benzofurans and rocagloic-acid

Rocaglates are a class of eukaryotic translation initiation inhibitors that are being explored as chemotherapeutic agents. They function by targeting eukaryotic initiation factor (eIF) 4A, an RNA helicase critical for recruitment of the 40S ribosome (and associated factors) to mRNA templates. Rocaglates perturb eIF4A activity by imparting a gain-of-function activity to eIF4A and mediating clamping to RNA. To appreciate how rocaglates could best be enabled in the clinic, an understanding of resistance mechanisms is important, as this could inform on strategies to bypass such events as well as identify responsive tumor types. Here, we report on the results of a positive selection, ORFeome screen aimed at identifying cDNAs capable of conferring resistance to rocaglates. Two of the most potent modifiers of rocaglate response identified were the transcription factors FOXP3 and NR1I3, both of which have been implicated in ABCB1 regulation-the gene encoding P-glycoprotein (Pgp). Pgp has previously been implicated in conferring resistance to silvestrol, a naturally occurring rocaglate, and we show here that this extends to additional synthetic rocaglate derivatives. In addition, FOXP3 and NR1I3 impart a multi-drug resistant phenotype that is reversed upon inhibition of Pgp, suggesting a potential therapeutic combination strategy.

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Benzofurans; Cell Line; Constitutive Androstane Receptor; Eukaryotic Initiation Factor-4A; Forkhead Transcription Factors; Gene Expression Regulation; Genetic Testing; Humans; Receptors, Cytoplasmic and Nuclear

Rocaglates are natural compounds that have been extensively studied for their ability to inhibit translation initiation. Rocaglates represent promising drug candidates for tumor treatment due to their growth-inhibitory effects on neoplastic cells. In contrast to natural rocaglates, synthetic analogues of rocaglates have been less comprehensively characterized, but were also shown to have similar effects on the process of protein translation. Here, we demonstrate an enhanced growth-inhibitory effect of synthetic rocaglates when combined with glucose anti-metabolite 2-deoxy-D-glucose (2DG) in different cancer cell lines. Moreover, we unravel a new aspect in the mechanism of action of synthetic rocaglates involving reduction of glucose uptake mediated by downregulation or abrogation of glucose transporter GLUT-1 expression. Importantly, cells with genetically induced resistance to synthetic rocaglates showed substantially less pronounced treatment effect on glucose metabolism and did not demonstrate GLUT-1 downregulation, pointing at the crucial role of this mechanism for the anti-tumor activity of the synthetic rocaglates. Transcriptome profiling revealed glycolysis as one of the major pathways differentially regulated in sensitive and resistant cells. Analysis of synthetic rocaglate efficacy in a 3D tissue context with a co-culture of tumor and normal cells demonstrated a selective effect on tumor cells and substantiated the mechanistic observations obtained in cancer cell lines. Increased glucose uptake and metabolism is a universal feature across different tumor types. Therefore, targeting this feature by synthetic rocaglates could represent a promising direction for exploitation of rocaglates in novel anti-tumor therapies.

Topics: Benzofurans; Cell Proliferation; Glucose; Glucose Transporter Type 1; Humans; Neoplasms

Rocaglates, a class of natural compounds isolated from plants of the genus Aglaia, are potent inhibitors of translation initiation. They are proposed to form stacking interactions with polypurine sequences in the 5'-untranslated region (UTR) of selected mRNAs, thereby clamping the RNA substrate onto eIF4A and causing inhibition of the translation initiation complex. Since virus replication relies on the host translation machinery, it is not surprising that the rocaglate Silvestrol has broad-spectrum antiviral activity. Unfortunately, synthesis of Silvestrol is sophisticated and time-consuming, thus hampering the prospects for further antiviral drug development. Here, we present the less complex structured synthetic rocaglate CR-31-B (-) as a novel compound with potent broad-spectrum antiviral activity in primary cells and in an ex vivo bronchial epithelial cell system. CR-31-B (-) inhibited the replication of corona-, Zika-, Lassa-, Crimean Congo hemorrhagic fever viruses and, to a lesser extent, hepatitis E virus (HEV) at non-cytotoxic low nanomolar concentrations. Since HEV has a polypurine-free 5'-UTR that folds into a stable hairpin structure, we hypothesized that RNA clamping by Silvestrol and its derivatives may also occur in a polypurine-independent but structure-dependent manner. Interestingly, the HEV 5'-UTR conferred sensitivity towards Silvestrol but not to CR-31-B (-). However, if an exposed polypurine stretch was introduced into the HEV 5'-UTR, CR-31-B (-) became an active inhibitor comparable to Silvestrol. Moreover, thermodynamic destabilization of the HEV 5'-UTR led to reduced translational inhibition by Silvestrol, suggesting differences between rocaglates in their mode of action, most probably by engaging Silvestrol's additional dioxane moiety.

