Manipulation of Centelloside Production in Cell and Tissue Culture
As in the case of most plant-derived pharmacologically active compounds, pentacyclic triterpenoids
have complex structures, making chemical synthesis an economically uncompetitive option. Plant cell
culture has been used in attempts to increase the production of bio-active secondary metabolites of
pharmaceutical interest [85,86]. A particular important benefit is the potential ability to manipulate and
improve the production of desired compounds within the plant cell through experimentation with cell
culture. However, the relationship between cell differentiation and tissue organisation and the
biosynthesis of secondary compounds is somewhat obscure. Secondary metabolite production may
require interaction between roots and leaves with metabolic precursors generated in roots and passing
to aerial parts of plants for bioconversion in leaves [85]. The biosynthesis of major secondary
metabolites is often either tissue or organ specific [31], as found also in the case of C. asiatica
triterpenoid saponins [87]. Plant secondary metabolites are normally synthesised by specialised cells,
often at distinct stages of plant development and certain compounds are not synthesised, or synthesized
at a low level, if cells remain undifferentiated as in cell suspensions [87]. The distribution of mRNA
transcripts, enzymes and biosynthetic precursors within and between cells is an important component
of regulation for secondary plant metabolic processes. In addition, many metabolic pathways are
compartmentalised, enabling the separation of incompatible or competing reactions, and concentrating
enzymes and metabolites