ABSTRACT
This study investigated the relationships between lignin molecular and supramolecular structures and their functional properties within cellulose-based solid matrix, used as a model biodegradable polymer carrier. Two types of derivatives corresponding to distinct structuration levels were prepared from a single technical lignin sample (PB1000): phenol-enriched oligomer fractions and colloidal nanoparticles (CLP). The raw lignin and its derivatives were formulated with cellulose nanocrystals or nanofibrils to prepare films by chemical oxidation or pressure-assisted filtration. The films were tested for their water and lignin retention capacities, radical scavenging capacity (RSC) and antimicrobial properties. A structural investigation was performed by infrared, electron paramagnetic resonance spectroscopy and microscopy. The composite morphology and performance were controlled by both the composition and structuration level of lignin. Phenol-enriched oligomers were the compounds most likely to interact with cellulose, leading to the smoothest film surface. Their RSC in film was 4- to 6-fold higher than that of the other samples. The organization in CLP led to the lowest RSC but showed capacity to trap and stabilize phenoxy radicals. All films were effective against S. aureus (gram negative) whatever the lignin structure. The results show the possibility to tune the performances of these composites by exploiting lignin multi-scale structure.
Subject(s)
Lignin/chemistry , Anti-Bacterial Agents/pharmacology , Antioxidants/pharmacology , Escherichia coli/drug effects , Free Radical Scavengers/chemistry , Intercellular Signaling Peptides and Proteins/metabolism , Microbial Sensitivity Tests , Microscopy, Atomic Force , Nanoparticles/chemistry , Nanoparticles/ultrastructure , Phenols/chemistry , Spectroscopy, Fourier Transform Infrared , Staphylococcus aureus/drug effects , Suspensions , Water/chemistryABSTRACT
A series of polyhydroxy-pyrrolizidines were designed as constrained analogues of 6-deoxy-homoDMDP, a potent naturally occurring inhibitor of chitin synthase. Enzymatic evaluation revealed that 7-deoxycasuarine was the best inhibitor of the series (IC50 = 820 microM) displaying a noncompetitive inhibition pattern, whereas the other tested compounds had IC50 in the range 4.3-18.9 mM. This is the first report of pyrrolizidine-type iminosugars inhibiting a glycosyltransferase. In addition, the inhibitory potencies towards glycosidases of these synthetic casuarine analogues is also disclosed.
Subject(s)
Alkaloids/chemical synthesis , Alkaloids/pharmacology , Chitin Synthase/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Pyrroles/chemical synthesis , Pyrroles/pharmacology , Pyrrolizidine Alkaloids/chemical synthesis , Pyrrolizidine Alkaloids/pharmacology , Chitin Synthase/metabolism , Glycoside Hydrolases/antagonists & inhibitors , Glycoside Hydrolases/metabolism , Inhibitory Concentration 50 , Molecular Structure , Saccharomyces cerevisiae/enzymology , StereoisomerismABSTRACT
A series of polyhydroxy-pyrrolizidines were designed as constrained analogues of 6-deoxyhomoDMDP, a potent naturally occurring inhibitor of chitin synthase. Enzymatic evaluation revealed that 7-deoxycasuarine was the best inhibitor of the series (IC50 = 820 microM) displaying a non-competitive inhibition pattern, whereas the other tested compounds had IC50 in the range 4.3-18.9 mM. This is the first report of pyrrolizidine-type iminosugars inhibiting a glycosyltransferase. In addition, the biological evaluation towards glycosidases of these synthetic casuarine analogues is also disclosed.
