Filipin compound

In order to ameliorate the problem of solvolytic degradation, compound 109 was treated with TIPSOTf, to provide silyl ether 113 in 72% yield (Scheme 19). The acetonides were removed with PPTS in warm MeOH to provide a mixture of compounds in which the TBS groups were also partially removed. Exposure of this mixture to HF-pyridine successfully generated filipin III (114), in 39 % overall yield from 113. 

Lipid raft domains of plasma membranes are enriched in cholesterol and sphingolipids. As a consequence, compounds that extract or sequester cholesterol, such as fS-cyclodextrins, nystatin, and filipin, can block selectively endocytosis of cholera toxin, GPI-linked proteins, and other receptors that associate with lipid rafts and caveolae. However, cholesterol is also critical for CME, secretion of proteins, and the actin network. Therefore, conditions designed to affect selectively raft-mediated endocytosis by perturbing cholesterol levels must be carefully controlled to avoid disrupting other mechanisms of endocytosis (40). 

Filipin. Filipin was recently shown to be a mixture of at least four components, which were designated filipins I, II, III, and IVaccording to mass spectral studies the four compounds were present in the approximate proportion... 

Polyene antibiotics such as amphotericin, nystatin, or filipin are examples of inainly hydrophobic molecules that also have polar groups. In water, these cyclic molecules tend to aggregate to shield their hydrophobic surfaces from water. These compounds are readily incorporated into natural as well as model membranes and tend to aggregate in the bilayer, now in a reversed manner, i.e. shielding their polar groups from the hydrophobic interior of the membrane. The antibiotics form complexes with sterols and act as membrane active compounds in the sense that the bilayers become leaky [116,117]. 

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