(62aj) Alkaloid Extraction and Purification From Catharanthus roseus Hairy Root Tissue

Plant metabolic engineering of Catharanthus roseus
may provide improved ways of producing vincristine (Oncovin®) and vinblastine
(Velbe®) which are used in the treatment of cancer.  The tabersonine branch
point is very important for the synthesis of vindoline which is a key precursor
to vincristine and vinblastine.  Genetically modified C. roseus hairy
root lines are used to analyze the flux of metabolites at the tabersonine
branch point.  Genes inserted by recombinant DNA techniques can amplify or
suppress flux through existing metabolic pathways and can create new metabolic
pathways for desired products that are not expressed in the wild-type line.  By
suppressing flux to undesired products like hörhammericine, tabersonine flux
can be diverted to the vindoline-vinblastine-vincristine pathway.  One of the
current research challenges is the lack of commercially available standards to
quantify low-level metabolites at the tabersonine branch point.  A biomass
extraction and analytical HPLC protocol was adapted for semi-preparative scale
in order to obtain tabersonine, lochnericine, and hörhammericine standards from
C. roseus hairy root tissue.  Standards will enable improved study of
the metabolic pathways originating at the tabersonine branch point and will
allow for the determination of previously unidentified co-eluting
tabersonine-like compounds.