الفهرس | Only 14 pages are availabe for public view |
Abstract research involves the enzymatic biotransformation of silymarin extract. In this work, the main achievements and key factors affecting biocatalytic structural modification of silymarin into silymarin glycoside using cellulase enzymes were discussed and the research prospect was outlined. A sequential optimization strategy based on statistical experimental designs was employed to enhance the production of cellulase enzyme by Trichoderma viride in a submerged culture. A 2-level Plackett-Burman design was used to screen the bioprocess parameters significantly influencing cellulase enzyme production. Among the tested variables, volume of media (aeration), peptone concentration and surfactant (tween 80) concentration were selected, owing to their significant positive effect on cellulase production. A response surface methodology (RSM) involving a 3-level Box-Behnken design was adopted to acquire the best process conditions. Thus, a polynomial model was created to correlate the relationship between the three tested variables and the cellulase yield. The optimal combination of the major media constituents for cellulase production was evaluated using SAS JMP 8 NULL program; it was as follow: volume of media, 40 % of the total flask volume; peptone concentration, 1.5 g/l and surfactant concentration, 0.4 g/l. Experimental verification of the predicted model resulted in a cellulase yield, representing 89% of the calculated yield. An estimation trial for screening of the factors affecting the enzymatic biotransformation of the silymarin extract was adopted. Then, the products of this trial were isolated using the different methods of chromatography. from the spectra of UV shift reagents and 1H-NMR, a novel silymarin dirhamnoside derivative was identified. The same statistical experimental designs was employed to enhance the production of this rhamnoside derivative from highly pure powdered extract of silymarin (Silybum marianum) by cellulases mixture extracted from Trichoderma viride using the enzymatic biotransformation technology. Among the tested variables; substrate concentration, agitation rate (aeration) and the reaction time were selected, owing to their significant positive effect on silymarin rhamnoside production. Thus, a polynomial model was created to correlate the relationship between the three tested variables and the silymarin rhamnoside yield. The optimal combination of the major reaction mixture components for silymarin rhamnoside production was evaluated as follow: substrate concentration, 0.05 g%; agitation rate, 150 rpm and the reaction time, 1 hr. Experimental verification of the predicted model resulted in a silymarin rhamnoside yield, representing 93% of the theoretically calculated yield. |