- Characterization of peracylated β-cyclodextrins with different chain lengths as a novel sustained release carrier for water-soluble drugs
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A new series of peracylated β-cyclodextrins(β-CyDs) with different alkyl chains (acetyl-lauroyl) was prepared in high purity by acylating all hydroxyl groups of β-CyD using acid anhydrides in pyridine, and their physicochemical properties of solubility, hydrolysis and release and interaction capacity were evaluated. The solubility of peracylated β-CyDs in water decreased with lengthening alkyl chain, whereas that in ethanol/water increased with increase in ethanol concentration, but tended to decrease at higher ethanol concentration. The solubility parameter of peracylated β-CyDs was determined by analyzing the peak-solubility phenomenon by a modified Hildebrand equation. The alkaline hydrolysis rate of peracylated β-CyDs decreased with lengthening alkyl chain, and was about 4-fold faster than that of the corresponding fatty acid ethyl esters. The interaction of perbutanoyl-β-CyD (TB-β-CyD) with a water-soluble drug, molsidomine, in the solid state was investigated by differential scanning calorimetry (DSC). The analysis of DSC curves suggested that molsidomine and TB-β-CyD form a binary solid dispersion with a 2:1 (drug: TB-β-CyD) molar ratio. The rate of drug release was markedly retarded by the combination with peracylated β-CyDs in the increasing order of the hydrophobicity of host molecules.
- Hirayama,Yamanaka,Horikawa,Uekama
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- Emulsion preparation using β-cyclodextrin and its derivatives acting as an emulsifier
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The preparation and formation mechanism of n-hexadecane/water emulsions using natural β-cyclodextrin (β-CD) and chemically modified β-CDs (triacylated β-cyclodextrins) as an emulsifier were investigated. The stable water/oil (W/O) emulsion was formed using tripropanoyl-β-CD (TP-β-CD). From observation using the contact angle (θow) of precipitates derived from CD, it was clarified that oil/water (O/W) emulsion at θowow>90° are formed when the composition of each oil and water was mixed with natural β-CD or triacylated β-CDs.
- Inoue, Motoki,Hashizaki, Kaname,Taguchi, Hiroyuki,Saito, Yoshihiro
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- 13C NMR study on peracetylated derivatives of cyclomaltoheptaose (β- cyclodextrin, β-CD) and its methylated derivative
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Peracetylated samples of cyclomaltoheptaose (β-cyclodextrin, β-CD) and its methylated derivative were studied by 13C NMR. The acetyl carbonyl carbon signal in peracetylated β-CD was resolved into a triplet, and the three peaks were assigned by long-range C-H COSY and INAPT techniques. The individual carbonyl peak was found to be indicative of the location of the acetyl group on the 2, 3, and 6 position in the glucose residues. An acetylated derivative of a partly methylated β-CD was also subjected to 13C NMR analysis to determine the distribution of acetyl and, subsequently, methyl groups on the glucose residues.
- Tezuka,Hermawan
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- Peracylated β-cyclodextrins as novel sustained-release carriers for a water-soluble drug, molsidomine
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Peracylated β-cyclodextrins with different alkyl chains (acetyl-octanoyl) were prepared by acylating all hydroxyl groups of β-cyclodextrin (β-CyD), and their physical properties were evaluated. These hydrophobic β-CyDs decreased the release rate of molsidomine, a peripheral vasodilator, in proportion to the lengthening of alkyl chain and suppressed a peak plasma level of molsidomine following oral administration of peracylated β-CyD complexes to dogs. Among the peracylated β-CyDs tested, perbutanoyl-β-CyD maintained sufficient plasma drug levels for a long period of time, while other peracylated β-CyDs having shorter or longer chains were inappropriate to control the in-vivo release behaviour of molsidomine. The prominent retarding effect of perbutanoyl-β-CyD was ascribable to the appropriate mucoadhesive property and hydrophobicity, compared with other peracylated β-CyDs. The present results suggest that perbutanoyl-β-CyD is particularly useful in modifying the release rate of water-soluble drugs as a novel slow-release carrier.
