Novel permethylated beta-cyclodextrin derivatives appended with chromophores as efficient fluorescent sensors for the molecular recognition of bile salts

Two novel permethylated beta-cyclodextrin (PM-beta-CD) derivatives, i.e., 6I-O-(1-naphtholxy)-2I,31-di-O-methylhexakis(2II-VII,3II-VII,6II-VII-tri-O-methyl)-beta-cyclodextrin (1) and 6I-O-(8-hydroxyquinoline)-2I,31-di-O-methylhexakis(2II-VII,3II-VII,6II-VII- tri-O-methyl)-beta-cyclodextrin (2), were synthesized in satisfactory yields, and their inclusion modes, complex-induced fluorescent behaviors, binding ability, and selectivity for bile salts of biological relevance (cholic acid sodium salt, CA; deoxycholic acid sodium salt, DCA; glycochoic acid sodium salt, GCA; taurocholic acid sodium salt, TCA) were investigated by the circular dichroism, 2D NMR, steady-state, and time-resolved fluorescent spectra. The results obtained from induced circular dichroism and ROESY spectra show that the chromophore groups of 1 and 2 reside in the central cavity of PM-beta-CD, and are expelled to the region of narrow torus rim upon complexation with bile guests, which presents the binding mode of cooperative inclusion. The transfer of the chromophore groups from the central cavity to the more hydrophobic torus rim leads to the remarkable increase of fluorescent intensities and longer fluorescent lifetimes of hosts 1 and 2 upon gradual addition of bile salts, which is importantly distinct from the molecular recognition of the chromophore-modified beta-CD species with bile salts. Interestingly, hosts 1 and 2 present much stronger binding ability for bile guests than PM-beta-CD. Differing from native beta-CD, all the PM-beta-CDs are more prone to include bile salts with longer tails, such as GCA and TCA. Their corresponding binding ability and molecular selectivity are closely discussed from the viewpoints of difference of cavity size/shape between beta-CD and PM-beta-CD, effect of substituent groups, and structures of bile guests, respectively.     

Comparative study on the enantiomer separation of 1,1'-binaphthyl-2,2'diyl hydrogenphosphate and 1,1'-bi-2-naphthol by liquid chromatography and capillary electrophoresis using single and combined chiral selector systems

The chiral recognition ability of single and dual selectors, that were used as additives, have been investigated by HPLC and CE. Native beta- and gamma-cyclodextrins, permethylated beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin, cholic acid and taurodeoxycholic acid sodium salts were applied as chiral selectors, whereas the atropisomers of 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate, and 1,1'-bi-2-naphthol served as model compounds. It was found that all investigated selectors, except for gamma-cyclodextrin, display the same affinity pattern for binaphthyl enantiomers, i.e., binding the S more strongly than the R enantiomer. However, the differences in the phase distribution of chiral selectors led to the opposit elution order of enantiomers: with cyclodextrins, the first eluted is S enantiomer, while R is the first eluted for bile salts. Under the conditions studied, cyclodextrins (except gamma-cyclodextrin), as well as cholic acid sodium salts acting singly, enable the separation of 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate enantiomers both by HPLC and CE methods, while 1,1'-bi-2-naphthol enantiomers were resolved only under CE conditions with permethylated cyclodextrin or bile salts. In both techniques the application of dual systems could improve resolution or make it worse (oreven cancel), depending on the sign of enantioselectivity of particular selectors, their concentrations and localization: mobile or stationary phase. It has been found that the mechanism of separation as well as interactions occurring between two selectors may be followed by using combined HPLC and CE methods. The obtained results proved that, as well as beta-CD, TM-beta-D and gamma-CD also form inclusion complexes with cholic acid sodium salts. The reversal of elution order may be realized by two procedures: changing a single selector, i.e., cyclodextrin on cholic acid sodium salt or vice versa, and by changing the proportion of selectors in the combined bile salt-cyclodextrin system.     

New lamellar structure formed by an adamantyl derivative of cholic acid

The self-aggregation of the sodium salt of a new adamantyl amide of the 3beta-amino derivative of cholic acid (Na-AdC) in aqueous solution has been investigated by surface tension, dynamic light scattering, fluorescence, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) measurements. These last two techniques suggest that a lamellar phase, consisting of charged bilayers of Na-AdC separated by solvent and periodically stacked, is formed in aqueous solution. The structure of the bilayer is inferred from the resolution of the crystal of the compound in its acid form. The adamantyl moieties, which are mutually interlocked, reside in the central region of the bilayer, and the carboxylic groups are directed toward the hydrophilic region. The structure is open enough to allow water molecules to interact with a fluorescence probe located at the central hydrophobic region.     

