ABSTRACT
Liposomes are regarded as promising drug carriers for enhancing the pharmacological effects of poorly absorbed drugs, such as peptides, following oral administration. Liposomal surface modifications by mucoadhesive polymers could improve drug absorption through interactions with the mucus layer. The main purpose of this study was to establish a method of monitoring the behavior of liposomes within the body after oral administration, particularly in the gastrointestinal (GI) tract, using a real-time in vivo imaging system (IVIS) to elucidate the behavior of surface-modified liposomes. Indocyanine green (ICG) was used as a near-infrared dye to label chitosan (CS) or glycol CS (GCS)-modified liposomes, and to observe the dynamic behavior of the liposomes in rats by noninvasive IVIS after oral administration. First, we validated IVIS results of the rat abdomens by comparing them to quantitative measurements of ICG fluorescence intensity in tissue homogenates. Nano-sized small unilamellar vesicles were retained longer than micro-sized multilamellar vesicles in the GI tract. Furthermore, surface-modified liposomes showed longer-term retention in the GI tract than unmodified liposomes in fasted rats. Moreover, surface modification by CS or GCS effectively prevented the excretion of liposomes from the GI tract and prolonged retention in fed rats.
Subject(s)
Gastrointestinal Tract/diagnostic imaging , Gastrointestinal Tract/metabolism , Liposomes/metabolism , Administration, Oral , Animals , Chitosan/chemistry , Drug Delivery Systems , Eating , Fluorescence , Glycols/chemistry , Indocyanine Green , Intestinal Absorption , Male , Particle Size , Rats , Rats, Wistar , Spectroscopy, Near-Infrared , Surface PropertiesABSTRACT
In the course of screening for an inhibitor of ER stress-induced XBP1 activation, we isolated a new member of the triene-ansamycin group compound, trierixin, from a culture broth of Streptomyces sp. AC 654. Trierixin was purified by column chromatography on silica gel and by HPLC. The molecular formula of trierixin is C(37)H(52)N(2)O(8)S. Trierixin inhibited thapsigargin-induced XBP1-luciferase activation in HeLa/XBP1-luc cells and endogenous XBP1 splicing in HeLa cells with an IC(50) of 14 ng/ml and 19 ng/ml, respectively. Moreover, in the process of isolating trierixin, we isolated structurally related mycotrienin II and trienomycin A as inhibitors of ER stress-induced XBP1 activation from a culture broth of a trierixin-producing strain. This study provides the first observation that triene-ansamycins have a novel inhibitory effect against XBP1 activation.
Subject(s)
Anti-Bacterial Agents/pharmacology , DNA-Binding Proteins/antagonists & inhibitors , Lactams, Macrocyclic/pharmacology , Nuclear Proteins/antagonists & inhibitors , Streptomyces/chemistry , Alanine/analogs & derivatives , Alanine/isolation & purification , Anti-Bacterial Agents/classification , Anti-Bacterial Agents/isolation & purification , Endoplasmic Reticulum/drug effects , Endoplasmic Reticulum/metabolism , Fermentation , HeLa Cells , Humans , Hydroquinones/isolation & purification , Inhibitory Concentration 50 , Lactams, Macrocyclic/classification , Lactams, Macrocyclic/isolation & purification , Luciferases/drug effects , Regulatory Factor X Transcription Factors , Reverse Transcriptase Polymerase Chain Reaction , Stress, Physiological/chemically induced , Stress, Physiological/physiopathology , Thapsigargin , Transcription Factors , X-Box Binding Protein 1ABSTRACT
Trierixin, a new member of the triene-ansamycin group, has been isolated from the fermentation broth of Streptomyces sp. AC654 as an inhibitor of ER stress-induced XBP1 activation. The structure of trierixin was determined on the basis of its spectroscopical and chemical properties. Trierixin possessed a 21-membered macrocyclic lactam, which contains a methylthio-benzenediol structure, and a cyclohexanecarbonylalanine moiety. Trierixin is thus elucidated as 21-thiomethylmycotrienin II.
