Amphipathic, definition

Non-Aqueous Processes. Dispersions of composite particles in non-aqueous media (12) have been prepared. The particles were sterically stabilised to prevent flocculation and aggregation. This was achieved by physical absorption of amphipathic graft or block copolymer (13,14) or by covalent attachment of diluent-soluble oligomer or polymer chains (15) at the particle surface so that by definition different polymers were situated at the surface and in the bulk of the particles, even for single-polymer particles. Composite particles were prepared by slow addition of the second monomer which was fully miscible with the diluent phase, obviating a monomer droplet phase further monomer-soluble initiation and amphipathic graft stabiliser was included as appropriate so that the process comprised continued dispersion... 

Palytoxin is a white, amorphous, hydroscopic solid that has not yet been crystallized. It is insoluble in nonpolar solvents such as chlorophorm, ether, and acetone sparingly soluble in methanol and ethanol and soluble in pyridine, dimethyl sulfoxide, and water. The partition coefficient for the distribution of palytoxin between 1-butanol and water is 0.21 at 25°C based on comparison of the absorbance at 263 nm for the two layers. In aqueous solutions, palytoxin foams on agitation, like a steroidal saponin, probably because of its amphipathic nature. The toxin shows no definite melting point and is resistant to heat but chars at 300°C. It is an optically active compound, having a specific rotation of -i-26° 2° in water. The optical rotatory dispersion curve of palytoxin exhibits a positive Cotton effect with [a]25o being -i-700° and [a]2,j being +600° (Moore and Scheuer 1971 Tan and Lau 2000). 

The most recent definition of lipids was provided by a group of lipid chemists who formed the consortium of lipid metabolites and pathways strategy (Lipid MAPS). They defined lipids based on the origin of the lipid structures as hydrophobic or amphipathic small molecules that may originate entirely or, in part, by carbanion-based condensations of thioesters (fatty acids, polyketides, etc.) and/or by carbocation-based condensations of isoprene units (prenols, sterols, etc.). In this book, this definition, its classification (see the following), and its recommended nomenclature are largely accepted. 

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