Synthesis of proline derivatives of bile acids and their evaluation as organocatalysts in the asymmetric direct aldol reaction

A new family of bile acid derived organocatalysts was obtained by linking l- or d-proline to amino derivatives of cholic and deoxycholic acids, which were used to promote the asymmetric direct aldol reaction between acetone and 4-nitrobenzaldehyde. Both the activity and enantioselectivity of the organocatalytic systems were dependent not only on the position of the proline moiety on the cholestanic backbone and its absolute configuration, but also on the presence of free hydroxyl group on the steroidal skeleton. The cholic acid derivative bearing a d-prolinamide moiety at the 12-position and free hydroxyl groups at the 3- and 7-positions emerged as the best organocatalytic system giving complete conversion of the substrate, even when using only 2% of catalyst loading and ee up to 80%.     

Photoproduct selectivity in reactions involving singlet and triplet excited states within bile salt micelles

Generally, photochemical reactions tend to give more than one product. For such reactions to be useful one should be able to control them to yield a single product. Of the many approaches used in this context, the use of reaction media with features different from those of isotropic solutions has been very effective. We provide results of our studies on four reactions within bile salt micelles (cholic acid and deoxycholic acid). These four reactions involve homolytic cleavage of a C-C or C-O bond to yield either a singlet or triplet radical pair. The bile salt micelles control the rotational and translational mobilities of the radical pair, resulting in photoproduct selectivity. The dynamic nature of the bile salt micelles results in differential effects on the singlet and triplet radical pairs.     

杯[4]芳烃黄原酸酯衍生物的合成与阳离子萃取性能

以二氧六环作溶剂, 杯[4]芳烃二甲氧基二羟乙氧基衍生物2与氢氧化钾、二硫化碳作用合成了杯芳烃黄原酸盐衍生物3, 并进一步与碘甲烷或氯化苄反应首次合成了含黄原酸酯基的杯芳烃衍生物4a和4b. 阳离子萃取试验表明该新型杯芳烃衍生物比单硫杂杯芳烃衍生物具有更好的过渡金属离子萃取性能.     

Water-insoluble condensed tannins content of young persimmon fruits-derived crude fibre relates to its bile acid-binding ability

In this study, we prepared crude fibre samples from young fruits of 10 persimmon (Diospyros kaki) cultivars and from young fruits of Japanese pear (Pyrus pyrifolia var. culta) and peach (Prunus persica) and compared their bile acid-binding abilities in?vitro. All crude fibre samples from young fruits of persimmon were able to bind to cholic acid in a 4?mM cholic acid solution, but crude fibre samples from young fruits of Japanese pear and peach did not show bile acid-binding ability. The bile acid-binding ability was strongly correlated with the water-insoluble condensed tannins content in crude fibre samples (r?=?0.909, p?相似文献   

Adsorption of bile acid by chitosan-orotic acid salt and its application as an oral preparation

The orotic acid (OT) salt of chitosan (CS), CS-OT, and that of a CS derivative, CP, were prepared, and the adsorption of primary or secondary bile acid was investigated. Calcium-induced alginate gel beads (Alg-Ca) containing CS-OT were also prepared and autoclaved, and the possibility of these beads to act as a vehicle for oral administration to prevent hyperlipidemia was investigated. When taurocholate (TCA) and glycocholate (GCA) were present together in the medium, CS-OT adsorbed identical amounts of both bile acids. This trend was seen in all CPs, although the capacity to adsorb bile acid was affected by the number and/or structure of the amino groups in the CP. On the other hand, taurodeoxycholate, a secondary bile acid was preferentially adsorbed over TCA and GCA. Alg-Ca containing CS-OT took up bile acids in a similar manner as CS-OT irrespective of the water content of the gel matrix. As all elements can be taken as a food, Alg-Ca containing CS-OT could serve as a useful dietary agent for the prevention of hyperlipidemia, which is a lifestyle-related disease.     

Formation of Giant Needle‐Like Polycation‐Bile Acid Complexes

The complexation of bile acids with various solvated polycations was studied. A one‐to‐one complex was precipitated when an aqueous solution of cholic acid sodium salt (CA) was mixed with aqueous solutions of 3,3‐ionene and grew to form crystals with needle‐like morphology, 3 millimeters in length. Hydrogen bonding of hydroxyls at the steroid face and the spacing between cationic sites of polycations were crucial for the formation of the giant needle.

Crossed polarizing microscopic photograph of the complex composed of cholic acid sodium salt and 3,3‐ionene.     

