Aqueous Solubility and Stability Enhancement of Astilbin through Complexation with Cyclodextrins

Abstract

The complexation of astilbin with α-, β-, and γ-cyclodextrin (CD) was studied by phase solubility test and UV-vis spectral titration. Complexation with CDs gradually decreased the absorbance of astilbin at 291 nm and obviously increased its water solubility. The formation constant (K(a)) between astilbin and the three CDs was calculated. The stability of astilbin complexes increased in the order α-CD < γ-CD < β-CD, attributed to the CDs' cavity size. Temperature studies showed that the K(a) value decreased along with the rise of temperature. The negative values of enthalpy and entropy during complexation indicated that the complexation process was enthalpy-controlled. In alkaline medium isomerization and decomposition of astilbin were found; however, the addition of CDs significantly improved its stability through complexation. The solubility of astilbin in β-CD microcapsules prepared by the freeze-drying method was enhanced by 122.1-fold, and its dissolution profile was improved.

Improved biosynthesis of ethyl (S)-4-chloro-3-hydroxybutanoate by adding l-glutamine plus glycine instead of NAD+ in β-cyclodextrin–water system

“…Proposed mechanism for the biotransformation by supplementation of L-glutamine (200 mM) plus glycine (500 mM) in b-CD-water system It was reported that b-CD could enhance the solubility and bioavailability of hydrophobic substrates (Zidovetzki and Levitan, 2007). Moreover, b-CD can form a complex with such compounds (Zhang et al, 2013). As shown in Fig.…”

“…S2A in the Supplementary materials available on-line, the diminished transmittances of the C@O group at 1731 and 1659 cm À1 by infrared spectrometry indicated that the substrate molecule COBE had been included by b-CD. Moreover, inclusion complex formation with b-CDs often causes UV-vis spectral changes of substrates (Zhang et al, 2013). With the addition of b-CD, the absorption maximum of COBE at 236 nm was red-shifted to 246 nm at pH 7.0, whereas the absorbance decreased gradually.…”

“…Recently, b-cyclodextrin (b-CD) has been used for increasing the availability of insoluble substrates, reducing substrate inhibition, and enhancing the efficiency of catalysis by increasing the reaction rate (LucasAbellán et al, 2008;Zhang et al, 2013). b-CD is one kind of cyclic oligosaccharides that can be employed frequently as host molecules in supramolecular chemistry.…”

Purification of total flavonoids from Rhizoma Smilacis Glabrae through cyclodextrin‐assisted extraction and resin adsorption

“…Our previous works showed that astilbin, the most dominant flavonoid in RSG , is a poorly soluble compound. However, β‐CD could significantly increase its solubility through complexes formation (Zhang, Cheung, & Zeng, ; Zhang, Nie et al., ).…”

Preparation, Characterization, and Preliminary Antibrowning Evaluations of Norartocarpetin Microemulsions

“…Many methods have been applied to increase the solubility and bioavailability of phytochemicals, nutraceuticals, and food additives through delivery systems such as microemulsions, 8−11 nanoemulsions, 12−14 solid lipid nanoparticles, 15 complexation with cyclodextrin, 16 and liposome encapsulation. 17 Among them, microemulsions (ME) have attracted much interest in recent years as drug delivery systems because they are not only highly dispersed, stable, and transparent systems and easily prepared but also help to improve the solubility and stability of many food and medical bioactive components.…”