الفهرس 
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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.