|Abstract or Summary
- Pelargonium graveolens Ait., rose geranium, contains
several oxygenated monoterpenes, most of which are related
to each other structurally. In this work, the metabolism
and interconversions of these terpenes was investigated.
A chromatographic analysis of geranium oil was performed
initially for the purposes of identifying the terpenes
and determining which chromatographic method was
most desirable for this work. It was found that gas-liquid
chromatography was superior to thin layer chromatography
both in resolution and in affording a convenient
and sensitive method of counting radioactivity.
Three types of experiment were used in attacking this
(1) Variations in terpene synthesizing ability with leaf age were noted in order to determine the site of most
(2) Leaves were exposed to C¹⁴O₂ in light for periodically increasing time intervals, and samples were taken
at those intervals. The radioactive terpenes were extracted, and were separated by means of gas-liquid chromatography,
and the terpene fractions were counted in a liquid
(3) Isolated carbon-14 labeled terpenes were used as
substrates in interconversion reactions by placing them in
contact with sliced or minced geranium leaves in the light.
From the above, it was determined that the interconversions
of the terpenes of geranium are very rapid and
proceed through the biosynthetic pathway mainly by a series
of reductions. It was also shown that the biosynthesis
of terpenes is very active only in those leaves that
are still expanding.
Besides the above, two types
that were not directly related to the interconversion problem
Because it is a widely postulated precursor of terpenes,
the incorporation of mevalonic acid into the terpenes
of geranium was attempted, and possible incorporation
of mevalonic acid-2-C¹⁴ into geraniol-citronellol, citral, and a fraction which migrates to the solvent
front in thin layer chromatography was observed.
Studies were performed to develop methods of obtaining
enzymatically active cell-free extracts from monoterpene
producing plants. The enzyme activities extracted
were glutamyl transferase (from Mentha piperita, peppermint,
Mentha puleqium, pennyroyal, and geranium), mevalonic
kinase (from peppermint), and an enzyme activity which
possibly produced piperitenone, a monoterpene of peppermint
and pennyroyal, using mevalonic acid-2-C¹⁴ as the
substrate and extracts of either peppermint or pennyroyal
as the enzyme system.