Nancy Rita, M (2013) Enantioselective Esterification of Ibuprofen using Lipase Immobilized on Various Supports in Comparison with Free Lipase. Masters thesis, College of Pharmacy, Sri Ramakrishna Institute of Paramedical Sciences, Coimbatore.
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Abstract
Enzymes act on substrates specifically and ultimately cause transformation/conversion of substrate to products. Enzymes present numerous potential of applications in diversified areas like food technology, environmental and pharmaceutical sectors. Lipase is the most frequently used enzyme because it has an enantioselective reaction property of racemic mixtures. However enzymes are costly because almost all the commercially available lipases are made available from genetically engineered organisms, which in turn make the enzyme expensive. The above drawback can be partly eliminated by immobilization of enzyme onto different supports. The immobilization of enzymes is a useful tool to meet cost targets and has a number of technological advantages, as for instance, it enables repeated use of the enzyme resulting in significant cost savings. Immobilized enzyme can be easily separated from the reaction liquid and thereby reduces laborious separation steps. Additional benefits arise from stabilization against harsh reaction condition, which are deleterious to soluble enzyme preparation. Immobilization of enzymes can be carried out by different techniques like adsorption, ionic binding, covalent binding by chemical coupling, cross linking, entrapment and encapsulation. We have selected the following methods for the advantages mentioned here: 1. Calcium alginate beads were prepared by entrapment method which is very simple and inexpensive to perform. 2. Immobilization of lipase on glutaraldehyde pretreated chitosan allows easy recovery and reuse of the catalytic material with no activity decrease. It also gives higher temperature resistance to the enzymes. 3. Physical adsorption advantages like simplicity, little effect on activity of biocatalyst and possibility of regenerating inactive enzyme by addition of fresh enzyme. Activity studies were carried on various supports like entrapment into calcium alginate beads, covalent bonding of lipase on glutaraldehyde pretreated chitosan and on chitosan by physical adsorption from which it was seen that lipase immobilized on glutaraldehyde pretreated chitosan by covalent bonding and on chitosan by physical adsorption exhibited maximum activity at pH 6.5 and at 45°C. Enantioselective esterification of ibuprofen to produce S- enantiomer ester was carried out by enzymatic process using lipase from Candida rugosa as the biocatalyst in the presence of amyl alcohol and isooctane as the primary alcohol and solvent respectively. Enzyme activity and enantioselectivity could be improved by medium engineering, immobilization, optimization of cultural conditions, genetic engineering and chemical modifications. Esterification reaction has been more effective when surfactant coated lipase was used (Ganesh R et al, 2008). The lipase used in that study was porcine pancreatic lipase. The same modification could be tried for Candida rugosa that has been used in our work. Surfactant coating of lipases is known to increase the lipase activity by a mechanism which “opens-up” the lid covering the active site of the enzyme. If a surfactant coated lipase is used in esterification reaction under optimum conditions, the percentage conversion of ester could be enhanced. Natural supports like kaolin could be tried for immobilization of lipases (Abdul Rahman et al, 2005). Rhizopus oryzae lipase immobilized on cellulose fibers was used in esterification to synthesize ethyl oleate (Maha Karra-Chaabouni et al, 2008). On similar lines our work on the enantioselective esterification could be extended for increased yields of the eutomer form of Ibuprofen that is the S(+) enantiomeric form of the drug. Variables like drug selected for conversions, alcohol used for esterification, solvent used, effect of immobilization, water content and other factors could be optimized for increased yield of active enantiomer.
| Item Type: | Thesis (Masters) |
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| Additional Information: | Reg No. 26073654 |
| Uncontrolled Keywords: | Enantioselective Esterification ; Ibuprofen ; Lipase Immobilized ; Various Supports in; Comparison ; Free Lipase. |
| Subjects: | PHARMACY > Pharmaceutical Biotechnology |
| Depositing User: | Subramani R |
| Date Deposited: | 17 Jun 2017 09:28 |
| Last Modified: | 16 May 2018 00:13 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/59 |
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