Deoxycholic acid inclusion compounds

Fig. 3. Channel inclusion compound of deoxycholic acid (6) with acetone. The crystal packing is affected by head-to-tail H-bond-mediated double layers of host molecules (H-bonds as dotted lines, guest molecules shaded) (Adapted from Ref. 13)...

Multimolecular helical inclusion networks formed by rigid alicyciic diols, urea, deoxycholic acid, and tri-o-thymotide are described and contrasted, followed by discussion of DNA intercalates, amylose compounds, and other inclusion systems formed by helical polymers. 

Deoxycholic acid (DCA) (17) and apoeholic acid (ACA) (18) are typical examples of the bile acid family of materials, but with the unique property of forming inclusion compounds with a wide variety of guest molecules 92). Partly due to the cis ring junction between rings A and B, and partly due to the conformation of the steroidal side chain these compounds present a convex hydrophobic P-face and a concave hydrophilic a-face, as shown for DCA (19), a classical aid to the formation of inclusion compounds 93). 

In contrast, the fluorescence spectra of the parent y-cyclodextrins (compounds y-CD1, y-CD2, y-CD3, y-CD4) exhibit both monomer and excimer bands in the absence of guests because the cavity is large enough to accommodate both fluorophores (Figure 10.38). The ratio of excimer and monomer bands changes upon guest inclusion. The ratio of the intensities of the monomer and excimer bands was used for detecting various cyclic alcohols and steroids (cyclohexanol, cyclo-dodecanol, i-borneol, 1-adamantanecarboxylic acid, cholic acid, deoxycholic acid and parent molecules, etc.). 

An important advantage of the inclusion complexes of the cyclodextrins over those of other host compounds, particularly in regard to their use as models of enzyme-substrate complexes, is their ability to be formed in aqueous solution. In the case of clathrates, gas hydrates, and the inclusion complexes of such hosts as urea and deoxycholic acid, the cavity in which the guest molecule is situated is formed by the crystal lattice of the host. Thus, these inclusion complexes disintegrate when the crystal is dissolved. The cavity of the cyclodextrins, however, is a property of the size and shape of the molecule and hence it persists in solution. In fact, there is evidence that suggests that the ability of the cyclodextrins to form inclusion complexes is dependent on the presence of water. Once an inclusion complex has formed in solution, it can be crystallized however, in the solid state, additional cavities appear in the lattice, as in the case of the hosts previously mentioned, which enable the inclusion of further guest molecules. ... 

Among other hosts108 for inclusion and/or clathrate compounds are deoxycholic acid,101 cholic acid,102 small ring compounds such as 29,103 perhydrotriphenylene,104 and the compound 30, which has been called a carcerand.105... 

Deoxycholic acid (DCA), apocholic acid (ACA), and cholic acid (CA) form channel-type inclusion compounds with a wide variety of organic molecules. Of these DCA has been extensively investigated. 

Figure 2. Deoxycholic acid packing illustrating the flexible size of the channel cross section. Packing viewed along the c axis (a) no guest, (b) phenanthrene, (c) norbornadiene, and (d) acetone as guests. The channels have variable size and shape depending on the mutual positions along the b axis of two adjacent bilayers. (Reproduced with permission from E. Giglio in Inclusion Compounds, Vol. 2, J. L. Atwood, J. E. D. Davies, and D. D. MacNicol, Eds., Academic Press, New York, 1984, p. 215.).

Free-radical attack on tertiary C—H bonds has been used for the direct hydroxyla-tion of steroids,but with almost random attack at the available tertiary centres. In a novel regio- and stereo-specific version of this procedure, the solid inclusion complex of deoxycholic acid and di-t-butyl diperoxycarbonate (4 1) gave the 5/8-hydroxy-derivative of deoxycholic acid as the only hydroxylated product, on heating at 90 °C or by photolysis. An X-ray study of the inclusion complex showed a normal arrangement of deoxycholic acid molecules to form a channel, but the guest peroxy-compound is apparently disordered within the channel, as it could not be located. 

