Page 157 - phytochemistry general program

burns), ubiquinone-10 (for congestive heart disease) are produced in Japan under
controlled conditions by P.T.C.

However P.T.C. with its expensive requirements can only be commercially
competetive if they are capable of at least one of the following:

1- Producing secondary metabolites at similar or higher rates to the intact plant.

2- Producing new physiologically active substances of medicinal interest.

3- Producing rare or expensive substances.

III) P.T.C and biotransformation.

Biotransformation is the transformation of a particular synthetic or natural
substrate to more useful products by using P.T.C. This is the most promising area
in practical applications of P.T.C. Plant cells show the ability to perform specific
biotransformation reactions on supplied substrates leading to the formation of
known substances as well as new compounds not found yet in nature. Both natural
and synthetic organic compounds with great variety of structures have been
investigated. All kinds of reactions are observed during biotransformations process
such as; oxidation, reduction, methylation, demethylation, hydroxylation,

conjugation, saponification, esterification, isomerization....etc.

Some reactions are unique to plant cell e.g. specific glucosylation of a
multifunctional substrate is a plant characteristic reaction, which in many cases
either cannot be carried out by chemical synthesis or only with a tedious procedure

of protective groups.

Examples of biotransformation reactions carried out by P.T.C to produce more .1
active compounds are:

Glycosylation

In vitro culture of Stevia rebaudiana to produce sweetening agents has been
performed. Steviol has been transformed to stevioside in vitro by callus culture. A
concentration four times higher than found in dry leaves has been produced of this
sweet glycosides by P.T.C. It has high sweetening power and its physical,
chemical, pharmacological and toxicological characteristics allows its use in

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