-
Oncology Reports Nov 2007Alkylolides and alkenylolides of 198-254 Da such as hexadecan-16-olide and 9-hexadecen-16-olide were chemically synthesized in the present study as new macrocyclic...
Alkylolides and alkenylolides of 198-254 Da such as hexadecan-16-olide and 9-hexadecen-16-olide were chemically synthesized in the present study as new macrocyclic lactones that are structurally different from widespread natural macrocyclic lactones including bryostatin (887 Da) and rhizoxin (613 Da), and were investigated for antitumor activity to Ehrlich ascites tumor cells by mitochondrial dehydroganase-based WST-1 assay and dye-exclusion assay. Of the alkylolides having 12, 15 or 16 carbon-atoms (D12:0, P15:0 or H16:0) and alkenylolides having 15 or 16 carbon-atoms with a double bond (P15:1 or H16:1), H16:0 was the most carcinostatic when administered at 37 degrees C for 20 h, with cell deformation and microvillus disappearance as detected by scanning electron microscopy. The carcinostatic activity was increased markedly for H16:0 and P15:0 when the administration period was prolonged to 72 h, but was not enhanced by intramolecular introduction of a double bond for P15:1 or H16:1. Hyperthermia at 42 degrees C for 30 min additively intensified the carcinostatic activity for H16:0 and P15:0, but scarcely for D12:0, and intensified the alkenyloides P15:1 and H16:1 only upon the subsequent 72-h treatment. Invasion of human fibrosarcoma HT-1080 cells through the reconstituted basement membrane was inhibited by alkyl- and alkenylolides even after the short-term exposure at 25 microM for 3 h without diminishing the cell viability. H16:0 also exhibited the most inhibitory activity to tumor invasion in addition to the highest carcinostatic activity. Both inhibitions were promoted by combination with hyperthermia. Thus diverse alkyl-/alkenylolides, may be potent multi-applicable anticancer agents in terms of either dual inhibitory activities against both tumor progression and invasion or hyperthermia-combined therapy.
Topics: Animals; Antineoplastic Agents; Bryostatins; Carcinoma, Ehrlich Tumor; Cell Survival; Combined Modality Therapy; Fibrosarcoma; Humans; Hyperthermia, Induced; Lactones; Macrolides; Neoplasm Invasiveness; Tumor Cells, Cultured
PubMed: 17914582
DOI: No ID Found -
Organic & Biomolecular Chemistry Jul 2007Targeted gene inactivation and metabolic profiling revealed that the cryptic PKS-NRPS gene cluster in the genome of the plant commensal Pseudomonas fluorescens Pf-5...
Targeted gene inactivation and metabolic profiling revealed that the cryptic PKS-NRPS gene cluster in the genome of the plant commensal Pseudomonas fluorescens Pf-5 codes for the biosynthesis of antiproliferative and antifungal rhizoxin derivatives.
Topics: Antimitotic Agents; Genes, Bacterial; Genome, Bacterial; Macrolides; Models, Biological; Pseudomonas fluorescens
PubMed: 17609750
DOI: 10.1039/b707762a -
Chembiochem : a European Journal of... Jan 2007
Topics: Antimitotic Agents; Burkholderia; Chromatography, High Pressure Liquid; Cosmids; Fungi; Gene Library; Macrolides; Models, Chemical; Multigene Family; Mutation; Rhizopus; Sequence Analysis, DNA; Symbiosis; Time Factors
PubMed: 17154220
DOI: 10.1002/cbic.200600393 -
Journal of the American Chemical Society Sep 2006The potent antimitotic polyketide macrolide rhizoxin, the causal agent of rice seedling blight, is not produced by the fungus Rhizopus microsporus, as has been believed...