- Uekama,Horikawa,Yamanaka,Hirayama
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- Complexes of peracetylated cyclodextrin in a non-aqueous aprotic medium: the role of residual water
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This paper describes the interaction between aromatic esters and peracetylated cyclodextrins (CDs) studied by NMR spectroscopy in deuterochloroform (CDCl3). The observed chemical shift changes highlight the existence of interactions between an aromatic alkyl ester, water and peracetylated CDs. In some cases, substituent chemical shift determination was influenced by the low water content of CDCl3 and/or the host molecule. Higher CD concentrations resulted in water signal drifts in all studied cases. It was not possible to obtain a completely dry sample of peracetyl γCD: ～1 mol of water remained and the water signal showed reversed movement, with respect to the other two CD analogues, upon increasing host concentration. The estimated 1 : 1 stability constants for the water : peracetyl CD complexes are in the 50-150 M-1 range in CDCl3, but show a relatively large calculation error. The calculated 1 : 1 stability constants for the peracetyl CD : ester complexes are also in this range, but 1 : 2 and 2 : 1 complex compositions are also possible. Overall, our results highlight dynamic aspects of water nanoconfined in a highly hydrophobic environment, thus mimicking biological recognition where a few water molecules often play a pivotal role.
- Jicsinszky, Laszlo,Martina, Katia,Caporaso, Marina,Cintas, Pedro,Zanichelli, Andrea,Cravotto, Giancarlo
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p. 17380 - 17390
(2015/07/02)
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- Synthesis and characterization of acetylated sept-d-glucopyranose carbamate as an oligosaccharide donor
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An oligosaccharide donor, acetylated sept-d-glucopyranose tetradecyl carbamate, was designed and synthesized. This compound could be easily linked to hydroxyl-containing compounds through an O-glycosidic bond. Characterization of all the oligosaccharide intermediates and the final product was thoroughly discussed.
- Lian, Chang-Ming,Jiang, Li-Ping,Liu, Dong-Liang
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supporting information
p. 134 - 136
(2014/02/14)
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- DABCO: An efficient promoter for the acetylation of carbohydrates and other substances under solvent-free conditions
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A simple, mild and efficient solvent-free method for the acetylation of carbohydrates, and their partially protected derivatives, as well as non-carbohydrate substances in excellent yields in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) is described with the advantage of tolerance to various functional groups, short reaction time and ease of product isolation.
- Ch, Ratnasekhar,Tyagi, Mohit,Patil, Premanand Ramrao,Kartha, K.P. Ravindranathan
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experimental part
p. 5841 - 5846
(2011/12/03)
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- H2SO4-SiO2: Highly efficient and reusable catalyst for per-O-acetylation of carbohydrates under solvent-free conditions
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Sulfuric acid immobilized on silica gel (H2SO 4-SiO2) was used as an efficient promoter for per-O-acetylation of carbohydrates with acetic anhydride under solvent-free conditions. The substrates include not only monosaccharides and disaccharides, but also glycosides. The catalyst is recyclable and stable at room temperature, and the reaction protocol is simple, is cost-effective, and gives good isolated yield with high purity. The large-scale reactions also proceeded conveniently and in high yields. Taylor & Francis Group, LLC.
- Zhang, Jianbo,Zhang, Bo,Zhou, Jiafen,Li, Juan,Shi, Chunjuan,Huang, Ting,Wang, Zhongfu,Tang, Jie
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experimental part
p. 165 - 177
(2012/01/19)
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- Acetylation of α- And β-cyclodextrines
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Applying acetyl chloride and versatile bases and solvents per- and regioacetylated derivatives of α- and β-cyclodextrines were prepared. Conditions were established for performing regiodirected acetylation of the primary hydroxy groups of α- and β-cyclodextrines in the presence of free secondary hydroxy groups.
- Grachev,Edunov,Kurochkina,Popkov,Levina,Nifant'Ev
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experimental part
p. 284 - 289
(2011/05/04)
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- A simple and convenient per-O-acylation of cyclodextrins catalyzed by molecular iodine
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Per-O-acylated cyclodextrins with different alkyl chains were prepared in good to high yields by iodine-catalyzed acylation of all hydroxy groups of cyclodextrins with carboxylic anhydrides under solvent-free conditions. Georg Thieme Verlag Stuttgart - New York.