Topics: A549 Cells; Animals; Antiviral Agents; Benzofurans; Bronchi; Cell Culture Techniques; Cells, Cultured; Epithelial Cells; Eukaryotic Initiation Factor-4A; Hepatocytes; Humans; Mice; Triterpenes; Virus Replication; Viruses

The PI3K/Akt/mTOR kinase pathway is extensively deregulated in human cancers. One critical node under regulation of this signaling axis is eukaryotic initiation factor (eIF) 4F, a complex involved in the control of translation initiation rates. eIF4F-dependent addictions arise during tumor initiation and maintenance due to increased eIF4F activity-generally in response to elevated PI3K/Akt/mTOR signaling flux. There is thus much interest in exploring eIF4F as a small molecule target for the development of new anticancer drugs. The DEAD-box RNA helicase, eIF4A, is an essential subunit of eIF4F, and several potent small molecules (rocaglates, hippuristanol, pateamine A) affecting its activity have been identified and shown to demonstrate anticancer activity in vitro and in vivo in preclinical models. Recently, a number of new small molecules have been reported as having the capacity to target and inhibit eIF4A. Here, we undertook a comparative analysis of their biological activity and specificity relative to the eIF4A inhibitor, hippuristanol.

Topics: Antineoplastic Agents; Benzofurans; Cell Proliferation; Cell Survival; Epoxy Compounds; Eukaryotic Initiation Factor-4A; Eukaryotic Initiation Factor-4F; Humans; Macrolides; Neoplasms; Phosphatidylinositol 3-Kinases; Protein Biosynthesis; Proto-Oncogene Proteins c-akt; Small Molecule Libraries; Sterols; Thiazoles; TOR Serine-Threonine Kinases

Rocaglates share a common cyclopenta[b]benzofuran core that inhibits eukaryotic translation initiation by modifying the behavior of the RNA helicase, eIF4A. Working as interfacial inhibitors, rocaglates stabilize the association between eIF4A and RNA, which can lead to the formation of steric barriers that block initiating ribosomes. There is significant interest in the development and expansion of rocaglate derivatives, as several members of this family have been shown to possess potent anti-neoplastic activity in vitro and in vivo. To further our understanding of rocaglate diversity and drug design, herein we explore the RNA clamping activity of >200 unique rocaglate derivatives. Through this, we report on the identification and characterization of a potent class of synthetic rocaglates called amidino-rocaglates. These compounds are among the most potent rocaglates documented to date and, taken together, this work offers important information that will guide the future design of rocaglates with improved biological properties.

Topics: Amidines; Animals; Antineoplastic Agents; Benzofurans; Cell Survival; DEAD-box RNA Helicases; Drug Design; Eukaryotic Initiation Factor-4A; Female; Humans; Lymphoma; Mice; Mice, Inbred C57BL; Protein Biosynthesis; Recombinant Proteins; Ribosomes; RNA; Structure-Activity Relationship

Herein, we report the development of continuous flow photoreactors for large scale ESIPT-mediated [3+2]-photocycloaddition of 2-(p-methoxyphenyl)-3-hydroxyflavone and cinnamate-derived dipolarophiles. These reactors can be efficiently numbered up to increase throughput two orders of magnitude greater than the corresponding batch reactions.

Topics: Alkaloids; Benzofurans; Biological Products; Cinnamates; Cycloaddition Reaction; Flavonoids; Light; Photochemical Processes

Topics: Benzofurans; Biomimetics; Eukaryota; Flavonoids; HeLa Cells; Humans; Molecular Structure; Photochemistry; Protein Biosynthesis

Topics: Animals; Benzofurans; Molecular Structure; Rabbits; Reticulocytes; Stereoisomerism; Triterpenes

Two new rocaglamide derivatives, 1-O-formylrocagloic acid (1) and 3'-hydroxy rocagloic acid (2), together with five known compounds, rocaglaol (3), rocagloic acid (4), 3'-hydroxymethylrocaglate (5), 1-O-formylmethyl rocaglate (6), and methylrocaglate (7), were isolated from the fruits of Amoora cucullata. Their structures were elucidated by spectroscopic methods. Compounds 1-3, 6, and 7 exhibited potent cytotoxicity against KB, BC, and NCI-H187 cell lines, whereas 4 and 5 showed selective cytotoxicity against NCI-H187 cell line.

