Structural elucidation of novel isoquercitrin-γ-cyclodextrin (IQC-γCD) molecular inclusion complexes of potential health benefits

• Published in: Carbohydrate polymer technologies and applications 2021-12, Vol.2, p.100046, Article 100046
• Main Authors: Kapoor, Mahendra P., Moriwaki, Masamitsu, Ozeki, Makoto, Timm, Derek
• Format: Article
• Language: English
• Subjects: Complex; Cyclodextrin; Inclusion; Isoquercitrin; Spectroscopic; Structural
• ISSN: 2666-8939; 2666-8939
• DOI: 10.1016/j.carpta.2021.100046

•The structure of the novel isoquercitrin-γ-cyclodextrin (IQC-γCD) inclusion complex is elucidated.•Isoquercitrin molecule was completely included inside γ-CD cavity.•Isoquercitrin solubility was increased nearly 1000 times after complexation with γ-CD compared to isolated isoquercitrin.•IQC-γCD inclusion complex formation was confirmed by NMR, FTIR, DSC, SEM, UV-VIS, PXRD and Raman spectroscopy methods. Isoquercitrin has a higher bioavailability than quercetin and has various pharmacological effects. In the present study, we aim to elucidate the structure of the novel isoquercitrin-γ-cyclodextrin (IQC-γCD) inclusion complex derived through controlled enzymatic hydrolysis of rutin into isoquercitrin in-situ included in γ-cyclodextrin. Several vibrational, electronic and analytical spectral measurement techniques (FTIR, 1H-NMR, 13C-NMR, UV-Vis, DSC, PXRD, Raman spectroscopy, and SEM) were employed. The detailed structural comparison of the IQC-γCD inclusion complex with isolated isoquercitrin revealed the shielding of isoquercitrin –OH groups inside the γ-CD cavity, and thus, confirmed the successful formation of the inclusion complex that exhibit distinct spectroscopic features from both guest and host molecules. The phase-solubility studies showed that isoquercitrin formed a 1:1 stoichiometric inclusion complex with γ-CD. The aqueous solubility of isoquercitrin was significantly enhanced by complexation with γ-CD complex possibly due to increased isoquercitrin dissolution rate compared to the isolated isoquercitrin. The IQC-γCD inclusion could have enhanced pharmacokinetics that will be useful for future applications in functional foods and health benefits.