- Ide, Yasuhiro,Hori, Yuji,Kobayashi, Soichi,Hossain, Md. Delwar,Kitamura, Tsugio
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experimental part
p. 3083 - 3086
(2010/10/21)
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- Nucleophilic acyl substitutions of anhydrides with protic nucleophiles catalyzed by amphoteric, oxomolybdenum species
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(Chemical Equation Presented) Among six different group VIb oxometallic species examined, dioxomolybdenum dichloride and oxomolybdenum tetrachloride were the most efficient catalysts to facilitate nucleophilic acyl substitution (NAS) of anhydrides with a myriad array of alcohols, amines, and thiols in high yields and high chemoselectivity. In contrast to the well-recognized redox chemical behaviors associated with oxomolybdenum(VI) species, the catalytic NAS was unprecedented and tolerates virtually all kinds of functional groups. By using benzoic anhydride as a mediator for in situ generation of an incipient mixed anhydride-MoO2Cl2 adduct with a given functional alkanoic acid, one can achieve oleate, dipeptide, diphenylmethyl, N-Fmoc-α-amino, pyruvic, and tert-butylthio ester, N-tert-butylamide, and trityl methacrylate syntheses with appropriate protic nucleophiles. The amphoteric character of the Mo=O unit in oxomolybdenum chlorides was found to be responsible for the catalytic NAS profile as supported by a control NAS reaction of using an authentic adduct-MoOCl2(O2-CBu t)2 between pivalic anhydride and MoO2Cl 2 as the catalyst.
- Chen, Chien-Tien,Kuo, Jen-Huang,Pawar, Vijay D.,Munot, Yogesh S.,Weng, Shieu-Shien,Ku, Cheng-Hsiu,Liu, Cheng-Yuan
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p. 1188 - 1197
(2007/10/03)
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- Simple and efficient per-O-acetylation of carbohydrates by lithium perchlorate catalyst
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Lithium perchlorate is demonstrated to be a highly efficient and convenient catalyst for the per-O-acetylation of various saccharides with excellent yields. Graphical Abstract
- Lu, Kuo-Cheng,Hsieh, Shu-Yi,Patkar, Laxmikant N.,Chen, Chien-Tien,Lin, Chun-Cheng
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p. 8967 - 8973
(2007/10/03)
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- Lipase catalysed regioselective esterification of protocatechuic aldehyde
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Protocatechuic aldehyde (3,4-dihydroxybenzaldehyde-PA) is acetylated using acetic anhydride in presence of porcine pancreas lipase and two preparations of Rhizomucor miehei to give a mixture of 3-acetoxy and 3,4-diacetoxy derivatives in good yields. All the three lipases show better selectivity towards formation of 3-acetoxy-4-hydroxybenzaldehyde than the diacetoxy and 4-acetoxy derivatives.
- Divakar, Soundar
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p. 1119 - 1122
(2007/10/03)
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- SYNTHESIS OF 6-O-α-D-GLUCOPYRANOSYLCYCLOMALTOHEPTAOSE
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(2,3-Di-O-acetyl)hexakis(2,3,6-tri-O-acetyl)cyclomaltoheptaose was prepared by reaction of cyclomaltoheptaose with tert-butyldimethylsilyl chloride in pyridine followed by acetylation and desilylation.Glycosylation with 2,3,4,6-tetra-O-benzoyl-1-O-trichloroacetimidoyl-α-D-glucopyranose, using trifluoromethanesulfonic acid as catalyst, and removal of the protecting groups from the product then afforded the title compound.
- Fuegedi, Peter,Nanasi, Pal,Szejtli, Jozsef
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p. 173 - 182
(2007/10/02)
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- O-β. -D (and O-α.. -D) Multigalactopyranosyl, xylopyranosyl and glucopyranosyl sulfate salts
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O-β-D (and O-α-D) multi-galactopyranosyl (or xylopyranosyl or glucopyranosyl) 1α,1α' galactopyranosyl (or xylopyranosyl or glucopyranosyl) sulfate salts, useful as complement inhibitors, the intermediates thereof and the process for preparation of such compounds.
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