A new steroid aromatization rearrangement involving inversion of sidechain configuration

The bile acid, cholic acid, has been transformed into 3α-hydroxy-12-methyl-18-nor-5β, 17α-chola-8,11,13-trien-24-oic acid. The constitution of this novel type of steroid (benzenoid C-ring with 17α-sidechain) has been supported by chemical degradation, and confirmed by crystal structure analysis of the methyl ester iodoacetate derivative.     

胆酸盐参与的自组装及微纳米材料制备

胆酸盐类物质可看作是一类阴离子型甾族生物表面活性剂,鉴于其特殊的两亲性骨架结构、独特的物理化学性质及其良好的生物相容性和环境友好性,其在溶液中能够参与超分子自组装形成有序聚集结构,且可以作为模板在微纳材料制备领域有着重要应用。本文结合我们课题组的研究工作,综述了近期国内外相关研究,详细介绍了生物小分子氨基酸对胆酸盐聚集行为的影响、胆酸盐参与形成的超分子凝胶及胆酸盐参与构筑的微纳米材料制备等方面的研究进展,以期对胆酸盐参与的自组装及微纳米材料制备领域的研究有更全面更深入的了解,为后续的应用研究提供坚实的基础。     

Hydrophilic polymethacrylates containing cholic acid‐ethylene glycol derivatives as pendant groups

In an effort to improve the hydrophilicity of bile acid containing polymers, we have synthesized new methacrylate monomers by incorporating ethylene glycol and oligo(ethylene glycol) spacers of different lengths between cholic acid and methacrylate residues. The monomers were subsequently polymerized by free radical reaction in solution. The methyl ester protecting groups on the cholic acid residue were selectively hydrolyzed to restore the carboxylic acid group of cholic acid. Water absorption tests showed that the hydrophilicity of the polymers was improved with increasing length of oligo(ethylene glycol) spacers and upon restoration of the carboxylic acid group of the cholic acid residue.     

Enzymatic fluorimetric determination of the individual bile acids in blood serum

An enzymatic fluorimetric method is described for the determination of total bile acids (cholic acid and deoxycholic acid), primary bile acids (cholic and chen acids and individual bile acids in serum without prior separation of the acids. Total and primary bile acids are determined by equilibrium procedures by conver of the 3α- and 7α-hydroxy bile acids to 3-oxo and 7-oxo bile acids by α-NAD⁺, in the presence of 3α- and 7α-hydroxysteroid dehydrogenase (HSD), respectively, and measurement of the generated NADH fluorimetrically. Chenodeoxycholic acid is determined with 7α-HSD in the presence of cholic and deoxycholic acids by a differential kinetic procedure, and cholic and deoxycholic acids are calculated by difference. Interferents are removed by treatment of serum with Sachrom rein. Only 1.00 ml of serum is required. Low cost, simplicity and reliability are the main features of the method. The recovery of bile acids added to serum averaged 103% (range 83–122%). The method is suitable for routine use in small clinical laboratories.     

Enzymatic fluorimetric determination of cholic acid and chenodeoxycholic acid in aqueous solutions and blood serum using a differential kinetic method

An enzymatic fluorimetric method is described for the determination of chenodeoxycholic acid and its conjugates and of cholic acid and its conjugates in aqueous solutions and serum. The method is based on the oxidation of 7 α-hydroxy bile acids by β-NAD⁺ in the presence of 7 α-hydroxysteroid dehydrogenase; the NADH produced is monitored fluorimetrically. Chenodeoxycholic acid is determined in the presence of cholic acid by a differential kinetic procedure; the sum of the two acids (primary bile acids) is determined by an equilibrium procedure, and cholic acid is calculated by difference. The r.s.d. was ca. 3% and 10% for aqueous solutions and sera, respectively. Recoveries of chenodeoxycholic acid, cholic acid and primary bile acids added to serum samples averaged 100.5, 105.1, and 102.9%, respectively. Ten samples can be analyzed per working day.     

Effects of aminotriazole treatment on biosyntheses of primary bile acids in vivo.