The potent antimitotic polyketide macrolide rhizoxin, the causal agent of rice seedling blight, is not produced by the fungus Rhizopus microsporus, as has been believed for over two decades, but by endosymbiotic bacteria that reside within the fungal mycelium. Here we report the successful isolation and large-scale fermentation of the bacterial endosymbiont ("Burkholderia rhizoxina") in pure culture, which resulted in a significantly elevated (10x higher) production of antimitotics. In addition to several known rhizoxin derivatives, numerous novel natural and semisynthetic variants were isolated, and their structures were fully elucidated. Cell-based assays as well as tubulin binding experiments revealed that methylated seco-rhizoxin derivatives are 1000-10000 times more active than rhizoxin and thus rank among the most potent antiproliferative agents known to date. Furthermore, more stable didesepoxy rhizoxin analogues were obtained by efficiently inhibiting a putative P-450 monooxygenase involved in macrolide tailoring.
Topics: Animals; Antimitotic Agents; Burkholderia; Cell Proliferation; Cell Survival; Chromatography, High Pressure Liquid; Fibroblasts; HeLa Cells; Humans; K562 Cells; Macrolides; Mice; Microtubule Proteins; Molecular Structure; Oryza; Rhizopus; Structure-Activity Relationship; Symbiosis
PubMed: 16939276
DOI: 10.1021/ja062953o -
Bioorganic & Medicinal Chemistry Letters Sep 20064,7-Difluoro-2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione [4,7FPP-33 (14)] has a potent tubulin-polymerization-inhibiting activity comparable with those of the known...
4,7-Difluoro-2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione [4,7FPP-33 (14)] has a potent tubulin-polymerization-inhibiting activity comparable with those of the known tubulin-polymerization inhibitors rhizoxin and colchicine. The structure-activity relationship for fluorine substitution was elucidated.
Topics: Fluorine; Molecular Structure; Phthalimides; Structure-Activity Relationship; Tubulin
PubMed: 16870433
DOI: 10.1016/j.bmcl.2006.06.091 -
Organic & Biomolecular Chemistry Dec 2005An enantioselective synthesis of rhizoxin D, isolated from the plant pathogenic fungus Rhizopus chinensis, is described. The overall strategy is based on elaboration of...
An enantioselective synthesis of rhizoxin D, isolated from the plant pathogenic fungus Rhizopus chinensis, is described. The overall strategy is based on elaboration of the delta-lactone-substituted vinyl stannane and the phosphonate-substituted vinyl iodide, followed by their coupling to the core 16-membered macrolide via a sequential intermolecular Horner-Wadsworth-Emmons olefination, leading to (50), and by an intramolecular Stille reaction. The triene oxazole-containing side chain in rhizoxin D is then introduced using the phosphine oxide in an E-selective Horner-Wittig reaction with the macrolide aldehyde.
Topics: Antineoplastic Agents; Lactones; Macrolides; Molecular Structure
PubMed: 16327903
DOI: 10.1039/b507570j -
Nature Oct 2005A number of plant pathogenic fungi belonging to the genus Rhizopus are infamous for causing rice seedling blight. This plant disease is typically initiated by an...
A number of plant pathogenic fungi belonging to the genus Rhizopus are infamous for causing rice seedling blight. This plant disease is typically initiated by an abnormal swelling of the seedling roots without any sign of infection by the pathogen. This characteristic symptom is in fact caused by the macrocyclic polyketide metabolite rhizoxin that has been isolated from cultures of Rhizopus sp.. The phytotoxin exerts its destructive effect by binding to rice beta-tubulin, which results in inhibition of mitosis and cell cycle arrest. Owing to its remarkably strong antimitotic activity in most eukaryotic cells, including various human cancer cell lines, rhizoxin has attracted considerable interest as a potential antitumour drug. Here we show that rhizoxin is not biosynthesized by the fungus itself, but by endosymbiotic, that is, intracellular living, bacteria of the genus Burkholderia. Our unexpected findings unveil a remarkably complex symbiotic-pathogenic relationship that extends the fungus-plant interaction to a third, bacterial, key-player, and opens new perspectives for pest control.
