Enzymatic synthesis of selected glycosides

Vijayakumar, G. R. (2006) Enzymatic synthesis of selected glycosides. PhD thesis, University of Mysore.

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Abstract

The present investigation attempts to explore the potentiality of amyloglucosidase and beta-glucosidase in effecting glycosylation of a wide variety of glycosyl acceptors from straight chain alcohols to few selected substituted phenols like guaiacol, eugenol, curcumin and alpha-tocopherol. Many glycosides are used in broad range of applications as surfactants (Busch et al. 1994), as food colorants and flavoring agents (Sakata et al. 1998), sweeteners (Shibata et al. 1991), antioxidants, anti-inflammatory (Gomes et al. 2002), antitumor (Kaljuzhin and Shkalev 2000), antibiotics (Ikeda and Umezawa 1999), antifungal(Tapavicza et al. 2000), antimicrobial (Zhou 2000) and cardiac related drugs (Ooi et al.1985). Glycosylation renders lipophilic compounds more water soluble and thereby increase bioavailability of biologically active compounds besides imparting stability to the aglycon (Kren and Martinkova 2001). Thus enzymatic synthesis of alkyl glycosides used as surfactants in food, glycosides of guaiacol, eugenol, curcumin and alpha-tocopherol which exhibit antioxidant activity have been investigated. Of these glycosides of selected phenols can be also made water-soluble, and stable necessary to enhance the bioavailability of the compounds in food and pharmaceutical applications. Besides, curcumin glycosides can also be used as a water-soluble food colorant. Amyloglucosidase from Rhizopus sp. and beta-glucosidase from sweet almonds catalyzed synthesis of above mentioned alcohols and phenols were carried out in diisopropyl ether solvent in an experimental setup where larger concentration of substrates can be employed with lesser concentration of enzyme to get better conversion. The carbohydrate molecules employed for the glycoside preparations were D-glucose, Dgalactose, D-mannose, D-fructose, D-arabinose, D-ribose, maltose, sucrose, lactose, D-40 mannitol and D-sorbitol. The reactions were investigated in detail in terms of incubation period, pH and buffer concentration, enzyme concentration, substrate concentration,regio and stereo selectivity and kinetics. The glycosides prepared were isolated and characterized and few of them showed angiotensin-converting enzyme inhibition activities.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Enzymatic transformations Glycosidases Amylolytic enzymes Glycosylation
Subjects:	500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 16 Enzyme Chemistry
Divisions:	Fermentation Technology and Bioengineering
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	03 Dec 2007 05:45
Last Modified:	28 Dec 2011 09:31
URI:	http://ir.cftri.res.in/id/eprint/1525

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