The influence of aminotriazole treatment on primary bile acid biosynthesis was studied in detail. After administration of aminotriazole to rats, bile was collected for 8 h. The content of chenodeoxycholic acid in the bile was increased to 144% of the control by aminotriazole treatment, but that of cholic acid was decreased to 48.4%. In another experiment, [4-14C]cholesterol was injected into rats immediately after aminotriazole treatment, and then bile was collected. The content of radioactive chenodeoxycholic acid in the bile was significantly increased to 130% of the control, but that of radioactive cholic acid was unchanged. In a similar experiment with [2-14C]mevalonate, the content of radioactive chenodeoxycholic acid in the bile was hardly changed by aminotriazole treatment, but that of radioactive cholic acid was greatly decreased to 41.2% of the control. Aminotriazole treatment did not affect the ratios of tauroconjugate to glycoconjugate of the two bile acids. Thus, aminotriazole treatment affects the syntheses of not only cholesterol (F. Hashimoto, C. Sugimoto and H. Hayashi, Chem. Pharm. Bull., 38, 2532 (1990); F. Hashimoto and H. Hayashi, Biochim. Biophys. Acta, 1086, 115 (1991)) but also primary bile acids in vivo. Namely, aminotriazole treatment activated biosynthesis of chenodeoxycholic acid from exogenous cholesterol, but did not affect that of cholic acid. Aminotriazole hardly affected the synthesis of chenodeoxycholic acid through endogenous cholesterol (from mevalonate), but inhibited that of cholic acid.     

The Effect of the Side Chain on Gelation Properties of Bile Acid Alkyl Amides

Six bile acid alkyl amide derivatives were studied with respect to their gelation properties. The derivatives were composed of three different bile acids with hexyl or cyclohexyl side chains. The gelation behaviour of all six compounds were studied for 36 solvents with varying polarities. Gelation was observed mainly in aromatic solvents, which is characteristic for bile-acid-based low molecular weight gelators. Out of 108 bile acid-solvent combinations, a total of 44 gel systems were formed, 28 of which from lithocholic acid derivatives, only two from deoxycholic acid derivatives, and 14 from cholic acid derivatives. The majority of the gel systems were formed from bile acids with hexyl side chains, contrary to the cyclohexyl group, which seems to be a poor gelation moiety. These results indicate that the spatial demand of the side chain is the key feature for the gelation properties of the bile acid amides.     

Preparation of a protected triamino analogue of cholic acid and sequential incorporation of amino acids in solution and on a solid support

We have prepared a triamine derivative of cholic acid with protecting groups on the amines that allow sequential amide formation. The triamine was formed from 3 alpha,7 alpha, 12 alpha-trihydroxycholan-24-ol with good stereoselectivity. Sequential removal of the amine protecting groups and amide formation was achieved in high-yielding steps and was performed in solution and on a solid support.     

Synthesis and antineoplastic activity of novel water-soluble curcumol derivatives

6-Succinyl curcumol sodium salt was synthesized by reaction of curcumol with succinic acid. The structure of the derivative was confirmed by NMR spectroscopy and mass spectrometry. Furthermore, the derivative showed antitumor activity, which makes it a promising antitumor drug candidate that overcomes the insolubility in water.     

胆酸盐在酸性介质中自聚集作用的共振瑞利散射光谱及其分析应用研究

研究了牛磺胆酸钠、甘牛胆酸钠、胆酸钠和脱氧胆酸钠等四种胆酸盐在酸性介质中的聚集作用对共振瑞利散射光谱的影响及其分析应用. 结果表明: 在一定浓度的HCl, H₂SO₄或HNO₃溶液中, 四种胆酸盐均能自聚集形成粒径增大的聚集体. 该聚集体能导致溶液RRS显著增强, 并产生了新的RRS光谱. 不同胆酸盐在同种介质中的反应产物具有相似的光谱特征, 最大RRS波长分别位于349 (HNO₃介质), 359 (H₂SO₄介质)和369 nm (HCl介质). 在一定范围内, 胆酸盐的浓度与散射强度(ΔI_RRS)成正比. 对于不同的体系其检出限在12.0～21.8 ng/mL之间. 方法灵敏度高, 选择性较好, 而且十分简便快速. 可用于市售蛇胆川贝液和血清样品中胆酸盐的测定.     

FUNCTIONALIZED β-CYCLODEXTRIN POLYMERS FOR THE SORPTION OF BILE SALTS

Poly(β-cyclodextrin) (PCD) resins were prepared by a crosslinking reaction of β-cyclodextrin with different amounts of epichlorhydrin. Some hydroxyl groups of these polymers were functionalized with alkyl quaternary ammonium groups. The polymers were tested for their ability to bind several bile salts (including the sodium salts of cholic acid, glycocholic acid, and chenodeoxycholic acid), individually and competitively, from phosphate buffer solutions. In all cases, the aminated PCD resin had a higher binding capacity for bile salts. The binding of chenodeoxycholate by the resins was much more effective than that of cholate and its conjugate, which indicates the importance of the host cavity size relative to that of the guest molecules. The degree of hydrophobicity of bile acids also plays a role in their binding by PCD resins. The variable temperature studies indicate that the electrostatic interactions become weaker at higher temperatures while the hydrophobic interactions are not as much affected.