Phenoxy- and Phenylamino-Heterocyclic Quinones: Synthesis and Preliminary Anti-Pancreatic Cancer Activity.

The successful application of fragment-based drug discovery strategy for the efficient synthesis of phenoxy- or phenylamino-2-phenyl-benzofuran, -benzoxazole and -benzothiazole quinones is described. Interestingly, in the final step of the synthesis of the target compounds, unusual results were observed on the regiochemistry of the reaction of bromoquinones with phenol and aniline. A theoretical study was carried out for better understanding the factors that control the regiochemistry of these reactions.

Cytotoxic and Radiosensitising Effects of a Novel Thioredoxin Reductase Inhibitor in Brain Cancers.

The thioredoxin (Trx) system, a key antioxidant pathway, represents an attractive target for cancer therapy. This study investigated the chemotherapeutic and radiosensitising effects of a novel Trx reductase (TrxR) inhibitor, IQ10, on brain cancer cells and the underlying mechanisms of action. Five brain cancer cell lines and a normal cell type were used.

Diazophosphonates: Effective Surrogates for Diazoalkanes in Pyrazole Synthesis.

Diazophosphonates, readily prepared from α-ketophosphonates by oxidation of the corresponding hydrazones in batch or in flow, are useful partners in 1,3-dipolar cycloaddition reactions to alkynes to give N-H pyrazoles, including the first intramolecular examples of such a process. The phosphoryl group imbues a number of desirable properties into the diazo 1,3-dipole. The electron-withdrawing nature of the phosphoryl stabilizes the diazo compound making it easier to handle, whilst the ability of the phosphoryl group to migrate readily in a [1,5]-sigmatropic rearrangement enables its transfer from C to N to aromatize the initial cycloadduct, and hence its facile removal from the final pyrazole product.

Cytotoxic and radiosensitising effects of a novel thioredoxin reductase inhibitor in breast cancer.

Radiotherapy is an effective treatment modality for breast cancer but, unfortunately, not all patients respond fully with a significant number experiencing local recurrences. Overexpression of thioredoxin and thioredoxin reductase has been reported to cause multidrug and radiation resistance - their inhibition may therefore improve therapeutic efficacy. Novel indolequinone compounds have been shown, in pancreatic cancer models, to inhibit thioredoxin reductase activity and exhibit potent anticancer activity.

Origin of the Thiopyrone CTP-431 "Unexpectedly" Isolated from the Marine Sponge Cacospongia mycofijiensis.

An intriguing hypothesis that latrunculin A, a well-known natural product, might have undergone transformation into the unprecedented thiopyrone CTP-431 upon long-term storage in methanol is advanced. Thus, opening of the hemiacetal of latrunculin A, followed by E1CB elimination, and dehydration would give a polyene that could undergo intramolecular Diels-Alder reaction, followed by methanolysis of the thiazolidinone ring and ring closure by intramolecular thiol addition to an enone. Experimental evidence that the novel thiazolidinone to thiopyrone rearrangement can occur is presented.

Total Synthesis of the Cyclic Dodecapeptides Wewakazole and Wewakazole B.

The cyclic dodecapeptides wewakazole and wewakazole B have been synthesized by a divergent strategy via a common tris-proline containing oxazole octapeptide and two separate bis-oxazole containing tetrapeptide units, followed by peptide coupling and macrocyclization. The three oxazole amino acid fragments are readily accessible by rhodium(II)-catalyzed amide N-H insertion of diazocarbonyl compounds, or by the cycloaddition of rhodium carbenoids with nitriles.

Synthesis of the Reported Pyranonaphthoquinone Structure of the Indoleamine-2,3-dioxygenase Inhibitor Annulin B by Regioselective Diels-Alder Reaction.

Annulin B, isolated from the marine hydroid isolated from Garveia annulata, is a potent inhibitor of the tryptophan catabolizing enzyme indoleamine-2,3-dioxygenase (IDO). A synthesis of the reported pyranonaphthoquinone structure is described, in which the key step is a regioselective Diels-Alder reaction between a pyranobenzoquinone dienophile and a silyl ketene acetal diene.

Antitumour indolequinones: synthesis and activity against human pancreatic cancer cells.

An important determinant of the growth inhibitory activity of indolequinones against pancreatic cancer cells is substitution on the 2-position with 2-unsubstituted derivatives being markedly more potent. A series of indolequinones bearing a range of substituents on nitrogen and at the indolylcarbinyl position was prepared by copper(II)-mediated reaction of bromoquinones and enamines, followed by functional group interconversions. The compounds were then assayed for their ability to inhibit the growth of pancreatic cancer cells.