Topics: Antibiotics, Antineoplastic; Burkholderia; Cell Extracts; Chromatography, High Pressure Liquid; Lactones; Lasers; Macrolides; Molecular Sequence Data; Molecular Structure; Mycelium; Oryza; Phylogeny; Plant Diseases; Polymerase Chain Reaction; Rhizopus; Symbiosis; Toxins, Biological
PubMed: 16208371
DOI: 10.1038/nature03997 -
Nature Oct 2005
Topics: Burkholderia; Lactones; Macrolides; Oryza; Plant Diseases; Polyketide Synthases; Rhizopus; Symbiosis; Toxins, Biological
PubMed: 16208353
DOI: 10.1038/437823a -
Journal of Cell Science Oct 2005Procyclic-form Trypanosoma brucei is arrested in G1 phase with extended and/or branched posterior morphology when expression of its cdc2-related kinases 1 and 2 (CRK1...
Procyclic-form Trypanosoma brucei is arrested in G1 phase with extended and/or branched posterior morphology when expression of its cdc2-related kinases 1 and 2 (CRK1 and CRK2) is knocked down by RNA interference. Transmission electron microscopy indicated that the mitochondrion in the cell is also extended and branched and associated with cortical microtubules in each elongated/branched posterior end. This posterior extension is apparently driven by the growing microtubule corset, as it can be blocked by rhizoxin, an inhibitor of microtubule assembly. In the bloodstream form of T. brucei, however, a knockdown of CRK1 and CRK2 resulted only in an enrichment of cells in G1 phase without cessation of DNA synthesis or elongated/branched posterior ends. A triple knockdown of CRK1, CRK2 and CycE1/CYC2 in the bloodstream form resulted in 15% of the cells arrested in G1 phase, but no cells had an abnormal posterior morphology. The double and triple knockdown bloodstream-form cells were differentiated in vitro into the procyclic form, and the latter thus generated bore the typical morphology of a procyclic form without an extended/branched posterior end, albeit arrested in the G1 phase as the bloodstream-form precursor. There is thus a major distinction in the mechanisms regulating G1-S transition and posterior morphogenesis between the two life stages of T. brucei.
Topics: Animals; CDC2 Protein Kinase; Cell Shape; Cells, Cultured; Cyclins; Cytoskeleton; DNA; Fluorescent Dyes; G1 Phase; Humans; Life Cycle Stages; Macrolides; Microtubules; Mitochondria; Protozoan Proteins; RNA Interference; S Phase; Trypanosoma brucei brucei; Tubulin Modulators
PubMed: 16144864
DOI: 10.1242/jcs.02567 -
Journal of Agricultural and Food... Mar 2005Fast-growing Zygomycetes, most notably Rhizopus oligosporus, are traditionally used in many food fermentations, for example, for soybean tempeh production. R.... (Comparative Study)
Comparative Study
Fast-growing Zygomycetes, most notably Rhizopus oligosporus, are traditionally used in many food fermentations, for example, for soybean tempeh production. R. oligosporus is considered to belong to the Rhizopus microsporus group. Certain R. microsporus strains have been reported to produce either the pharmaceutically active rhizoxins or the highly toxic rhizonins A and B. In this study was investigated the formation of secondary metabolites by R. microsporus, R. oligosporus, and Rhizopus chinensis grown on a wide range of different semisynthetic and natural substrates. Liquid chromatography, combined with photodiode array detection and high-resolution mass spectrometric techniques, was used to identify secondary metabolites. Growth on maize, brown rice, and Pharma agar gave both the highest amounts and the maximum diversity of rhizoxins and rhizonins. Rhizoxins were produced by all four R. microsporus strains, whereas only one strain produced rhizonins. The six R. oligosporus and four R. chinensis strains investigated did not produce any of these two classes of metabolites.
Topics: Chromatography, Liquid; Fermentation; Lactones; Macrolides; Mass Spectrometry; Mycotoxins; Oryza; Peptides, Cyclic; Rhizopus; Species Specificity; Zea mays
PubMed: 15740082
DOI: 10.1021/jf048147n