Topics: Benzofurans; Cell Line, Tumor; Cell Proliferation; Drug Screening Assays, Antitumor; Humans; Magnetic Resonance Spectroscopy; Meliaceae; Molecular Conformation; Reference Standards; Seeds; Sensitivity and Specificity; Stereoisomerism; Structure-Activity Relationship

Many acute and chronic neurodegenerative diseases are characterized by a localized inflammatory response and constitutive activation of the transcription factors nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1) as well as their upstream activating signaling cascades. Ample evidence indicates the implication of these processes in the pathogenesis of several diseases of the central nervous system. In this study, we show that a synthetic derivative of the natural product rocaglaol (compound A) displays potent anti-inflammatory properties in human endothelial and murine glial cells in vitro. Compound A inhibited cytokine- and lipopolysaccharide-induced release of various cytokines/chemokines and of nitric oxide as well as expression of the adhesion molecule endothelial leukocyte adhesion molecule-1 and the inducible enzymes nitric-oxide synthase and cyclooxygenase-2. As shown by immunocytochemistry and immunoblotting, compound A inhibited NF-kappa B and AP-1 activity in mixed glial cultures. Compound A exhibited neuroprotective activity in vitro and in vivo. 1-Methyl-4-phenylpyridinium-induced damage of mesencephalic dopaminergic neurons was significantly decreased, and long-term treatment of 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine-injected mice with compound A significantly and dose-dependently reduced dopaminergic neuronal cell death. In addition, shortterm application of compound A to rats suffering from traumatic brain injury induced by subdural hematoma resulted in a significant reduction of the cerebral infarct volume. These results suggest that by inhibiting NF-kappa B and AP-1 signaling, compound A is able to reduce tissue inflammation and neuronal cell death, resulting in significant neuroprotection in animal models of neurodegeneration.

Topics: Animals; Benzofurans; Brain Injuries; Cells, Cultured; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Humans; Male; Mice; Mice, Inbred C57BL; Neuroprotective Agents; Parkinson Disease; Plant Extracts; Rats; Rats, Wistar

Activity-guided fractionation of a CHCl(3)-soluble extract of the twigs of Aglaia rubiginosa, using human oral epidermoid carcinoma (KB) cells as a monitor, led to the isolation of a new naturally occurring cyclopenta[b]benzofuran, 1-O-acetylrocaglaol (1), along with seven known compounds, methyl rocaglate (2), rocagloic acid (3), 1-O-acetylmethyl rocaglate (4), desyclamide, eryodictiol, 5-hydroxy-3,7,4'-trimethoxyflavone, and naringenin. A CHCl(3) extract of the leaves of A. rubiginosa yielded the new compound (3S,4R,22R)-cholest-7,24-diene-3,4,22-triol (5), as well as 11 known compounds, including 2 and 4 and cabraleone, dammarelonic acid, (20S,23E)-20,25-dihydroxy-3,4-secodammara-4(28),23-dienoic acid, (20S,23E)-20,25-dihydroxy-3,4-secodammara-4(28),23-dienoic acid methyl ester, (3beta,4beta,22R)-ergosta-5,24(24')-diene-3,4,22-triol, ocotillone, shoreic acid, beta-sitosterol, and beta-sitosterol glycoside. The structures of 1 and 5 were elucidated by spectral and chemical methods. Isolates were evaluated with a human cancer cell panel, and compounds 1-4 were found to exhibit potent cytotoxic activity.

Topics: Aglaia; Antineoplastic Agents, Phytogenic; Benzofurans; Drug Screening Assays, Antitumor; Humans; Hydroxycholesterols; Indonesia; KB Cells; Molecular Structure; Plant Leaves; Plant Stems; Plants, Medicinal; Stereoisomerism; Tumor Cells, Cultured

Three new cytotoxic compounds, rocagloic acid (1), elliptifoline (2), and elliptinol (3) were isolated from the leaves of Aglaia elliptifolia. The structures of compounds 1-3 were determined by spectral (NMR, MS) and chemical analysis.

Topics: Antineoplastic Agents, Phytogenic; Benzene Derivatives; Benzofurans; China; Chromatography, Thin Layer; Diamide; Drug Screening Assays, Antitumor; Humans; Magnetic Resonance Spectroscopy; Mass Spectrometry; Plant Leaves; Plants, Medicinal; Pyrroles; Spectrophotometry, Infrared; Tumor Cells, Cultured