a study of the quality of a local herbal tea and volatiles of parinari ...

alkylating agent. DMAPP possesses a good leaving group the diphosphate (Dewick,
2009). DMAPP acts as a `primer` molecule and undergoes condensation with IPP to give
the C10 intermediate geranyl pyrophosphate (GPP) precursor of monoterpenes (Britton,
1983). Geraniol is a result of addition of water to the geranyl cation. Linalyl PP and neryl
PP are isomers of GPP, and are likely to be formed from GPP by ionization to the allylic
cation, allowing a change in attachment of the diphosphate group. These compounds by
relatively modest changes can give rise to a range of linear monoterpenes found as
components of volatile oils used in flavouring and perfumery. Neryl PP or linalyl PP are
immediate precursors of the monocyclic menthane system, generating a carbocation
(termed menthyl or α-terpinyl). The newly generated menthyl cation could be quenched
by attack of water, in which case the alcohol α-terpineol would be formed, or it could
lose a proton to give limonene (Dewick, 2009). Successive addition of two further
molecules of IPP to GPP gives the C15 farnesyl pyrophosphate (FPP), precursor to
sesquiterpenes, steroids and triterpenes, and the C20 (Geranyl geranyl pyrophosphate)
GGPP. The chain-lengthening process may continue to give long-chain polyprenols, or
the GGPP may be used to form C20 diterpenes, including phytol, the sidechain of
chlorophyll, or to give the C40 carotenoids (Britton, 1983).
2.4.5 Metabolism of amino acids
Metabolism of amino acids acting as direct precursors generates alcohols, carbonyls,
acids and esters, aliphatic, branched, or aromatic (Sanz et al., 1997). Enzymes remove
both amine and carboxyl groups from the amino acid to produce aldehydes. The
aldehydes are either enzymatically oxidized or reduced and then esterified (Fisher and
Scott, 1997).
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