Polymorphic Self-Organization of Lauroyl Peptide in Response to pH and Concentration

Lipopeptides as tools in catalysis, supramolecular, materials and medicinal chemistry

Lipopeptides are amphiphilic peptides in which an aliphatic chain is attached to either the C or N terminus of peptides. Their self-assembly - into micelles, vesicles, nanotubes, fibres or nanobelts - leads to applications in nanotechnology, catalysis or medicinal chemistry. Self-organization of lipopeptides is dependent on both the length of the lipid tail and the amino acid sequence, in which the chirality of the peptide sequence can be transmitted into the supramolecular species. This Review describes the use of lipopeptides to design synthetic advanced dynamic supramolecular systems, nanostructured materials or self-responsive delivery systems in the area of medical biotechnology. We examine the influence of external stimuli, the ability of lipopeptide-derived structures to adapt over time and their application as medicinal agents with antibacterial, antifungal, antiviral or anticancer activities. Finally, we discuss the catalytic efficiency of lipopeptides, with the aim of building minimal synthetic enzymes, and recent efforts to incorporate metals into lipopeptide assemblies.

Identification and characterization of biocontrol agent Lysinibacillus boronitolerans P42 against Cerrena unicolor that causes root rot of arecanut palm

The arecanut palm is one of the most important industrial crops in tropical area around the world. The root rot of arecanut palm, which is caused by Cerrena unicolor, has led to heavy economic losses and restricted greatly the development of arecanut industry, especially in Hainan province of China. The common use of chemical agents has worsened the problems of the emergence of resistant pathogens and the pollution of agricultural environment. This study aims to screen and identify a more effective and environment friendly biocontrol method for the prevention and treatment of root rot of arecanut palm. The mycelium growth rate is investigated to select antagonistic bacteria from tropical crop rotation fields which show improved resistance against soil-borne pathogens, and the strain P42 is revealed with the strongest antagonistic effects (82.18%). Based on 16 s rDNA sequence analysis, the strain P42 is identified as Lysinibacillus boronitolerans. In vitro antimicrobial activity shows that the strain P42 exhibits broad-spectrum antagonistic activity against a wide variety of tropical agricultural fungal pathogens, including Cerrena unicolor, Magnaporthe oryzea, Botryodiplodia theobromae, Neoscytalidium dimidiatum, Thanatephorus cucumeris, Fusarium oxysporum, and Botrytis cinerea Per.. The antagonistic activity of the culture of P42 is tolerant to common proteases, longer storage time, and temperature range of 40-121 °C; and is significantly influenced by alkaline (7-9) and acidic (1-2) pH, as well as by ultraviolet ray treatment for more than 30 min. The investigation on the antagonistic activity of the crude extract of fermentation filtrate indicates that the active compounds might be lipopeptides, polyketones, or proteins. To our knowledge, this is the first report of L. boronitolerans as potential bio-reagents for controlling root rot of arecanut palm caused by Cerrena unicolor.

Amphiphilic self-assembly peptides: Rational strategies to design and delivery for drugs in biomedical applications

Amphiphilic self-assembling peptides are widely used in tissue and cell engineering, antimicrobials, drug-delivery systems and other biomedical fields due to their good biocompatibility, functionality, flexibility of design and synthesis, and tremendous potential as delivery carriers for drugs. Currently, the design and study of amphipathic peptides by a bottom-up method to develop new biomedical materials have become a hot topic. However, defined rules have not been established for the design and development of self-assembled peptides. Therefore, the focus of this review is to summarize and provide several rational strategies for the design and study of amphiphilic self-assembly peptides. In addition, this paper also describes the types and general self-assembling mechanism of amphipathic peptides, and outlines their applications in the delivery of hydrophobic drugs, nucleic acid drugs, peptide drugs and vaccines. Amphiphilic self-assembled peptides are expected to exploit new functional materials for drug delivery and other applications.

Time-programmable pH: decarboxylation of nitroacetic acid allows the time-controlled rising of pH to a definite value

In this report it is shown that nitroacetic acid 1 (O2NCH2CO2H) can be conveniently used to control the pH of a water solution over time. Time-programmable sequences of the kind pH1(high)-pH2(low)-pH3(high) can be achieved, where both the extent of the initial pH jump (pH1(high)-pH2(low)) and the time required for the subsequent pH rising (pH2(low)-pH3(high)) can be predictably controlled by a judicious choice of the absolute and relative concentrations of the reagents (acid 1 and NaOH). Successive pH1(high)-pH2(low)-pH3(high) sequences can be obtained by subsequent additions of acid 1. As a proof of concept, the method is applied to control over time the pH-dependent host-guest interaction between alpha-cyclodextrin and p-aminobenzoic acid.