ABSTRACT
Lipid peroxidation is a major deleterious effect caused by oxidative stress. It is involved in various diseases such as atherosclerosis, rheumatoid arthritis and neurodegenerative diseases. In order to inhibit lipid peroxidation, antioxidants must efficiently scavenge free radicals and penetrate inside biological membranes. Lipocarbazole has recently been shown to be a powerful antioxidant in solution. Here, we show its powerful capacity as lipid peroxidation inhibitor. Its mechanism of action is rationalized based on molecular dynamics simulations on a biomembrane model, quantum calculations and experimental evaluation. The role of the lipocarbazole side chain is particularly highlighted as a critical chemical feature responsible for its antioxidant activity.
Subject(s)
Antioxidants/chemistry , Carbazoles/chemistry , Fatty Acids/chemistry , Unilamellar Liposomes/chemistry , Antioxidants/metabolism , Carbazoles/metabolism , Fatty Acids/metabolism , Molecular Dynamics Simulation , Quantum Theory , Thermodynamics , Unilamellar Liposomes/metabolismABSTRACT
The antibiotic feglymycin is a linear 13-mer peptide synthesized by the bacterium Streptomyces sp. DSM 11171. It mainly consists of the nonproteinogenic amino acids 4-hydroxyphenylglycine and 3,5-dihydroxyphenylglycine. An alanine scan of feglymycin was performed by solution-phase peptide synthesis in order to assess the significance of individual amino acid side chains for biological activity. Hence, 13 peptides were synthesized from di- and tripeptide building blocks, and subsequently tested for antibacterial activity against Staphylococcus aureus strains. Furthermore we tested the inhibition of peptidoglycan biosynthesis enzymes MurA and MurC, which are inhibited by feglymycin. Whereas the antibacterial activity is significantly based on the three amino acids D-Hpg1, L-Hpg5, and L-Phe12, the inhibitory activity against MurA and MurC depends mainly on L-Asp13. The difference in the position dependence for antibacterial activity and enzyme inhibition suggests multiple molecular targets in the modes of action of feglymycin.
Subject(s)
Alanine/chemistry , Anti-Infective Agents/chemistry , Proteins/chemistry , Alkyl and Aryl Transferases/antagonists & inhibitors , Alkyl and Aryl Transferases/metabolism , Anti-Infective Agents/chemical synthesis , Anti-Infective Agents/pharmacology , Microbial Sensitivity Tests , Peptides/chemical synthesis , Peptides/chemistry , Peptides/pharmacology , Proteins/chemical synthesis , Proteins/pharmacology , Staphylococcus aureus/drug effectsABSTRACT
Feglymycin (FGM), a natural Streptomyces-derived 13mer peptide, consistently inhibits HIV replication in the lower µM range. FGM also inhibits HIV cell-to-cell transfer between HIV-infected T cells and uninfected CD4(+) T cells and the DC-SIGN-mediated viral transfer to CD4(+) T cells. FGM potently interacts with gp120 (X4 and R5) as determined by SPR analysis and shown to act as a gp120/CD4 binding inhibitor. Alanine-scan analysis showed an important role for l-aspartic acid at position 13 for its anti-HIV activity. In vitro generated FGM-resistant HIV-1 IIIB virus (HIV-1 IIIB(FGMres)) showed two unique mutations in gp120 at positions I153L and K457I. HIV-1 IIIB(FGMres) virus was equally susceptible to other viral binding/adsorption inhibitors with the exception of dextran sulfate (9-fold resistance) and cyclotriazadisulfonamide (>15-fold), two well-described compounds that interfere with HIV entry. In conclusion, FGM is a unique prototype lead peptide with potential for further development of more potent anti-HIV derivatives.
Subject(s)
Anti-HIV Agents/pharmacology , HIV Envelope Protein gp120/antagonists & inhibitors , HIV-1/drug effects , Proteins/pharmacology , Virus Internalization/drug effects , Amino Acid Sequence , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Anti-HIV Agents/chemistry , Bacterial Proteins/chemistry , Bacterial Proteins/pharmacology , CD4 Antigens/drug effects , Cell Line , Drug Discovery , Giant Cells/drug effects , HIV-1/classification , HIV-1/pathogenicity , HIV-1/physiology , Humans , Peptides , Proteins/chemistrySubject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Models, Biological , Peptide Synthases/antagonists & inhibitors , Peptidoglycan/biosynthesis , Proteins/pharmacology , Binding, Competitive , Enzyme Activation/drug effects , Enzyme Inhibitors/pharmacology , Escherichia coli/enzymology , Molecular Structure , PeptidesABSTRACT
A family of new secondary metabolites with a carbazole moiety and an alkyl side chain was isolated from Tsukamurella pseudospumae strain Acta 1857. They were named lipocarbazoles in accordance with their chemical structures, which were determined by mass spectrometry and NMR spectroscopy. Lipocarbazoles are free radical scavengers showing antioxidative activity.
Subject(s)
Actinomycetales/chemistry , Antioxidants/isolation & purification , Antioxidants/pharmacology , Carbazoles/isolation & purification , Carbazoles/pharmacology , Lipids/isolation & purification , Antioxidants/chemistry , Carbazoles/chemistry , Lipids/chemistry , Lipids/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Spectrometry, Mass, Electrospray IonizationABSTRACT
An adaptable approach: The first highly convergent stereoselective synthesis of feglymycin (see structure) and its enantiomer is based on the coupling of repeating peptide fragments. The use of weakly basic conditions throughout the synthesis suppressed the epimerization of sensitive aryl glycine units. Feglymycin has strong anti-HIV activity as well as potent (previously identified as weak) antibacterial activity against Staphylococcus aureus.