Polymerization of cis- or trans-pentadienes as inclusion compounds with deoxycholic acid, by y-irradiation, gave optically active polymers.The electrochemical determination of vitamin D in the presence of vitamin A has been explored. Substantial losses of corticosterone and its 11-deoxy-derivative occurred when methanolic solutions were evaporated in soda-lime test tubes, although borosilicate tubes were satisfactory. The fire and explosion hazards have been assessed for a variety of commercial steroids in aerosol form. A review of... 

Deoxycholic acid crystallizes from aromatic solvents as inclusion compounds with characteristic properties. A single molecule of solvent appears to be trapped in the cavity formed by association of a pair of deoxycholic acid molecules. ... 

Model building of deoxycholeic acid assemblies and x-ray studies of inclusion compound fibers (choleic acids) show that about eight deoxycholic acid molecules may entrap one palmitic acid molecule (Fig. 3.5.2). 

Figure 3.5.2 Schematic stracture of a choleic acid, an inclusion compound of a fatty acid in deoxycholic acid assembUes in water (From Conte et al., 1984.)...

Porous host substructures with parallel channels are typical of many inclusion compounds formed by bile acids and their derivatives (see Deoxycholic, Cholic, and Apocholic Acids). In this class of compounds, host molecules are always optically active, and the resulting host networks are chiral. The best known among them are inclusion compounds of deoxycholic acid (DCA) (also known as choleic acidsj. With most guests. DCA molecules assemble via hydrogen bonds into a coiTugated... 

Channel Inclusion Compounds, p. 223 Clathrate Hydrates, p. 274 Deoxycholic, Cholic, and Apocholic Acids, p. 441 Gossypol, p. 606... 

Giglio. E. Inclusion Coinpounds of Deoxycholeic Acid. In Inclusion Compounds Atwood. J.L.. Davies, J.E.D.. MacNicoI, D.D.. Eds. Academic Press London. 1984 Vol. 2. 207. 

A chiral host could readily be available from a naturally occurring compound. The use of steroidal acid, deoxycholic acid (Fig. 3d), yielded coinprehensive polymers, particularly, optically active polymers from pro-chiral monomers. Many derivatives of deoxy cholic acid have the corresponding characteristic inclusion abilities. For example, use of apocholic acid (Fig. 3e), cholic acid (Fig. 3f), and chenodeoxycholic acid (Fig. 3g) enabled us to perform one-dimensional inclusion polymerization of various diene and vinyl monomers. 

Polar and coordinatively active functional groups are structural elements frequently found in the constitution of crystal inclusion hosts, mainly including conventional host molecules Typical examples are urea (2), diiourea (5), hydroquinone (4), Dianin s compound (J), deoxycholic acid (d) or simply water (Fig. 1). This was the reason to asume that fuiK tional groups play an important part in the construction of crystal indtision compounds. 

Figure 1 Molecular structures of some organic molecules that form the host structures in solid inclusion compounds (these specific host structures are encountered freqnently in this chapter) urea, thiourea, tri-orfto-thymotide (TOT), perhydrotriphenylene (PHTP), deoxycholic acid (DCA) and varions molecules related to deoxycholic acid, host A (l,l,6,6-tetraphenylhexa-2,4-diyne-l,6-diol), host B (frans-2,3-bis(hydroxydiphenylmethyl)-l,4-dioxaspiro[5.4]decane), and host C (irans-2,3-bis(hydroxydiphenylmethyl)-l,4-dioxaspiro[5.4]nonane).

Deoxycholic acid, C24H40O4, has an arched shape (Fig. 26) and forms inclusion compounds of the channel type with a wide variety of organic molecules. 

Inclusion compounds are one of the most important molecular self-assemblies made of synthetic molecular parts. Urea, thiourea, and deoxycholic acid are frequently used as host molecules for small guest molecules. Inor-... 

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