosadienoic acid (1a) and (2R,5Z,9Z)-2-methoxy-24-methyl-5,9-hexacosadienoic acid (1b) were isolated in 80 % purity from the Caribbean sponge Asteropus niger by chloroform/methanol extraction followed by solvent partitioning and silica gel column chromatography. The compounds were characterized by utilizing a combination of gas chromatography-mass spectrometry, nuclear magnetic resonance, and circular dichroism. Acids 1a and 1b were not detected in the phospholipids (PtdCho and PtdIns) of the sponge, but rather as free FA and possibly in glycosylceramides. The mixtures of 1a and 1b displayed cytotoxicity towards THP-1 and HepG2 cells with EC50's between 41 and 35 μg/mL. Apoptosis was not the preferred mode of cell death induced by 1a-1b in the THP-1 cells. This implies other types of cytotoxicity mechanisms, such as membrane disruption and/or the inhibition (EC50 = 1.8 μg/mL) of the human topoisomerase IB enzyme (hTopIB), with a mechanism of inhibition different from the one displayed by camptothecin (CPT). In a separate experiment, the mixture of 1a and 1b also displayed cytotoxicity towards ex vivo mouse splenocytes infected with Leishmania infantum amastigotes (IC(50) = 0.17 mg/mL) and free living promastigotes (IC(50) = 0.34 mg/mL). It was also found that the FA were inhibitory of the Leishmania topoisomerase IB (LTopIB) with an EC(50) = 5.1 μg/mL. Taken together, 1a and 1b represent a new class of FA with potential as TopIB inhibitors that preferentially inhibit hTopIB over LTopIB.

Catalytic cyclometallation in steroid chemistry III: Synthesis of steroidal derivatives of 5Z,9Z-dienoic acid and investigation of its human topoisomerase I inhibitory activity

Two approaches to stereoselective synthesis of steroid 5Z,9Z-dienoic acids were developed, the first one being based on the cross-cyclomagnesiation of 2-(hepta-5,6-dien-1-yloxy)tetrahydro-2H-pyran and 1,2-diene cholesterol derivatives on treatment with EtMgBr catalyzed by Cp2TiCl2, while the other involving the synthesis of esters of hydroxy steroids with (5Z,9Z)-tetradeca-5,9-dienedioic acid, prepared in two steps using homo-cyclomagnesiation of 2-(hepta-5,6-dien-1-yloxy)tetrahydro-2H-pyran as the key step. High inhibitory activity of the synthesized acids against human topoisomerase I (hTop1) was found.