Benzofuranquinones as inhibitors of indoleamine 2,3-dioxygenase (IDO). Synthesis and biological evaluation.

A series of benzofuranquinones, analogues of the marine metabolite annulin A, has been synthesized and evaluated as inhibitors of human indoleamine 2,3-dioxygenase (IDO). The synthesis was carried out by copper(II)-mediated reaction of bromobenzoquinones with 1,3-dicarbonyl compounds followed by functional group interconversions. The most potent compounds were 5-methoxy-2-methylbenzofuranquinones containing a CH2OR group at position-3 with IC50 ~ 0.

Copper(II)-Mediated Synthesis of Indolequinones from Bromoquinones and Enamines.

The reaction of enamines and bromoquinones in the presence of copper(II) acetate and potassium carbonate results in a regiospecific synthesis of indolequinones. The reaction is broad in scope and scalable and provides a route to the core structure that is present in several biologically interesting natural and synthetic compounds.

Carbophilic 3-component cascades: access to complex bioactive cyclopropyl diindolylmethanes.

Naturally occurring indole-3-carbinol and 3,3-diindolylmethane show bioactivity in a number of disparate disease areas, including cancer, prompting substantial synthetic analogue activity. We describe a new approach to highly functionalised derivatives that starts from allene gas and proceeds via the combination of a three-component Pd(0)-catalysed cascade with a one-pot, three-component carbophilic Pt(II) cascade linked to a stereoselective acid-catalysed Mannich-Michael reaction that generates complex cyclopropyl diindolylmethanes which show selective activity against prostate cancer cell lines.

Induction of differentiation and apoptosis in leukaemic cell lines by the novel benzamide family histone deacetylase 2 and 3 inhibitor MI-192.

Histone deacetylase inhibitors (HDACIs) are in advanced clinical development as cancer therapeutic agents. However, first generation HDACIs such as butyrate and valproate are simple short chain aliphatic compounds with moieties resembling acetyl groups, and have a broad spectrum of activity against HDACs. More complex second generation HDACIs undergoing clinical trials, such as the benzamide group compounds MS-275 and MGCD0103, are specific primarily for HDAC1 and HDAC2.

Two-step route to indoles and analogues from haloarenes: a variation on the Fischer indole synthesis.

In a new variation on the Fischer indole synthesis, readily available haloarenes are converted into a wide range of indoles in just two steps by halogen-magnesium exchange and quenching with di-tert-butyl azodicarboxylate, followed by reaction with aldehydes or ketones under acidic conditions. The protocol, which is readily extended to the preparation of indole isosteres, 4- and 6-azaindoles and thienopyrroles, obviates the need to prepare potentially toxic aryl hydrazines, simultaneously avoiding undesirable anilines such as naphthylamines.

Histone deacetylases are dysregulated in rheumatoid arthritis and a novel histone deacetylase 3-selective inhibitor reduces interleukin-6 production by peripheral blood mononuclear cells from rheumatoid arthritis patients.

Objective: To characterize the role of histone deacetylase (HDAC) activity in rheumatoid arthritis (RA) and to evaluate the effects of MI192, a novel HDAC-3-selective inhibitor, compared with the established nonselective HDAC inhibitor trichostatin A (TSA), on proinflammatory cytokine production.

Methods: Activity of HDAC and histone acetyltransferase was measured in peripheral blood mononuclear cells (PBMCs) from RA patients by spectrophotometric assay, prior to and after 12 weeks of etanercept therapy. The effects of HDAC inhibitor treatment on cytokine production in both RA and healthy PBMCs were assessed by enzyme-linked immunosorbent assay.

A two step route to indoles from haloarenes--a versatile variation on the Fischer indole synthesis.

In a new variation on the Fischer indole synthesis, readily available haloarenes are converted into a wide range of indoles in just two steps by halogen-magnesium exchange, quenching with di-tert-butyl azodicarboxylate, followed by reaction with ketones under acidic conditions.

Synthesis of indolequinones from bromoquinones and enamines mediated by Cu(OAc)2.H2O.

A Cu(II)-mediated synthesis of indolequinones from the corresponding bromoquinones and enamines is reported. The key oxidative cyclization proceeds in good yield for a broad range of substrates and can be performed on a multigram scale, allowing access to biologically interesting structures.