Biocatalytic Production, Preparation and Characterization of Large-ring Cyclodextrins

• Main Author: Mokhtar, Mohd Noriznan
• Other Authors: TU Chemnitz, Fakultät für Maschinenbau
• Format: Doctoral Thesis
• Language: English
• Published: Universitätsbibliothek Chemnitz 2009
• Subjects: Large-ring cyclodextrins (LR-CD); central composite design; co-grinding; co-precipitation; cyclodextrin glucanotransferase (CGTase); host-guest complexation; molecular recognition; supramolecular chemistry; ddc:570; Bacillus macerans; Molekulare Erkennung
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900431; http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900431; http://www.qucosa.de/fileadmin/data/qucosa/documents/5765/data/Thesis.pdf; http://www.qucosa.de/fileadmin/data/qucosa/documents/5765/20090043.txt

Cyclodextrins (CD) are cyclic oligosaccharides composed of six to more than sixty glucose units. Large-ring cyclodextrins (LR-CD) are novel CD comprised of more than eight glucose units with cavity structures and sizes different from that of commercially available CD₆ – CD₈. LR-CD may offer unique molecular recognition properties and can be produced biocatalytically from starch using cyclodextrin glucanotransferase (CGTase, E.C. 2.4.1.19) in a short reaction time. LR-CD were isolated from glucose, CD₆ – CD₈ and other compounds by complexation of CD₆ – CD₈ as well as precipitation techniques. The yield of LR-CD (degree of polymerization from 9 to 21) was optimized using central composite design. Addition of polar organic solvents to the synthesis resulted in higher yields of LR-CD. LR-CD composed of 9 to 21 glucose units were successfully separated using reversed-phase of ODS-AQ chromatography and normal-phase of polyamine II chromatography. Maintaining optimized reaction conditions aided in a high yield of CD₉; it could be separated with reasonable yield using a single step of polyamine II chromatography. A co-grinding method helped to obtain higher solubilization levels of glibenclamide, vitamin A acetate and vitamin D₃ in CD₁₃, CD₁₀ and CD₁₁, respectively when compared to other CD. Vitamin K₁ was solubilized in distilled water with CD₆ – CD₁₃ using a co-precipitation method. When compared with other CD, CD₉ was seen to be the best solubilizer. The analysis of complexes using ESI MS showed spironolactone and glibenclamide complexed with CD₉ and CD₁₃, respectively.