Subject(s)
Lactams, Macrocyclic/chemistry , Streptomyces/chemistry , DNA-Binding Proteins/antagonists & inhibitors , Fermentation , HeLa Cells , Humans , Hydroquinones/chemistry , Hydroquinones/isolation & purification , Lactams, Macrocyclic/isolation & purification , Magnetic Resonance Spectroscopy , Mass Spectrometry , Nuclear Proteins/antagonists & inhibitors , Optical Rotation , Regulatory Factor X Transcription Factors , Spectrophotometry, Ultraviolet , Transcription Factors , Transition Temperature , X-Box Binding Protein 1Subject(s)
Acremonium/metabolism , Interleukin-4/antagonists & inhibitors , Pyrrolidinones/metabolism , Signal Transduction/drug effects , Acremonium/growth & development , Cell Line , HeLa Cells , Humans , Inhibitory Concentration 50 , Interleukin-4/metabolism , Magnetic Resonance Spectroscopy , Molecular Structure , Pyrrolidinones/chemistry , Pyrrolidinones/isolation & purification , Pyrrolidinones/pharmacologyABSTRACT
A novel inhibitor of STAT6 activation, named as TMC-264 (1), was discovered from the fermentation broth of Phoma sp. TC 1674. Based on spectroscopic analyses, TMC-264 was found to be a novel tricyclic polyketide with chloro-1H-dibenzo[b,d]pyran-4,6-dione. TMC-264 suppressed expression of IL-4 driven luciferase and germline Cepsilon mRNA with IC50 values of 0.3 microM and 0.4 microM, respectively. TMC-264 exhibited a potent inhibitory activity against tyrosine phosphorylation of STAT6 with an IC50 value of 1.6 microM, whereas TMC-264 weakly inhibited tyrosine phosphorylation of STAT5 with an IC50 value of 16 microM, but did not inhibit the phosphorylation of STAT1 up to 40 microM. TMC-264 blocked formation of the complexes between phosphorylated STAT6 and STAT6 oligonucleotides in a dose dependent manner, while TMC-264 did not affect the formation of phosphorylated STAT1/STAT1 oligonucleotides complexes. These results suggested that TMC-264 selectively inhibited IL-4 signaling by interfering both of phosphorylation of STAT6 and binding of the phosphorylated STAT6 to the recognition sequence.
Subject(s)
Heterocyclic Compounds, 3-Ring/pharmacology , Trans-Activators/antagonists & inhibitors , Chromatography, High Pressure Liquid , Drug Interactions , Fermentation , HeLa Cells , Heterocyclic Compounds, 3-Ring/isolation & purification , Humans , Interleukin-4/pharmacology , Phosphorylation/drug effects , STAT6 Transcription Factor , Signal Transduction/drug effectsABSTRACT
[structure: see text] TMC-264 (1), a novel tricyclic heptaketide with a unique chloro-1H-dibenzo[b,d]pyran-4,6-dione skeleton, was discovered from the fungus Phoma sp. TC 1674. The structure was elucidated on the basis of NMR analyses of normal abundance and biosynthetically (13)C-enriched TMC-264. TMC-264 showed potent inhibitory activity against tyrosine phosphorylation of STAT6.
Subject(s)
Fungi/chemistry , Heterocyclic Compounds, 3-Ring/chemistry , Heterocyclic Compounds, 3-Ring/isolation & purification , Fungi/classification , Heterocyclic Compounds, 3-Ring/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Phosphorylation/drug effects , Phosphotyrosine/metabolism , STAT6 Transcription Factor , Trans-Activators/metabolismABSTRACT
New inhibitors of IL-4 signal transduction, designated as TMC-256A1 and C1, were discovered together with TMC-256B1, a previously known dihydronaphthopyrone, from the fermentation broth of Aspergillus niger var niger TC 1629 by using an IL-4 driven reporter gene assay. Based on spectroscopic analyses, TMC-256A1 and C1 were found to be new members of the naphthopyrone antibiotics. TMC-256A1, B1 and C1 inhibited the IL-4 driven luciferase activity with IC50 values of 25 microM, 30 microM and 1.7 microM, respectively in this assay system. Furthermore, these compounds inhibited the expression of germline C epsilon mRNA with IC50 values of 6.6 microM , 34 microM and 0.31 microM, respectively.
